# The Evolution of Forest Restoration in Europe: A Synthesis for a Step Forward Based on National Expert Knowledge

Maitane Erdozain, Iciar Alberdi, Réka Aszalós, Kurt Bollmann, Vassilis Detsis, Jurij Diaci, Martina Đodan, Georgios Efthimiou, László Gálhidy, Marie Haase, et al.

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## To cite this version:

Maitane Erdozain, Iciar Alberdi, Réka Aszalós, Kurt Bollmann, Vassilis Detsis, et al. The Evolution of Forest Restoration in Europe: A Synthesis for a Step Forward Based on National Expert Knowledge. Current Forestry Reports, 2024, 11 (1), pp.4. 10.1007/s40725-024-00235-3. hal-04919423

HAL Id: hal-04919423

https://amu.hal.science/hal-04919423v1

Submitted on 24 Apr 2025

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# The Evolution of Forest Restoration in Europe: A Synthesis for a Step Forward Based on National Expert Knowledge

Maitane Erdozain² · Iciar Alberdi³ · Réka Aszalós⁴ · Kurt Bollmann⁶ · Vassilis Detsis⁷ · Jurij Diaci⁸ · Martina Đodan⁹ ·

Georgios Efthimiou¹⁰ · László Gálhidy¹¹ · Marie Haase¹² · Johanna Hoffmann¹³ · Delphine Jaymond¹⁴,³⁰ ·

Elisabeth Johann¹⁵ · Henrik Jørgensen¹⁶ · Frank Krumm⁶ · Timo Kuuluvainen¹⁷ · Thibault Lachat⁵,⁶ ·

Katharina Lapin¹³ · Marcus Lindner¹² · Palle Madsen¹⁸ · Liviu Nichiforel¹⁹ · Maciej Pach²⁰ · Yoan Paillet¹⁴ ·

Ciprian Palaghianu¹⁹ · Jordi Palau²¹ · Jesús Pemán¹ · Sanja Peric⁹ · Susanne Raum²²,²⁹ · Silvio Schueler²³ ·

Jerzy Skrzyszewski²⁰ · Johan Svensson²⁴ · Sander Teeuwen²⁵ · Giorgio Vacchiano²⁶ · Kris Vandekerkhove²⁷ ·

Isabel Cañellas³ · María Menéndez-Miguélez³ · Leland Leland K. Werden²⁸ · Aitor Àvila² · Sergio de-Miguel¹,²

Accepted: 29 October 2024

© The Author(s) 2024

## Abstract

**Purpose of review** We are amid a historical momentum encouraging forest restoration, yet the translation of ambitious targets into reality is hindered by poor documentation and understanding of the success and failure of past restoration efforts. This review aims to evaluate the ecological, social, political and economic characteristics of forest restoration across Europe, their development over time and key lessons learned to guide future restoration initiatives. The analysis is based on the synthesis of expert assessments from 18 European countries.

**Recent findings** Early restoration initiatives in central and southern Europe were largely reactive to natural disasters or timber shortages, and while effective in erosion control and timber production, their ecological benefits were often limited due to monoculture plantations and short-rotation systems. Geopolitical crises intensified timber production, with nationalized and centrally managed forests in several countries, but often at the cost of biodiversity. Since the 1990s, a shift toward multifunctionality has emerged driven by the convergence of environmental, social, political and economic events.

**Summary** Forest restoration in Europe has transitioned from disaster reduction and production-driven efforts to a more multifunctional approach that promotes biodiversity. Changes have been driven by a combination of environmental (e.g., catastrophic consequences following natural disasters), political (e.g., wars, forest nationalization and management centralization), legal (e.g., strict and ambitious national and international policies), social (e.g., rural abandonment and changes in societal values) and economic (e.g., new funding mechanisms or market fluctuations) events. Despite the development, conflicting goals, insufficient funding, climate change and short-term thinking persist as key barriers.

**Keywords** Afforestation · Drivers of change · Ecological recovery · Economy · Historical · Obstacles · Political · Social · Success

Réka Aszalós, Kurt Bollmann, Vassilis Detsis, Jurij Diaci, Martina Đodan, Georgios Efthimiou, Laszlo Galhidy, Marie Haase, Johanna Hoffmann, Delphine Jaymond, Elisabeth Johann, Henrik Jørgensen, Frank Krumm, Timo Kuuluvainen, Thibault Lachat, Katharina Lapin, Marcus Lindner, Palle Madsen, Liviu Nichiforel, Maciej Pach, Yoan Paillet, Ciprian Palaghianu, Jordi Palau, Jesús Pemán, Sanja Perić, Susanne Raum, Silvio Schüler, Jerzy Skrzyszewski, Johan Svensson, Sander Teeuwen, Giorgio Vacchiano, Kris Vandekerkhove these authors contributed equally to this work (as national experts).

Extended author information available on the last page of the article

## Introduction

While human influence is and has been at the root of most forest degradation, humankind also has a long history of stimulating the recovery of degraded forests. The practice of forest restoration can be traced as far back as the Chou dynasty (1100–256 BC), when a forest service was established to protect forests and restore bare land in China [1] or to the Mauryan dynasty when Emperor Ashoka (268–232
BC) ordered wide-scale afforestation and conceived the first concept of a national park to restore forests in ancient India [2]. Documented efforts to increase forest cover in Europe date back to the Middle Ages, with large-scale planting to reforest a highly degraded area around Nuremberg (Germany) being reported as early as the thirteenth century [1].

Despite this long history, it is only recently that we are experiencing an unprecedented momentum that encourages forest restoration at the global, national and regional scales [3]. The growing recognition that functional forests are key to tackling many of humanity's challenges (e.g., biodiversity, water and climatic crises) has elevated forest restoration to the forefront of environmental agendas. Initiatives such as the declaration of the UN Decade on Ecosystem Restoration [4], the Bonn Challenge/New York Declaration on Forests aiming to restore 350 million ha of degraded land by 2030 [5] and the Convention on Biological Diversity's call to restore at least 30% of degraded ecosystems by 2030 (target #2 in the Kunming-Montreal Global Biodiversity Framework) [6] underscore the global commitment to this endeavor. Europe's willingness to materialize restoration wishes is evidenced by the ambitious goals and targets highlighted in the recently approved European Nature Restoration Law, which aims to restore at least 20% of land and sea by 2030 by mandating Member States to develop National Restoration Plans. Moreover, the growing attention to forest restoration within the global political arena parallels its exponential growth in scientific literature, exemplified by a 50-fold increase in publications between 2000 and 2013 [7].

However, translating these ambitious goals into tangible outcomes continues to pose significant social, financial, political and technical challenges, which are exacerbated by the uncertainty inherent to a changing climate and disturbance regimes [8, 9]. A pivotal and over-arching obstacle hindering current forest restoration ambitions lies in the insufficient documentation and dissemination of both successes and failures from past restoration initiatives [10]. Hence, there is a clear need to capitalize upon past experiences in forest restoration to minimize mistakes and maximize the efficient use of resources in the future [3], especially considering the wealth of untapped knowledge generated by past initiatives [11].

In this article, we address this limitation by collecting and synthesizing detailed information on the major practices and on the historical evolution of forest restoration in Europe to provide insights into the factors for successful (and unsuccessful) forest restoration. Specifically, we aim to: 1) examine the ecological, social, political and economic characteristics of the main forest restoration initiatives across Europe, 2) understand how the nature of these initiatives has evolved over time and what the main drivers of change have been, and 3) synthesize the lessons learned from past and present restoration practices to make recommendations

for the implementation of the European Nature Restoration Law. This has been achieved by analyzing and synthesizing the detailed information provided by 32 forest restoration national experts from 18 European countries in the form of national narratives.

## Methods

Narrative analysis is a type of qualitative data analysis that involves the documentation and analysis of narratives from a study group to understand events and phenomena [12]. Although this approach has mostly been used in social sciences, it has also been successfully applied in environmental research [e.g., [13]]. To conduct this study, national experts on forest restoration were selected following a systematic approach and asked to develop a narrative on the development of forest restoration in their country using a pre-defined template. The narratives were then systematically analyzed, and the main patterns were identified and synthesized. This study was developed as part of the European Green Deal H2020 Project SUPERB on upscaling forest restoration.

## National Expert Identification

To make sure that different sociopolitical and economic contexts as well as different biomes and ecoregions were represented, a sub-sample (n = 18) of countries covering all five European regions was selected: 1) North - Finland, Sweden and Denmark, 2) Central-West - Germany, France, Belgium, Netherlands, Switzerland, Austria and UK, 3) Central-East - Hungary, Poland and Romania, 4) South-West - Spain and Italy, and 5) South-East - Greece, Croatia and Slovenia (Fig. 1). Potential expert candidates from these countries were identified following two complementary approaches. On the one hand, considering that many of these countries are represented within SUPERB, we used all the experience and knowledge within the consortium by asking partners to propose national experts. In parallel, we conducted a literature search in Google Scholar for each country using the following keywords: forest restoration AND country OR forest regeneration AND country OR reforestation AND country. When a relevant publication was found, a first screening of the authors of the publication was conducted. If their previous/current work was related to forest restoration and relevant to the narratives, they were identified as potential experts for that particular country. After harmonizing the information obtained from both approaches, we compiled a list of 120 potential experts.

All the candidates identified during the previous step were assessed and ranked based on how related their previous work was to the contents of the narrative (see next section). Specifically, their suitability was quantified based

<figure><img src="image_3.png" /></figure>
<figure><img src="image_4.png" /><figcaption>**Fig. 1** The 18 European countries included in this study, as well as A the five regions they represent (colors) and the % forest area relative to total land area as reported by the FAO (numbers) [14], and B the terrestrial biomes they cover [15]</figcaption></figure>

on five criteria that defined the profile we were looking for: (1) forest restoration related work – 2 points, (2) historical perspective – 1 point, (3) national scope – 1 point, (4) other aspects indirectly related to forest restoration – 0.5 points, and (5) seniority and network of subject-matter experts – 0.5 points. After assessing each candidate's background based on these five criteria and assigning a score (0–5), the potential experts were ranked, and the two with the highest score were identified and invited to collaborate and write the national narrative for their country. This process resulted in the participation of 32 experts from 18 European countries (Fig. 1).

## The Template for the Narratives

The template (51 pages) defined the structure and the indicators to be developed to ensure that all experts followed a similar flow and to facilitate the integration and synthesis of the information (Figure S1). In the introduction section, the experts were provided with the contextual information

needed to develop the narratives. In the main body of the template, the structure and indicators to be developed were specified. To trace the historical evolution of forest restoration in Europe, we initially divided the template into two time periods (pre-1990 and post-1990, coinciding with the implementation of pivotal European environmental policies). However, experts were encouraged to move beyond this division and pinpoint the most significant periods in the evolution of forest restoration specific to their country. Within each period, the narrative was guided by 38 indicators distributed into 6 sections (see Table S1). An imaginary narrative for a fictitious country was presented as an example to facilitate comparable narratives across countries (Figure S2). To complement the qualitative and descriptive nature of the narratives and facilitate quantitative analyses, some of the indicators were included in a table format to encourage sharing concise and quantitative information on the indicators. The experts were provided with the template
in December 2022 and given 9–12 months to write the
narratives.

Data Analysis and Synthesis

Once the experts submitted the first draft of the narrative, the
quality was assessed by checking whether the template had
been followed, all sections had been completed and every indi-
cator had been addressed. Additionally, once all the narratives
had been received, a harmonization exercise was done to ensure
that all the narratives were as consistent as possible regard-
ing definitions (e.g., interpretation of the term restoration) and
content (e.g., level of detail provided). Based on this, experts
from each country were provided with specific feedback that
included major and/or minor comments. This revision process
was repeated until the quality of the narrative was sufficient
based on information availability and ended in March 2024.

We systematically analyzed and categorized the final
versions of the 18 national narratives following thematic
analysis techniques [16]. Each sentence or group of sen-
tences was tagged in Excel with a country, period, type of
initiative, section, indicator and keyword(s) to facilitate the
thematic analysis of the narratives. Then, using the filtering
function according to the theme of interest, the results of the
different countries on a specific topic (e.g., main drivers of
degradation in the second period, funding mechanisms in the
first period) were compared and synthesized to extract the
main patterns. The results provided by the narratives were
complemented by the information available in the literature.

What is Forest Restoration – Solving Discrepancies

Responding to this question was one of the main challenges when harmonizing the narratives, as different experts had diverging perspectives on the broad definition provided: “*any activity within the restorative continuum that aims to improve the biodiversity, ecological integrity and provision of services in forest ecosystems*” [17]. In particular, Sweden and Finland differed from others as they only considered purely ecological restoration in their narratives. This is understandable considering that, unlike in other countries, the trigger for restoration in these boreal countries has not been a critically low forest cover, but a critically high share of simplified clearcut rotation forests with single age and species plantations. Therefore, while countries in temperate and mediterranean biomes initiated their narratives by describing the afforestation (i.e., establishment of forest through planting or deliberate seeding on land that was under a different land use) or reforestation (i.e.,

re-establishment of forest on land classified as forest) [18]
that started a couple of centuries ago, the Swedish and Finn-
ish narratives emphasized the biodiversity-oriented ecologi-
cal restoration over the last few decades.

This question was also key when deciding how to inter-
pret the 1940–1990 period characterized by an overwhelming
focus on increasing wood biomass provision at the expense of
other forest ecosystem services. This slightly deviates from the
chosen definition of forest restoration, and although most did,
some experts did not feel comfortable with including these
initiatives in the narratives. This is understandable, consider-
ing that some of these purely productive initiatives resulted in
ecological degradation or decreased biodiversity. But, accord-
ing to Gann et al. [17] definition of the restoration continuum,
rehabilitation is included and refers to a management activ-
ity conducted to reinstate a level of ecosystem functioning to
ensure the provision of ecosystem services. This also aligns
with the importance that the United Nations Agenda 2030
places on the socioeconomic aspect of sustainable develop-
ment. Additionally, understanding this period is crucial to
comprehending the problems that European forests face these
days as well as to learning from past decisions and outcomes.
Therefore, although the provision of a single ecosystem ser-
vice was targeted, and this often compromised the provision
of other services, these initiatives are also discussed. The col-
lected information, thus, better reflected the following defini-
tion: any activity within the restorative continuum that aims to
improve the biodiversity, ecological integrity and/or provision
of services in forest ecosystems. To work with it, a clear dis-
tinction was made between restoration success, understood as
the achievement of the restoration goals (e.g., timber produc-
tion, erosion control, job creation, biodiversity conservation),
and ecological recovery, understood as the improvement in
biodiversity, ecological integrity (composition, structure and
function) and the provision of multiple ecosystem services.

Development of Forest Restoration
in Europe

Despite the sociopolitical, ecological and economic dif-
ferences of the countries studied in the narratives, most of
them depicted a similar story regarding the development
of forest restoration, with three main restoration periods
identified (Figure S3): 1) disaster reduction focused period
(< 1940), 2) production focused period (1940–1990), and
3) multifunctionality focused period (> 1990). Below, we
describe the main environmental, technical, social, politi-
cal and economic characteristics of each of the three peri-
ods based on the response to the indicators provided by
the experts.

<figure><img src="image_5.png" /></figure>
# First Period (< 1940): Disaster Reduction

## Main Drivers of Change, Goals and Types of Initiatives

European forests experienced centuries of overexploitation as the growing human population increasingly used forests to extract a wide variety of subsistence products as well as cleared them for livestock grazing and agriculture. Thus, the main drivers of degradation during this period were over-grazing, overharvesting and erosion, with litter raking, fire, agriculture and browsing also mentioned by some countries (Fig. 2). These led to a deficient ecological condition, with very poor soil conditions, low productivity and historically low levels of forest cover (Figure S4). This, in turn, triggered natural disasters such as floods (e.g., Spain, Croatia, France, Austria, Greece, Italy, Switzerland, Slovenia), avalanches (e.g., Austria, Switzerland) and shifting sands (e.g., Belgium, Denmark, Spain, Poland, Hungary, Netherlands) that had dramatic effects on the human population. Additionally, this depletion of forests led to wood shortages for the expanding mining and iron industries, which incentivized some countries to re-stock degraded forests and deforested lands. Hence, the main restoration goals in this first period across the 18 countries were the reduction of disaster risk, protection against erosion and production of timber, but improving water quality and creating jobs were also mentioned by several countries (Fig. 3).

Afforestation represented the main forest restoration initiatives in the nineteenth century and the first half of the twentieth century (Table 1). This included mountain slope afforestation to halt the problems resulting from torrential rains on bare slopes (flooding, avalanches...) in countries such as Spain, Italy, Greece, France, Austria and Switzerland, heathland afforestation to boost productivity and/or to stop the disasters caused by drifting sands (Belgium, Denmark, Netherlands, UK, Germany), Karst afforestation to protect from the harsh conditions and erosion that resulted from deforestation (Slovenia, Croatia, Austria), and afforestation of plains on sandy soils to reduce erosion (Hungary, Romania, Austria).

## Restoration Activities and Species Used

To achieve these goals, countries reported a combination of passive and active approaches. The main passive activity was the cessation or attenuation of the degrading factor in the form of regulations that prohibited or limited forest grazing, litter raking or overharvesting, such as the Croatian Forestry Ordinance from 1775, the Danish Forest Act from 1805 or the Belgian Forest Code from 1854. Because of the high degree of degradation, natural regeneration was failing in most cases and, thus, active approaches that involved planting or sowing in high densities as well as labor-intensive soil preparation were common during the first period.

<figure><img src="image_6.png" /><figcaption>**Fig. 2** The percentage of countries that include these drivers of forest degradation in the first (before 1940), second (1940–1990) and third (after 1990) periods of the narratives</figcaption></figure>
<figure><img src="image_7.png" /><figcaption>**Fig. 3** Forest restoration goals and the proportion of countries identifying them as important during the first (before 1940), second (1940–1990) and third (after 1990) periods of the narratives</figcaption></figure>

In the case of mountain afforestation, steep slopes had to be stabilized before planting by reshaping slopes, using fASCines, sowing herbs, etc., while in wet forests draining was commonly applied before planting. A common follow-up activity was building fences to protect the young trees from livestock grazing.

The tree species used in afforestation varied across countries, but mostly fast-growing pioneer tree species were chosen, with pines (*Pinus* sp. L.) being the preferred trees in many initiatives because of the challenging site conditions in degraded areas (see Table S2 for details on pine species used). Norway spruce (*Picea abies* H. Karst) was mostly used in the subalpine areas of Switzerland and Austria, where it is native, but also in out-of-range areas in countries such as Germany, Denmark, Slovenia, Italy and the UK due to its economic value, wood quality and high growth rate. European larch (*Larix decidua* Mill.) was marginally used in countries such as Austria, Switzerland, the UK and France. Broadleaved trees (oaks, poplar and ash) were used to a lesser extent in countries such as Croatia, Spain, Switzerland and the UK, and private initiatives with the exotic eucaulypts (*Eucalyptus* sp.) are reported during this first period in Spain, Italy and Greece. The exception to this dominance of conifer tree species was found in the afforestation of sandy soils in Hungary and Romania, where the non-native and invasive black locust (*Robinia pseudoacacia* L.) was widely

used (> 80% in Romania) [18]. In Hungary, besides black locust, other invasive exotic species such as box elder (*Acer negundo* L.), tree of heaven (*Ailanthus altissima* Swingle) and black cherry (*Prunus serotina* Ehrh.) were used in the afforestation of the Great Hungarian Plain, with thousands of hectares of non-native invasive species remaining in forests to this day [19].

## Governance and Funding

Most of the afforestation was promoted and funded by the State and regional administrations during the first period. However, the land to be afforested was not only state-owned but also community-owned or private, especially in countries and regions with a high share of privately owned land. Therefore, the public administration in several countries had to either encourage private owners and communities to afforest their lands (e.g., by offering tax exemptions, technical support or forest reproductive material) or acquire their land by buying, expropriating or establishing agreements. Acquiring land represented a considerable expenditure of the total budget (e.g., 23.8% of the expenditure of the UK Forestry Commission 1920–1933).

The governments spent considerable funds on these initial afforestation initiatives (Figure S5): the French government allocated 10 million francs (44 million constant euros$_{2023}$)

<figure><img src="image_8.png" /></figure>
<table><caption>**Table 1** The main types of forest restoration initiatives (columns) described in each of the 18 national narratives (rows) for each time period (1: < 1940, 2: 1940–1989, 3: > 1990). The last three rows show the total number of countries that report a given initiative in a given time period</caption><thead><tr><th></th><th>Afforestation for erosion control</th><th>Afforestation for production</th><th>Agribusiness cultural afforestation</th><th>Afforestation for carbon sequestration</th><th>Urban/periurban afforestation</th><th>Conversion to plantation</th><th>Reforestation for productivity</th><th>Mining rehabilitation</th><th>Post natural disturbance</th><th>Designation of protected areas</th><th>Close-to-nature forest management</th><th>Ecological restoration for biodiversity</th><th>Rewilding, reintroduction</th><th>Riparian restoration</th><th>Diversification of restoration</th><th>Prestoration</th><th>Diminishing</th><th>Invasive control</th><th>Forest hydrology restoration</th></tr></thead><tbody><tr><td>Austria</td><td>1.2</td><td>1</td><td>3</td><td></td><td>2</td><td>2</td><td>2</td><td>1.2</td><td></td><td>3</td><td>3</td><td>3</td><td></td><td>3</td><td></td><td>3</td><td></td><td>3</td><td></td></tr><tr><td>Belgium</td><td>1.2</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>3</td><td>3</td><td>3</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Croatia</td><td>1.2</td><td>1.2</td><td>3</td><td></td><td></td><td></td><td></td><td></td><td>2</td><td></td><td>2.3</td><td></td><td></td><td></td><td></td><td>3</td><td>3</td><td>3</td><td></td></tr><tr><td>Denmark</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>3</td><td>2.3</td><td>3</td><td>3</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Finland</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>1.2.3</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>France</td><td></td><td>1</td><td>2</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>2.3</td><td>3</td><td>3</td><td></td><td>3</td><td></td><td></td><td></td><td></td></tr><tr><td>Germany</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>3</td><td>2.3</td><td>3</td><td>3</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Greece</td><td>1.2.3</td><td>2.3</td><td>3</td><td>1.2</td><td></td><td>1.2</td><td></td><td>2.3</td><td>1.2.3</td><td>1.2.3</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Hungary</td><td>1.2.3</td><td>2</td><td>3</td><td>2</td><td></td><td></td><td></td><td></td><td></td><td></td><td>3</td><td>3</td><td>3</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Italy</td><td>1</td><td>2</td><td></td><td>3</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>3</td><td>3</td><td>3</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Netherlands</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Poland</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Romania</td><td></td><td>1</td><td>1.2.3</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Slovenia</td><td>1.2.3</td><td></td><td>2.3</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Spain</td><td>1.2.3</td><td></td><td>1</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Sweden</td><td></td><td>1.2</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Switzerland</td><td>1.2</td><td>2</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>UK</td><td></td><td>1.2.3</td><td>2</td><td>3</td><td>3</td><td>2</td><td>2</td><td>2.3</td><td>2.3</td><td>2.3</td><td>3</td><td>3</td><td>3</td><td>2</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Total Period 1</td><td>12</td><td>6</td><td>2</td><td>0</td><td>1</td><td>1</td><td>4</td><td>0</td><td>1</td><td>1</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td></tr><tr><td>Total Period 2</td><td>8</td><td>10</td><td>4</td><td>0</td><td>2</td><td>5</td><td>10</td><td>3</td><td>2</td><td>10</td><td>2</td><td>2</td><td>2</td><td>2</td><td>2</td><td>0</td><td>0</td><td>0</td><td>0</td></tr><tr><td>Total Period 3</td><td>4</td><td>2</td><td>6</td><td>2</td><td>2</td><td>0</td><td>2</td><td>4</td><td>9</td><td>15</td><td>13</td><td>3</td><td>4</td><td>8</td><td>3</td><td>1</td><td>5</td><td>4</td><td></td></tr></tbody></table>

<figure><img src="image_9.png" /></figure>
for afforestation during the 10 years following the promulgation of the 1860 law on mountain afforestation, and in Romania, 150 million lei (30 million euros, without considering inflation) from the state budget were spent between 1882 and 1887 for the afforestation of the southern degraded lands. Still, insufficient funding was one of the main constraints. The establishment of administrative units specialized in restoration to conduct the work and provide technical assistance (e.g., the Reforestation Commissions (1888, Spain), the Karst Afforestation Commissions (1881, Slovenia), the Forestry Commissions (1919, UK)) was key in the success of these large-scale, state-led initiatives.

## Restoration Success and Ecological Recovery

Most of the forest restoration initiatives were classified as having a moderate to good level of success in achieving the objectives, especially considering the degree of land degradation. Tree plantations successfully halted or reduced erosion and related problems in most countries. For example, in Hungary, stabilizing the shifting sands after afforesting 65,000 ha was an important achievement. In France and Spain, the erosion problem was mostly halted, and in Croatia, the last devastating flood hit the country in 1856 (i.e., no more floods after 19,000 ha of Karst were afforested). The economic objective of increasing timber production was also achieved in countries such as Germany, Denmark and Belgium, as degraded former farmlands were turned into productive plantations. Job creation was also successful in countries such as Spain, where it is estimated that one million working days were created in relation to restoration during this period [20].

Overall, most countries experienced an increase in forest cover during this period, but several countries (e.g., Romania, Hungary, France) fell short of meeting the defined targets and some even experienced no net gain (e.g., northern Belgium, the UK) as afforestation efforts were 'counter-balanced' by further deforestation, mainly on fertile soils for agriculture and infrastructure. Regarding the quality of the forests, most countries reported a marginal or moderate ecological recovery. The established forests were mostly even-aged plantations managed with relatively short-rotation clearcut systems (namely in the temperate biome) and, thus, deficient in biodiversity compared to reference ecosystems. For example, the black pine plantations established in the Slovenian Karst and in France should be considered as an intermediate stage in the successional development of the forest towards oak woodlands, but most of the stands were poorly managed/thinned, so the return of native vegetation has been rather slow. In Hungary, black locust plantations were often created on former grasslands, which could mean a significant deterioration in ecological terms. Similarly, in Belgium and the Netherlands, the afforestation of

transformed (i.e., resulting from previous deforestation) yet valuable open habitats such as heathlands and grasslands with conifer monocultures is considered to have resulted in a decline in biodiversity, and in Switzerland, clearcut prohibitions and continuous cover forest management put pressure on light-demanding species for decades. In several countries, species that were introduced as nurse species or productive species in forest restoration (e.g., black cherry) also became challenging invasive species.

## Main Obstacles

One of the main obstacles to successful restoration reported by several countries for this first period was conflicting goals and local opposition (Fig. 4). The subsistence nature of the economy in rural areas made forest restoration work difficult as neighbors lost their rights to the communal use of forest resources (generally grazing, crops and firewood) and hence showed resistance to the land use change in countries such as Spain, Austria, Switzerland, Belgium, France, Hungary, Croatia and Slovenia. This was aggravated by related factors such as poverty, lack of enforcement and lack of stakeholder involvement. Another common obstacle was limited knowledge or lack of trained staff, which led to problems such as poor planting techniques or poor choice of species or provenances. Although the shortcomings of the contemporary forest management approaches started to become evident (e.g., low resilience towards biotic and abiotic disturbances), large-scale alterations did not ensue [21]. This was in part due to other obstacles such as insufficient funding, political instability, grazing/browsing and lack of post-restoration management, which prevented the successful implementation of emerging ideas such as close-to-nature forest management. Country-level examples of all these obstacles can be found in Table S3.

## Second Period (1940–1989): Production

### Main Drivers of Change, Goals and Types of Initiatives

The beginning of the second period was marked by a geopolitical crisis accompanied by changes in the wood market that strongly influenced the type and amount of forest restoration. The two World Wars led to significant forest degradation through direct destruction (e.g., shelling) and indirect overexploitation (Fig. 2), as wood was needed for military and household purposes due to coal shortages. Post-war reconstruction further drove deforestation, and many early 20th-century restoration efforts were halted due to shifting priorities. Additionally, deforestation for agriculture was exacerbated by the difficult socioeconomic conditions. The combination of these resulted in a marked decline in forest cover in the countries that were more actively involved in the

<figure><img src="image_10.png" /></figure>
<figure><img src="image_11.png" /><figcaption>**Fig. 4** Main obstacles for successful restoration and the proportion of countries identifying them as important during the first (before 1940), second (1940–1990) and third (after 1990) periods of the narratives</figcaption></figure>

wars (e.g., Germany, UK, Belgium, Spain, Austria, Poland) and a renewed interest in the restoration of forests for timber production. Additionally, timber production became integral for the economic growth and flourishing industry between the 50 s and 70 s, and the new wave of rural abandonment following the socioeconomic crisis post World War II further facilitated many large-scale afforestation/reforestation initiatives. Thus, the main restoration goal shared by most countries during this second period was timber production, followed by the reduction of disaster risk and job creation as reported by half of the countries (Fig. 3).

To achieve these goals, large-scale afforestation and reforestation efforts, particularly on abandoned or marginal farmland, grasslands, peat bogs and degraded forests, characterized the first half of this period. Although afforestation for protective purposes remained important, the period saw a shift toward productive purposes, including the conversion of low-productivity forests (e.g., beech or oak coppice) into monoculture plantations (Table 1). However, this period was not only about disaster reduction and production, but other ecosystem services such as aesthetics, recreation, hunting or the provision of drinking water were also increasingly valued and protected by taking some forests out of harvesting and designating protected areas. Other initiatives that were not discussed in the previous period but that a few countries include in this one were the restoration post natural disturbances (e.g., fire, windthrow), post mining or rewilding by reintroducing extinct animal species.

## Restoration Activities and Species Used

Most afforestation and reforestation initiatives followed an active approach, but passive approaches became increasingly common by the end of the period as natural regeneration was encouraged and facilitated by rural abandonment and the designation of protected areas gained momentum. Passive approaches were also favored post-fire in countries such as Spain, Greece and France due to the fire-tolerant nature of the mediterranean vegetation. Restoration activities were similar to those employed in the previous period, including soil preparation (ploughing, draining…), planting and fencing. Soil preparation was increasingly mechanized throughout the period. Planting was still done in relatively high densities, although densities tended to decline over time. Weeding, herbicide/pesticide application and thinning were also used in many countries during this period to boost tree growth. While in many countries draining was a prerequisite for afforestation, in mediterranean countries, water retention was key for successful establishment.

Conifer tree species, namely spruce and pine, were widely planted in all countries. Norway spruce became very popular due to its economic value, easy and cheap establishment, and rapid growth: not only was this the dominant species in countries within its natural range (e.g., Sweden, Austria and Switzerland), but it was also artificially expanded to sites outside its natural growth area in Switzerland (lowlands), Italy, Croatia, Denmark, France, Germany, Hungary, Slovenia, Romania, Netherlands, Sweden and the UK. Spruce
was usually planted in higher soil quality sites, whereas pines were used in poor quality sites. All pine species mentioned in the previous period (Table S2, mostly Scots pine and black pine, but also Aleppo pine, maritime pine, mountain pine, Turkish pine and lodgepole pine) continued to be used during this period, as well as new conifers such as Silver fir (Abies alba Mill.), European larch, Sitka spruce (Picea sitchensis Carr.), Douglas fir (Pseudotsuga menziesii Franco) and Nordmann fir (Abies nordmanniana Spach).

Among deciduous tree species, the fast-growing poplar hybrids became popular for the afforestation/reforestation of riparian areas due to their economic value in the expanding paper industry in several countries (e.g., Hungary, Belgium, Greece, France, Spain, Netherlands). The invasive and fast-growing black locust was still popular in the afforestation of barren and sandy areas in Hungary, Greece, Croatia or Romania. By the end of the period, once the vulnerability of conifer monocultures became obvious, enrichment planting with beech (Fagus sylvatica L.) or black cherry became more common in countries such as Germany and the Netherlands. In the afforestation efforts of Slovenian Karst, increasingly greater numbers of native broadleaves such as oaks (Quercus sp. L.), sycamore (Acer pseudoplatanus L.), the European nettle tree (Celtis australis L.) and chestnut (Castanea sativa Mill.) were used in enrichment planting. Finally, in addition to tree species, extinct animal species that assisted forest restoration were also re-introduced in countries such as Switzerland (lynx – Lynx lynx (Linnaeus, 1758) and beaver – Castor fiber (Linnaeus, 1758)) and Sweden (beaver).

## Governance and Funding

Like in the previous period, forest restoration happened in public and private lands, and it was promoted mainly by the government that aimed for higher self-sufficiency and provision of raw materials after the war. However, unlike the previous period, the second period is characterized by a considerable nationalization of privately owned forests post World War II in Romania, Croatia, Slovenia, Hungary and Poland, as well as by a strong and centralized state control of forest management (in these and other countries such as Greece, Spain and Italy). These changes in ownership and governance facilitated the efficient implementation of the projects and, thus, large-scale afforestation/reforestation goals were mostly achieved. In countries where private ownership was still prevalent, the motivation to plant trees was often economically driven as timber demand and prices were high during this period. Similarly, state funding mechanisms were often derived from the sale of timber, including the French National Forestry Funds (Fonds Forestier National or NFF) or the Slovenian biological depreciation fund [22, 23].

The main restoration goal of this period (i.e., timber production) was reflected in policies (e.g., the 1952 German Forest Law, the 1951 UK Forestry Act) and was enacted through regulations (e.g., obligation to replant after felling – e.g., the 1962 Dutch Forest Act) or financial incentives (e.g., tax benefits). However, policies reflecting environmental conservation became increasingly common throughout the period as well, which were instrumental in promoting the declaration of protected forest areas. Also, legal frameworks supporting multifunctional and close-to-nature forest management (e.g., the Slovenian Forest Act 1949, the Austrian Forest Act 1975, the Romanian Forest Law 1976) started to be published throughout this period.

## Restoration Success and Ecological Recovery

This tight and centralized state control and funding resulted in large areas being afforested/reforested in many countries during the second period (Fig. 5), which contributed to forest cover increasing in most countries (e.g., by 7% in Switzerland, Poland and the UK). From an economic perspective, these initiatives can be considered successful as the new plantations delivered profitable goods to the industrial market (see Table S4 for country-specific examples). The afforestation for protective functions was also considered successful in countries such as Spain, the Netherlands, Italy, Slovenia and Hungary, where erosion and related problems (floods, drifting sands) were reduced. The restoration goal of job creation was also successful in countries like Spain and Romania, but in the Netherlands, harsh working conditions and insufficient salaries led to strikes and consequent dismissals [24].

Much of this socioeconomic success came at a high ecological price. Many of the initiatives did not result in a clear ecological recovery, but to the contrary, were a driver of ecological degradation as structurally and compositionally poor plantations replaced habitats of high ecological value. Examples of such replacements include the plantation of Norway spruce in mixed beech-coniferous stands (e.g., Switzerland, Romania), the expansion of acacia in oak-favorable sites (e.g., Hungary, Romania), the substitution of native species-rich meadows and riparian forests with hybrid popular plantations (e.g., Belgium, Spain, Greece), the creation of conifer monocultures for cellulose production in biodiverse heathlands and grasslands (e.g., Netherlands, Belgium), and the drainage of functionally important wetland forests (e.g., Sweden, UK). The use of exotic invasive species oftentimes prevented the establishment of native species (e.g., Italy, Hungary), and the even-aged single species plantations showed low resilience to disturbances in later periods (e.g., Germany, France). Additionally, this period saw a marked shift in the European tree composition, with a considerable increase in the share of coniferous trees (Table S4) and
<figure><img src="image_12.png" /><figcaption>**Fig. 5** Afforested/reforested area (solid bars, secondary y-axis) and percentage of the country (stripped bars, primary y-axis) reported by different countries in the narratives for the second period (~1940–1990). The countries that report the area for the first and second periods combined (<1990) are shown with an asterisk</figcaption></figure>

associated consequences for the forest communities and their biodiversity. However, it is important to note that there were also examples of good ecological recovery (e.g., by the end of the period, spruce monocultures as well as black pine plantations were diversified with a broadleaved tree under-storey in Slovenia) and the increasing number of protected areas in most countries during this period meant that some forests (albeit limited in space) were being spared from deg radation (Table S4).

## Main Obstacles

The main obstacles during this period were conflicting goals, browsing, severe degradation, lack of knowledge, issues with the forest reproductive material, lack of management and lack of stakeholder involvement (Fig. 4). As it was the case in the previous period, conflicting goals between agricul-ture/farming and forest restoration led to limitations in the land available for afforestation in countries such as Spain, Romania, Greece and the UK. Additionally, in this second period, conflicts between forestry and nature conservation stakeholders emerged, as reported by Hungary, Sweden and Austria. Despite a reduction in livestock grazing, the density of wild ungulates surged during this period, posing a chal-lenge to the natural regeneration of deciduous and fir tree species due to intensive browsing in countries like Austria, Germany, Hungary and Slovenia. Also, in these and other countries, the lack of initial knowledge and adequate forest reproductive material for restoration with deciduous tree species contributed to their failure [25–29].

Severe stages of degradation and harsh abiotic/biotic conditions were also reported to negatively affect restora-tion initiatives in Croatia, Denmark, Greece and Hungary. In countries such as Spain, Italy, France and Poland, a lack

of post-restoration management has been reported to hinder the success of afforestation/reforestation. The lack of tend-ing of the established forests (e.g., thinning) has resulted in dense stands of single pioneer species that are vulner-able to natural disturbances (e.g., pests and fire). In fact, disturbances such as fire (e.g., Slovenia, Greece), pests (e.g., pine processionary (*Thaumetopoea pityocampa* (Denis & Schiffermüller, 1775) – Slovenia, Greece), acid rain (e.g., Belgium, Netherlands) and windthrow (e.g., Poland) were reported to be another common obstacle to the success of the initiatives during this period. Finally, several narratives also described the lack of stakeholder involvement (Greece, Italy, Romania, Spain, UK and Sweden) and bureaucracy (Greece and France) as obstructing or delaying forest restoration.

## Third Period (> 1990): Multifunctionality

### Main Drivers of Change, Goals and Types of Initiatives

This period marks a shift in the focus of restoration efforts from increasing forest quantity to improving quality, along-side the diversification of key aspects like degradation sources, restoration goals and activities, promoted forest functions, funding sources and stakeholders. This shift was facilitated by the coming together of several environmental, social, political and economic drivers of change between the 1970s and the 1990s: 1) severe disturbances hit the forests, leading to huge economic losses that highlighted the vulner-ability of monospecific even-aged plantations to acid rain, drought, wildfires, windthrow or bark beetle (*Ips typogra-phus* L.) outbreaks, which were and are being exacerbated by climate change, 2) societies started to demand change based on a growing interest in recreation and tourism, as well as growing environmental concerns, 3) the value of timber
decreased due to a lower demand (e.g., closure of mines) and the opening of the international timber market, and 4) the increasing influence of international and EU environmental policies (e.g., the Convention on Biological Diversity 1992, the EU Habitats Directive 1992) elevated the significance of biodiversity conservation on national political agendas. Thus, although the goals from previous periods (i.e., timber production, erosion control and reduction of disaster risk) remained relevant, biodiversity conservation took center stage and was highlighted by most countries, followed by restoration for tourism and recreational uses (Fig. 3). Restoration for climate change-related issues (mitigation, adaptation and carbon sequestration/storage) was also a new goal driving forest restoration in several countries.

Considering the diversification of restoration goals, a multifunctional forest restoration approach was increasingly undertaken. The level of multifunctional uptake, however, varied across countries and was done following both seg- negative (designation of protected areas) and integrative (close-to-nature forest management) strategies (sensu [30]) (Table 1) with varying ratios across countries. Afforestation and reforestation initiatives for productive purposes were mostly absent from the narratives, while initiatives for pro- tective purposes were not discussed as much as in previous periods. Instead, ecological restoration initiatives for biodi- versity conservation and the diversification of plantations were commonly included. Finally, new types of initiatives that aimed to address current challenges were described and included: post-natural disturbance restoration, forest hydrology restoration, invasive species control, riparian res- toration, initiatives of rewilding or nature-based solutions, afforestation for carbon sequestration, urban/periurban forest restoration and prestoration.

There was also a diversification of the main drivers of deg-
radation addressed. The main sources of degradation from
previous periods (i.e., agriculture, overgrazing, erosion, over-
harvest) were still reported by several countries, but new ones
(many of which, interestingly, derived from the type of restora-
tion conducted in the previous period) appeared and attracted
much attention in forest restoration post-1990 (Fig. 2). Exces-
sive homogeneity and its negative effect on biodiversity and
resilience became a source of concern, which resulted from
either intensive rotation forestry (e.g., Finland, Netherlands),
the abandonment of diversifying silvicultural treatments such
as thinning (e.g., Spain, Italy) or the suppression of natural
diversifying elements such as fire (e.g., Finland, Spain). Other
current drivers of degradation related to past forest manage-
ment activities include drainage and invasive species. For
example, black cherry, which was introduced in the previous
period to enrich pine plantations (e.g., Netherlands, Belgium,
Poland), turned out to be an invasive alien species that domi-
nated the understorey of thousands of hectares, obstructing the
natural development of a native admixture.

Natural disturbances were reported as an important driver of degradation during this period as well, which were related to both the vulnerability of homogeneous plantations derived from past afforestation/reforestation campaigns, and to the increasing frequency and intensity of natural disasters due to climate change. Extreme drought events, wind throws and wildfires started to become increasingly common and caused large-scale forest damage in most countries. Pests (e.g., bark beetle, pine processionary) and diseases (e.g., ash dieback caused by an invasive fungal pathogen) also raised concern and attracted much attention and resources in restoration. Finally, forests degraded due to acidification and eutrophication resulting from various industry activities and pollution were restored in countries such as Belgium, Netherlands, Germany and Poland. However, note that the disturbance of plantations also created opportunities for restoration and that it can lead to increased biodiversity [31, 32].

Restoration Activities and Species Used

The types of activities also diversified in response to the diversification of threats and goals. Passive approaches gained relevance and included activities that range from landscape-level protection (e.g., restriction of active management in strictly protected forest reserves) to tree-level protection (e.g., retention of habitat trees during forest management). Assisted forest restoration also became very prevalent during this period, with techniques such as management for old-growth forests and the emulation of natural disturbances being employed in ecological forest restoration initiatives. The creation and retention of deadwood were some of the most commonly used techniques to favor species that depend on deadwood (e.g., white-backed woodpecker), which was usually done by felling trees and leaving downed logs or by girdling trees and leaving standing dead wood. Some of the first experiments to restore deadwood by girdling trees were carried out in 1994 in the Finnish Mäntsälä region. Because the suppression of natural disturbances negatively impacted light-demanding species in uniformly dense plantations, restoration techniques that emulate these disturbances (e.g., gap creation, prescribed burns) were increasingly used namely in boreal countries.

Several countries increasingly adopted close-to-
nature forest management throughout this period,
promoting aspects that favour forest restoration. The
cessation/attenuation of degrading factors as a resto-
ration activity became increasingly incorporated into
forest management, including the prohibition to use
hazardous pesticides or intensive soil preparation, the
obligation to retain habitat trees and deadwood, or the
limitations on clearcutting. The diversification of plan-
tations was a widespread objective that was pursued

<figure><img src="image_13.png" /></figure>
through the promotion of natural regeneration in for-
est management when possible, or by planting more
native – often deciduous – tree species. Because of the
growing browsing pressure, fencing, tree protectors
and regulating wildlife populations became very com-
mon assisted restoration activities (especially when
broadleaved species were being promoted). Sanitary
fellings also became an increasingly important (albeit
controversial) post-disturbance restoration technique
in countries such as Germany, Poland, Croatia and
Slovenia and could represent a high percentage of the
total annual harvest due to the growing incidence of
pests and diseases. Hydrological interventions such
as rewetting forests by blocking or filling ditches to
restore the original species association were reported
by several countries such as Sweden, Denmark and
Switzerland.

Although planting was less prevalent than in the
previous period, active approaches that involved the
introduction of biota were still common in the third
period. In general, planting densities decreased, but the
most common tree species from previous periods (i.e.,
pines, spruce, black locust) continued to be planted
despite their shortcomings. However, there has been
a clear shift towards promoting native deciduous tree
species. For example, beech was widely planted to
enrich spruce plantations in Germany, and oak spe-
cies (namely holm oak (Q. ilex L.) in Spain; pedun-
culate oak (Q. robur L.) and sessile oak [Q. petraea
(Matt) Liebl. in Poland) were commonly planted in
pine stands during this period. Other deciduous tree
species that were increasingly incorporated to enrich
forests include sycamore, rowan (Sorbus aucuparia L.),
wych elm (Ulmus glabra Huds.) or linden (Tilia sp. L.).
Additionally, fruit-bearing tree and shrub species are
increasingly being favored to support animal biodiver-
sity, and native riparian tree species to replace exotic
poplar hybrid plantations from the previous period. It is
also worth noting that recently attention has been paid
to the selection of tree species that are adapted and
resilient to anticipated climate change impacts (i.e.,
prestoration), but, beyond policy recommendations
and research, very little progress has been made on the
ground in most countries. However, provenances are
increasingly being taken into account when planting,
with decision support tools being developed to help
foresters decide the best alternatives for the current
and future site conditions. Finally, several countries
reported that animals were also introduced as part of
restoration, including birds (capercaillie), wild species
valued as game (deer, roe deer, fallow deer, mountain
goat), large domestic herbivores (e.g., cows and mares)
and predators (e.g., bears, wolves, lynx).

Governance and Funding

The governance and funding of the initiatives also diversified during this period. If before 1990 almost all the work was centralized in the state forestry administration, after 1990, not only did the administration fragment (i.e., decentralization) into regional and local administrations (e.g., Spain, UK, Netherlands, Belgium, Greece), but new actors emerged which, on occasions, became as important or even more so (e.g., associations, foundations, companies, research centers, neighborhood communities). In addition, the beginning of the third period was characterized by ownership privatization in countries that nationalized forests during the second period (e.g., Slovenia, Romania, Hungary). These two movements generally slowed down the implementation or led to regional divergences in policies, approaches and implementation.

However, strong national regulatory policies that became
very important for the implementation of multifunctional
forest restoration were also developed, including the Roma-
nian Law on the Conservation, Protection and Develop-
ment of forests (1986), the Flemish Forest Decree (1990),
the Swiss Forest Law (1991), the Polish Forest Act (1991)
and the Danish Nature Protection Act (1992). Additionally,
a very influential new actor entered the restoration arena
and elevated the importance of biodiversity conservation in
national and regional policies: the EU. In particular, the EU
Habitats Directive (1992) and its key instrument (i.e., the
Natura 2000 network) were mentioned by several narratives
to have been a cornerstone for nature conservation in their
countries.

The lack of available public land for restoration was perceived as an obstacle due to the fragmentation of holdings, the large number of owners and their perceived disinterest in forest restoration [33]. In this third period, three financial policy instruments became very relevant to overcome this limitation and encourage private owners to restore forests: subsidies or payments for ecosystem services, certification and EU funding. In several countries (e.g., Finland, Belgium, Austria, Germany UK), landowners that adhered to higher ecological standards (e.g., prohibition on clearcutting and the use of fertilizers and pesticides, or the promotion of native deciduous species and deadwood) received a greater subsidy to compensate for potential income loss or increased costs.

Contracts between forest owners and the administration
also became increasingly common in countries such as Swit-
zerland, Finland, Sweden and Spain. The goal of these con-
tracts is to encourage the consideration of nature conserva-
tion values on top of legal requirements within a certain time
period and with a certain level of economic compensation.
The introduction in the 1990s of soft voluntary regulations
in the form of market-based certification schemes (PEFC
and FSC) also required the involved forest owners to take
biodiversity and ecological aspects into consideration in for-
est management.

Finally, EU funds are a new source of funding that has
been shaping the type of restoration conducted in the third
period. The European Agricultural Fund for Rural Develop-
ment (EAFRD), which is implemented by EU countries and
co-financed by national/regional budgets, funded multiple
restoration programs across most countries, but also gave
rise to conflicts (agriculture vs. conservation) [34]. LIFE
and Interreg programs funded ~ 700 projects aiming at eco-
logical forest restoration over the past 20 years [35, 36]. For
countries such as Greece, although spatially limited, this
type of EU funding was pivotal for supporting a new line of
restoration with new objectives and stakeholders.

Restoration Success and Ecological Recovery

Evaluating the success of restoration actions during this
last period is challenging because of the diversification of
goals and because ecological recovery takes time. Most
experts assessed it more positively than in previous peri-
ods, but there are still multiple examples of moderate
success. The most positively evaluated initiative, overall,
was the adoption of close-to-nature forest management,
especially in the temperate forest biome. Such a statement
was based on National Forest Inventory data and indica-
tors that showed an upward trend in the amount of dead-
wood, in the proportion of deciduous species and mixed
stands, in the use of natural regeneration or in stand age.
In boreal countries, although the awareness of the need
to diversify the widespread even-aged rotation forestry
is increasing, uneven-aged management practices would
need to upscale dramatically in practice to have the needed
ecological impact.

Similarly, diversification efforts have been largely suc-
cessful, evidenced by the increasing share of broadleaved
species and mixed stands. Nonetheless, challenges persist,
especially in post-fire restoration efforts in some mediter-
ranean countries, where the use of deciduous species has
proven difficult (see obstacles below). In central Europe,
the widespread use of beech as a diversification species
has raised concerns due to unexpectedly high mortality
rates following recent droughts, highlighting limitations
in its use for prestoration. On a more positive note, natural
post-disturbance (e.g., windthrow) regeneration has shown
the potential for the development of diverse and resilient
forest communities with minimal human intervention in
several countries.

Regarding forest quantity, although several countries saw
increases in forest cover during this period, such increases
mostly resulted from natural regeneration, which was
facilitated, in some cases, by rural abandonment. In fact,

countries such as the UK, Belgium, Romania and Denmark
reported failures in meeting annual afforestation and forest
expansion targets, and the Netherlands even experienced a
decrease in forest cover over the past decade. Finally, the
area of protected forests increased in most countries during
this period, but the level of success differs depending on the
type of protection and country.

Main Obstacles

The main obstacle reported by all countries during this
third period was insufficient funding (Fig. 4) as shown
in the country-level examples in Table S5. Even when
the financial compensation was adequate, the lack of
trust in whether subsidies would be maintained in the
long term discouraged many owners from engaging in
restoration (e.g., Belgium, Denmark). In fact, subsi-
dies, as a financial policy instrument, have shown sev-
eral shortcomings in the context of forest restoration,
including uncertainty on the long-term implications, the
external financial dependency that it creates, the bureau-
cracy it entails and the burden for the administration
due to the high budget that has to be committed for an
extended period.

Conflicting goals was another obstacle which was again
reported by most countries in this period. The main two
conflicts were between agricultural and forest land covers
and between timber production and nature conservation,
and they were present at both the social (i.e., conflicts
among stakeholders) and political (i.e., inconsistent cross-
sectoral policies) dimensions (Table S5). Several experts
raised concerns about the recent polarization of perspec-
tives and how they hinder successful restoration. There
were also growing concerns that climate change mitigation
and bioenergy policies, such as the EU Renewable Energy
Directive focused on accumulating carbon through tree
planting, can contradict forest biodiversity policy objec-
tives and lead to policy fragmentation and ecological deg-
radation [37, 38].

Furthermore, the dissolution of the unitary organiza-
tion of forest management and the reprivatization of the
forests continued to challenge forest restoration in sev-
eral countries (Table S5). In fact, the lack of silvicultural
knowledge (e.g., missing thinning treatments to facili-
tate the establishment of target species) and ecological
understanding of private forest owners was reported as
an obstacle by several countries. Finally, climate change,
the consequent intensification of natural disturbances,
the growing browsing pressure (which especially hinders
the establishment of deciduous species) and excessive
bureaucracy that make measures unattractive to appli-
cants were also reported as major obstacles by several
countries.
Conclusions – 10 Lessons Learned

Analyzing expert national narratives is a valuable tool for
deriving long-term, large-scale practical knowledge, ena-
bling us to extract lessons and general guidelines to suc-
cessfully navigate the UN Decade on Ecosystem Restora-
tion and implement the European Nature Restoration Law.
Results show that changes in forest restoration over the last
two centuries as well as the success or failure of national
initiatives have been driven and/or conditioned by a com-
bination of environmental, technical, political, legal, social
and economic factors. Below, we highlight these factors and
summarize the main conclusions extracted based on the 18
national expert narratives in the form of 10 lessons learned
to help guide future restoration.

1. **Natural disasters trigger change:** Some of the first large-scale forest restoration initiatives in several countries were a response to catastrophic natural disturbances (e.g., floods, avalanches, shifting sands) that resulted from centuries of overexploitation and deforestation. The changes in forest restoration observed after 1990 were also triggered, in part, by growing environmental disasters (e.g., acid rain, large-scale windthrow, bark beetle outbreaks, fires) and global environmental crises (the climate change and biodiversity crises, and to a lesser extent, the water crisis). Sound ecological understanding and strong political will to act upon it are crucial to prevent such catastrophic tipping points.

2. **Geopolitical turmoil forces change:** Wars have strongly influenced forest restoration in Europe in an ambivalent way. On the one hand, wars acted as strong drivers of degradation by directly destroying forests or sharply increasing timber demand. Wars also represented clear obstacles to restoration by halting previous efforts and forcing changes in objectives, priorities and funding. Finally, the geopolitical vulnerability resulting from timber shortages during the war encouraged many countries to initiate strong afforestation/reforestation campaigns with a focus on timber production, with clear legacy effects on the structure and composition of forests decades later.

3. **Forest ownership and governance accelerate or decelerate change:** The nationalization/privatization of forests and centralization/decentralization of forest competencies have been some of the most influential political decisions for forest restoration. Some narratives show that the centralized management and funding of state forests usually led to efficiency and success in meeting large-scale targets, whereas the fragmentation of property into many private owners and forest

governance into many administrations slowed down
progress. Throughout history, governments have tried
different mechanisms with different levels of success
to deal with the lack of available public land for res-
toration (e.g., expropriation, purchase, contracts, tax
benefits, in-kind support), and currently, certification
and subsidies are popular choices. However, they all
have shortcomings, and thus, property fragmentation
continues to be a burning issue in forest restoration. On
the bright side, there are many examples of success-
ful local initiatives [11]; therefore, innovative govern-
ance solutions that catalyze the upscaling of these good
practices are essential.

4. **Funding mechanisms support change:** One of the most common obstacle throughout time has been the lack of funding, whereas most successful initiatives reported in the narratives are based on strong and stable funding mechanisms (e.g., state funding of the Karst afforestation program based on the sale of forestry products). The shift in the type of forest restoration experienced in the third period has been possible partly due to EU funding programs such as the European Agricultural Fund for Rural Development (EAFRD) or LIFE programs. Still, all countries report insufficient funding as a main obstacle to successful restoration nowadays and shortcomings of some financial instruments (e.g., subsidies), highlighting the urgent need for innovative funding mechanisms and regulations that are as resistant as possible to political and market fluctuations.

5. **Market fluctuations drive change:** Changes in the demand and value of different forest products (e.g., charcoal, fuelwood, timber) and services (e.g., tourism, carbon sequestration) over time have strongly influenced the type of restoration. For example, the decreased demand for fuelwood following the introduction of fossil fuels and the growing timber demand for the mining industry led to the conversion of many deciduous coppice forests to coniferous high forests. This highlights the importance of ensuring that future forest restoration initiatives provide marketable benefits (e.g., non-timber products such as truffles, wildlife tourism, payments for carbon sequestration), as this will encourage landowners to engage in long-lasting restoration (especially considering the reluctance of many to depend on subsidies).

6. **Sociodemographics and societal values demand or enable change:** Rural abandonment has facilitated restoration in some cases by reducing the conflict between agricultural and forest land uses and enabling natural forest regeneration. However, the lack of forest management resulting from this abandonment can also lead to forest degradation (e.g., overly dense stands with
high flammability), showing that the involvement of an active rural population can contribute to successful forest restoration. Shifts in societal values can also drive change, as exemplified by the crucial role of the increased environmental awareness of the population and demand for the recreational use of forests in diversifying restoration objectives after 1990, highlighting the need for effective communication and education of society.

7. **Policies guide change:** Although a policy analysis is not within the scope of this review and the myriads of policies included in the narratives cannot be captured, it can be said that some of the most successful and influential policies have been national forest laws that were strict (not overly autocratic, not overly soft) and sought to balance socioeconomic benefits and ecological protection. The creation over time of administrative units and institutions specialized in forest restoration as well as the nationally centralized education of foresters have also been instrumental in the success of restoration in many countries. Forward-looking and ambitious international and European environmental policies have also been reported to exert a strong influence on national strategies.

8. **Convergence of multidimensional drivers accelerates change:** Drivers of change do not act in isolation but synergistically (or antagonistically). Usually, several drivers of change have to come together to have a real impact, showing the interrelation of social, environmental, economic and political aspects of forest restoration. For example, at the beginning of the twentieth century, the limitations of even-aged monocultural conifer plantations started to show, and some forest managers and researchers advocated for continuous cover forestry. However, this movement did not materialize in most countries (Slovenia could be considered an exception) because the geopolitical and economic situation of the time prioritized maximizing wood supply. It was not until the 1970s to 1990s that the convergence of social, political, economic and environmental factors enabled this change.

9. **Conflicting goals impede change:** One of the main obstacles to successful forest restoration based on the narratives has been conflicting goals, both at the socioeconomic (e.g., among stakeholders) and political (e.g., among policy sectors) levels. The most recurrent conflicts are those between agricultural and forest land uses (e.g., agricultural subsidies are much more attractive than afforestation subsidies), and between timber production and biodiversity conservation goals. Moreover, new conflicts (e.g., between climate change mitigation and forest biodiversity policies) are raising growing concerns.

10. **Short-term solutions can cause long-term problems:** The final general lesson that we have extracted based on the narratives of these 18 countries is that when solutions to a particular problem are taken based on short-term thinking or without considering other interconnected components of the system, these solutions can become the source of future problems. For example, the fixation of sandy soils or enrichment of conifer plantations with invasive exotic species has caused the unintentional introduction of new threats. The afforestation/reforestation of degraded land with conifer monocultures has resulted in increased vulnerability to natural disturbances such as fire and windthrow. The complete suppression of past drivers of degradation (e.g., fire, grazing, harvesting) has led to simplified forests lower in biodiversity. Some experts have expressed concerns that current approaches to solve immediate problems such as climate change and biodiversity crises may lead to a type of restoration (e.g., afforestation with monocultures of fast-growing species to sequester carbon or prohibitions on timber harvest to create forest reserves) that threatens the system in the future (e.g., loss of biodiversity, lack of sustainably grown wood for the green transition).

Therefore, we conclude that a shift in how we view and manage the landscape may be necessary as: “some problems consistently resist solution … These are the problems for which a new way of looking is required” [39]. Specifically, our perception of the landscape should evolve from an aggregation of static and isolated patches towards understanding the landscape as a dynamic and interconnected socioecological mosaic of different habitats that vary in space and time. A holistic landscape approach to forest restoration (in research, policy and practice) may be the only way to minimize tradeoffs and conflicts among sectors and stakeholders and to simultaneously address the many challenges that all habitats on the planet face. Additionally, innovative funding mechanisms, as well as restoration initiatives that provide marketable benefits are crucial to engage landowners and address both property fragmentation and rural abandonment issues. Finally, long-term thinking that is aware of the interconnectedness of the system is key for successful forest restoration. As Donella Meadows [39] wrote, “The world is a complex, interconnected, finite, ecological-social-psychological-economic system. We treat it as if it were not, as if it were divisible, separable, simple, and infinite. Our persistent, intractable global problems arise directly from this mismatch”.

**Supplementary Information** The online version contains supplementary material available at https://doi.org/10.1007/s40725-024-00235-3.
**Acknowledgements** This research has been supported by SUPERB project funded by the European Union's Horizon 2020 Research and Innovation Programme under grant agreement No. 101036849. S.R. has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 101023713. A.A. has an Investigo Programme contract funded by the European Union, Next Generation EU.

**Author Contribution** M.E. and S.dM. conceptualized the research study, supervised the development of national narratives, analyzed and synthesized the results, led the writing of the manuscript, and developed the methodology with the collaboration and contribution of I.A., I.C., M.M.M., L.W., K.L. and J.H. A.A. prepared maps and figures. The rest of the coauthors contributed through the development of the corresponding national narratives. All authors reviewed the manuscript.

**Funding** Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.

**Data Availability** No datasets were generated or analysed during the current study.

## Compliance with Ethical Standards

**Competing Interests** The authors declare no competing interests.

**Human and Animal Rights and Informed Consent** This article does not contain any studies with human or animal subjects performed by any of the authors.

**Open Access** This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

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<figure><img src="image_14.png" /></figure>
## Authors and Affiliations

Maitane Erdozain² · Iciar Alberdi³ · Réka Aszalós⁴ · Kurt Bollmann⁶ · Vassilis Detsis⁷ · Jurij Diaci⁸ · Martina Đodan⁹ ·

Georgios Efthimiou¹⁰ · László Gálhidy¹¹ · Marie Haase¹² · Johanna Hoffmann¹³ · Delphine Jaymond¹⁴,³⁰ ·

Elisabeth Johann¹⁵ · Henrik Jørgensen¹⁶ · Frank Krumm⁶ · Timo Kuuluvainen¹⁷ · Thibault Lachat⁵,⁶ ·

Katharina Lapin¹³ · Marcus Lindner¹² · Palle Madsen¹⁸ · Liviu Nichiforel¹⁹ · Maciej Pach²⁰ · Yoan Paillet¹⁴ ·

Ciprian Palaghianu¹⁹ · Jordi Palau²¹ · Jesús Pemán¹ · Sanja Peric⁹ · Susanne Raum²²,²⁹ · Silvio Schueler²³ ·

Jerzy Skrzyszewski²⁰ · Johan Svensson²⁴ · Sander Teeuwen²⁵ · Giorgio Vacchiano²⁶ · Kris Vandekerkhove²⁷ ·

Isabel Cañellas³ · María Menéndez-Miguélez³ · Leland Leland K. Werden²⁸ · Aitor Àvila² · Sergio de-Miguel¹,²

<figure><img src="image_15.png" /></figure>

Sergio de-Miguel
sergio.demiguel@udl.cat

¹ Department of Agricultural and Forest Sciences and Engineering, University of Lleida, Lleida, Spain

² Forest Science and Technology Centre of Catalonia (CTFC), Solsona, Spain

³ Department of Silviculture and Forest Management, ICIFOR-INIA (CSIC), Madrid, Spain

⁴ Center for Ecological Research, Budapest, Hungary

⁵ School of Agricultural, Forest and Food Sciences HAFL, Bern University of Applied Sciences, Zollikofen, Switzerland

⁶ Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland

⁷ Department of Economics and Sustainable Development, Harokopio University, Athens, Greece

⁸ Department of Forestry and Renewable Forest Resources, University of Ljubljana, Ljubljana, Slovenia

⁹ Croatian Forest Research Institute, Jastrebarsko, Croatia

¹⁰ Agricultural University of Athens, Athens, Greece

¹¹ WWF Hungary, Budapest, Hungary

¹² European Forest Institute, Bonn, Germany

¹³ Department Forest Biodiversity & Nature Conservation Austrian Research Centre for Forests, Vienna, Austria

¹⁴ Univ. Grenoble Alpes, National Research Institute for Agriculture, Food and the Environment (INRAE), LESSEM, Saint Martin d'Hères, France

¹⁵ Austrian Forest Association, Group of Experts Forest History, Vienna, Austria

¹⁶ Department of Forest Ecology, Independent Nature Conservation Consultant, Copenhagen, Denmark

¹⁷ Department of Forest Sciences, University of Helsinki, Helsinki, Finland

¹⁸ InNovaSilva ApS, Vejle, Denmark

¹⁹ Forestry Faculty of Suceava, “Ștefan Cel Mare Forestry Faculty, Ștefan cel Mare University of Suceava, Suceava, Romania

²⁰ Department of Ecology and Silviculture, University of Agriculture in Krakow, Krakow, Poland

²¹ Department of Chemistry, Physics and Environmental and Soil Sciences, University of Lleida, Lleida, Spain

²² Chair of Strategic Landscape Planning & Management, Technical University of Munich, Munich, Germany

²³ Department Forest Growth, Silviculture & Genetics, Austrian Research Centre for Forests, Vienna, Austria

²⁴ Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden

²⁵ Stichting Probos / Probos Foundation, Wageningen, Netherlands

²⁶ Department of Agricultural and Environmental Sciences, University of Milan, Milan, Italy

²⁷ Research Institute for Nature and Forest, Brussels, Belgium

²⁸ Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland

²⁹ Centre for Environmental Policy, Imperial College London, London, UK

³⁰ Avignon Université, Aix Marseille Univ, CNRS, IRD, IMBE, Avignon, France