<figure><img src="image_1.png" /></figure>

HAL
open science

# Arboretums, common gardens and forest tree resilience

Gaspard Rihm, Bruno Fady

► To cite this version:

Gaspard Rihm, Bruno Fady. Arboretums, common gardens and forest tree resilience. New Forests, 2022, 10.1007/s11056-022-09908-y. hal-03669883

HAL Id: hal-03669883

https://hal.inrae.fr/hal-03669883

Submitted on 8 Jun 2023

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_2.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# Title: Arboretums, common gardens and forest tree resilience

This manuscript is a preliminary version of a paper now published under the reference:

Fady, B., Rihm, G. Arboretums, common gardens and forest tree resilience. New Forests (2022). https://doi.org/10.1007/s11056-022-09908-y

5

**Authors:** Bruno Fady*, Gaspard Rihm

* Corresponding author: bruno.fady@inrae.fr

**Affiliation:**

10

INRAE, Ecology of Mediterranean Forests, URFM, Domaine St Paul, Avignon, France.

**Abstract:**

15

Climate change triggered forest die-back is a huge concern worldwide. Arboretums and common gardens comparing geographic origins within species can provide a large body of valuable information and material usable to increase their resilience. Common gardens have been foundational in demonstrating the existence of genetic diversity, local adaptation and phenotypic plasticity. They have also been instrumental for forest management and policy, e.g. for guiding seed transfer rules and their marketing. While the current generation of common gardens has seen a renewed interest for developing process-based niche models or genome-trait-environment association studies, they are too limited in the number of species, provenances and habitats they sample in the context of climate change and novel bioeconomy focus. A new generation of common gardens is now needed.

20

**Short abstract:**

25

Common gardens are needed more than ever for developing climate-smart forestry

**Keywords:**

30

Breeding; Climate change; Genetic diversity; Local adaptation; Natural selection; Niche modeling.

**Acknowledgements:**

This research was part of the GenTree project which has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement # 676876.
## Main Text:

In the December 2021 issue 6572 of Science, Gabriel Popkin presents an all too true story about forest dieback. Climate change triggered forest dieback is a huge concern worldwide, disrupting biodiversity and long-established businesses and jeopardizing the potential of forests for mitigating greenhouse gas emissions. The author suggests that an arboretum established in the 1800s could offer “a rare opportunity to assess how the mature trees are handling climate change”.

5

A single arboretum alone, cannot provide even hints on resilience. Many are needed, testing varied environments. And not just arboretums comparing species, but also common gardens comparing geographic origins within species, so called provenances, which often demonstrate that diversity within-species is as large as that among species. Europe is fortunate enough to hold a wealth of arboretums and common gardens, some indeed dating back to the 19th century (Langlet 1971).

10

Common gardens have demonstrated the existence of genetic diversity, local adaptation and phenotypic plasticity. Replicated across well-characterized environments, they provide much-needed reliable information for forest management (Fady et al. 2020). They have been instrumental for policy, guiding seed transfer rules across regions and have served as the basis for Directive 1999/105/EC on Forest Reproductive Material, which has governed the marketing of seeds in the European Union since 1999.

15

20

Considered old-fashioned and outdated in the omics era, funding for common garden maintenance and monitoring decreased regularly during the past three decades. Scientific interest for common gardens has remained intact, though, e.g. for developing process-based niche models or genome-trait-environment association studies (Martínez-Sancho et al. 2021; Prasad and Leites 2021). Forest owners and managers are aware of the importance of selecting genetically appropriate material for plantation success (Vinceti et al. 2020). Yet, with climate change and a novel bioeconomy focus, current data and estimations show that long-established common gardens are limited to too few species and provenances, and cover too few habitats (Fady et al. 2020; GEN4X 2021). New types of common gardens are needed for testing material from currently underused native and exotic species (Figure 1). They are also needed for testing a wider range of populations from commonly used native and exotic species, in a wider range of habitats, including currently marginal habitats likely to become widespread in our climate change future (Figure 2). Early stage tests in nurseries offer the possibility of repeated, comparatively inexpensive evaluations of the germination and seedling niches under environments of varying severity. At the other end of the life cycle, compiled data from wider-scale forestry operations that have used identified material repeatedly could be harnessed to “assess how the mature trees are handling climate change” (Popkin 2021). Funding for these new types of common gardens and data archiving is needed both for better understanding the limits to adaptation and for expanding options available for forest managers to increase forest resilience.

25

30

35

40
## References and Notes

Fady B, Aravanopoulos F, Benavides R, González-Martínez S, Grivet D, Lascoux M, Lindner M, Rellstab C, Valladares F, Vinceti B (2020) Genetics to the rescue: managing forests sustainably in a changing world. Tree Genetics & Genomes 16(6), 1-11 [https://doi.org/10.1007/s11295-020-01474-8].

5

GEN4X (2021) Details on the INRAE common garden network GEN4X can be accessed from two files in an open ccess repository: [https://doi.org/10.15454/50RS8C](https://doi.org/10.15454/50RS8C) and [https://doi.org/10.15454/MQKQ10](https://doi.org/10.15454/MQKQ10).

Langlet O (1971). Two hundred years genecology. Taxon 20, 653-721.

10

Martínez-Sancho E, Rellstab C, Guillaume F, Bigler C, Fonti P, Wohlgemuth T, Vitasse Y (2021) Post-glacial re-colonization and natural selection have shaped growth responses of silver fir across Europe. Science of the Total Environment 779, 146393 [https://doi.org/10.1016/j.scitotenv.2021.146393].

Médail F, Monnet AC, Pavon D, Nikolic T, Dimopoulos P, Bacchetta G, Arroyo J, Barina Z, Cheikh Albassatneh M, Domina G, Fady B, Matevski V, Mifsud S, Leriche A (2019) What is a tree in the Mediterranean Basin hotspot? A critical analysis. Forest Ecosystems 6: 17 [https://doi.org/10.1186/s40663-019-0170-6].

15

Popkin G (2021) Forest Death. Science 374,1184-1189 [https://doi.org/10.1126/science.acx9735].

Prasad A, Leites L (2021) Ecological analysis of intraspecific variability of eastern white pine (Pinus strobus) under climate change by combining provenance and demographic data. Landscape Ecology, 1-20. [https://doi.org/10.1007/s10980-021-01333-4].

20

Vinceti B, Manica M, Lauridsen N, Verkerk PJ, Lindner M, Fady B (2020) Managing forest genetic resources as a strategy to adapt forests to climate change: perceptions of European forest owners and managers. European Journal of Forest Research [https://doi.org/10.1007/s10342-020-01311-6].

25
Figure 1: A partial view of the Saint Lambert (southern France) common garden which tests different provenances of *Abies cephalonica* Loud., a rarely used exotic Mediterranean fir of potential interest for plantation and restoration in France and other temperate countries with climate change related die-back. The seed crop from common gardens can also be used to provide new genetic material having passed a first step of selection under climate conditions different from those of the original habitat of the provenances.

<figure><img src="image_3.png" /></figure>
Figure 2: distribution of the 1208 forest tree common gardens of the French GEN4X network (panel A, common gardens appear as orange dots). While common gardens are planted in almost all ecological regions of the French territory (panel A, ecological regions are delineated by black lines), Mediterranean tree species, of potential value under changing environmental conditions towards a drier and hotter climate in France, are tested in only 185 sites, in too few habitats outside of the Mediterranean bioclimate region (panel B, common gardens containing at least one Mediterranean tree species (sensu Médail et al. 2019) appear as orange dots and the part of France under Mediterranean climate appears in green).

A

<figure><img src="image_4.png" /></figure>
B

<figure><img src="image_5.png" /></figure>