# The Use of Muld and Shading Improves the Survival of
## 1 Introduction  
The Mediterranean-type climate zone of central Chile is mainly dominated by the Savannah-like 'espismal' ecosystems and sclerophyllous forests with a high level of species endemism. This area has been historically degraded by anthropogenic activities, including agriculture, forestry, grazing, mining, urban development, and fires [1; 2; 3; 4; 5; 6]. Currently, there are concerns about the ecological restoration of this type of Mediterranean ecosystems, especially regarding the lower water availability and higher temperatures imposed by climate change, which decrease seedling recruitment, establishment, and survival [7; 8; 9; 10]. Moreover, this area has experienced a succession of dry years since 2010, the so-called \"mega drought\" [11], which highlights the necessity to identify successful establishment techniques that assure seedling survival and growth of tree species in this ecosystem. Planting tree seedlings and direct seeding are two active restoration methods used in native species in these ecosystems [12], where the former has shown better survival [13]. In Chile, planting tree seedlings has been traditionally carried out at regular spacing and using one or a few more species, with still low survival rates after outplanting [14]. Otherwise, there is still scarce information about other restoration strategies that might mimic the natural succession processes, such as the use of heterogeneous group planting (i.e., applied nucleation or tree island planting) [15; 16]. This approach might be more effective for forest restoration on small and larger scales and have positive effects, speeding up the species succession [17; 18]. Nucleation by tree island planting corresponds to a nature-based restoration technique that considers both diversity of plant species and functional groups [19; 20], which may reduce planting and maintenance costs [21]. Securing seedling survival during the first growing season is critical in restoring Mediterranean environments, primarily because of the biotic stresses that plants face following transplant [22]. In Chile, some studies support the use of eco-technologies (e.g., tree shelters, fertilizers, muching, and hydrogel) and proper establishment design in planting seedlings to alleviate those stresses and increase plant survival and growth [18; 23]. Tree shelters were initially designed to protect plants from animal browsing, but several studies have shown their positive effect on survival in the Mediterranean and semiarid zones by reducing the light and thermal stress at outplanting (i.e., shading effect of shelters) [24; 25; 26; 27]. However, the effect of shading through shelters and light transmissivity is species-specific and determined by site factors such as temperature and water stress experienced by plants [28]. On the other hand, water conservation in the soils may be achieved with some type of muching, with their permeability negatively related to their effectiveness [29]. This has increased the production of synthetic biodegradable much, which has been less explored in forest restoration. Mulching influences tree growth by decreasing soil evaporation, regulating the soil temperature, and preserving soil fertility [30; 31; 32; 33], but other studies have shown low or no response [34; 35]. Central Chile is characterized by severe summer droughts, and water is the main limiting factor of forest productivity. For this reason, most forest plantations are established in winter and early spring when soils have sufficient moisture. However, there is an increasing need to extend the planting period to the summer months, especially in forest reclamation on mine lands. Although much of the semiarid sclerophyllous forests are dominated by drought-tolerant species, the mega drought has affected large areas of the native forests and expressed as foliage desiccation (i.e., browning) [36]. Consequently, this is affecting several of the current restoration efforts in the country.