A new approach to study local adaptation in long‐lived woody species: virtual transplant experiments

1.Despite the importance of local adaptation and the extended literature that has addressed it, there are few methods available to explore local adaptation across large temporal scales. However, long‐term patterns are likely to be essential to understanding adaptation in long‐lived species, such as trees. 2. Here, we propose a methodology named ‘virtual transplant experiment' (VTE), which uses long‐term climatic variability to explore local adaptation to climate in natural tree populations. VTEs evaluate the historical response of populations to their local climate and to climates representative of conditions in other populations. We tested our methodology using simulated data and applied it in two case studies on: (i) Pinus nigra populations at the edge of the species distribution, where previous research has suggested strong climate adaptation, and (ii) Fagus sylvatica mesic populations, where parallel experiments showed no adaptation to macroclimate. 3. VTE results from simulated and real‐world data matched our expectations, suggesting that the method accurately identified the patterns of local adaptation to climate in tree populations. VTEs consistently discriminated locally adapted populations in synthetic data with a known degree of local adaptation. As expected, P. nigra populations showed adaptation to local climate in the VTE, while F. sylvatica populations showed no overall local advantage. 4. Our method provides a new way to test for local adaptation over time scales encompassing the complete lifespan of trees. VTEs can complement current methods to study local adaptation by adding the ability to explore the long‐term response to local climate in natural populations. The advantages and limitations of the different approaches to studying local adaptation stress the importance of combining multiple approaches to test for local adaptation in long‐lived organisms

Dendro+local_data

Original tree ring and climate data for: (i) tree ring simulations (only precipitation data was used to generate the growth time series, folder 'Precipitation data for sinthetic'); (ii) pinus nigra growth and climate data for 5 populations in south spain, folder 'Pinus nigra data'; (iii) Fagus sylvatica growth and climate data for 3 population in Germany (total_germany_def.csv), and Romania (total_romania_def.csv)

Fading regulation of diurnal temperature ranges on drought-induced growth loss for drought-tolerant tree species

Abstract Warming-induced droughts caused tree growth loss across the globe, leading to substantial carbon loss to the atmosphere. Drought-induced growth loss, however, can be regulated by changes in diurnal temperature ranges. Here, we investigated long term radial growth responses of 23 widespread distributed tree species from 2327 sites over the world and found that species’ drought tolerances were significantly and positively correlated with diurnal temperature range-growth loss relationships for the period 1901-1940. Since 1940, this relationship has continued to fade, likely due to asymmetric day and night warming trends and the species’ ability to deal with them. The alleviation of reduced diurnal temperature ranges on drought-induced growth loss was mainly found for drought resistant tree species. Overall, our results highlight the need to carefully consider diurnal temperature ranges and species-specific responses to daytime and nighttime warming to explore tree growth responses to current and future warmer and drier climates

Global Forest Types Based on Climatic and Vegetation Data

Forest types are generally identified using vegetation or land-use types. However, vegetation classifications less frequently consider the actual forest attributes within each type. To address this in an objective way across different regions and to link forest attributes with their climate, we aimed to improve the distribution of forest types to be more realistic and useful for biodiversity preservation, forest management, and ecological and forestry research. The forest types were classified using an unsupervised cluster analysis method by combining climate variables with normalized difference vegetation index (NDVI) data. Unforested regions were masked out to constrict our study to forest type distributions, using a 20% tree cover threshold. Descriptive names were given to the defined forest types based on annual temperature, precipitation, and NDVI values. Forest types had distinct climate and vegetation characteristics. Regions with similar NDVI values, but with different climate characteristics, which would be merged in previous classifications, could be clearly distinguished. However, small-range forest types, such as montane forests, were challenging to differentiate. At macroscale, the resulting forest types are largely consistent with land-cover types or vegetation types defined in previous studies. However, considering both potential and current vegetation data allowed us to create a more realistic type distribution that differentiates actual vegetation types and thus can be more informative for forest managers, conservationists, and forest ecologists. The newly generated forest type distribution is freely available to download and use for non-commercial purposes as a GeoTIFF file via doi: 10.13140/RG.2.2.19197.90082).ISSN:2071-105

Growth response to climate and drought change along an aridity gradient in the southernmost Pinus nigra relict forests

Tree populations at the rear edge of species distribution are sensitive to climate stress and drought. However, growth responses of these tree populations to those stressors may vary along climatic gradients. To analyze growth responses to climate and drought using dendrochronology in rear-edge Pinus nigra populations located along an aridity gradient. Tree-ring width chronologies were built for the twentieth century and related to monthly climatic variables, a drought index (Standardized Precipitation-Evapotranspiration Index), and two atmospheric circulation patterns (North Atlantic and Western Mediterranean Oscillations). Growth was enhanced by wet and cold previous autumns and warm late winters before tree-ring formation. The influence of the previous year conditions on growth increased during the past century. Growth was significantly related to North Atlantic and Western Mediterranean Oscillations in two out of five sites. The strongest responses of growth to the drought index were observed in the most xeric sites. Dry conditions before tree-ring formation constrain growth in rear-edge P. nigra populations. The comparisons of climate-growth responses along aridity gradients allow characterizing the sensitivity of relict stands to climate warming

Nuevas aportaciones a la distribución de Pinus nigra Arnold, subsp. mauretanica (Maire & Peyerimh.) Heywood en el Rif (Marruecos).

New locations of Pinus nigra Arnold subsp. mauretanica were described along the western Rif mountain chain (Talassemtane National Park) in northwestern Morocco. These locations are in humid and hiperhumid montane forest habitats with mixed forests of Cedrus atlantica, Abies maroccana, endemic taxa of the limestone northwestern Rif mountain chain, and Pinus pinaster. We include a new cartography of the species in north Morocco.Se describen nuevas localizaciones de Pinus nigra subsp. mauretanica en el Rif occidental (Parque Nacional de Talassemtane, dorsal caliza rifeña), en el noroeste de Marruecos. Las localidades indicadas se encuentran en hábitat forestal húmedo e hiperhúmedo de montaña, en formaciones forestales mixtas de Cedrus atlantica y Abies maroccana, especie endémica del Rif calizo noroccidental, y Pinus pinaster. Se aporta una cartografía actualizada de la distribución de la especie en el norte de Marruecos

ITRDB-Rscript

R code used for analysis and PSI generatio

The International Tree-Ring Data Bank (ITRDB) revisited: Data availability and global ecological representativity

Aim: The International Tree‐Ring Data Bank (ITRDB) is the most comprehensive database of tree growth. To evaluate its usefulness and improve its accessibility to the broad scientific community, we aimed to: (a) quantify its biases, (b) assess how well it represents global forests, (c) develop tools to identify priority areas to improve its representativity, and d) make available the corrected database. Location: Worldwide. Time period: Contributed datasets between 1974 and 2017. Major taxa studied: Trees. Methods: We identified and corrected formatting issues in all individual datasets of the ITRDB. We then calculated the representativity of the ITRDB with respect to species, spatial coverage, climatic regions, elevations, need for data update, climatic limitations on growth, vascular plant diversity, and associated animal diversity. We combined these metrics into a global Priority Sampling Index (PSI) to highlight ways to improve ITRDB representativity. Results: Our refined dataset provides access to a network of >52 million growth data points worldwide. We found, however, that the database is dominated by trees from forests with low diversity, in semi‐arid climates, coniferous species, and in western North America. Conifers represented 81% of the ITRDB and even in well‐sampled areas, broadleaves were poorly represented. Our PSI stressed the need to increase the database diversity in terms of broadleaf species and identified poorly represented regions that require scientific attention. Great gains will be made by increasing research and data sharing in African, Asian, and South American forests. Main conclusions: The extensive data and coverage of the ITRDB show great promise to address macroecological questions. To achieve this, however, we have to overcome the significant gaps in the representativity of the ITRDB. A strategic and organized group effort is required, and we hope the tools and data provided here can guide the efforts to improve this invaluable database

Appendix S1: Corrected and harmonized dataset

Content: - Cleaned datasets - Conflictive dataset - Duplicated (removed) datasets - Sampling coordinates - Error correction log - .rwl files metadat