Restoring species diversity is proposed as a strategy to improve ecosystem resistance to extreme droughts, but the impact of species diversity on resistance has not been evaluated across global forests. Here we compile a database that contains tree species richness from more than 0.7 million forest plots and satellite-based estimation of drought resistance. Using this database, we provide a spatially explicit map of species diversity effect on drought resistance. We found that higher species diversity could notably enhance drought resistance in about half of global forests but was spatially highly variable. Drought regimes (frequency and intensity) and climatic water deficit were important determinants of differences in the extent that species diversity could enhance forest drought resistance among regions, with such benefits being larger in dry and drought-prone forests. According to a predictive model of species diversity effect, the conversion of current monoculture to mixed-species tree plantations could improve drought resistance, with the large increase in dry forests. Our findings provide evidence that species diversity could buffer global forests against droughts. Restoration of species diversity could then be an effective way to mitigate the impact of extreme droughts on large scales, especially in dry and drought-prone regions.
This is a preview of subscription content, access via your institution
Subscribe to Nature+
Get immediate online access to the entire Nature family of 50+ journals
Subscribe to Journal
Get full journal access for 1 year
only $9.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
The GFBI species-richness data can be accessed at https://www.gfbinitiative.org/metadata-gfb1. The BIEN species-richness dataset is available from https://doi.org/10.6084/m9.figshare.7436951.v1. The SPEI dataset can be downloaded from https://spei.csic.es/database.html. The MOD13C2 collection 6 NDVI product can be accessed at https://e4ftl01.cr.usgs.gov/MODV6_Cmp_C/MOLT/MOD13C2.006/. The MOD17A2 dataset was derived from http://files.ntsg.umt.edu/data/NTSG_Products/MOD17/GeoTIFF/Monthly_MOD17A2/. The forest-change data are available at https://earthenginepartners.appspot.com/science-2013-global-forest. The distribution of global plantations is freely available at https://www.environmentalgeography.nl/site/. Other datasets supporting the findings of this manuscript are available in the main text or Supplementary Information. The estimated species diversity effect for global forests can be accessed at https://zenodo.org/record/6948912#.YufcT3ZByUk. Source data are provided with this paper.
All computer codes used in this study can be provided by the corresponding author upon reasonable request.
Beer, C. et al. Terrestrial gross carbon dioxide uptake: global distribution and covariation with climate. Science 329, 834 (2010).
Anderegg, W. R. L. et al. Pervasive drought legacies in forest ecosystems and their implications for carbon cycle models. Science 349, 528–532 (2015).
Ciais, P. et al. Europe-wide reduction in primary productivity caused by the heat and drought in 2003. Nature 437, 529–533 (2005).
Peñuelas, J. et al. Shifting from a fertilization-dominated to a warming-dominated period. Nat. Ecol. Evol. 1, 1438–1445 (2017).
Morin, X. et al. Temporal stability in forest productivity increases with tree diversity due to asynchrony in species dynamics. Ecol. Lett. 17, 1526–1535 (2014).
Isbell, F. et al. Biodiversity increases the resistance of ecosystem productivity to climate extremes. Nature 526, 574 (2015).
De Boeck, H. J. et al. Patterns and drivers of biodiversity–stability relationships under climate extremes. J. Ecol. 106, 890–902 (2018).
Grossiord, C. Having the right neighbors: how tree species diversity modulates drought impacts on forests. N. Phytol. 228, 42–49 (2020).
O’Brien, M. J. et al. Resistance of tropical seedlings to drought is mediated by neighbourhood diversity. Nat. Ecol. Evol. 1, 1643–1648 (2017).
Gazol, A. & Camarero, J. J. Functional diversity enhances silver fir growth resilience to an extreme drought. J. Ecol. 104, 1063–1075 (2016).
Pretzsch, H., Schütze, G. & Uhl, E. Resistance of European tree species to drought stress in mixed versus pure forests: evidence of stress release by inter-specific facilitation. Plant Biol. 15, 483–495 (2013).
Grossiord, C. et al. Tree diversity does not always improve resistance of forest ecosystems to drought. P. Natl Acad. Sci. USA 111, 14812–14815 (2014).
Grossiord, C. et al. Does drought influence the relationship between biodiversity and ecosystem functioning in boreal forests. Ecosystems 17, 394–404 (2014).
Loreau, M., Mouquet, N. & Gonzalez, A. Biodiversity as spatial insurance in heterogeneous landscapes. P. Natl Acad. Sci. USA 100, 12765 (2003).
Lloret, F. et al. Woody plant richness and NDVI response to drought events in Catalonian (northeastern Spain) forests. Ecology 88, 2270–2279 (2007).
He, Q. & Bertness, M. D. Extreme stresses, niches, and positive species interactions along stress gradients. Ecology 95, 1437–1443 (2014).
Hafner, B. D. et al. Hydraulic redistribution under moderate drought among English oak, European beech and Norway spruce determined by deuterium isotope labeling in a split-root experiment. Tree Physiol. 37, 950–960 (2017).
Forrester, D. I. & Bauhus, J. A review of processes behind diversity–productivity relationships in forests. Curr. For. Rep. 2, 45–61 (2016).
Vitali, V., Forrester, D. I. & Bauhus, J. Know your neighbours: drought response of Norway spruce, silver fir and Douglas fir in mixed forests depends on species identity and diversity of tree neighbourhoods. Ecosystems 21, 1215–1229 (2018).
The State of the World’s Forests 2020: Forests, Biodiversity and People (FAO and UNEP, 2020).
Zhang, J., Fu, B., Stafford-Smith, M., Wang, S. & Zhao, W. Improve forest restoration initiatives to meet Sustainable Development Goal 15. Nat. Ecol. Evol. https://doi.org/10.1038/s41559-020-01332-9 (2020).
Schulze, K., Malek, Ž. & Verburg, P. H. Towards better mapping of forest management patterns: a global allocation approach. For. Ecol. Manage. 432, 776–785 (2019).
Harris, N. L. et al. Global maps of twenty-first century forest carbon fluxes. Nat. Clim. Change https://doi.org/10.1038/s41558-020-00976-6 (2021).
Maxwell, S. L. et al. Area-based conservation in the twenty-first century. Nature 586, 217–227 (2020).
Williams, A. P. et al. Large contribution from anthropogenic warming to an emerging North American megadrought. Science 368, 314–318 (2020).
Blackman, C. et al. Leaf hydraulic vulnerability is related to conduit dimensions and drought resistance across a diverse range of woody angiosperms. N. Phytol. 188, 1113–1123 (2010).
Liang, J. et al. Positive biodiversity–productivity relationship predominant in global forests. Science 354, aaf8957 (2016).
Wieczynski, D. J. et al. Climate shapes and shifts functional biodiversity in forests worldwide. P. Natl Acad. Sci. USA 116, 587–592 (2019).
Tomppo, E. et al. National Forest Inventories: Pathways for Common Reporting (Springer, 2010).
Chirici, G. et al. National Forest Inventories: Contributions to Forest Biodiversity Assessments (Springer, 2011).
Magnussen, S., Smith, B. & Uribe, S. National Forest inventories in North America for monitoring forest tree species diversity. Plant Biosyst. 141, 113–122 (2007).
Lesiv, M. et al. Global forest management data for 2015 at a 100 m resolution. Sci. Data 9, 199 (2022).
Vicente-Serrano, S. M., Beguería, S. & López-Moreno, J. I. A. Multiscalar drought index sensitive to global warming: the Standardized Precipitation Evapotranspiration Index. J. Clim. 23, 1696–1718 (2010).
Hansen, M. C. et al. High-resolution global maps of 21st-century forest cover change. Science 342, 850 (2013).
Forest Resources Assessment 2015 (FAO, 2015).
Lyapustin, A. et al. Scientific impact of MODIS C5 calibration degradation and C6+ improvements. Atmos. Meas. Tech. 7, 4353–4365 (2014).
Didan, K. & Brreto, A. NASA MEaSUREs Vegetation Index and Phenology (VIP) Phenology EVI2 Yearly Global 0.05Deg CMG, NASA EOSDIS Land Processes DAAC, https://doi.org/10.5067/MEaSUREs/VIP/VIPPHEN_EVI2.004 (2016).
Olson, D. M. et al. Terrestrial Ecoregions of the World: A New Map of Life on Earth: a new global map of terrestrial ecoregions provides an innovative tool for conserving biodiversity. Bioscience 51, 933–938 (2001).
Kline, T. J. B. Sample issues, methodological implications, and best practices. Can. J. Behav. Sci. 49, 71–77 (2017).
Gourlet-Fleury, S. et al. Tropical forest recovery from logging: a 24 year silvicultural experiment from Central Africa. Phil. Trans. R. Soc. B 368, 20120302 (2013).
Obiang, N. L. E. et al. Spatial pattern of central African rainforests can be predicted from average tree size. Oikos 119, 1643–1653 (2010).
Plotkin, J. B. et al. Predicting species diversity in tropical forests. P. Natl Acad. Sci. USA 97, 10850–10854 (2000).
Graham, M. H. Confronting multicollinearity in ecological multiple regression. Ecology 84, 2809–2815 (2003).
Tukey, J. W. Exploratory Data Analysis (Addison-Wesley,1977).
This study was supported by the National Natural Science Foundation of China (41922004 and 41871104) (T.W.), Second Tibetan Plateau Scientific Expedition and Research Programme (2019QZKK0606) and the NSFC project Basic Science Centre for Tibetan Plateau Earth System (41988101-04) (D.L., T.W. and S.P.).
The authors declare no competing interests.
Peer review information
Nature Geoscience thanks Michael O’Brien, Carsten Dormann and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Primary Handling Editors: Simon Harold and Xujia Jiang, in collaboration with the Nature Geoscience team.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Resistance (a), species richness (b), drought frequency (c) and intensity (d) along spatial gradient of water availability. The annual climatic water deficit (CWD), which considers both water supply and atmospheric water demand was used to describe water availability. The CWD was calculated as precipitation minus potential evapotranspiration, with positive values suggest wet climate and negative values dry climate. The line illustrates the mean value of the response variable for each 100-mm interval of CWD, and the range of the error band shows the associated standard deviation. The significance was based on the t-statistics using two-tailed test (N = 21).
Comparison of θ estimated using the multiple regression model against that based on the sequential regression models. The multiple regression model was constructed as ‘\(R_t\sim \hat S_i + X_1 + X_2 + \ldots + X_n\)’. The first type of sequential regression model was constructed as ‘\(\hat S_i\sim X_1 + X_2 + \ldots + X_n\); \(R_t\sim residual(\hat S_i) + X_1 + X_2 + \ldots + X_n\)’. The second type of sequential regression model was constructed as ‘\(R_t\sim X_1 + X_2 + \ldots + X_n\); \(residual(R_t)\sim \hat S_i\)’. The significance was based on the t-statistics using two-tailed test with sample size of 79 ecoregions.
A structural equation model representing the relationships among the 18 environmental variables (X1~X18), species richness (S), a composite variable (ENV), and the response variable (Rt). (a) shows the structure of the model. Arrows depict the linkage among variables. (b) is the histogram of the estimated coefficients from all investigated ecoregions. All variables are standardized, and the coefficients are then comparable between each other. (c) shows the comparison between the estimated θ derived from multiple regression model and that from structural equation model. The significance was based on the t-statistics using two-tailed test with sample size of 79 ecoregions.
Estimated species diversity effect (θ) at the ecoregion level.
The blue bars show the number of sites using δ13C change to measure drought resistance at both tree and ecosystem levels (Δδ13C), using changes in annual tree rings to measure drought resistance at the tree level (Growth, Tree level) and using changes in annual tree rings at the ecosystem scale (Growth, Ecosystem level). The red bars show the number of sites where the sign of predicted θ is consistent with that of documented species diversity effect from field studies. The data used in this plot are listed in Supplementary Table 2.
Extended Data Fig. 6 Increase in drought resistance induced by converting monocultured plantations to forests with four species.
The average change in resistance for each biome is marked with a distinct color, and the associated distribution of forest plantations for the biome is presented in the inset with the same color, and area in grey shows global forest distribution.
Estimated species diversity effect for each ecoregion and the associated driving variables.
The forest drought resistance, species richness, drought frequency and drought intensity changes along CWD gradient.
Estimated species diversity effect by multiple regression model and two sequential regression models.
Results from structural equation model and the comparison against multiple regression model.
About this article
Cite this article
Liu, D., Wang, T., Peñuelas, J. et al. Drought resistance enhanced by tree species diversity in global forests. Nat. Geosci. (2022). https://doi.org/10.1038/s41561-022-01026-w