The biodiversity-productivity relationship (BPR) is foundational to our understanding of the global extinction crisis and its impacts on ecosystem functioning. Understanding BPR is critical for the accurate valuation and effective conservation of biodiversity. Using ground-sourced data from 777,126 permanent plots, spanning 44 countries and most terrestrial biomes, we reveal a globally consistent positive concave-down BPR, showing that continued biodiversity loss would result in an accelerating decline in forest productivity worldwide. The value of biodiversity in maintaining commercial forest productivity alone—US$166 billion to 490 billion per year according to our estimation—is more than twice what it would cost to implement effective global conservation. This highlights the need for a worldwide reassessment of biodiversity values, forest management strategies, and conservation priorities. (Résumé d'auteur

The identity of the dominant microbial symbionts in a forest determines the ability 70 of trees to access limiting nutrients from atmospheric or soil pools 1,2 , sequester 71 carbon 3,4 and withstand the impacts of climate change 1-7 . Characterizing the global 72 distribution of symbioses, and identifying the factors that control it, are thus integral to 73 understanding present and future forest ecosystem functioning. Here we generate the first 74 spatially explicit map of forest symbiotic status using a global database of 1.2 million forest 75 inventory plots with over 28,000 tree species. Our analyses indicate that climatic variables, 76 and in particular climatically-controlled variation in decomposition rate, are the primary 77 drivers of the global distribution of major symbioses. We estimate that ectomycorrhizal 78 (EM) trees, which represent only 2% of all plant species 8 , constitute approximately 60% of 79 tree stems on Earth. EM symbiosis dominates forests where seasonally cold and dry 80

[1] Carbon, nitrogen, and material fluxes were quantified at 48 sampling locations along the 1957 km coastline of the Beaufort Sea, Alaska. Landform characteristics, soil stratigraphy, cryogenic features, and ice contents were determined for each site. Erosion rates for the sites were quantified using satellite images and aerial photos, and the rates averaged across the coastline increased from 0.6 m yr −1 during circa 1950-1980 to 1.2 m yr −1 during circa 1980-2000. Soils were highly cryoturbated, and organic carbon (OC) stores ranged from 13 to 162 kg OC m −2 in banks above sea level and averaged 63 kg OC m −2 over the entire coastline. Long-term (1950Long-term ( -2000 annual lateral fluxes due to erosion were estimated at −153 Gg OC, −7762 Mg total nitrogen, −2106 Tg solids, and −2762 Tg water. Total land area loss along the Alaska Beaufort Sea coastline was estimated at 203 ha yr −1. We found coastal erosion rates, bank heights, soil properties, and material stores and fluxes to be extremely variable among sampling sites. In comparing two classification systems used to classifying coastline types from an oceanographic, coastal morphology perspective and geomorphic units from a terrestrial, soils perspective, we found both systems were effective at differentiating significant differences among classes for most material stores, but the coastline classification did not find significant differences in erosion rates because it lacked differentiation of soil texture.

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Late-spring frosts (LSFs) affect the performance of plants and animals across the world’s temperate and boreal zones, but despite their ecological and economic impact on agriculture and forestry, the geographic distribution and evolutionary impact of these frost events are poorly understood. Here, we analyze LSFs between 1959 and 2017 and the resistance strategies of Northern Hemisphere woody species to infer trees’ adaptations for minimizing frost damage to their leaves and to forecast forest vulnerability under the ongoing changes in frost frequencies. Trait values on leaf-out and leaf-freezing resistance come from up to 1,500 temperate and boreal woody species cultivated in common gardens. We find that areas in which LSFs are common, such as eastern North America, harbor tree species with cautious (late-leafing) leaf-out strategies. Areas in which LSFs used to be unlikely, such as broad-leaved forests and shrublands in Europe and Asia, instead harbor opportunistic tree species (quickly reacting to warming air temperatures). LSFs in the latter regions are currently increasing, and given species’ innate resistance strategies, we estimate that ∼35% of the European and ∼26% of the Asian temperate forest area, but only ∼10% of the North American, will experience increasing late-frost damage in the future. Our findings reveal region-specific changes in the spring-frost risk that can inform decision-making in land management, forestry, agriculture, and insurance policy.