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

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Five population‐specific response functions were developed from quadratic models for 110 populations of Pinus sylvestris growing at 47 planting sites in Eurasia and North America. The functions predict 13 year height from climate: degree‐days > 5 °C; mean annual temperature; degree‐days < 0 °C; summer‐winter temperature differential; and a moisture index, the ratio of degree‐days > 5 °C to mean annual precipitation. Validation of the response functions with two sets of independent data produced for all functions statistically significant simple correlations with coefficients as high as 0.81 between actual and predicted heights. The response functions described the widely different growth potentials typical of natural populations and demonstrated that these growth potentials have different climatic optima. Populations nonetheless tend to inhabit climates colder than their optima, with the disparity between the optimal and inhabited climates becoming greater as the climate becomes more severe. When driven by a global warming scenario of the Hadley Center, the functions described short‐term physiologic and long‐term evolutionary effects that were geographically complex. The short‐term effects should be negative in the warmest climates but strongly positive in the coldest. Long‐term effects eventually should ameliorate the negative short‐term impacts, enhance the positive, and in time, substantially increase productivity throughout most of the contemporary pine forests of Eurasia. Realizing the long‐term gains will require redistribution of genotypes across the landscape, a process that should take up to 13 generations and therefore many years.

Summary Based on review and original data, this synthesis investigates carbon pools and fluxes of Siberian and European forests (600 and 300 million ha, respectively). We examine the productivity of ecosystems, expressed as positive rate when the amount of carbon in the ecosystem increases, while (following micrometeorological convention) downward fluxes from the atmosphere to the vegetation (NEE = Net Ecosystem Exchange) are expressed as negative numbers. Productivity parameters are Net Primary Productivity (NPP=whole plant growth), Net Ecosystem Productivity (NEP = CO2 assimilation minus ecosystem respiration), and Net Biome Productivity (NBP = NEP minus carbon losses through disturbances bypassing respiration, e.g. by fire and logging). Based on chronosequence studies and national forestry statistics we estimate a low average NPP for boreal forests in Siberia: 123 gC m–2 y–1. This contrasts with a similar calculation for Europe which suggests a much higher average NPP of 460 gC m–2 y–1 for the forests there. Despite a smaller area, European forests have a higher total NPP than Siberia (1.2–1.6 vs. 0.6–0.9 × 1015 gC region–1 y–1). This arises as a consequence of differences in growing season length, climate and nutrition.  For a chronosequence of Pinus sylvestris stands studied in central Siberia during summer, NEE was most negative in a 67‐y old stand regenerating after fire (– 192 mmol m–2 d–1) which is close to NEE in a cultivated forest of Germany (– 210 mmol m–2 d–1). Considerable net ecosystem CO2‐uptake was also measured in Siberia in 200‐ and 215‐y old stands (NEE:174 and – 63 mmol m–2 d–1) while NEP of 7‐ and 13‐y old logging areas were close to the ecosystem compensation point. Two Siberian bogs and a bog in European Russia were also significant carbon sinks (– 102 to – 104 mmol m–2 d–1). Integrated over a growing season (June to September) we measured a total growing season NEE of – 14 mol m–2 summer–1 (– 168 gC m–2 summer–1) in a 200‐y Siberian pine stand and – 5 mol m–2 summer–1 (– 60 gC m–2 summer–1) in Siberian and European Russian bogs. By contrast, over the same period, a spruce forest in European Russia was a carbon source to the atmosphere of (NEE: + 7 mol m–2 summer–1 = + 84 gC m–2 summer–1). Two years after a windthrow in European Russia, with all trees being uplifted and few successional species, lost 16 mol C m–2 to the atmosphere over a 3‐month in summer, compared to the cumulative NEE over a growing season in a German forest of – 15.5 mol m–2 summer–1 (– 186 gC m–2 summer–1; European flux network annual averaged – 205 gC m–2 y–1).  Differences in CO2‐exchange rates coincided with differences in the Bowen ratio, with logging areas partitioning most incoming radiation into sensible heat whereas bogs partitioned most into evaporation (latent heat). Effects of these different surface energy exchanges on local climate (convective storms and fires) and comparisons with the Canadian BOREAS experiment are discussed.  Following a classification of disturbances and their effects on ecosystem carb...

Observations and general circulation model projections suggest significant temperature increases in Siberia this century that are expected to have profound effects on Siberian vegetation. Potential vegetation change across Siberia was modeled, coupling our Siberian BioClimatic Model with several Hadley Centre climate change scenarios for 2020, 2050 and 2080, with explicit consideration of permafrost and fire activity. In the warmer and drier climate projected by these scenarios, Siberian forests are predicted to decrease and shift northwards and forest-steppe and steppe ecosystems are predicted to dominate over half of Siberia due to the dryer climate by 2080. Despite the large predicted increases in warming, permafrost is not predicted to thaw deep enough to sustain dark (Pinus sibirica, Abies sibirica, and Picea obovata) taiga. Over eastern Siberia, larch (Larix dahurica) taiga is predicted to continue to be the dominant zonobiome because of its ability to withstand continuous permafrost. The model also predicts new temperate broadleaf forest and forest-steppe habitats by 2080. Potential fire danger evaluated with the annual number of high fire danger days (Nesterov index is 4000-10 000) is predicted to increase by 2080, especially in southern Siberia and central Yakutia. In a warming climate, fuel load accumulated due to replacement of forest by steppe together with frequent fire weather promotes high risks of large fires in southern Siberia and central Yakutia, where wild fires would create habitats for grasslands because the drier climate would no longer be suitable for forests.