Nadja M. Tchebakova

Positive biodiversity-productivity relationship predominant in global forests.

Global biodiversity and productivity The relationship between biodiversity and ecosystem productivity has been explored in detail in herbaceous vegetation, but patterns in forests are far less well understood. Liang et al. have amassed a global forest data set from >770,000 sample plots in 44 countries. A positive and consistent relationship can be discerned between tree diversity and ecosystem productivity at landscape, country, and ecoregion scales. On average, a 10% loss in biodiversity leads to a 3% loss in productivity. This means that the economic value of maintaining biodiversity for the sake of global forest productivity is more than fivefold greater than global conservation costs. Science, this issue p. 196 Global forest inventory records suggest that biodiversity loss would result in a decline in forest productivity worldwide. INTRODUCTION The biodiversity-productivity relationship (BPR; the effect of biodiversity on ecosystem productivity) is foundational to our understanding of the global extinction crisis and its impacts on the functioning of natural ecosystems. The BPR has been a prominent research topic within ecology in recent decades, but it is only recently that we have begun to develop a global perspective. RATIONALE Forests are the most important global repositories of terrestrial biodiversity, but deforestation, forest degradation, climate change, and other factors are threatening approximately one half of tree species worldwide. Although there have been substantial efforts to strengthen the preservation and sustainable use of forest biodiversity throughout the globe, the consequences of this diversity loss pose a major uncertainty for ongoing international forest management and conservation efforts. The forest BPR represents a critical missing link for accurate valuation of global biodiversity and successful integration of biological conservation and socioeconomic development. Until now, there have been limited tree-based diversity experiments, and the forest BPR has only been explored within regional-scale observational studies. Thus, the strength and spatial variability of this relationship remains unexplored at a global scale. RESULTS We explored the effect of tree species richness on tree volume productivity at the global scale using repeated forest inventories from 777,126 permanent sample plots in 44 countries containing more than 30 million trees from 8737 species spanning most of the global terrestrial biomes. Our findings reveal a consistent positive concave-down effect of biodiversity on forest productivity across the world, showing that a continued biodiversity loss would result in an accelerating decline in forest productivity worldwide. The BPR shows considerable geospatial variation across the world. The same percentage of biodiversity loss would lead to a greater relative (that is, percentage) productivity decline in the boreal forests of North America, Northeastern Europe, Central Siberia, East Asia, and scattered regions of South-central Africa and South-central Asia. In the Amazon, West and Southeastern Africa, Southern China, Myanmar, Nepal, and the Malay Archipelago, however, the same percentage of biodiversity loss would lead to greater absolute productivity decline. CONCLUSION Our findings highlight the negative effect of biodiversity loss on forest productivity and the potential benefits from the transition of monocultures to mixed-species stands in forestry practices. The BPR we discover across forest ecosystems worldwide corresponds well with recent theoretical advances, as well as with experimental and observational studies on forest and nonforest ecosystems. On the basis of this relationship, the ongoing species loss in forest ecosystems worldwide could substantially reduce forest productivity and thereby forest carbon absorption rate to compromise the global forest carbon sink. We further estimate that the economic value of biodiversity in maintaining commercial forest productivity alone is

Global vegetation change predicted by the modified Budyko model

166 billion to

A global vegetation model based on the climatological approach of Budyko

490 billion per year. Although representing only a small percentage of the total value of biodiversity, this value is two to six times as much as it would cost to effectively implement conservation globally. These results highlight the necessity to reassess biodiversity valuation and the potential benefits of integrating and promoting biological conservation in forest resource management and forestry practices worldwide. Global effect of tree species diversity on forest productivity. Ground-sourced data from 777,126 global forest biodiversity permanent sample plots (dark blue dots, left), which cover a substantial portion of the global forest extent (white), reveal a consistent positive and concave-down biodiversity-productivity relationship across forests worldwide (red line with pink bands representing 95% confidence interval, right). 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

Reconstruction of the mid-Holocene palaeoclimate of Siberia using a bioclimatic vegetation model

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.

Needle, crown, stem, and root phytomass of Pinus sylvestris stands in Russia

A modified Budyko global vegetation model is used to predict changes in global vegetation patterns resulting from climate change (CO2 doubling). Vegetation patterns are predicted using a model based on a dryness index and potential evaporation determined by solving radiation balance equations. Climate change scenarios are derived from predictions from four General Circulation Models (GCMs) of the atmosphere (GFDL, GISS, OSU, and UKMO). Global vegetation maps after climate change are compared to the current climate vegetation map using the kappa statistic for judging agreement, as well as by calculating area statistics. All four GCM scenarios show similar trends in vegetation shifts and in areas that remain stable, although the UKMO scenario predicts greater warming than the others. Climate change maps produced by all four GCM scenarios show good agreement with the current climate vegetation map for the globe as a whole, although over half of the vegetation classes show only poor to fair agreement. The most stable areas are Desert and Ice/Polar Desert. Because most of the predicted warming is concentrated in the Boreal and Temperate zones, vegetation there is predicted to undergo the greatest change. Specifically, all Boreal vegetation classes are predicted to shrink. The interrelated classes of Tundra, Taiga, and Temperate Forest are predicted to replace much of their poleward (mostly northern) neighbors. Most vegetation classes in the Subtropics and Tropics are predicted to expand. Any shift in the Tropics favoring either Forest over Savanna, or vice versa, will be determined by the magnitude of the increased precipitation accompanying global warming. Although the model predicts equilibrium conditions to which many plant species cannot adjust (through migration or microevolution) in the 50–100 y needed for CO2 doubling, it is nevertheless not clear if projected global warming will result in drastic or benign vegetation change.

Change in phytomass and net primary productivity for Siberia from the Mid-Holocene to the Present

A global vegetation model based on the climato- logical approach of Budyko is developed. The major vege- tation zones of the world are predicted by a two- dimensional ordination of a Dryness Index and Potential Evaporation, which is derived from radiation balance. Mean temperature of the warmest month is also used to separate the Ice/Polar Desert, Tundra, and Taiga zones. Pre- dictions of vegetation distributions are made using a global climate database interpolated to a 0.5? by 0.5? terrestrial grid. The overall impression from examining the resulting global vegetation map is that the modified Budyko model predicts the location and distribution of the worlds vegeta- tion fairly well. Comparison between model predictions and Olsons actual vegetation map were based on Kappa statistics and indicate good agreement for Ice/Polar Desert, Tundra, Taiga, and Desert (even though we predict too much Desert). Agreement with Olsons map was fair for predicting the specific location of Tropical Rain Forest and Tropical Savannas, and was good for predicting their general location at a larger scale. Agreement between Olsons map and model predictions were poor for Steppe, Temperate Forest, Tropical Seasonal Forest, and Xerophy- tic Shrubs, although the predictions for Temperate Forest and Tropical Seasonal Forest improved to fair at a larger scale for judging agreement. Agreement with the baseline map of Olson was poor for Steppe and Xerophytic Shrubs at all scales of comparison. Based on Kappa statistics, overall agreement between model predictions and Olsons map is between fair and good, depending on the scale of comparison. The model performed well in comparison to other global vegetation models. Apparently the calculation of radiation balance and the resulting Dryness Index and Potential Evaporation provides important information for predicting the distribution of the major vegetation zones of the world.

Energy and mass exchange and the productivity of main Siberian ecosystems (from Eddy covariance measurements). 1. heat balance structure over the vegetation season

Abstract A bioclimatic vegetation model is used to reconstruct the palaeoclimate of Siberia during the mid-Holocene, a warm, moist period also known as the Holocene climatic optimum. Our goal is to determine the magnitude of climatic anomalies associated with mapped changes in vegetation classes. Reconstructed anomalies are the logical outcome of the bioclimatic assumptions in the Siberia vegetation model operating on location-specific differences in the palaeomap of Khotinsky and the modern map of Isachenko. The Siberian vegetation model specifies the relationship between vegetation classes and climate using climatic indices (growing-degree days, dryness index, continentality index). These indices are then converted into parameters commonly used in climatic reconstructions: January and July mean temperatures, and annual precipitation. Climatic anomalies since the mid-Holocene are then displayed by latitude and longitude. An advantage of a model-based approach to climatic reconstruction is that grid cells can be modelled independently, without the need for interpolation to create smoothed temperature and precipitation contours. The resulting pattern of anomalies is complex. On average, Siberian winters in the mid-Holocene were 3.7°C warmer than now, with greater warming in higher latitudes. The major winter warming was concentrated in the Taiga zone on the plains and tablelands of East Siberia, where a warm and moist climate was necessary to support a broad expanse of shade-tolerant dark-needled Taiga. January temperatures averaged about 1°C warmer than now across southern Siberia, although large areas show no change. July temperature anomalies (0–5°C) are distributed mostly latitudinally, with anomalies increasing with latitude above 65°N. At latitudes below 65°N, July temperature was nearly the same as today across Siberia. Based on July temperatures, Siberian summers in the mid-Holocene were 0.7°C warmer than todays. Annual precipitation in Siberia was predicted to be 95 mm greater in the mid-Holocene than now. Most of the increase was concentrated in East Siberia (154 mm average increase). The precipitation anomalies are small in the south. Large precipitation anomalies are found in central and northeastern Siberia. This location corresponds rather closely to the large anomalies in January temperature in East Siberia. The annual precipitation increase was >200 mm more than present precipitation in Yakutia. This increase corresponds to the deep penetration of moisture-demanding dark-needled species ( Pinus sibirica, Abies sibirica, Picea obovata ) into East Siberia in the mid-Holocene, where currently only drought-resistant light-needled species ( Larix spp.) are found. Another area of increased precipitation was along the Polar Circle in West Siberia and at the base of the Taymyr Peninsula in East Siberia. In combination with 2–5 C warmer summers, moister climates there allowed forests to advance far northward into what is now the Tundra zone.

Energy and mass exchange and the productivity of main Siberian ecosystems (from Eddy covariance measurements). 2. carbon exchange and productivity

Abstract With growing concern about predicted global warming, increasing attention is being paid to the phytomass (living plant mass) components of forest stands and their role in the carbon cycle. The ability to predict phytomass components from commonly available inventory data would facilitate our understanding of the latter. We focus on Scots pine ( Pinus sylvestris L.) stands in Russia, with the objective of predicting stand phytomass (Mg ha −1 ) for the four major stand components: needles, crown, stems, and roots. The study area includes regions in Russia where Scots pine is a stand-forming species: from European Russia (33°E) to Yakutia (130°E) in eastern Siberia. To ensure that results will be widely applicable, only variables consistently measured in forest inventories were considered as possible predictors: stand age, site quality class, and stocking (stand stem volume with bark, m 3 ha −1 ). Stand phytomass data were obtained from numerous regional and local phytomass studies, and supplemented with additional unpublished data. This is the first comprehensive study synthesizing stand level phytomass relations for P. sylvestris for most of its range in Russia. The combined results from over 18 regional and local phytomass studies provide a level of generality that is not possible with individual local studies. In addition to estimating stand phytomass components across a wide range of conditions, these phytomass models can also be used to verify carbon allocation rules in process-based models.

Energy and Mass Exchange and the Productivity of the Main Ecosystems of Siberia (From Eddy Covariance Measurements). 2. Carbon fluxes and productivity

Phytomass (live plant mass) and net primary productivity are major components of the terrestrial carbon balance. A major location for phytomass storage is the subcontinent of Siberia, which is dominated by extensive reaches of taiga (boreal forest). The responsiveness of the phytomass component of the carbon pool is examined by comparing vegetation in the mid-Holocene (4600–6000 years before present) to modern potential vegetation. The mid-Holocene was warmer and moister in middle and northern Siberia than today, producing conditions ideal for boreal forest growth. As a result, both northern and middle taiga were dominated by shade-tolerant dark-needled species that thrive in moist climates. Today, shade-tolerant dark-needled taiga is restricted to western Siberia and the highlands of central Siberia, with its central and eastern components in the mid-Holocene replaced today by light-demanding light-needled species with lower productivity and phytomass. Total phytomass in Siberia in the mid-Holocene was 105.0 ± 3.1 Pg, compared to 85.9 ± 3.2 Pg in modern times, a loss of 19.1 ± 3.1 Pg of phytomass. The reduction in dark-needled northern and middle taiga classes results in a loss of 28.8 Pg, while the expansion of the corresponding light-needled taiga results in a gain of 13.5 Pg, a net loss of 15.3 Pg. The loss is actually greater, because the modern figures are for potential vegetation and not adjusted for agriculture and other anthropogenic disturbances. Given long periods for vegetation to approach equilibrium with climate, the phytomass component of the carbon pool is responsive to climate change. Changes in net primary productivity (NPP) for Siberia between the mid-Holocene and the present were not as large as changes in phytomass. A minor decrease in NPP (0.6 Pg yr−1, 10%) has occurred under our cooler modern climate, primarily due to the shift from dark-needled taiga in the mid-Holocene to light-needled taiga today.

Energy and mass exchange and the productivity of the main ecosystems of Siberia (According to the results of measurements by the method of turbulent pulsation). II. Carbon exchange and productivity

Direct measurements of heat balance (latent heat and sensible heat fluxes) by the eddy covariance method, undertaken in 1998–2000 and 2002–2004, are used to obtain information on the daily, seasonal, and annual dynamics of energy and mass exchange between the atmosphere and the typical ecosystems of Siberia (middle taiga pine forest, raised bog, and true four grass steppe with data for typical tundra) along the Yenisei meridian (90° E).