Scenarios of changes in biodiversity for the year 2100 can now be developed based on scenarios of changes in atmospheric carbon dioxide, climate, vegetation, and land use and the known sensitivity of biodiversity to these changes. This study identified a ranking of the importance of drivers of change, a ranking of the biomes with respect to expected changes, and the major sources of uncertainties. For terrestrial ecosystems, land-use change probably will have the largest effect, followed by climate change, nitrogen deposition, biotic exchange, and elevated carbon dioxide concentration. For freshwater ecosystems, biotic exchange is much more important. Mediterranean climate and grassland ecosystems likely will experience the greatest proportional change in biodiversity because of the substantial influence of all drivers of biodiversity change. Northern temperate ecosystems are estimated to experience the least biodiversity change because major land-use change has already occurred. Plausible changes in biodiversity in other biomes depend on interactions among the causes of biodiversity change. These interactions represent one of the largest uncertainties in projections of future biodiversity change.

Изучена роль факторов урбанизации, фрагментации местообитаний и структуры лесных насаждений в распространении адвентивных растений подлеска в лесопарках Екатеринбурга. Выполнены учеты подроста и взрослых особей подлеска на 11 трансектах, проанализировано 103 геоботанических описания на круговых площадках 400 м 2. Первая гипотеза состояла в том, что с ростом урбанизации видовое богатство и обилие адвентивных растений увеличивается, а аборигенных-снижается. Она подтверждена частично. С ростом урбанизации богатство и обилие адвентивных растений увеличиваются, но доля аборигенных-не снижаются. Вторая гипотеза состояла в том, что степень адвентизации подлеска выше на границах лесопарков по сравнению с их внутренними частями. Она не подтверждена. Краевой эффект, т.е. изменение признаков состояния подлеска от границ в глубь насаждений не установлен ни в отношении группы аборигенных, ни в отношении группы адвентивных видов. Третья гипотеза определяла, что степень адвентизации подлеска выше на участках лесопарков, примыкающих к дорогам, и с длительно существующими границами насаждений. Она подтверждена частично. С одной стороны, степень адвентизации подлеска выше на участках вблизи дорог по сравнению с участками вблизи пустырей. Но, с другой стороны, она выше на участках с недавно возникшими границами насаждений по сравнению с участками с длительно существующими границами.

Understanding and predicting ecosystem functioning (e.g., carbon and water fluxes) and the role of soils in carbon storage requires an accurate assessment of plant rooting distributions. Here, in a comprehensive literature synthesis, we analyze rooting patterns for terrestrial biomes and compare distributions for various plant functional groups. We compiled a database of 250 root studies, subdividing suitable results into 11 biomes, and fitted the depth coefficient β to the data for each biome (Gale and Grigal 1987). β is a simple numerical index of rooting distribution based on the asymptotic equation Y=1-β, where d = depth and Y = the proportion of roots from the surface to depth d. High values of β correspond to a greater proportion of roots with depth. Tundra, boreal forest, and temperate grasslands showed the shallowest rooting profiles (β=0.913, 0.943, and 0.943, respectively), with 80-90% of roots in the top 30 cm of soil; deserts and temperate coniferous forests showed the deepest profiles (β=0.975 and 0.976, respectively) and had only 50% of their roots in the upper 30 cm. Standing root biomass varied by over an order of magnitude across biomes, from approximately 0.2 to 5 kg m. Tropical evergreen forests had the highest root biomass (5 kg m), but other forest biomes and sclerophyllous shrublands were of similar magnitude. Root biomass for croplands, deserts, tundra and grasslands was below 1.5 kg m. Root/shoot (R/S) ratios were highest for tundra, grasslands, and cold deserts (ranging from 4 to 7); forest ecosystems and croplands had the lowest R/S ratios (approximately 0.1 to 0.5). Comparing data across biomes for plant functional groups, grasses had 44% of their roots in the top 10 cm of soil. (β=0.952), while shrubs had only 21% in the same depth increment (β=0.978). The rooting distribution of all temperate and tropical trees was β=0.970 with 26% of roots in the top 10 cm and 60% in the top 30 cm. Overall, the globally averaged root distribution for all ecosystems was β=0.966 (r =0.89) with approximately 30%, 50%, and 75% of roots in the top 10 cm, 20 cm, and 40 cm, respectively. We discuss the merits and possible shortcomings of our analysis in the context of root biomass and root functioning.