分类: 地球科学 >> 地球科学史 提交时间: 2020-10-20 合作期刊: 《干旱区科学》
摘要: In forest ecosystems, interactions between overstory trees and understory herbs play an important role in driving plant species diversity. However, reported links between overstory tree and understory herb species diversity have been inconsistent, due to variations in forest types and environmental conditions. Here, we measured species richness (SR) and diversity (Shannon-Wiener (H') and Simpson's (D) indices) of overstory trees and understory herbs in the protected Tianshan Wild Fruit Forest (TWFF), Northwest China, to explore their relationships along the latitudinal, longitudinal, elevational, and climatic (current climate and paleoclimate) gradients in 2018. We found that SR, and H' and D diversity indices of overstory trees and understory herbs exhibited a unimodal pattern with increasing latitude and elevation (P<0.05) and negative associations with longitude (P<0.01). Along the climatic gradients, there were U-shaped patterns in SR, and H' and D diversity indices between trees and herbs (P<0.05). SR, and H' and D diversity indices for overstory tree species were positively associated with those for understory herbs (P<0.01). These findings indicate that overstory trees and understory herbs should be protected concurrently in the TWFF to increase effectiveness of species diversity conservation programs.
分类: 环境科学技术及资源科学技术 >> 环境科学技术基础学科 提交时间: 2019-12-06 合作期刊: 《干旱区科学》
摘要: The association between biodiversity and belowground biomass (BGB) remains a central debate in ecology. In this study, we compared the variations in species richness (SR) and BGB as well as their interaction in the top (0–20 cm), middle (20–50 cm) and deep (50–100 cm) soil depths among 8 grassland types (lowland meadow, temperate desert, temperate desert steppe, temperate steppe desert, temperate steppe, temperate meadow steppe, mountain meadow and alpine steppe) and along environmental gradients (elevation, energy condition (annual mean temperature (AMT) and potential evapotranspiration (PET)), and mean annual precipitation (MAP)) based on a 2011–2013 survey of 379 sites in Xinjiang, Northwest China. The SR and BGB varied among the grassland types. The alpine steppe had a medium level of SR but the highest BGB in the top soil depth, whereas the lowland meadow had the lowest SR but the highest BGB in the middle and deep soil depths. The SR and BGB in the different soil depths were tightly associated with elevation, MAP and energy condition; however, the particular forms of trends in SR and BGB depended on environmental factors and soil depths. The relationship between SR and BGB was unimodal in the top soil depth, but SR was positively related with BGB in the middle soil depth. Although elevation, MAP, energy condition and SR had significant effects on BGB, the variations in BGB in the top soil depth were mostly determined by elevation, and those in the middle and deep soil depths were mainly affected by energy condition. These findings highlight the importance of environmental factors in the regulations of SR and BGB as well as their interaction in the grasslands in Xinjiang.
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: Water-use efficiency(WUE) is a key plant functional trait that plays a central role in the global cycles of water and carbon. Although increasiing precipitahon may cause vegetation changes, few studies have explored the linkage between alteration in vegetation and WUE.