分类： 生物学 >> 生态学 提交时间： 2023-05-11 合作期刊: 《干旱区科学》
摘要：Soil faunas account for 23% of known animal species and play a crucial role in ecosystem processes such as mineralizing nutrients, regulating microbial community composition, forming soil aggregates, and enhancing primary productivity. However, due to global climate change, population density, community composition, and distribution patterns of soil fauna vary. Understanding the responses of soil fauna to major environmental change facilitate the conservation of biodiversity. Therefore, a review work of recent researches for analysing the effects of key environmental factors on soil fauna, such as warming, drought, food quality, and soil physical-chemical properties was studied. For most species, warming may exert a positive effect on their abundance and population development, however, it can inhibit the survival and reproduction of hibernating species. Drought leads to low soil porosity and water holding capacity, which reduces soil fauna population and changes their community composition. Drought also can reduce the coverage of flora and alter microclimate of the soil surface, which in turn indirectly reduces fauna abundance. Climate warming and elevated atmospheric carbon dioxide can reduce litter quality, which will force soil fauna to change their dietary choices (from higher-quality foods to poor quality foods) and reduce reproduction for survival. However, it is still predicted that enhanced species richness of plant (or litter) mixtures will positively affect soil fauna diversity. Habitat loss caused by the deterioration of soil physical-chemical property is primary factor affecting soil fauna. We mainly discuss the threats of increased salinity (a major factor in arid land) to soil fauna and their potential responses to anthropogenic disturbance in saline soils. The increase in soil salinity can override other factors that favour habitat specialists, leading to negative effects on soil fauna. Moreover, we find that more studies are needed to explore the responses of soil fauna in saline soils to human activities. And the relationship of important ecological processes with soil fauna density, community structure, and diversity needs to be redefined.
分类： 地球科学 >> 地理学 提交时间： 2021-12-03 合作期刊: 《干旱区科学》
摘要： The purpose of the current study was to investigate the eco-physiological responses, in terms of growth and C:N:P stoichiometry of plants cultured from dimorphic seeds of a single-cell C4 annual Suaeda aralocaspica (Bunge) Freitag and Schütze under elevated CO2. A climatic chamber experiment was conducted to examine the effects of ambient (720 μg/L) and CO2-enriched (1440 μg/L) treatments on these responses in S. aralocaspica at vegetative and reproductive stages in 2012. Result showed that elevated CO2 significantly increased shoot dry weight, but decreased N:P ratio at both growth stages. Plants grown from dimorphic seeds did not exhibit significant differences in growth and C:N:P stoichiometric characteristics. The transition from vegetation to reproductive stage significantly increased shoot:root ratio, N and P contents, but decreased C:N, C:P and N:P ratios, and did not affect shoot dry weight. Moreover, our results indicate that the changes in N:P and C:N ratios between ambient and elevated CO2 are mainly caused by the decrease of N content under elevated CO2. These results provide an insight into nutritional metabolism of single-cell C4 plants under climate change.
分类： 地球科学 >> 地球科学史 提交时间： 2020-06-22 合作期刊: 《干旱区科学》
摘要： Since 1996, transgenic Bacillus thuringiensis (Bt) cotton has been commercially grown in numerous countries in an effort to stem the losses caused by key lepidopteran pests. However, the development of pest resistance to Bt toxins has jeopardized the continued utilization of Bt cotton. As a strategy designed to circumvent the development of resistance, Bt cotton varieties expressing two or more toxins targeting the same pest have been introduced. Nevertheless, from the perspective of long-term planting of Bt cotton, the potential risk of cross-resistance to these Bt toxins is a threat that cannot be ignored. In this paper, we review current research (including that based on the analysis of protein binding sites and resistance genes) on the resistance of cotton bollworm (Helicoverpa armigera) to the Bt toxins Cry1Ac and Cry2Ab and the interrelationship between these toxins. On the basis of existing evidence, we assume that the actions of Cry1Ac and Cry2Ab against cotton bollworm are not completely independent, and then propose the ''resistance-associated gene mutation potential hypothesis''. Although the mechanisms underlying the resistance of pests to Bt toxins are yet to be comprehensively elucidated, this hypothesis could undoubtedly have important implications for adopting ''pyramid'' strategy in the future. Further research is recommended to devise strategies to retard the development of H. armigera resistance to Bt cotton, either using different Bt toxins or their various combinations.
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