The Mixed Addition of Biochar and Nitrogen Improves Soil Properties and Microbial Structure of Moderate-Severe Degraded Alpine Grassland in Qinghai-Tibet Plateau

Effective microorganisms input efficiently improves the vegetation and microbial community of degraded alpine grassland

Soil beneficial microorganism deficiency in the degraded grasslands have emerged as the major factors negatively impacting soil quality and vegetation productivity. EM (effective microorganisms) has been regarded as a good ameliorant in improving microbial communities and restoring degraded soil of agricultural systems. However, knowledge was inadequate regarding the effects of adding EM on the degraded alpine grassland. Four levels of EM addition (0, 150, 200, 250 mL m-2) were conducted to investigate the effects of EM addition on soil properties and microorganisms of degraded alpine grassland. The addition of EM increased aboveground biomass, soil organic carbon, total nitrogen, available phosphorus, and microbial biomass, but decreased soil electric conductivity. Meanwhile, the relative biomasses of gram-negative bacteria decreased, while the ectomycorrhizal fungi and arbuscular mycorrhizal fungi increased after EM addition. The relationship between microbial communities and environmental factors has been changed. The restore effect of EM increased with the increase of addition time. These results indicated that EM addition could be a good practice to restore the health of the degraded alpine grassland ecosystem.

Spatiotemporal variation of microbial communities in surficial sediments of Cochin estuary, southwest coast of India

Microorganisms play a major role in the degradation of organic matter in sediments. However, the spatiotemporal variation and factors affecting these communities are not clearly understood. At the same time, conventional hydrographic and geochemical parameters do not offer an accurate assessment of transitional ecosystems. PLFA biomarkers which are specific to different taxonomic groups of microorganisms are able to provide a detailed assessment of the community composition in an environment and reflect a more direct assessment of the biological health of transitional ecosystems. We, therefore, conducted a comparison of PLFA biomarkers at four stations (Barmouth, B; Vaduthala, V; Munambam, M; and Arookutty, A) during three seasons (pre-monsoon, PRE; monsoon, MON; and post-monsoon, POST) in the Cochin estuary (CE). Each of the stations represented either a reference point (B), high pollution (V), high salinity (M), or low pollution (A). The communities determined using PLFA profiles could be categorized into six major groups with each group capable of reflecting the state of the ecosystem which correlated with the conventional parameters. The six groups were: G + ve Bacillota (formerly Firmicutes) and G-ve anaerobes (G-I), G-ve aerobic prokaryotes (G-II), ectomycorrhizal fungi (G-III), arbuscular mycorrhizae (G-IV), type-I methanotrophs (G-V), and microeukaryotes (G-VI). The prokaryotes were predominant in sediments amounting to over 78% of the total PLFAs detected, followed by the microeukaryotes. The freshwater-influenced stations were partially anaerobic in nature during PRE and MON and were mainly affected by both marine and terrestrial organic matter inputs, at times prominent in sewage matter. During POST season, CE behaves uniformly, especially in station M. Salinity and DO of BW and texture and organic matter of the sediment were the driving forces for microbial community structure. The reduced presence of cyclopropane fatty acids suggested that the CE was not under any stress during the study period. Our results using PLFA-based community profiling not only provide the fundamental information required to quickly access the impact of stress and other environmental inputs on the CE but also offer a more robust and realistic assessment of the nature of microbial communities in the ecosystem. A periodic and systemic assessment of PLFA profiles at these stations in CE throughout the year will enable the generation of enough metadata enabling a better understanding of this ecosystem and its efficient management in the long term.

Spatiotemporal Variations of Human Pressure on Key Biodiversity Areas in the Qinghai–Tibet Plateau: A Comparative Analysis

A key biodiversity area (KBA) is one of the important emerging area-based conservation measures that is being implemented recently in China; however, the human pressure faced by a KBA is still unclear. This study analyzed the spatiotemporal variation of human pressure on KBAs from 1990 to 2017 and compared it with the human pressure on national natural reserves (NNRs) through a case study of the Qinghai–Tibet Plateau. In addition, changes in the trend of human pressure before and after 2010 were analyzed to examine the influence of conservation policies on human pressure. Results showed that human pressure on KBAs and NNRs gradually increased from 1990 to 2017. Furthermore, the growth rates and mean values of human pressure in KBAs were higher than those in NNRs. After the implementation of conservation policies in 2010, the growth rates of human pressure on both KBAs and NNRs have significantly slowed, and the areas with negative growth in both KBAs and NNRs have gradually expanded. In addition to providing an understanding of the changing spatiotemporal trends of human pressure on KBAs, this study can serve as a reference to formulate policies for the improvement of the effectiveness of conservation.