滇池敞水区和湖滨带大型底栖动物群落特征研究

通过2022年开展滇池大型底栖动物调查,对动物物种种类、密度与生物量、群落结构相似性等进行了研究。结果显示,滇池大型底栖动物隶属4门8纲20目32科,敞水区26种,湖滨带54种。敞水区平均密度167.76 ind./m^(2),湖滨带平均密度160.88 ind./m^(2)。软体动物生物量占比较高,节肢动物生物量湖滨带大于敞水区,环节动物生物量敞水区大于湖滨带。敞水区和湖滨带底栖动物群落结构组成差异性显著,优势种差异大。敞水区底栖动物丰富度分布较湖滨带均匀,湖滨带底栖动物多样性较高但丰富度分布相对不均匀。以Shannon-Wiener指数评价分级,敞水区点位5%为“良好”,95%为“中等”;湖滨带点位41%为“良好”,47%为“中等”,6.0%为“较差”,6.0%为“很差”。以Pielou指数评价分级,敞水区点位5%为“优秀”,95%为“良好”;湖滨带点位5.9%为“优秀”,70.4%为“良好”,11.9%为“中等”,5.9%为“较差”,5.9%为“很差”。以期为滇池大型底栖动物监测及针对性开展区域保护修复提供基础性资料参考。

青藏高原极端生境细菌多样性差异及影响因素

土壤微生物组对于生态系统的可持续性至关重要,青藏高原独特的地理环境孕育了多样的极端环境,其土壤细菌组成差异及其驱动因素尚不清楚。【目的】探究不同极端生境土壤细菌多样性及其影响因素。【方法】对7种典型的青藏高原极端生境土壤DNA进行16S rRNA基因高通量测序,通过生物信息分析,找出不同生境细菌群落组成、功能差异;结合土壤理化因子,进一步分析细菌组成差异的潜在影响因素。【结果】通过高通量测序,从7个不同生境的36个土壤样品中共获得16323712高质量reads,26504个可操作分类单元(operational taxonomic units,OTUs)。在门分类水平上,各生境中注释到的放线菌门(Actinomycetota)与假单胞菌门(Pseudomonadota)相对丰度均最高;在属分类水平上,芽孢杆菌属(Bacillus)、Ambiguous_taxa、土壤红杆菌属(Solirubrobacter)、假节杆菌属(Pseudarthrobacter)等为优势属。另外,不同生境中的细菌α多样性无显著差异,但是β多样性差异显著,并且通过LEfSe分析进一步说明了不同生境细菌群落结构的差异性。通过冗余分析(redundancy analysis,RDA)发现,Mg2+、Na+和K+等常量元素是影响细菌群落结构的主要因子,而且其他土壤理化因子对不同生境中优势菌群的分布具有一定的特异性。最后,利用FAPROTAX工具对细菌群落功能预测,发现不同生境的细菌类群参与的氮、硫元素生物地球化学循环过程差异较大。【结论】青藏高原不同极端生境细菌群落结构差异较大,这一成因受到不同土壤理化因子的驱动,并且各生境下大量未注释菌属表明青藏高原具有极为丰富的潜在细菌新物种资源。

Recovery of Collembola in Pinus tabulaeformis Plantations

Large areas of forest plantations have been developed in China. It is important to evaluate the soil fauna in plantations and the conditions needed for their recovery in view of the large areas of plantations in China. Three Pinus tabulaeformis forests, a 26-year-old plantation （P26） and a 45-year-old plantation （P45）, exposed to clear-cutting before plantation, and an 80 260-year-old natural forest （N260）, were chosen to study the effects of different forest ages/types on Collembola community in the lifter and soil layers during 2008 and 2009. Soil conditions in P26 and P45 were significantly deteriorated when compared to N260. A higher value of soil bulk density and lower values of soil organic matter, soil N, litter depth, soil pH, and soil water content were observed in P26 and P45. Totally, the same genera of Collembola tended to occur in the forests of all ages studied; however, the Collembola community structure was significantly impacted by the differences in forest age. Both in the litter and soil layers, the density and generic richness of the Collembola were the highest in N260 and the lowest in P26. Some collembolan groups were sensitive to soil conditions in particular forest ages. N260 was associated with relatively high abundance of Plutomus collembolans and P45 with relatively high abundance of Pseudofolsomia collembolans. The canonical correspondence analysis showed that the community structure of Collembola was mainly affected by forest age in both litter and soil layer. The ordination analysis of non-metric multidimensional scaling also found that the Collembola community did not recover to the level of natural forests in 26-year regeneration after clear-cutting. Even in 45-year regeneration after clear-cutting, the Collembola community only showed a slight recovery to the level of natural forests. Our results clearly showed that both Collembola community and soil conditions did not recover in 26- and 45-year regeneration after clear-cutting in P. tabulaeforrnis plantations; however, they might have the potential to recover in the future because the same genera of Collembola were distributed in the plantations and natural forests.