氮添加对不同坡度退化高寒草甸土壤真菌多样性的影响

为明确不同坡度退化高寒草甸土壤真菌多样性对外源氮添加的响应规律,选取三江源区果洛州不同坡度退化程度相近的高寒草甸,进行外源氮添加试验,探讨不同氮添加水平：低等量氮添加（LN,2 g ·m^-2）、中等量氮添加（MN,5 g ·m^-2）和高等量氮添加（HN,10 g ·m^-2）对不同坡度退化草地土壤真菌多样性的影响.结果表明：①土壤中真菌分布类群集中于子囊菌门（Ascomycota）、担子菌门（Basidiomycota）、被孢霉门（Mortierellomycota）和球囊菌门（Glomeromycota）,其中优势菌门为子囊菌门和担子菌门.子囊菌门、根肿黑粉门和油壶菌门等相对丰度在不同坡度间差异显著（P<0.05）.而同一坡度不同氮添加处理下真菌各门丰度变化差异均不显著.②优势属为被孢霉属和Archaeorhizomyces,它们对不同坡度和不同氮添加水平的响应无差异性.③已鉴定95个菌属在不同坡度间存在显著差异（P<0.05）.④一些相对丰度<1%的属在同一坡度不同水平氮添加间存在显著差异（P<0.05）.5 α和β多样性分析整体表现为在不同坡度和不同氮添加水平下土壤真菌群落无差异性.表明退化高寒草甸土壤真菌对外源氮添加的响应不敏感.     

黄河源区斑块化退化高寒草甸土壤细菌群落多样性变化

为研究海拔变化和退化过程中高寒草甸土壤细菌群落多样性的变化规律,利用MiSeq高通量测序技术,分析不同海拔活动斑块、非活动斑块、恢复斑块和高寒草甸土壤细菌群落多样性,利用冗余分析对细菌多样性和环境因子进行分析.结果发现,3种类型斑块中主要的土壤细菌门均是变形菌门（Proteobacteria）、放线菌门（Actinobacteriota）和酸杆菌门（Acidobacteriota）.细菌优势属为RB 41 、鞘脂单胞菌属（Sphingomonas）和慢生根瘤菌属（Bradyrhizobium）.RB 41 和慢生根瘤菌属相对丰度随海拔升高而下降,随斑块演替而增加,但3种类型退化斑块相对丰度均显著低于高寒草甸（P<0.05）.退化斑块土壤碳固定功能的细菌丰度,大于健康高寒草甸.不同斑块的细菌Chao1指数和物种数显著高于高寒草甸（P<0.05）.冗余分析发现,生物结皮盖度和全氮是海拔4013 m处细菌优势门的主要影响因子;生物量、全氮和pH对高海拔4224 m细菌优势门影响较大.生物量和全钾显著影响海拔4013 m的细菌属分布,海拔4224 m地区莎草科盖度和速效氮为细菌优势属的主要影响因子.生物结皮和pH对细菌多样性影响较大.不同海拔地区细菌的影响因子发生着较大变化,在研究细菌多样性变化的过程中,不仅要关注高寒草地退化的影响,还应考虑海拔高度的作用.     

生物炭和秸秆还田对微咸水滴灌棉田土壤真菌群落结构多样性的影响

微咸水灌溉增加土壤盐分,改变土壤环境,进而影响土壤真菌的结构和多样性.在长期微咸水灌溉的基础上,分别添加生物炭和秸秆（采用等碳量设计,分别为3.7 t·hm^-2和6 t·hm^-2）,探究生物炭和秸秆对土壤理化性质和真菌群落结构多样性的影响.结果表明：与不施生物炭和秸秆（对照）相比,生物炭施用显著增加土壤的pH、全碳、速效钾和速效磷含量,但显著降低土壤电导率,降低幅度为20.71%;秸秆处理显著增加土壤的速效钾和速效磷含量,但显著降低土壤容重和电导率,降低幅度为4.17%和64.50%.生物炭和秸秆处理对真菌群落Chao1指数和ACE指数有增加趋势,对Shannon指数和Simpson指数有降低趋势.土壤优势真菌门类为子囊菌门、被孢霉门、担子菌门、壶菌门和球囊菌门;优势真菌属为毛壳菌属、赤霉菌属、镰刀菌属、Idriella和被孢霉属.施加生物炭和秸秆提高子囊菌门、被孢霉门、担子菌门、球囊菌门和毛壳菌属的相对丰度;但降低壶菌门、赤霉菌属和Idriella的相对丰度.LEfSe分析表明,施用生物炭和秸秆还田降低真菌群落潜在生物标志物数量.RDA结果显示,土壤真菌群落结构与EC_1：5和TN显著相关.微咸水灌溉给土壤带来了不利影响,其中EC_1：5和TN是驱动土壤真菌群落结构变化的主要因子,土壤真菌群落通过生物炭和秸秆对土壤的改良作用来适应盐胁迫环境.     

滇西北高原生态恢复过程中土壤侵蚀特征及其影响因子

滇西北高原由于地处生态脆弱的石灰岩区,水土流失严重,探讨该区生态恢复过程中土壤侵蚀的变化规律,为开展人工植被建设提供依据。以时空互代的方法,通过径流小区,对坡面的产沙产流特性及其影响因素进行研究。结果表明:天然次生林和人工混交林均有较好的调节径流和减少泥沙的作用,产沙量分别比坡耕地减少了51.46%、43.18%,产流量也相应降低了39.39%、24.24%。在最大次降雨条件下,荒草丛、坡耕地、次生林和混交林单次降雨的产沙量分别占试验期产沙总量的55.38%、55.58%、58.35%和58.05%,产流量相应占产流总量的64.72%、64.63%、73.85%和55.39%。而且,产流产沙量与土壤有机质质量分数均存在明显正相关,与乔、灌层植物多样性及均匀度指数等呈显著负相关性(P<0.05)。因此,乔灌草结合的群落结构配置模式是滇西北地区水土保持林营造的目标和方向。     

Pseudoreplication in Tropical Forests and the Resulting Effects on Biodiversity Conservation

Tropical forest ecosystems are threatened by habitat conversion and other anthropogenic actions. Timber production forests can augment the conservation value of primary forest reserves, but studies of logging effects often yield contradictory findings and thus inhibit efforts to develop clear conservation strategies. We hypothesized that much of this variability reflects a common methodological flaw, simple pseudoreplication, that confounds logging effects with preexisting spatial variation. We reviewed recent studies of the effects of logging on biodiversity in tropical forests (n = 77) and found that 68% were definitively pseudoreplicated while only 7% were definitively free of pseudoreplication. The remaining proportion could not be clearly categorized. In addition, we collected compositional data on 7 taxa in 24 primary forest research plots and systematically analyzed subsets of these plots to calculate the probability that a pseudoreplicated comparison would incorrectly identify a treatment effect. Rates of false inference (i.e., the spurious detection of a treatment effect) were >0.5 for 2 taxa, 0.3–0.5 for 2 taxa, and <0.3 for 3 taxa. Our findings demonstrate that tropical conservation strategies are being informed by a body of literature that is rife with unwarranted inferences. Addressing pseudoreplication is essential for accurately assessing biodiversity in logged forests, identifying the relative merits of specific management practices and landscape configurations, and effectively balancing conservation with timber production in tropical forests. Pseudoreplicación en Bosques Tropicales y Efectos Resultantes Sobre la Conservación de Biodiversidad     

Lichen Conservation in Heavily Managed Boreal Forests

Lichens are an important component of the boreal forest, where they are long lived, tend to accumulate in older stands, and are a major food source for the threatened woodland caribou (Rangifer tarandus caribou). To be fully sustainable, silvicultural practices in the boreal forest must include the conservation of ecological integrity. Dominant forest management practices, however, have short‐term negative effects on lichen diversity, particularly the application of herbicides. To better understand the long‐term effects of forest management, we examined lichen regeneration in 35 mixed black spruce (Picea mariana) and jack pine (Pinus banksiana) forest stands across northern Ontario to determine recovery following logging and postharvest silvicultural practices. Our forest stands were 25–40 years old and had undergone 3 common sivilcultural treatments that included harvested and planted; harvested, planted, and treated with N‐[phosphonomethyl] glycine (glyphosate); and harvested, planted, and treated with 2,4‐dichlorophenoxyacetic acid (2,4‐D). Forest stands with herbicide treatments had lower lichen biomass and higher beta and gamma diversity than planted stands that were not treated chemically or control stands. In northwestern Ontario, planted stands that were not treated chemically had significantly greater (p < 0.05) alpha diversity than stands treated with herbicides or control stands. Our results show that common silvicultural practices do not emulate natural disturbances caused by wildfires in the boreal forest for the lichen community. We suggest a reduction in the amount of chemical application be considered in areas where lichen biomass is likely to be high and where the recovery of woodland caribou is an objective. Conservación de Líquenes en Bosques Boreales Manejados Intensivamente     

教育与区域经济发展差异--基于江苏和江西的实证分析

本文主要分析了教育对于区域经济发展差异的影响及作用机理。通过对江苏和江西两省的实证分析，提出并验证了教育发晨所引起的地区经济发展的差异，主要有两个方面共同作用的结果：即教育总体发展程度不同所产生的规模效应和不同教育层次发晨的侧重差异所引起的结构效应。最后。对今后区域教育发展战略的进一步完善提出了政策建议。     

Nitrogen deposition alters soil chemical properties and bacterial communities in the Inner Mongolia grassland

Nitrogen deposition has dramatically altered biodiversity and ecosystem functioning on the earth; however, its effects on soil bacterial community and the underlying mechanisms of these effects have not been thoroughly examined. Changes in ecosystems caused by nitrogen deposition have traditionally been attributed to increased nitrogen content. In fact, nitrogen deposition not only leads to increased soil total N content, but also changes in the NH₄⁺-N content, NO₃^--N content and pH, as well as changes in the heterogeneity of the four indexes. The soil indexes for these four factors, their heterogeneity and even the plant community might be routes through which nitrogen deposition alters the bacterial community. Here, we describe a 6-year nitrogen addition experiment conducted in a typical steppe ecosystem to investigate the ecological mechanism by which nitrogen deposition alters bacterial abundance, diversity and composition. We found that various characteristics of the bacterial community were explained by different environmental factors. Nitrogen deposition decreased bacterial abundance that is positively related to soil pH value. In addition, nitrogen addition decreased bacterial diversity, which is negatively related to soil total N content and positively related to soil NO₃^--N heterogeneity. Finally, nitrogen addition altered bacterial composition that is significantly related to soil NH₄⁺-N content. Although nitrogen deposition significantly altered plant biomass, diversity and composition, these characteristics of plant community did not have a significant impact on processes of nitrogen deposition that led to alterations in bacterial abundance, diversity and composition. Therefore, more sensitive molecular technologies should be adopted to detect the subtle shifts of microbial community structure induced by the changes of plant community upon nitrogen deposition.