科尔沁沙地农牧交错区景观持续性研究

科尔沁沙地农牧交错区景观持续性的分析表明,在不同时间尺度上,景观多样性的持续性增加1.038(±0.033),而景观优势度持续性下降0.873(±0.112),说明在1958年固定沙丘地占主导地位的景观逐渐演化成流动沙丘、半固定沙丘、固定沙丘和农田相间分布、平分秋色的景观。在农牧业生产活动的影响下,景观格局的持续性在空间形状的变化上趋向复杂(景观分维数持续性为1.008),而其相邻性下降(景观修改分维数0.953)。斑块尺度上,不同时间尺度的分析显示,流动沙丘和半固定沙丘斑块面积持续性增加,而固定沙丘和农田斑块面积持续减少;从斑块格局的持续性来看,半固定沙丘地空间格局的持续性呈增加的趋势最明显,为1.038(±0.087),固定沙丘地空间格局的持续性呈减少的趋势最明显,为0.806(±0.032);40年来科尔沁沙地的农牧交错活动对斑块修改分维数的持续性影响是一致的,呈下降的趋势,说明该过程减少了景观中斑块间的相邻性。     

都昌县多宝砂山物种多样性研究及保护初探

对鄱阳湖都昌县多宝砂山地区土地风沙化过程中物种多样性的变化特征进行了分析,依据植物种在各类型风沙化土地的出现频率与不同风沙化阶段各生活型植物种的组成,探讨了风沙化过程中植物种的绝灭与定居特点.物种多样性指数分析表明:风沙化过程是物种多样性衰减的过程,风沙化首先导致特有种的绝灭,其次为稀有种.从植物的生活型来看,多年生草本与乔木类植物受风沙化影响最大,而灌木类植物可存活于风沙化过程的各个阶段,在风沙化过程中植物种的绝灭速率大于定居速率.最后,针对造成多宝砂山生物多样性衰减的原因,提出了治理对策,即在控制人类行为干扰的同时,要加强对固定沙丘的管理与保护.      

科尔沁沙地和浑善达克沙地流动沙丘中土壤微生物学特征比较

通过对科尔沁沙地和浑善达克沙地流动沙丘中0～10 cm和>10～20 cm层土壤中微生物数量和生物量碳的比较表明:土壤微生物三大类群(细菌、放线菌和真菌)数量和微生物生物量碳均表现为浑善达克沙地 > 科尔沁沙地,其中两大沙地真菌数量差异显著,细菌和放线菌数量差异不显著,微生物生物量碳差异显著;两大沙地土壤微生物数量和生物量碳在不同土壤层次均表现为>10～20 cm 层高于 0～10 cm层,其中微生物三大类群数量差异均不显著,微生物生物量碳差异显著. 土壤性质的差异导致两大沙地流动沙丘中微生物数量和生物量碳略有不同. 细菌和真菌数量与土壤有机碳和土壤全氮呈显著正相关,与土壤水分含量和pH呈显著负相关,微生物生物量碳与土壤有机碳和土壤全氮呈显著正相关. 两大沙地土壤微生物与土壤养分的层化比率均小于1,科尔沁沙地中微生物数量、生物量碳和土壤养分的层化比率均大于浑善达克沙地,可以推断两大沙地的流动沙丘处于退化状态,而且浑善达克沙地退化速度更快.      

某石化厂区土壤和地下水微生物群落结构特征

为了探明某石化厂微生物群落多样性及与潜在污染物之间的关系,文章利用高通量测序技术开展土壤和地下水微生物群落结构研究,检测了不同深度土壤和地下水中重金属和有机污染物含量。结果表明：土壤中的重金属和C₁₀～C₄₀,以及地下水中的苯、Mn和As都有一定的积累。不同采样点的土壤和地下水微生物群落结构存在显著差异(Bray-Curtis ANOSIM=0.382 7,p=0.001)。土壤的优势菌群有绿弯菌门、放线菌门、变形菌门和酸杆菌门等。地下水的优势菌群有变形菌门、放线菌门和拟杆菌门等。相关关系结果显示,p H、Cd、Hg、Ni、Pb和C₁₀～C₄₀是影响土壤变形菌门、酸杆菌门、绿弯菌门、硝化螺旋菌门、MBNT15、放线菌门、芽单胞菌门和Methylomirabilia等细菌群落结构的主要环境因子,而p H、苯酚、Mn、As、Ni、C₆～C₉和C₁₀～C₄₀是影响地下水变形菌门、Desulfobacteria、放线菌门...     

抚仙湖悬浮颗粒物正构烷烃来源及季节特征

为了探究抚仙湖水体中有机质的正构烷烃来源和时空变化特征,对2016年4月~2017年3月抚仙湖水柱悬浮颗粒物中正构烷烃的分布特征、来源、季节变化特征及其与沉积物中正构烷烃的关系进行了研究.结果表明：抚仙湖水柱悬浮颗粒物中正构烷烃的碳数分布范围在C₁₇~C₃₃之间,呈现以优势峰C₂₇和C₂₉为主的单峰分布模式.在垂直梯度的空间分布上,正构烷烃在变温层和温跃层的浓度高于深水层,最大浓度出现在深20m水层,深层水体中正构烷烃浓度受沉积物再悬浮作用影响微弱;在季节变化上,正构烷烃含量存在明显的季节波动,在10月和4月呈现最高值;其中,中长链正构烷烃（C₂₅、C₂₇和C₂₉）丰度与浮游植物生物量季节变化趋势一致,证明浮游植物是抚仙湖水柱中正构烷烃的主要来源,水温是限制抚仙湖水柱中正构烷烃时空分布的关键因子.浮游植物、流域表土和沉水植物的共同输入是抚仙湖沉积物中正构烷烃C₂₉具有较高丰度的原因,沉积物中正构烷烃（C₃₁和C₂₃）来源相对单一,可以有效指示流域陆源植物和沉水植物输入.本文结果可多应用正构烷烃指标进行抚仙湖长序列钻孔古环境重建研究提供数据支持.     

不同设障年限沙丘土壤粒径和有机碳分布特征

为探讨沙柳沙障对毛乌素沙地土壤粒径和SOC(土壤有机碳)的影响,选取流动沙丘、设障2和7 a的半固定和固定沙丘为研究对象,利用多重分形理论分析不同设障年限沙丘PSD(土壤粒径分布)(以φ计)和w(SOC)的分布特征. 结果表明:设置沙障后,φ(黏粒)、φ(粉粒)与φ(极细砂)增加,φ(细砂)与φ(中砂)下降;土壤粒径的多重分形参数D₁/D₀(D₁为PSD均匀性程度,D₀为PSD宽度)和~f()谱图可以反映沙丘土壤PSD的宽度与均匀性程度,随着设障年限延长,PSD的D₁/D₀均小于流动沙丘,土壤中细粒物质显著增多. D₀表现为设障7 a沙丘(1.01)>流动沙丘(1.00)>设障2 a沙丘(0.93),D₁表现为流动沙丘(0.91)>设障2 a沙丘(0.88)>设障7 a沙丘(0.65). w(SOC)随着设障年限的延长而显著增加,设障7 a沙丘与其他2类沙丘间w(SOC)差异显著;多重分形参数可以表征土壤养分状况与流沙防治状况,设障沙丘上部、下部的w(SOC)与PSD的D₁/D₀之间有明显的相关关系,设障沙丘上部、下部D₁/D₀间呈明显负相关,设障沙丘中部D₁/D₀之间则呈正相关,流动沙丘各部位w(SOC)与D₁/D₀间无显著相关关系.      

科尔沁沙质草地群落物种多样性、生产力与土壤特性的关系

研究了科尔沁沙地6个典型生境类型的沙质草地群落物种多样性与生产力的变化,分析了植物群落格局、物种多样性、生产力与土壤特性的关系.结果表明,从湿草甸向干草甸、固定沙丘、半固定沙丘、半流动沙丘和流动沙丘退化过程中,群落生产力逐渐下降;群落物种多样性先增加后减小,表现出由湿生化和土壤贫瘠化生境向中生、中旱生生境逐渐增加的趋势;土壤极细沙和粉粒含量逐渐递减,土壤有机碳和全氮含量、电导率逐渐递减.典范对应分析(CCA)表明,土壤有机碳、全氮、有效氮、有效钾、土壤含水量、酸碱度和盐分含量的变化共同影响植物群落分布格局,其解释总方差为40％,其中土壤养分梯度是沙质草地群落分布格局的主要土壤限制因子. 沙质草地植物群落的生态优势度、物种多样性指数分别与土壤养分梯度和水盐及酸碱因子二元指标之间存在显著的二元线性关系.沙质草地群落物种多样性变化受土壤养分、水盐及酸碱度因子的共同影响.多元回归模型分析表明,土壤养分对生物量的贡献率为86.73%,明显大于水盐及酸碱度对群落生产力的影响.     

洱海入湖河流水体悬浮颗粒物有机碳氮来源特征

以洱海主要入湖河流水体悬浮颗粒物为研究对象,运用稳定同位素技术,研究了不同季节、不同河流水体悬浮颗粒物中有机碳、氮的来源,探讨了其与流域环境和人类活动之间的关系. 结果表明:①入湖河流水体悬浮颗粒物δ13C的离散程度为夏季<秋季<冬季<春季,变化范围分别为-25.1‰~-16.9‰、-30.0‰~-10.7‰、-20.9‰~-11.0‰和-28.6‰~-14.4‰;δ15N的离散程度为冬季>夏季>春季>秋季,变化范围分别为-0.5‰~8.8‰、5.4‰~10.6‰、3.4‰~7.9‰和6.2‰~8.7‰. ②入湖河流水体悬浮颗粒物有机质的来源,春季以陆源C₃植物和自生有机质为主,并且C₃植物来源的有机质贡献呈逐渐增大趋势;夏季主要来源于陆源C₃植物;秋季仍以陆源C₃植物和水生植物的混合来源为主,但水生植物来源有机质比例有所上升;冬季则以陆源C₃、C₄植物和水生植物来源有机质混合来源为主. ③入湖河流水体悬浮颗粒物中的氮,春季主要来源于土壤流失和水生植物残体,并且土壤流失氮比例逐渐升高;夏季主要来源于土壤流失;秋季来源于土壤流失、化学肥料和水生植物死亡的共同作用;冬季来源于化学肥料、土壤流失和水生植物,并且化学肥料带来的氮比例有所上升.      

互花米草入侵对长江河口湿地CH4排放的影响

为了探讨互花米草入侵对长江河口湿地CH₄排放的影响以及入侵至不同潮位对CH₄排放影响程度的差异及其可能机制,采用邻近互花米草与土著植物群落相配对的试验设计,在长江口东滩湿地的高潮滩和低潮滩各设置1条样线.结果表明,与土著植物相比,互花米草入侵显著增加了长江河口湿地的植物生物量,显著增加了土壤含水量、土壤有机碳含量、总氮含量、微生物碳和氮含量.高潮滩互花米草群落年均CH₄排放强度为（0.68±0.08）mg/（m²·h）,显著高于芦苇群落（0.21±0.01）mg/（m²·h）,低潮滩互花米草和海三棱藨草群落年均CH₄排放速率分别为（8.31±0.50）和（3.93±0.18）mg/（m²·h）,前者显著高于后者.此外,高潮滩互花米草与芦苇群落之间年均CH₄排放强度的差异为（0.47±0.08）mg/（m²·h）,显著低于低潮滩互花米草与海三棱藨草群落之间年均CH₄排放强度的差异（4.37±0.48）mg/（m²·h）.上述结果表明,互花米草入侵通过改善CH₄产生所需底物的质和量,增加土壤含水量和微生物的量,从而显著增加了长江河口湿地CH₄排放量.互花米草入侵至低潮滩增加的CH₄排放量是互花米草入侵至高潮滩的10倍左右,表明互花米草入侵至长江河口湿地对CH₄排放的影响程度可能会有很强的空间异质性,互花米草入侵至更厌氧的土壤环境可能会对CH₄排放的影响程度更大.本研究可为准确估算互花米草入侵对中国海岸带湿地CH₄排放的影响程度,科学管理和合理利用海岸带湿地资源以及应对全球气候变化提供理论依据和科技支撑.     

不同微生物处理工艺对全氟化合物的去除效果

以辽宁省4个采用不同微生物处理工艺的污水处理厂为研究对象,采用WAX固相萃取分离富集和高效液相-质谱联用(HPLC/MS/MS)方法测定了4个污水处理厂中13种PFCs(全氟化合物)〔9种PFCAs(全氟羧酸类化合物,C₄~C₁₂)和4种PFSAs(全氟磺酸类化合物,C₄、C₆、C₈、C₁₀)〕的质量浓度. 研究发现,9种PFCAs(C₄~C₁₂)(记为∑PFCAs)和2种PFSAs(C₄、C₈)(记为∑PFSAs)均有不同程度的检出,水体中各PFCs浓度水平与碳链长度呈显著负相关. 进水中ρ(∑PFCAs)和ρ(∑PFSAs)分别为81.5~135.9和3.7~4.6 ng/L,出水中ρ(∑PFCAs)和ρ(∑PFSAs)分别为47.4~63.3和2.8~3.7 ng/L. 进、出水受PFCAs尤其是短链PFCAs污染较为严重. 4个污水处理厂对PFCs的去除呈现相似的去除效果及规律,即PFCs的去除主要靠活性污泥的吸附作用,而与污水处理厂所采用的微生物处理工艺相关性不大.      

库布齐沙漠典型地区景观变化研究

Spatial pattern analysis is the core component in landscape ecology research. We analyzed the landscape pattern and dynamic process of the Kubuqi Desert by using a typical region as a study area. This study area includes four towns: ShuLinZhao, WangAiZhao, BaiNiJing and JiGeSiTai. The area of cropland, fixed sand dune, woodland, residential area and wetland increased and centralized gradually, while the area of semi-fixed sand dune, drifting sand dune, meadow and washland decreased and dispersed gradually from 1987 to 2003. On the landscape level, the patch shape tended to be regular, and the landscape pattern tended to be simple, causing the fragmentation degree, heterogeneity and diversity of the landscape to decrease. Fixed sand dune, Semi-fixed sand dune, drifting sand dune, meadow and river flood plains were the five main export classes, and residential area, cropland and wetland were the three main import classes. The classes that had a relatively large total area and large average patch area had a smaller extent of gravity center migration, whereas the classes with small total area and small average patch area had a larger extent of gravity center migration; this is because the small patches are easily influenced by human activities or natural factors. In addition, the desertification area and desertification degree reduced gradually in the study area during the period from 1987 to 2003.     

Sown species richness and realized diversity can influence functioning of plant communities differently

Biodiversity–ecosystem functioning experiments (BEF) typically manipulate sown species richness and composition of experimental communities to study ecosystem functioning as a response to changes in diversity. If sown species richness is taken as a measure of diversity and aboveground biomass production as a measure of community functioning, then this relationship is usually found to be positive. The sown species richness can be considered the equivalent of a local species pool in natural communities. However, in addition to species richness, realized diversity is also an important community diversity component. Realized diversity is affected by environmental filtering and biotic interactions operating within a community. As both sown species richness and the realized diversity in BEF studies (as well as local species pool vs observed realized richness in natural communities) can differ markedly, so can their effects on the community functioning. We tested this assumption using two data sets: data from a short-term pot experiment and data from the long-term Jena biodiversity plot experiment. We considered three possible predictors of community functioning (aboveground biomass production): sown species richness, realized diversity (defined as inverse of Simpson dominance index), and survivor species richness. Sown species richness affected biomass production positively in all cases. Realized diversity as well as survivor species richness had positive effects on biomass in approximately half of cases. When realized diversity or survivor species richness was tested together with sown species richness, their partial effects were none or negative. Our results suggest that we can expect positive diversity–productivity relationship when the local species pool size is the decisive factor determining realized observed diversity; in other cases, the shape of the diversity–functioning relationship may be quite opposite.     

Effects of plant diversity on greenhouse gas emissions in microcosms simulating vertical constructed wetlands with high ammonium loading

Wastewater with relatively high nitrogen concentrations is a major source of nitrous oxide (N₂O) and methane (CH₄) emissions and exerts multiple stresses on the environment. Studies have shown that plant diversity plays an important role in ecosystem functioning. However, the effects of plant species diversity on CH₄ and N₂O emissions under high ammonium (NH₄⁺-N) loading rates remain unclear. In this study, a microcosm experiment simulating vertical constructed wetlands supplied with high NH₄⁺-N water levels was established. The treatments included four species richness levels (1, 2, 3, 4) and 15 species compositions. There was no significant relationship between species richness and N₂O emissions. However, N₂O emissions were significantly reduced by specific plant species composition. Notably, the communities with the presence of Rumex japonicus L. reduced N₂O emissions by 62% compared to communities without this species. This reduction in N₂O emissions may have been a result of decreased N concentrations and increased plant biomass. CH₄ emissions did not respond to plant species richness or species identity. Overall, plant species identity surpassed species richness in lowering N₂O emissions from constructed wetlands with high NH₄⁺-N water. The results also suggest that communities with R. japonicus could achieve higher N removal and lower greenhouse gas emissions than other wetland species.     

Variations of plant life form diversity along northeast China transect and its direct gradient analysis

Plant life form diversity and its direct gradientanalysis on a larger scale climate change gradient were tested,based on the data from Northeast China transect platform. Theresults showed that the species numbers, life form richness andlife form diversity were relative higher at the eastern forests andthe ecotone between typical vegetation, while those on the meadowgrasslands and typical steppes were lower. Although plant lifeforms can reflect the climate variations, life form diversity isnot consistent with the major global gradient along the NECT.     

Development of plant communities on set-aside in England

A survey of land taken out of production from the early 1990s onwards under the European Union's set-aside policy in England was carried out in 2008, to record plant communities in set-aside of different ages, effects of distance from the field edge, sowing and soil type. Communities were classified using the Countryside Vegetation System (CVS), Ellenberg indicators and Grime CSR strategy. Species richness declined with distance from the field boundary. Annuals declined with age of set-aside. In older set-aside, perennials dominated, 40-50% of species were grasses, and grasses covered over 70% of the area. Sown areas had a higher proportion of grass species and a lower proportion of wind-dispersed species. Perennial forbs increased over time in naturally regenerated swards but decreased on sown swards. Annuals and grasses were more prevalent on light soils, with more bare ground on heavy soils. Most transects fell into CVS aggregate classes ‘tall grassland/herb’ and ‘fertile grassland’. Ellenberg fertility values decreased initially but then stabilised. Competitor scores increased, and ruderal scores declined, with age. In general, the rate of change declined with age. Although few sites had plant communities of significant conservation interest, the value of set-aside is likely to be primarily to maintain botanical diversity in intensively farmed areas, as well as providing food and habitat for fauna.     

Variations of plant life form diversity along the Northeast China Transect and its direct gradient analysis

Plant life form diversity and its direct gradient analysis on a larger scale climate change gradient were tested, based on the data from Northeast China Transect platform. The results showed that the species numbers, life form richness and life form diversity were relative higher at the eastern forests and the ecotone between typical vegetation, while those on the meadow grasslands and typical steppes were lower.Although plant life forms can reflect the climate variations, life form diversity is not consistent with the major global gradient along the NECT.     

Effects of Oxalis pes-caprae L. invasion in olive groves

The present work aimed at studying the effect of Oxalis pes-caprae invasion in the herbaceous understory of olive groves in the island of Lesvos, Greece. The number of species, their biomass and dead plant material production was followed throughout the vegetative period in invaded and non-invaded plots. Species richness in the area invaded by O. pes-caprae gradually declined and was significantly smaller in comparison with the natural vegetation. Although biomass was equal in the invaded and non-invaded areas 1 month after germination, annual net primary production (NPP) was three times smaller in the invaded than the non-invaded area. Moreover, aboveground dead plant material of O. pes-caprae decomposed faster than a mixture of litter species of the natural vegetation. Lower biomass production in combination with increased decomposition rates of O. pes-caprae is expected to lead to reduced soil C sequestration in invaded areas. It was concluded that although O. pes-caprae does not add a new life form or functional type to the invaded herbaceous system it has considerable impacts on the diversity and ecosystem functions in olive groves.     

Communities of different plant diversity respond similarly to drought stress: experimental evidence from field non-weeded and greenhouse conditions

Accelerating rate of species loss has prompted researchers to study the role of species diversity in processes that control ecosystem functioning. Although negative impact of species loss has been documented, the evidence concerning its impact on ecosystem stability is still limited. Here, we studied the effects of declining species and functional diversity on plant community responses to drought in the field (open to weed colonization) and greenhouse conditions. Both species and functional diversity positively affected the average yields of field communities. However, this pattern was similar in both drought-stressed and control plots. No effect of diversity on community resistance, biomass recovery after drought and resilience was found because drought reduced biomass production similarly at each level of diversity by approximately 30?%. The use of dissimilarity (characterized by Euclidean distance) revealed higher variation under changing environments (drought-stressed vs. control) in more diverse communities compared to less species-rich assemblages. In the greenhouse experiment, the effect of species diversity affected community resistance, indicating that more diverse communities suffered more from drought than species-poor ones. We conclude that our study did not support the insurance hypothesis (stability properties of a community should increase with species richness) because species diversity had an equivocal effect on ecosystem resistance and resilience in an environment held under non-weeded practice, regardless of the positive relationship between sown species diversity and community biomass production. More species-rich communities were less resistant against drought-stressed conditions than species-poor ones grown in greenhouse conditions.     

喀斯特石漠化山区苔藓多样性及水土保持研究

喀斯特石漠化已成为制约我国西南地区可持续发展的重要生态环境问题. 以云南芝云洞山区苔藓植物为研究对象,于2012年1月进行调查和样地设置,共采集样品75份,采用经典形态分类法进行鉴定,分析苔藓多样性及其对水土保持的贡献. 结果表明:苔藓植物有11科25属53种;苔藓植物种数为无石漠化区(34)＞轻度石漠化区(14)＞中度石漠化区(12)＞强度石漠化区(7),丰富度指数也为无石漠化区(2.8748)＞轻度石漠化区(0.1941)＞中度石漠化区(-1.1767)＞强度石漠化区(-1.8923). 石漠化区苔藓植物相似性指数相差较小,其中强度石漠化区与中度石漠化区的相似性指数为0.3750,强度石漠化区与轻度石漠化区为0.3077,中度石漠化区与轻度石漠化区为0.3846;而石漠化区与无石漠化区相似性指数相差较大,其中无石漠化区与强度和轻度石漠化区的相似性指数分别为0.0714和0.0952. 强度、中度和轻度石漠化区与无石漠化区均匀度指数分别为0.5900、0.5133、0.4899和0.6107. 6种优势苔藓植物(长叶纽藓、卷叶湿地藓、东亚小石藓、黑扭口藓、卵叶青藓和狭叶湿地藓)的生物量、成土量和饱和吸水量分别在0.962~9.546、1.294~40.181、8.890~82.571g/m2之间,表明可以将苔藓植物作为该类地区的先锋植物.