Decadal plant composition changes in grazed native grassland

Most high value grasslands of south‐eastern Australia are restricted to small fragmented areas of public land. However, a significant proportion of native grassland is privately owned, managed with grazing rather than fire and is rarely monitored. Hence, a better understanding of grassland management and conservation on the private estate is required. Eco‐markets are policy instruments that incentivise private landholders to effectively manage and conserve native vegetation. However, short funding cycles restrict the capacity of monitoring programs to assess long‐term vegetation changes. In this study, 17 native grassland remnants on private land managed with livestock grazing were monitored before and during a 4‐year eco‐market and 6 years after it ended to determine how composition had changed over 10 years of monitoring. Numerous grassland attributes were either maintained or improved over the 10‐year period, which coincided with one of the most severe and long‐lasting droughts in recent history (i.e. the Millennium drought). In addition, several threatened species were identified as part of the program. A decline in exotic forb richness, native grass cover and native forb richness suggests there is also some impact of the Millennium drought on plant mortality as evidenced by altered litter dynamics. Inherent variability year‐to‐year for most measures of grassland attributes over the monitoring period indicates that climatic conditions have a strong influence on grassland dynamics. Our ability to determine the driver(s) of grassland composition was limited by monitoring program design. Future eco‐market monitoring programs should have adequate resources allocated to enable effective monitoring designs, that incorporate reference information and control sites, and should aim to be long‐term (i.e. >10 years). This will provide clearer insights into the drivers of grassland dynamics and allow for refinement of management options for conservation of this threatened community.     

滇西北高山微水体与溪流生境底栖动物多样性和环境特征

高山微水体由于面积微小且通过地表径流形成串联结构常常被认为与高山溪流具有类似的生境, 然而由于这两类生境中环境因子与底栖动物多样性存在差异, 它们在生态系统中的作用可能完全不同。滇西北地区是全球生物多样性热点区域之一, 境内高山微水体和高山溪流分布密集, 在区域底栖生物多样性维持方面具有重要的功能, 然而目前对这两类高山淡水生态系统的研究较少。为了比较这两类生境环境因子的异同及其对底栖动物多样性的维持作用, 2015年6月, 作者在云南省怒江州贡山县的高山峡谷内, 对27个高山微水体和同区域分布的1条高山溪流(海拔高差500 m范围)的底栖动物多样性和水环境因子进行了实地调查。结果表明: (1)高山微水体和高山溪流底栖动物群落中优势分类单元种群数量均比较庞大, 而稀有分类单元数量较多且种群较小; (2)两种生境在环境因子、物种多样性、功能多样性和群落结构方面的差异明显, 高山溪流有较高的物种丰富度、物种多样性和功能多样性; (3)高山微水体底栖动物多样性的分布与水环境因子无关, 而高山溪流底栖动物多样性与群落结构的形成受到与流速关联的水环境因子和海拔的影响。因此, 高山微水体与高山溪流不能简单地视为类似的生境类型, 它们对区域底栖动物多样性和生态功能维持可能具有不同的作用。     

圈养马麝的个性分类

本研究在甘肃兴隆山国家级自然保护区马麝繁育场展开,分别于2012年7月和2013年8月,针对374只圈养马麝,采用基于量表的个性评价法进行评价调查。结果表明:可建立包含17个个性项目的圈养马麝个性量表,因子分析显示每个项目公因子方差和载荷均大于0. 4,各因子累计贡献率为60. 33%,表明此量表具有较好的结构效度。此外Cronbach’sα系数为0. 787,表明量表具有较高的内部一致性信度,量表设计合理;因子分析和聚类分析结果显示,可将圈养马麝划分为五大个性维度:侵略性、社会性、刻板性、温顺性、活跃性。研究发现,圈养马麝个性维度与野生个体的个性类型划分存在差异,主要是受圈养条件和人为干扰等影响。圈养马麝个性量表和五大个性维度的建立对指导马麝繁育管理具有重要实践价值,填补了马麝个性研究的空缺,并为进一步进行麝类动物个性研究奠定了基础。另外,此类个性层次研究方法具有较好区分度,可为其他动物个性的初期研究提供参考。     

川西高山林线土壤活性碳、氮对短期增温的响应

随着温室效应的加剧,受低温限制的高山林线生态系统对全球气候变暖较为敏感,可能直接影响到植物的生长和土壤碳氮过程.本研究假设气候变暖会改变高山生态系统土壤活性碳氮含量,在四川省理县米亚罗高山生态系统定位站,采用开顶式模拟增温装置(OTC)模拟增温对土壤活性碳、氮的短期影响.分别于2017年4、7和10月,采集OTC以及对照样地(CK)内土壤有机层和矿质土壤层的原状土壤,测定土壤可溶性有机碳(DOC)、土壤微生物生物量碳(MBC)、土壤可溶性有机氮(DON)和土壤微生物生物量氮(MBN)含量.结果表明: 模拟增温使年均气温升高0.88 ℃,土壤有机层和矿质土壤层的年均温度分别提高0.48和0.23 ℃.模拟增温没有显著改变土壤有机质和含水量,但显著提高了矿质土壤层的pH值,同时显著降低了非生长季矿质土壤层的DOC、DON含量;季节变化对两个层次的DOC、DON和MBN含量有极显著影响,而MBC没有明显的季节动态;增温和季节交互作用对矿质土壤层的DOC和DON有显著影响.土壤有机层的MBC、MBN含量显著高于矿质土壤层.土壤活性碳、氮与土壤有机质和含水量呈极显著正相关,MBC、MBN与土壤pH呈极显著正相关,MBN与土壤温度呈显著负相关.     

A dynamic multi‐scale occupancy model to estimate temporal dynamics and hierarchical habitat use for nomadic species

Distribution models are increasingly being used to understand how landscape and climatic changes are affecting the processes driving spatial and temporal distributions of plants and animals. However, many modeling efforts ignore the dynamic processes that drive distributional patterns at different scales, which may result in misleading inference about the factors influencing species distributions. Current occupancy models allow estimation of occupancy at different scales and, separately, estimation of immigration and emigration. However, joint estimation of local extinction, colonization, and occupancy within a multi‐scale model is currently unpublished. We extended multi‐scale models to account for the dynamic processes governing species distributions, while concurrently modeling local‐scale availability. We fit the model to data for lark buntings and chestnut‐collared longspurs in the Great Plains, USA, collected under the Integrated Monitoring in Bird Conservation Regions program. We investigate how the amount of grassland and shrubland and annual vegetation conditions affect bird occupancy dynamics and local vegetation structure affects fine‐scale occupancy. Buntings were prevalent and longspurs rare in our study area, but both species were locally prevalent when present. Buntings colonized sites with preferred habitat configurations, longspurs colonized a wider range of landscape conditions, and site persistence of both was higher at sites with greener vegetation. Turnover rates were high for both species, quantifying the nomadic behavior of the species. Our model allows researchers to jointly investigate temporal dynamics of species distributions and hierarchical habitat use. Our results indicate that grassland birds respond to different covariates at landscape and local scales suggesting different conservation goals at each scale. High turnover rates of these species highlight the need to account for the dynamics of nomadic species, and our model can help inform how to coordinate management efforts to provide appropriate habitat configurations at the landscape scale and provide habitat targets for local managers.     

Grazing intensity enhances spatial aggregation of dominant species in a desert steppe

Understanding how grazing activity drives plant community structure or the distribution of specific species in a community remains a major challenge in community ecology. The patchiness or spatial aggregation of specific species can be quantified by analyzing their relative coordinates in the community. Using variance and geostatistical analysis methods, we examined the quantitative characteristics and spatial distribution of Stipa breviflora in a desert steppe in northern China under four different grazing intensities (no grazing, NG, light grazing, LG, moderate grazing, MG, and heavy grazing, HG) at three small spatial scales (10 × 10 cm, 20 × 20 cm, 25 × 25 cm). We found that grazing significantly increased cover, density, and proportion in standing crop of S. breviflora, but decreased height. The spatial distribution of S. breviflora was strongly dependent upon the sampling unit and grazing intensity. The patchiness of S. breviflora reduced with sampling scale, and spatial distribution of S. breviflora was mainly determined by structural factors. The intact clusters of S. breviflora were more fragmented with increasing grazing intensity and offspring clusters spread out from the center of the parent plant. These findings suggest that spatial aggregation can enhance the ability of S. breviflora to tolerate grazing and that smaller isolated clusters are beneficial to the survival of this dominant species under heavy grazing.     

Mismatches between breeding phenology and resource abundance of resident alpine ptarmigan negatively affect chick survival

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Phylogeography of Pulsatilla cernua (Ranunculaceae), a grassland species,in Japan

The genetic diversity and structure of Pulsatilla cernua, a continental‐grassland relict, were investigated using variations in chloroplast DNA (cpDNA) and microsatellites of nuclear DNA. In the analyses of three cpDNA regions, 17 haplotypes were found in 24 populations of P. cernua from Japan, Korea, and Russia. Although the route and time of migration between the continent of Asia and Japan could not be well resolved, the cpDNA haplotype network suggests the existence of several ancient lineages in Japan and a recent secondary migration from Japan to the continent. Microsatellite analyses did not indicate genetic structure among the Japanese populations, indicating the existence of gene flow across the distribution area until recently. These results indicate that the present fragmentation of P. cernua in Japan may reflect a rapid, recent reduction from a previously large, continuous distribution.