应用MODIS-NDVI对草原植被变化监测研究--以锡林郭勒盟为例

利用新一代卫星遥感数据MODIS,进行草原植被专题信息的提取,同时结合地面调查数据,分析2002、2003年5月30日归一化植被指数(NDVI),并根据其分级图,对天然草原植被长势的时间和空间变化特征和变化规律进行研究,从而对引起草原植被发生变化的可能原因,特别是由于禁牧、休牧的影响进行分析评价.     

黄河首曲流域草地生态与自然环境退化成因及对策研究

近50年来黄河首曲流域草场退化、沙化,水土流失,生物多样性减少,生态系统功能弱化.分析了黄河首曲流域气候、生态观测资料及统计资料,结果表明:造成生态与自然环境退化的主要原因是气候变化和环境蠕变.黄河首曲大部分区域降水量年际变化呈下降趋势,气温年际变化呈上升趋势,增温速度均大于全国增温速度.草地年干燥指数呈显著上升趋势,20世纪80年代末至2004年明显趋于干旱化,气候变化是草地生态退化的自然诱发因素.超载过牧、滥采乱挖、人为破坏、生物链失衡等环境蠕变是造成生态退化的人为因素.二者共同作用导致黄河首曲流域草地与湿地生态与自然环境退化.控制放牧、防止滥采乱挖、建立自然生态保护区是维护该区域生态系统平衡的措施.     

Voles and weasels in the boreal Fennoscandian small mammal community: what happens if the least weasel disappears due to climate change?

Climate change, habitat loss and fragmentation are major threats for populations and a challenge for individual behavior, interactions and survival. Predator–prey interactions are modified by climate processes. In the northern latitudes, strong seasonality is changing and the main predicted feature is shortening and instability of winter. Vole populations in the boreal Fennoscandia exhibit multiannual cycles. High amplitude peak numbers of voles and dramatic population lows alternate in 3–5‐year cycles shortening from North to South. One key factor, or driver, promoting the population crash and causing extreme extended lows, is suggested to be predation by the least weasel. We review the arms race between prey voles and weasels through the multiannual density fluctuation, affected by climate change, and especially the changes in the duration and stability of snow cover. For ground‐dwelling small mammals, snow provides thermoregulation and shelter for nest sites, and helps them hide from predators. Predicted increases in the instability of winter forms a major challenge for species with coat color change between brown summer camouflage and white winter coat. One of these is the least weasel, Mustela nivalis nivalis. Increased vulnerability of wrong‐colored weasels to predation affects vole populations and may have dramatic effects on vole dynamics. It may have cascading effects on other small rodent–predator interactions and even on plant–animal interactions and forest dynamics.     

北方农牧交错带气候变化及草地生产力的响应--以甘肃省定西县为例

根据北方农牧交错带(定西县1970～2000年)的气候资料,分析了该地区30年来气候变化周期、趋势及其草地气候生产力的变化.研究结果表明气温呈上升而降水呈减少的态势,并且都具有7年的准周期,预计在下一个周期平均气温可能会上升到7.88℃,而降水将减少到377.7mm.在温度升高而降水不变的情景下,温度每升高1℃草地生产潜力增加96.49kg/hm2·a;相反,在降水减少而温度不变的情况下,降水每减少1mm草地生产潜力减少5.06kg/hm2·a.     

The roles of calving migration and climate change in the formation of the weak genetic structure in the Tibetan antelope (Pantholops hodgsonii)

Geographical barriers and distance can reduce gene exchange among animals, resulting in genetic divergence of geographically isolated populations. The Tibetan antelope (Pantholops hodgsonii) has a geographical range of approximately 1600 km across the Qinghai–Tibet Plateau, which comprises a series of tall mountains and big rivers. However, previous studies indicate that there is little genetic differentiation among their geographically delineated populations. To better understand the genetic structure of P. hodgsonii populations, we collected 145 samples from the 3 major calving regions, taking into consideration their various calving grounds and migration routes. We used a combination of mitochondrial sequences (Cyt b, ATPase, D‐loop and COX I) to investigate the genetic structure and the evolutionary divergence of the populations. Significant, albeit weak, genetic differentiation was detected among the 3 geographical populations. Analysis of the genetic divergence process revealed that the animals gradually entered a period of rapid genetic differentiation approximately 60 000 years ago. The calving migration of P. hodgsonii cannot be the main cause of their weak genetic structure because this cannot fully homogenize the genetic pool. Instead, the geological and climatic events as well as the coupling vegetation succession process during this period have been suggested to greatly contribute to the genetic structure and the expansion of genetic diversity.     

气候变暖对新疆不同秋眠级紫花苜蓿种植适宜性的影响

基于新疆102个气象台站1961−2019年逐日平均气温、最低气温资料,采用统计学方法以及ArcGIS的空间插值技术,在对影响新疆紫花苜蓿种植的主要气候因子 ≥ 5 ℃积温、冬季最低气温时空变化特征分析的基础上,以80%保证率 ≥ 5 ℃积温和90%保证率冬季最低气温作为指标因子,研究了气候变暖背景下,新疆不同秋眠级紫...     

Sheep helminth parasitic disease in south eastern Scotland arising as a possible consequence of climate change

The climate in the UK is changing, with a trend towards increased rainfall in the autumn and winter and warmer average temperatures throughout the year. There has also been a 4-week extension of the herbage growing season over the past 40 years. These changes may have implications for the epidemiology of sheep helminth parasites. Here, we describe production-limiting disease outbreaks caused by Haemonchus contortus, Nematodirus battus, Teladorsagia circumcincta and Fasciola hepatica in sheep flocks in south eastern Scotland. The occurrence and timing of these disease outbreaks could not have been predicted in this region highlighting changes in the epidemiology of helminth infections from the patterns historically described. These cases are used to introduce discussion regarding the potential effects of climate change on the epidemiology of helminth parasites and the implications for sheep farming in the UK.     

Temperature control of the distributional range of five C3 grass species in the uKhahlamba-Drakensberg Park,KwaZulu-Natal,South Africa

Global climate change is expected to influence the distribution of global biodiversity. C₄ and C₃ perennial grasses co-occur in the fire-prone KwaZulu-Natal uKhahlamba-Drakensberg grasslands, with C₃ grass species occurring at cooler locations in the mountain range and C₄ grass species at warmer locations. If a warming climate is expected to cause a contraction in the ranges of C₃ grasses, evidence of temperature controlling current distributions is required. This study modelled the distribution of five C₃ grass species, namely Tenaxia stricta, Tenaxia disticha, Festuca costata, Merxmuellera drakensbergensis and Merxmuellera stereophylla, to temperature-related surrogate variables using presence–absence data collected across the environmental heterogeneity of the mountain range. Distributions of each species, and of all species combined, were modelled using generalised additive models. These temperature-related variables accounted for the distribution of all five species, least so for F. costata. Four species could therefore contract in range in response to climate change, whereas F. costata is least likely to have a range contraction directly related to a warming climate and could experience a range expansion owing to the fertilising effect of increased [CO₂].     

山西省肉牛养殖布局变动与成因分析

[目的]研究山西省肉牛养殖区域布局的演变规律,有利于科学制定肉牛养殖政策、有利于提高肉牛综合生产能力,为提升肉牛产业竞争力奠定基础。[方法]文章基于2005—2020年山西省肉牛养殖年度数据,运用区域重心分析法测算肉牛养殖区域布局重心变动的轨迹;运用面板数据模型对肉牛养殖区域布局变动因素进行了实证分析。[结果]结果表明,玉米产量、能繁母牛数量、人均收入、规模化品牌化农产品数量、支持养殖的财政政策、抑制散养的禁牧政策对山西省肉牛养殖布局有影响。[结论]提出了肉牛养殖数量应和当地的饲草资源紧密结合、发展种养一体化、降低养殖成本增加市场竞争力、积极应对环保要求、合理利用财政支持政策等建议。