Stable isotope analysis of diet confirms niche separation of two sympatric species of Namib Desert lizard

We used stable isotopes of carbon and nitrogen to study the trophic niche of two species of insectivorous lizards, the Husab sand lizard Pedioplanis husabensis and Bradfield's Namib day gecko living sympatrically in the Namib Desert. We measured the δ¹³C and δ¹⁵N ratios in lizard blood tissues with different turnover times (whole blood, red blood cells and plasma) to investigate lizard diet in different seasons. We also measured the δ¹³C and δ¹⁵N ratios in available arthropod prey and plant tissues on the site, to identify the avenues of nutrient movement between lizards and their prey. Through the use of stable isotope mixing models, we found that the two lizard species relied on a largely non‐overlapping but seasonally variable array of arthropods: P. husabensis primarily fed on termites, beetles and wasps, while R. bradfieldi fed mainly on ants, wasps and hemipterans. Nutrients originating from C₃ plants were proportionally higher for R. bradfieldi than for P. husabensis during autumn and late autumn/early winter, although not summer. Contrary to the few available data estimating the trophic transfer of nutrients in ectotherms in mixed C₃ and C₄/crassulacean acid metabolism (CAM) plant landscapes, we found that our lizard species primarily acquired nutrients that originated from C₄/CAM plants. This work adds an important dimension to the general lack of studies using stable isotope analyses to estimate lizard niche partitioning and resource use.     

钱穆的礼文化价值观研究

国学大师钱穆一生重视宣扬中国优秀传统文化,尤其把礼文化放在核心地位。钱穆对传统礼文化价值的评判素有主见,对传统礼文化秉持扬弃的态度。钱穆的礼文化价值观之形成离不开先祖、父母的教诲及家乡等地传统礼文化的环境影响。     

添加象草鲜茎叶饲喂对母猪繁殖性能的影响

选择年龄体重接近的健康大长二元杂交经产母猪 2 0头 ,随机分为 2组 ,每组 10头。 2组基础日粮一致 ,试验组母猪每天每头添加 1 2 5kg的桂牧 1号象草鲜茎叶 (预产期前 3天及哺乳期不添加 )采食 ,对照组不添加。结果 ,试验组比对照组配种受胎率提高 9个百分点 (P <0 0 5 ) ,初生窝重比对照组提高 8 9% (P <0 0 5 ) ,哺乳期母猪耗料比对照组提高 18% ,断奶窝重比对照组提高14 7% (P <0 0 1) ,说明桂牧 1号象草鲜茎叶对母猪繁殖性能有较好促进作用。     

Effects of chemical inhibitors on soil protozoan dynamics in a desert ecosystem

This field study was designed to monitor the composition, size, and dynamics of the protozoan population during the different seasons in an arid environment. The protozoan populations contribution to the ecological system was examined using chemical inhibitors. Samples were collected from the 0 to 10 and 10 to 20-cm depths from four different treatment plots: Nemacur (nematocide), Edigan (biocide), water, and control. The results obtained from the field study demonstrated that the number of protozoan individuals was affected by season and was significantly higher as spring neared. The flagellate population appeared in soil samples throughout the year, whereas the ciliate population appeared mainly during the wet seasons (winter and spring). Use of soil population inhibitors did not demonstrate any significant differences between treatments in the number of protozoan individuals in winter, summer, and autumn. During the populations proliferation in spring, a significant change between treatments occurred in population composition and size.     

宁夏黄土高原风沙区畜牧业发展的资源、环境问题及对策

本文对宁夏黄土高原风沙区着重从大农业生态经济系统中人口、资源和环境间协调的角度出发,探讨该区畜牧业的主要自然和人为限制因素及产生的问题,畜牧业发展的潜力及今后的主要对策等。     

青海省土砾质荒漠草地分布及基本特征

对青海省土砾质荒漠亚类草地的分布和基本特征进行了较为系统的描述,为该亚类草地的利用、保护和维护荒漠草地生态系统的良性循环提供了较为详尽的基本资料.     

毛乌素沙地不同地下水位埋深下土壤水补给特征及影响因素

土壤水分是毛乌素沙地植被恢复与生态重建的关键因子,揭示不同地下水位(Groundwater Level,GWL)埋深下土壤水的补给与转化特征对于提高水资源利用效率和植被可持续建设具有重要意义.试验通过定期测定毛乌素沙地东南缘圪丑沟流域沙柳(GWL范围253～260 cm)、樟子松(GWL范围87～93 cm)和长柄扁桃...     

阿拉善荒漠两种典型豆科植物主要物候期对气候变化的响应

基于近40a阿拉善荒漠监测点气候要素和植被物候观测资料,采用线性倾向率、逐步回归等方法,分析该地区1981−2019年气候变化特征以及短脚锦鸡儿、猫头刺两种豆科植物主要物候期时间的演化趋势,探讨阿拉善荒漠豆科植物物候变化的气候驱动因子,旨在为气候变化背景下典型荒漠地区植物物候研究提供科学依据。结果表明：（1）近40a监测点平均气温为8.8℃,并以0.46℃10a−1的趋势显著上升（P＜0.01）;年日照时数平均为3136h,以约98h10a−1的速率显著减少（P＜0.01）;年降水量平均为159.0mm,呈波动增加趋势,降水量变化倾向率为19.08mm10a−1（P＜0.05）;（2）研究区短脚锦鸡儿、猫头刺的返青期、开花期明显提前,黄枯期略有推后,整个生长季呈延长趋势;短脚锦鸡儿、猫头刺多年平均返青期日序分别为898、9010,开花期日序为11610、13116,黄枯期日序为30810、31510;（3）植被物候期与气候因子的相关分析发现,短脚锦鸡儿和猫头刺物候期变化主要受到气温的限制,日照时数对两种植物的返青期略有影响,降水量仅对短脚锦鸡儿黄枯期有一定影响。     

模拟降水对短花针茅荒漠草原土壤呼吸的影响

试验在内蒙古四子王旗短花针茅荒漠草原开展,旨在研究模拟降水对土壤呼吸、土壤温度和土壤湿度的影响。在长期不同放牧平台增设4个不同降水处理(减水50%、自然降水、增水50%和增水100%)。于2016年7月~10月使用土壤碳通量测试仪器(Li-8100)测量土壤呼吸速率,同时用仪器自带的温、湿度探针监测0~10cm土壤温度和0~5cm土壤体积含水量。结果表明:随着降水量的增加,土壤呼吸和土壤湿度呈现显著增加趋势,土壤温度显著降低(P<0.05);7月~10月土壤呼吸速率呈现下降趋势;土壤呼吸与0~10cm土壤温度和0~5cm体积含水量之间存在极显著正相关关系,决定系数分别是0.3117和0.7307(P<0.0001)。结果表明,水分是影响荒漠草原土壤呼吸的关键因子之一。     

The roles of salt (sodium nitrate) and fog in weathering: a laboratory simulation of conditions in the northern Atacama Desert, Chile

A laboratory experiment was used as a model to investigate interactions within a hyper-arid and hyper-saline weathering environment based on conditions observed in the Atacama Desert, northern Chile. The experimental design produced a matrix of 18 different weathering environments with six levels of salt (sodium nitrate) availability and three levels of fog precipitation. The experiment took place over an 11-week period. Over this time, 10 weekly fog applications modified the experimental conditions. From a theoretical perspective, the weekly fog applications generate an open rather than a closed system, which may be more representative of conditions in the field. The breakdown of the chalk blocks used was assessed in two ways. Firstly, qualitative observations were made at weekly intervals of the nature of morphological changes. Secondly, at the end of the experiment, breakdown was assessed by counting the number of discrete pieces greater than 1 g liberated by each block. The electrical conductivity at the base of each block was also measured. Collectively, the results indicate that fog appears to control the rate of breakdown and that salt availability controls the timing of the response. The style of breakdown was similar irrespective of the fog and salt levels. The morphological observations show the results of a sequence of events, with the blocks evolving as the experiment progresses; as such, they provide an experimental example of the role of inheritance in weathering processes.