Genetic variability of six indigenous goat breeds using major histocompatibility complex-associated microsatellite markers

The present study aimed at analyzing the genetic variability of indigenous goat breeds (Capra hircus) using the MHC-associated microsatellite markers BF1, BM1818, BM1258, DYMS1, and SMHCC1. The following breeds were included: Chinese Xuhuai, Indian Changthangi and Pashmina, Kenyan Small East African (SEA) and Galla, and Albanian Vendi. To examine genetic variability, the levels of heterozigosity, degrees of inbreeding, and genetic differences among the breeds were analyzed. The mean number of alleles ranged from nine in the Galla to 14.5 in the Vendi breed. The mean observed heterozygosity and mean expected heterozygosity varied from 0.483 in the Vendi to 0.577 in the Galla breed, and from 0.767 in the SEA to 0.879 in the Vendi breed, respectively. Significant loss of heterozygosity (p < 0.01) indicated that these loci were not in Hardy-Weinberg equilibrium. The mean F_IS values ranged from 0.3299 in the SEA to 0.4605 in the Vendi breed with a mean value of 0.3623 in all breeds (p < 0.001). Analysis of molecular variance indicated that 7.14% and 4.74% genetic variation existed among the different breeds and geographic groups, whereas 92.86% and 95.26% existed in the breeds and the geographic groups, respectively (p < 0.001). The microsatellite marker analysis disclosed a high degree of genetic polymorphism. Loss of heterozygosity could be due to genetic drift and endogamy. The genetic variation among populations and geographic groups does not indicate a correlation of genetic differences with geographic distance.     

林地土壤性质空间变异性与土壤入渗过程的研究

运用经典统计学和地统计学理论,研究了缙云山马尾松林地土壤水分、电导率和pH值的空间变异性。结果表明,各变量符合正态分布,电导率与pH值呈正相关关系(α=0.01)。行内变异性分析表明,各变量沿坡向各行变异系数的均值都大于垂直于坡向的均值。不同坡向对行间的差异分析表明,含水量在沿坡向和垂直于坡向上均无显著差异,在垂直于坡向上各行电导率和pH值存在显著差异(α=0.01)。地统计学分析结果显示,含水量在沿坡向和垂直于坡向上的变异具有漂移特征,电导率在垂直于坡向方向上具有空间结构性,在沿坡向上随机变异过大,不能体现出空间自相关的特点;pH值在垂直于坡向上具有漂移特征,沿坡向上为纯块金效应。典型植被下土壤水分入渗研究表明,农耕地和阔叶林稳渗率为4.81mm/min和3.15 mm/min,分别是针叶林的14倍和9倍;1 h入渗总量分别为1365.58 mm和518.46 mm,是针叶林的37倍和14倍。     

基于DPSIR模型的黄土高原生态敏感性演变格局及驱动力分析

摸清生态系统敏感性时空演变格局，对其驱动因素及未来发展趋势进行探测是修复和提高生态系统稳定性的重要内容。黄土高原是世界上水土流失最严重和生态环境最脆弱的地区之一，探究该地区生态敏感性时空演变特征及驱动因素，科学划分生态敏感性治理分区对于促进国家生态文明建设具有重要意义。基于“驱动-压力-状态-影响-响应”（driving-pressure-state-impact-response，DPSIR）框架，耦合空间距离指数和全排列多边形图示指标法构建生态敏感性指标体系，使用地理信息演变图谱和地理探测器研究黄土高原2000—2020年5个时间点生态敏感性时空格局和驱动力，最终划分生态敏感性治理分区。结果表明：1）研究期内黄土高原生态敏感性表现为西北高、东南低的分布特征，时间上先增加后下降。2）研究期内黄土高原生态敏感性转移类型以波动稳定型为主，生态改善区面积占比最大（35.17%），变化0次和1次的面积占比62.06%，生态环境演变稳定向好。3）生态敏感性的各驱动因素中，NDVI和降水量以及两者与其他因子的交互作用对于黄土高原生态敏感性具有明显的驱动作用。4）2030年低度敏感将成为黄土高原的主要敏感类型；沙地和农灌区以及黄土高塬沟壑区的中西部是生态敏感性治理的重点地区。整体来看，黄土高原生态环境有所好转，生态治理措施取得了积极成效，该研究可为黄土高原生态治理及高质量发展提供参考。     

稻田土壤养分的空间变异性研究

本研究以嘉善县陶庄农场内一块5.1hm2的水稻田为研究区,区内不规则采样,共128个采样点。以土壤的pH、有机质、全磷、全氮、碱解氮、速效钾和速效磷含量为研究对象,研究其相应的统计规律,结果表明土壤各养分属性的变异系数在6.3%~35.61%之间,pH为5.3%;采用地统计的半方差函数分析,发现有机质,全氮,碱解氮和速效钾在一定范围内存在空间相关性;采用克立格方法进行最优内插,绘制了养分含量分布图,并对其空间变异进行了初步分析。     

Spatial heterogeneity in the relocation of added C within the structure of an upland grassland soil

A pulse of ¹³CO₂ was added to the above ground vegetation in an upland grassland to determine the effects of faunal diversity on the flux of carbon to the surface horizons of the soil. Faunal diversity was manipulated by liming and biocide treatments for three years prior to the pulse addition. The relocation of ¹³C within roots and rhizosphere soil was determined by analysis of samples of bulk soil and of specific features identified on soil thin sections on four dates after the addition of the ¹³CO₂ pulse. Analysis of bulk soils showed only a small enrichment in ¹³C and no significant effects of the treatments. Analysis by isotope ratio mass spectrometry of the products of in situ laser combustion of root material and aggregates formed from faunal excrement showed that the distribution of the newly photosynthesised ¹³C is very localised, with large spatial variability in soil and root δ¹³C at scales of less than 1 mm. δ¹³C values ranged from the natural abundance level of around −28‰ to −4.9‰ in roots and to −8.4‰ in aggregates. The small pulse and large spatial variability masked any effects of the liming and biocide treatments in these soils. However, the variability in the relocation of newly photosynthesised carbon may help to explain the large spatial variability found in bacterial numbers at the sub-mm scale within soils and emphasises the importance of the accessibility of substrates to decomposers in undisturbed structured soils.     

地面灌溉土壤入渗参数时空变异性试验研究

基于典型田块的试验观测数据,开展地面灌溉条件下冬小麦生长期间土壤入渗性能时空变异性的试验研究,描述土壤入渗参数的时空变异分布特征,分析各参数间存在的相关关系。结果表明,在冬小麦生长期内,土壤入渗参数的空间变异强度呈持续性减弱趋势,其时间变异性逐渐下降并趋于稳定。土壤入渗性能在冬灌后各时段间的差异并不显著,故在此后的灌溉试验设计与管理或地面灌溉模拟中,可基本无需考虑土壤入渗性能的时间变异性影响。考虑到土壤入渗参数f0和Z180之间存在着强烈的互相关性和非常相近的时空变异分布特征,可借助f0的时空变异分布特点达到描述土壤入渗性能、衡量土壤入渗能力的目的。     

潮土区土壤有机质含量的趋势演变研究——以禹城市为例

通过分析山东省禹城市100个采样点1980年和2003年耕层土壤的有机质含量,研究了土壤有机质的时空变异特征,探讨了潮土区有机质含量的变化,形成了研究区1980年和2003年有机质含量空间分布图及1980~2003年有机质含量的空间变化图。分析了研究区有机质含量增加的原因。研究结果表明,该市目前土壤有机质含量平均为14.68g kg-1,比1980年的6.0g kg-1增加了8.68 g kg-1,年均提高0.38g kg-1。土壤表层含盐量的降低为土壤养分含量提高提供了条件。     

道路边坡与自然边坡对苔藓植物空间变异性的影响

苔藓植物在边坡生态系统中有着非常重要的作用，具有涵养水源，保持水土的功能。选择成渝铁路、成昆铁路沿线典型的路堑边坡和自然边坡，对苔藓植物的种类与生物特性的空间变异性以及环境因子进行了调查研究。结果表明，在不同地点苔藓植物种类差异明显。夹江县的试验点苔藓植物共7种，主要以藓纲植物为主，金堂县的试验点苔藓植物共2种，主要以苔纲植物为主。在同一地点，夹江县的试验点苔藓植物种类表现为路堑边坡多于自然边坡，而金堂点路堑边坡与自然边坡苔藓植物种类完全相同。同是路堑边坡，夹江点苔藓植物最大持水率显著大于金堂点。苔藓植物生物量与草本植物盖度、枯落物鲜重呈负相关关系，与土壤硬度呈正相关关系，其中与枯落物鲜重和土壤硬度的相关性达到了极显著的水平。     

Spatial variability of O layer thickness and humus forms under different pine beech–forest transformation stages in NE Germany

Spatial variability of humus layer (O layer) thicknesses can have important impacts upon soil water dynamics, nutrient storage and availability, as well as plant growth. The purpose of the present study was to elucidate the impact of forest‐transformation practices on the spatial variability of O layer thicknesses. The study focused on the Kahlenberg forest area (NE Germany) with stands of Scots pine (Pinus sylvestris) and European beech (Fagus sylvatica) of different age structures that form a transformation chronosequence from pure Scots pine stands towards pure European beech stands. Topsoil profiles including both, the O layer and the uppermost humic mineral soil horizon were excavated at intervals of 0.4 m along 15–20 m long transects, and spatial variability of O layer thicknesses was quantified by variogram analysis. The correlation lengths of total O layer thickness increased in the sequence consisting of pure pine stand (3.1 m) → older mixed stand (3.7 m) → pure beech stand (4.5 m), with the exception of the younger mixed stand, for which no correlation lengths of total O layer thickness could be determined. The degree of spatial correlation, i.e., the percentage of the total variance which can be described by variograms, was highest for the two monospecies stands, whereas this percentage was distinctly lower for the two mixed stands. A similar minimum for the two mixed stands was observed for the correlation lengths of the Oh horizon. These results suggest that the spatial structures of forest‐transformation stands may be interpreted in terms of a disturbance (in the form of the underplanting of beech trees). After this disturbance, the forest ecosystem requires at least 100 y to again reach relative equilibrium. These findings are in line with the results of other soil‐related investigations at these sites.