太行山低山石灰岩区水土保持林地类型研究

通过对太行山低山石灰岩区水保林定性和定量兼有的１３个变量，１７０块标地调查，采用主成分分析方法，对该区的水保林进行排序，结果≤５００ｍ丘陵区可划分为四个类型：灌木盖度〉２０％侧柏，山皂荚乔灌草型，灌木盖度≤２０％侧柏，白草乔草灌云南省 枯落物荆条，酸枣灌草型；无枯     

Tree species composition and similarity in semideciduous forest fragments of southeastern Brazil

This study investigates the influence of fragment size on tree species composition, species richness and on individual groups of species within 11 semideciduous forest fragments in southeastern Brazil. We compared same-sized samples of 500 trees from 10 fragments <100 ha, allocated to three size categories, with three 500-tree samples collected in different areas within a large forest, used as a reference forest. The variation in species richness, in the proportion of species/individuals in dispersal modes, and in the proportion of rare species was not related to fragment size. Nonetheless, comparisons between the mean values of these variables of each fragment size categories, using 95% confidence intervals, showed a wider range of variation within the category of small-sized fragments than in the other size categories. NMS ordination plot also suggested the absence of a relationship between fragment area and tree species composition. However, multiple regressions using the scores from the NMS ordination as response variables, and area and disturbance intensities as predictor variables, suggested that the interaction of area and disturbance might be a good predictor of species composition. Pre-existing environmental heterogeneity and geographical proximity also appeared to play a role in the variations of forest composition among the fragments studied. Our results demonstrated the high conservation value of small forest fragments.     

西天目山森林植被的研究：南坡的森林植被分类

本文是对西天目山自然保护区范围内的植被进行系统分类。用二维极点排序方法,结合现场绘制植被的二维空间结构图,初步将保护区范围内植被分为3个植被型组,9个植被型,35个群系。     

3个甜瓜品种不同生育期同工酶谱活性度的Fuzzy评判

根据3个甜瓜品种4个生育期的POD,SOD和EST同工酶酶谱,建立同工酶谱矩阵,并给出反映酶谱活性度的4个主要特征的量化指标。采用Fuzzy综合评判方法,确定这3种酶的同工酶谱在不同生育期的活性度高低。结果表明,3个甜瓜品种上述3种酶的同工酶活性度变化呈现明显的规律,即由高到低的排序为:(1)POD同工酶谱:开花期>幼苗期>座果期>子叶期;(2)SOD同工酶谱:幼苗期>子叶期>开花期>座果期;(3)Est同工酶谱:开花期>座果期>幼苗期>子叶期。     

Estimation of the bacterial community diversity of soybean-nodulating bradyrhizobia isolated from Rj-genotype soybeans

Abstract

The diversities of communities of soybean-nodulating indigenous bradyrhizobia in Japan were estimated using mathematical ecology methods based on the results of polymerase chain reaction–restriction fragment length polymorphism analysis of the 16S–23S rDNA internal-transcribed spacer region. Polar ordination analysis indicated a significant correlation between the compositions of bradyrhizobial communities and northern latitudes in Japan. This result suggests that the composition and the geographical distribution of indigenous soybean-nodulating bradyrhizobia might be affected by soil temperature and the associated diversity of the host plants acclimatized to a particular climate. Furthermore, for estimation of the compositional difference in bacterial communities among three different Rj-genotype soybean cultivars, an analysis of the diversity indexes was conducted and this analysis indicated differences in the composition of the communities isolated from the Rj ₂ Rj ₃-genotype compared with those from the non-Rj- and Rj ₄-genotype cultivars. This result suggests that Rj ₂ Rj ₃-genotype soybeans might affect not only compatibility with particular bradyrhizobia, but also preference to bradyrhizobia for nodulation.     

山茶亚科植物过氧化物酶同工酶分析

用聚丙烯酰胺凝胶电泳方法,研究10种山茶亚科植物的过氧化物酶同工酶.结果表明,山茶亚科植物属间、亚属间酶谱差异较大,种间差异次之,种内不同品种间差异较小.采用酶谱距离极点排序法,定量研究了各类型间的酶谱差异,排序结果与前人应用传统方法分类的结果相吻合.因此,酶谱距离的极点排序可用于植物亲缘关系的探讨.     

基于RDA排序的现代农业园土地利用功能分区:以剑河县南明镇为例

为给现代农业园区土地利用功能分区方法提供借鉴,以剑河县南明镇现代农业园区项目为例,通过专家决策与咨询法构建了17个因子的评价体系,采用RDA排序法选出功能分区主导因子,再结合园区内各行政村的主导因子指标数据完成对现代农业园区的土地利用功能分区。结果表明:在现代农业园区中人口密度、土地利用率、土地垦殖率、农林牧渔业总产值等指标可作为园区土地利用功能分区的主导因子;园区内22个行政村可划分为综合服务区、农业生产区、休闲农业区和生态农牧业区4类功能区;功能群的方法(RDA排序)可用于指导现代农业园区土地利用功能分区。     

Identification and selection of benchmark sites on litholitic soils of the western grassland biome of South Africa

Abstract

An approach to identify benchmarks for different ecological situations in the grassland biome is described. The approach is illustrated by using information on vegetation change, role of habitat factors and the relative palatability differences between the species of the vegetation on shallow soils of the litholitic complexes in the western parts of the grassland biome. The information was obtained from the ordination and interpretation of vegetation and habitat data gathered at different distances from watering points and in vegetation under different grazing pressures.     

A comparison of five methods for assessing veld condition in the natal midlands

Abstract

Site rankings obtained from five methods of scoring veld condition in the highland sourveld and the moist tall grassveld of the Natal Midlands were correlated with rankings from methods of multivariate analysis. With few exceptions, all methods gave rankings which were strongly correlated with rankings from detrended correspondence analysis, thus indicating that they all provide a practical means of indexing the relative veld condition of sites with reasonable precision. The weighted quantitative climax and key species methods were superior to the other three methods in this respect. The key species method has the advantage of simplicity and speed, and should stimulate farmers to undertake routine monitoring of their veld in these two regions.     

克拉玛依农业综合开发区外围荒漠植物群落分布的土壤环境排序解释

应用DCA数量排序方法,在群落水平上对克拉玛依农业综合开发区外围荒漠植物群落与土壤环境因子之间的关系进行了分析,并对排序轴进行了逐步回归分析。结果表明,该地区植物群落分为盐穗木群落、梭梭群落和白梭梭群落三个典型群落类型。通过排序分析土壤盐渍化与盐穗木群落相关性较强,梭梭群落与土壤肥力、白梭梭群落与土壤酸碱性具有明显的相关性。在梭梭＋白梭梭群落的过渡带上,土壤各因子含量也随之发生过渡变化,而盐穗木群落与梭梭、白梭梭群落有明显的界线,表现出了恶劣生境下的物种趋同性。综合分析表明了在隐域条件下土壤因子含量与植被格局的一致性,也反映了植被对生境的依赖性。