放牧利用白羊草灌丛草地的植被特征

在对放牧利用下的白羊草灌丛草地频度、盖度、密度、高度、生物量等数量特征调查基础上,运用系统聚类分析方法,可划分为轻牧、适牧、中牧、重牧和极牧五个阶段.在不同的利用阶段,白羊草种群都是优势种,而其他植物种则呈现不同的趋势.     

应用灰色关联度法评价北京潮河护坡植被质量

2008年在北京市密云县潮河河坡进行灌草植物护坡组合模式的筛选,以护坡植被质量评价6种灌草种植模式,应用灰色系统理论对密云潮河护坡不同种植模式的护坡植被质量进行了分析和评判,确定最优灌草组合模式。结果表明:荆条(Vitex negundo L.var.heterophylla(Franch)Rehd.)+小冠花(Coronilla varia L.)+白三叶(Trifolium repens L.)+高羊茅(Festuca arundinacea cv Fine Lawn)混植护坡植被质量最优,可以有效地护坡;高羊茅和小冠花是优秀的护坡植物,适用于北京地区固土护坡。     

帽儿山灌丛生境秋季鸟类群落的时间格局

以温带次生灌丛生境秋季鸟类群落为研究对象,2006年8月8日至10月24日,对黑龙江省帽儿山次生灌丛生境秋季鸟类群落时间格局进行了调查,分析由于鸟类迁徙所造成的鸟类群落的变化过程,进而探讨鸟类群落结构的时间异质性特征.使用雾网法共记录到鸟类96种共13620只,隶属于10目29科.采用聚类分析法对温带次生灌丛生境秋季鸟类群落的时间结构进行了聚类分析,发现秋季鸟类群落组成按时间顺序大致可分4个阶段.通过各阶段群落多样性、均匀性分析,发现不同时间鸟类群落结构的变化与鸟类的居留型、迁徙时间、生境外貌具有直接关系.     

两种灌丛化草原小叶锦鸡儿的叶片化学计量特征

本研究分析了内蒙古19个灌丛化草原样地（典型草原区11个、荒漠草原区8个）的小叶锦鸡儿（Caragana microphylla）叶片碳（Carbon，C）：氮（Nitrogen，N）：磷（Phosphorus，P）化学计量特征。结果显示：典型草原中小叶锦鸡儿叶片C含量，C：N，C：P，N：P显著低于荒漠草原，N，P含量显著高于荒漠草原；小叶锦鸡儿叶片N，P含量与土壤N，P含量呈正相关关系，叶片C含量与C：N，C：P呈正相关关系，叶片N与P含量呈正相关关系；小叶锦鸡儿叶片化学计量特征具有环境可塑性；叶片C含量在两种草原类型中，随年平均降水量（Mean annual precipitation，MAP）和年平均气温（Mean annual temperature，MAT）的变化趋势不一致；叶片N，P含量与MAP呈正相关关系，与MAT呈负相关关系；叶片C：N，C：P，N：P与MAP呈负相关关系，与MAT呈正相关关系；小叶锦鸡儿的生长主要受P限制。本研究结果有助于了解小叶锦鸡儿的养分利用策略，并为灌丛化草原植被的保护和恢复工作提供参考。     

不同带间距对柠条人工林影响的研究

文章采取典型样地调查的方法,对不同带间距对柠条林的影响进行研究,结果如下:①柠条灌丛生长中冠幅、树高、新梢的相关性较强,各带间距林地柠条3个生长指标排序均为:2m>16m>8m>4m;丛径排序均为:2m>4m>8m>16m;枝条数量排序均为:4m>8m>2m>16m。②2m、4m、8m、16m带间距林地一年生枝叶与多年生枝的比例依次为3∶7、1∶9、3.4∶6.4、4∶6,8m和16m带间距林地柠条的饲用价值更为突出。③4m、8m带间距林地土壤含水量接近,且垂直分布较均匀,好于2m、16m带间距林地。④随带间距增加风速和湿度增加,温度下降;2m带间距林地作用较明显,其他3种林地则作用相似。⑤4m、8m带间距林地优质牧草重要值占总值的51.79%~43.03%之间,多年生植物重要值占总值的1/3左右,好于2m、16m带间距林地。⑥柠条林带间植物多样性指数排序为:16m>4m>8m>2m,丰富度指数排序为:2m>8m>4m>16m,均匀度指数排序为:2m>8m>4m>16m。⑦综合柠条生长情况、带间植物重要值和多样性指标、林地土壤水分和林地对小气候的调控作用,4m、8m带间距林地在研究地是比较适合的造林模式。     

Common and distinguishing features of the bacterial and fungal communities in biological soil crusts and shrub root zone soils

Soil microbial communities in dryland ecosystems play important roles as root associates of the widely spaced plants and as the dominant members of biological soil crusts (biocrusts) colonizing the plant interspaces. We employed rRNA gene sequencing (bacterial 16S/fungal large subunit) and shotgun metagenomic sequencing to compare the microbial communities inhabiting the root zones of the dominant shrub, Larrea tridentata (creosote bush), and the interspace biocrusts in a Mojave desert shrubland within the Nevada Free Air CO₂ Enrichment (FACE) experiment. Most of the numerically abundant bacteria and fungi were present in both the biocrusts and root zones, although the proportional abundance of those members differed significantly between habitats. Biocrust bacteria were predominantly Cyanobacteria while root zones harbored significantly more Actinobacteria and Proteobacteria. Pezizomycetes fungi dominated the biocrusts while Dothideomycetes were highest in root zones. Functional gene abundances in metagenome sequence datasets reflected the taxonomic differences noted in the 16S rRNA datasets. For example, functional categories related to photosynthesis, circadian clock proteins, and heterocyst-associated genes were enriched in the biocrusts, where populations of Cyanobacteria were larger. Genes related to potassium metabolism were also more abundant in the biocrusts, suggesting differences in nutrient cycling between biocrusts and root zones. Finally, ten years of elevated atmospheric CO₂ did not result in large shifts in taxonomic composition of the bacterial or fungal communities or the functional gene inventories in the shotgun metagenomes.     

遂川县不同起源林下灌木的数量生态分析

对遂川县的天然林、人工林中乔木层下的灌木层进行调查研究 ,通过分析其生态特征及空间分布 ,得出天然林中灌木层的组成复杂 ,植物种类为 49种 ,人工林中组成结构简单 ,植物种类 40种 ,Shannon- Wiener物种多样性指数分别为 2 .3～ 4.0 30 7、1 .6～ 2 .0 574。天然林下的灌木之间表现出更为集群的分布 ,而人工林中的灌木是随机的分布 (物种之间的联结系数小并且相关关系不显著 )     

毛乌素沙区杨柴林,沙柳林沙地水文常数的研究

本文针对毛乌素沙地中广泛分布的两个人工林－－杨柴林和沙柳林，通过采用土壤物理分析测定法，研究了其沙地的颗料组成状况和水文常数。结果表明：受颗粒组成状史的影响，杨柴林沙地的最大吸湿量为：上层（０￣１５０ｃｍ深）０．７７６％，下层（１５０￣２００ｃｍ深）１．５０４％，田间持水量为３．４１２￣４．３８１％，凋萎湿度为０．７８１％（植物为杨柴）；沙柳林沙地迎风坡、丘顶和背风坡的最大吸湿量为：上层０．７９６     

Effects of fuel reduction on birds in pitch pine-scrub oak barrens of the United States

Fire-dependent ecosystems include some of the most threatened ecosystems in the world, and where fuels are allowed to accumulate, they can present significant threats to human life and property. Fuel reduction activities can be effective in reducing the risk of wildfire, but these practices need to be evaluated relative to their effect on biodiversity. We surveyed birds in an inland pitch pine-scrub oak barren, a fire-dependent plant community, in which fuel reduction had been carried out via thinning of canopy trees to reduce the risk of running crown fires. We hypothesized that thinning pitch pine forest would negatively affect the abundance of mature forest birds and positively affect the abundance of scrub-shrub birds. Our results confirmed these expectations: several mature forest bird species were less abundant in thinned pitch pine than unthinned pitch pine, although most of these species were also present in mixed deciduous forest, and therefore regionally well represented. In contrast, another group of bird species was scarce or absent from unthinned pitch pine and mixed deciduous forest, but present in thinned sites and scrub oak stands. These were scrub-shrub species that do not nest in mixed deciduous or pitch pine forest but depend on shrubland or savannah habitats that cover ∼3% of the region. We conclude that fuel reduction by thinning canopy trees at this site provides habitat for high-priority scrub-shrub bird species at the cost of modest reductions in numbers of forest birds whose regional aggregate population is large.     

值得推广的几种优良观赏灌木

介绍4种花、叶、茎、干、果都具有较高观赏价值的野生或栽培类型灌木的形态特征、生长习性、产地分布、观赏特点及园林用途。