石灰岩山地不同植被类型土壤活性有机碳变化研究

对徐州石灰岩山地4种不同植被类型中的两种土壤活性有机碳的含量进行研究,结果表明:微生物生物量碳(SMBC)、土壤水溶性有机碳(WSOC)的含量在针阔混交林、落叶阔叶林、针叶林、灌草地4种不同植被群落中均随灌草地向林地变化而呈现上升趋势。其中,微生物生物量碳在4种不同植被群落中的变化趋势为针阔混交林>落叶阔叶林>针叶林>灌草地;水溶性有机碳在4种不同植被群落中的变化趋势为落叶阔叶林>针阔混交林>针叶林>灌草地。两种土壤活性有机碳与总有机碳、全氮和pH值等主要生态因子的相关性均达到显著水平或极显著水平。在徐州石灰岩山地地区,与当地大面积栽植的侧柏相比,落叶阔叶林和针阔混交林可作为更好的替代树种,能够有效地改善土壤肥力状况。     

梅州客家村落风水林的群落特征初探和价值浅析

对梅州客家风水林的群落特征进行了初步研究,调查了其物种组成及层次结构,浅析了景观、生态、历史文化和旅游价值。结果表明,这些风水林具有南亚热带常绿阔叶林的典型群落结构,垂直结构分层现象明显、层次清晰、植物多样性和均匀度较高。通过对客家风水林的营造模式、传统保护方法及其价值进行研究,可以为我国南方地区,特别是岭南地区的新时代乡村环境景观营造提供新的思路。     

藏北高寒草甸不同退化阶段植物群落特征及其繁殖分配研究

以西藏北部羌塘草原高寒草甸为研究对象,研究不同退化阶段草地植物群落特征及16种主要组分种的繁殖分配,试图揭示多年生草本植物及其繁殖分配与草地退化程度的关系。结果表明:随着退化程度的加剧高寒草甸植物群落内优势植物发生明显变化,草地群落的各项指标随着草地退化程度的增加而降低;退化程度对群落内物种个体生物量大小和生物量分配有着显著影响,伴随退化程度的加剧各物种对繁殖的绝对投入所受影响不明显,但繁殖投入升高。在群落水平上,草地退化使植物群落繁殖分配增加,茎分配和叶分配减少。不同植物群落内共有种繁殖分配存在差异,表明其繁殖分配跟退化程度有关;植物繁殖投入随退化程度的变化,反映了植物繁殖对策和繁殖投入在生活史特征中的可塑性。     

Effects of single-tree selection harvesting on hymenopteran and saproxylic insect assemblages in the canopy and understory of northern temperate forests

Insects respond to changes in microhabitat caused by canopy disturbance, and thus can be used to examine the ecological impacts of harvesting. Single-tree selection harvesting is the most common silvicultural system used to emulate local small-scale natural disturbance and maintain uneven-aged forest structure in temperate forests. Here, we test for differences in richness, abundance, and composition of hymenopteran and saproxylic insect assemblages at four different taxon levels (selected insect orders; and all hymenopteran families, and braconid subfamilies and morphospecies) between the canopy and understory of unharvested and single-tree selection harvested sites in a northern temperate forest from central Canada. Harvesting had no effect on insect assemblage richness, composition or abundance at the three highest taxon levels (order, family and subfamily). Similarly, richness and abundance at the lowest-taxon level (braconid morphospecies) were similar, although composition differed slightly between unharvested and harvested stands. Insect assemblages were vertically stratified, with generally higher abundance (for Diptera, Hymenoptera, some hymenopteran families and braconid subfamilies) and richness (for braconid morphospecies) in the understory than the canopy. In particular, composition of the braconid morphospecies assemblage showed relatively low similarity between the understory and canopy. Single-tree selection harvesting appears to influ-ence wood-associated insect taxa only subtly through small changes in community composition at the lowest taxon level, and thus is recommended as a conservative approach for managing these northern temperate forests.     

祁连山高寒草甸生态系统昆虫群落特征

2009年7月中旬于祁连山地区的中国科学院海北高寒草甸生态系统研究站,在滩地草甸、金露梅（Potentilla fruticosa）灌丛、山坡草甸和沼泽化草甸4个不同的生境中对昆虫进行百网取样,共获得908头昆虫。分别隶属于10目42科 65种。发现该地区双翅目昆虫是最繁盛的类群：第2个优势目为膜翅目,其次优势目为鞘翅目。昆虫物种多样性和丰富度依次为滩地草甸>金露梅灌丛>山坡草甸>沼泽化草甸;均匀度差异不大;优势度指数沼泽化草甸最高,滩地草甸最低。滩地草甸和山坡草甸昆虫群落的相似性最大;其次是金露梅灌丛;差异最大的是沼泽化草甸。通过分析发现,生境的变迁和气候的变化引起了昆虫群落结构和多样性的差异变化。     

The influence of fire on rodent abundance at the N’washitshumbe enclosure site,Kruger National Park,South Africa

The relative population numbers of rodents were studied in nine habitats in and outside the N’washitshumbe enclosure site, Kruger National Park, before and after burning the firebreaks that surround the enclosure. Trap success was exceptionally high, and the field work is suspected to have coincided with a Mastomys population explosion. This genus dominated the small mammal communities before and after the burn, and never disappeared from the burnt patches. Its numbers also did not crash directly after the burn, as have been reported in most other studies. Movement from the burnt areas was observed, which may have had a significant impact on the numbers of rodents caught both inside the enclosure and in the more natural areas outside. Our study suggests that fire can be investigated as a tool to keep rodent densities down in areas where they are nuisance animals, especially when used in conjunction with models that forecast outbreaks of Mastomys. It also emphasizes the value of long-term studies informing management strategies for animal damage control and biodiversity and ecosystem conservation.     

Wildfire Effects on Understory Vegetation,Natural Regeneration,and Forest Floor Fuels in a Sierran Mixed Conifer Stand

Wildfire effects on understory shrubs and herbs, regeneration of the seedling and sapling size classes, and downed and dead fuels were assessed in a mixed conifer stand located in the Lake Tahoe Basin in which California white fir (Abies concolor var. lowiana [Gord.] Lemm.) was most abundant but with Jeffrey pine (Pinus jeffreyi Grev. & Balf.) also prevalent. In burned and unburned stand portions, prefire measurements served as a basis of comparison for the postfire measurements pertinent to each study component. Fire severely suppressed the understory vegetation, which was dominated by shrubs such as bush chinquapin (Chrysolepis sempervirens [Kellogg] Hjelmqvist) and antelope bitterbrush (Purshia tridentata [Pursh] DC.), while a tepid postfire recovery of most of the preexisting species in the burned stand portion was augmented by new ones, including shrubs such as snowbrush (Ceanothus velutinus Douglas ex Hook.) and whitethorn (Ceanothus cordulatus Kellogg) ceanothus and herbs such as Holboell's rockcress (Arabis holboellii Hornem.). Tree seedling abundance was also substantially reduced in the burned portion, but the postfire population was dominated by Jeffrey pine whereas white fir had been most prevalent originally. Sapling regeneration was eliminated from the burned stand portion regardless of species. Downed and dead fuel loading was severely diminished by the fire, especially regarding fine fuels, permitting subsequent sheet erosion to imperil new seedling regeneration. These results contribute to an understanding of the direction and pace of postwildfire succession on sites occupied by Sierra Nevada mixed conifer and similar forest cover types, which is critical in decisions concerning the need for, and extent of, postfire site rehabilitation measures.     

Effects of feeding bamboo vinegar and acidifier as an antibiotic substitute on the growth performance and intestinal bacterial communities of weaned piglets

Abstract

The experiment was designed to evaluate effects of feeding bamboo vinegar (BV) and acidifier to substitute antibiotic on the growth performance and intestinal bacterial communities of weaned piglets. Three hundred and sixty weaned piglets (body weight (BW) = 10 ± 2 kg) were allocated into three treatments for 25 days of experiment feeding, with three replicates (pen) per treatment. A basal diet was added with antibiotics (Control), 0.4% BV and 0.25% acidifier I (BVAI), or 0.4% BV and 0.25% acidifier II (BVAII), respectively. No significant differences were observed in feed intake, final weight, average daily gain and feed to gain ratio (P > 0.05) among different treatments. The species richness and bacterial community diversities in feces were higher for the pigs in treatment BVAI and BVAII than those of pigs in the Control (36.5 and 1.55, respectively), with a significant difference between BVAII and the Control (P < 0.05). The bacterial communities of pigs in BVAI and BVAII clustered together, forming a cluster we designated as Cluster C and separated from another cluster in pigs fed antibiotic designated as Cluster A in the Control treatment. The results indicate that the 0.4% BV and 0.25% acidifier can replace antibiotics in the diets for piglets without negative effects on production and allow for greater diversity of the intestinal bacterial community compared to antibiotics.     

DCA、CCA和DCCA三种排序方法在中国草地植被群落中的应用现状

排序是用来分析植被与环境之间生态关系的重要手段。该文主要是对除趋势对应分析（DCA）、典范对应分析（CCA）和除趋势典范对应分析（DCCA）这三种排序方法进行总结，讨论它们在中国草地植被群落研究中的应用现状，并得出除趋势对应分析与聚类分析结合使用效果比较好，主要是用来揭示群落之间的关系，并且在实际的应用中也比较多，而典范对应分析和除趋势典范对应分析在揭示种与环境关系方面具有明显的优势，但是由于某些条件的限制，在实际研究中应用的比较少。可见这几种排序方法在实际应用中具有一定的优势，所以应该加强这方面的应用，更加深入的研究草地植被群落，以期对草地生态学及草地植被群落生态关系的研究工作发挥重要的借鉴作用。     

北京百花山落叶阔叶林群落的物种多样性特征

应用物种丰富度、Simpson多样性指数、Shannon-Wiener多样性指数、Pielou均匀度指数、Alatalo均匀度指数研究北京百花山落叶阔叶林中3种群落的物种多样性特征。结果表明：1）群落总体的多样性特征为黑桦-柔毛绣线菊-野青茅＋矮紫苞鸢尾群丛的物种丰富度最大,核桃楸-绒毛绣线菊-蓝萼香茶菜＋大油芒群丛的多样性指数最大,辽东栎-小花溲疏-披针苔草群丛均匀度指数最大;2）不同生长型的物种多样性特征为,草本层的物种丰富度、多样性指数大于灌木层和乔木层,均匀度指数的变化规律为灌木层〉草本层〉乔木层;3）乔木层与草本层、灌木层与草本层间的丰富度指数、多样性指数均有极显著差异,乔木层与灌木层、乔木层与草本层间的Pielou均匀度指数有显著差异。