湘中地区不同石漠化类型植物群落组成及特征

通过对湘中5县不同石漠化类型进行植被调查分析,探讨了湘中地区不同石漠化类型的植被组成和群落特征。结果表明:湘中地区不同等级石漠化类型植物群落结构简单,物种组成比较单一,优势种比较明显,中度石漠化时期出现的乔木树种是石漠化地区乔木群落演替的先锋树种;潜在石漠化地区物种组成明显增加,群落结构比较复杂,具有明显的分层现象。通过树高和胸径进行分析表明,潜在石漠化地区植物群落还处于演替阶段,将向着壳斗科植物为主要建群树种的顶级群落方向演替。     

舟山本岛岩质边坡植被恢复植物多样性及群落演替

通过植被演替的时空互代,在舟山本岛选取具有代表性的不同恢复时期的矿山边坡作为研究样地,考察样地内植物物种构成特征,并根据样地内植物群落特征及不同恢复年限将其划分为4个不同的植物群落(草丛、草灌丛、灌丛、乔灌丛)演替阶段,对比分析不同演替阶段的植物多样性变化及植物群落的演替规律。结果表明:随着恢复年限的增加,多样性指数呈上升趋势,但均匀度指数则略呈下降趋势,植物群落演替总体呈良性发展趋势。岩质边坡植被恢复的研究为舟山地区或其它海岛生境条件下的岩质边坡植被重建过程中的植物配置及养护管理提供理论指导。     

伊春地区野生蓝靛果资源及群落特征的研究

为揭示野生蓝靛果在小兴安岭地区的资源分布规律,采用野外调查与室内试验相结合的方法对伊春地区野生蓝靛果资源分布及群落特征进行研究。结果表明:在该地区野生蓝靛果主要分布于海拔300～390m的沟台、缓坡和陡坡,坡向以南坡为主,生长在地势平坦、阳坡、土壤肥沃、pH近中性或偏酸的环境中;以毛果苔草+小叶樟-丛桦-红松群落和苔草-毛赤杨+兴安落叶松群落为主。因此,伊春地区发展蓝靛果产业应因地制宜,利用林缘、低洼地、沟台等地进行人工栽培。     

准噶尔盆地植被群落物种多样性与沙漠化防治

基于准噶尔盆地南缘荒漠植被样方的调查资料,从不同类型群落的物种多样性及其与生境的关系等方面对该区域植被分布现状进行了分析,并且用相似性系数对不同类型群落采取的沙漠化防治措施的可行性进行了探讨。结果表明:调查区内主要分布着20种荒漠植物,无乔木,只有灌木和草本植物;采取人工补植的方式恢复荒漠植被宜在距离沙漠较远的区域进行;在远离居民生活区的区域布设围栏生态效果不明显;三芒草适于作为沙丘植被恢复的先锋物种。     

2010-2018年淳安县公益林乔木层结构变化特征探究

以2010年、2018年2期公益林小班样地调查数据为基础,通过研究淳安县213个公益林固定监测样地的群落特征,分析淳安县公益林乔木层树种的组成结构、重要值及种间联结,以探明乔木种群动态变化特征,预测群落演替方向和进程,为淳安县生态公益林的经营和管理提供科学依据。     

不同方式有机物料处理对沙化土壤细菌多样性的影响

以宁夏银川腹地的沙化土壤为试材,使用变性梯度凝胶电泳法(DGGE),以不做任何处理的土壤为对照(CK),研究了添加杨树碎片、杨树碎片+柳树树枝覆盖、树枝混合粉碎材料覆盖的3种有机物处理方式对沙化土壤细菌多样性的影响。结果表明:3个处理均不同程度改变了土壤细菌群落结构,群落结构的丰富度大小依次为树枝混合粉碎材料覆盖杨树碎片+柳树树枝覆盖CK添加杨树碎片;聚类分析结果显示,CK和树枝混合粉碎材料覆盖,添加杨树碎片和杨树碎片+柳树树枝覆盖分别被聚类到一起,相似性分别是63%和67%;并且分离鉴定出了与降解有机物料相关的菌(Kocuriasp.NEAU-ST5-33)相似性为96%的菌。     

广东四个不同地域风景林下植被群落特征研究

以广东4个具有地域代表的风景林下植被为研究对象,采用典型取样调查法,研究了林下植被群落特征。结果表明:林下植被物种组成差异性较大,群落相似性系数表现出极不相似或中等不相似;植物地理区系以热带亚热带成分占优势,从南到北有一定减弱趋势;林下群落优势种具有一定相似性,灌木层优势种以九节、假鹰爪、梅叶冬青、五指毛桃等主;Simposon指数值均较高,林下植被群落多样性较好。     

北京怀沙河、怀九河水生植物区系初步研究

对北京怀沙河、怀九河水生植被的种类组成、分布区类型以及植被类型进行了调查.结果表明:该区共有水生植物16科18属24种;分布区类型以世界广泛分布成分最多,其次为北温带分布;水生植被分为沉水、浮水和挺水3个植被亚型和香蒲群落、慈菇群落、满江红群落、水毛茛群落、豆瓣菜群落等13个群系.     

岩石坡面植被群落演替与物种多样性动态研究——以舟山市长岗山森林公园采石宕口为例

选取4个典型样地对舟山市长岗山森林公园采石宕口植被演替与恢复进行动态监测,结合丰富度指数、多样性指数和均匀度指数法研究物种多样性在坡面植被群落演替过程中的变化。研究表明:经过3年的演替时间,人工建植的草本植物已逐渐被乡土植物替代,在其他条件相同时,阴坡物种数要高于阳坡,缓坡物种数高于陡坡;随着演替的进行,边坡植物物种渐趋于多样化,物种丰富度指数(Margalef指数)、多样性指数(Shannon-Wiener指数)和均匀度指数(Pielou指数)均表现为指数函数变化规律。从整个演替过程来看,3类指数均表现为阴坡高于阳坡、缓坡高于陡坡。     

内蒙古黄土丘陵区土地利用与土壤肥力的关系

为了研究不同土地利用方式与土壤肥力和土地退化的关系,以内蒙古黄土丘陵区为对象,选取耕地、草地、撂荒地、灌木林地和乔木林地5种土地利用类型的9个土壤理化指标,计算了不同土地利用类型的土壤肥力综合指数及土壤退化指数。结果表明:研究区内不同土地利用类型的土壤指标均存在显著性差异。5种土地利用类型的土壤肥力综合指数得分为耕地草地灌木林地乔木林地撂荒地。撂荒地和乔木林地土壤退化指数为负值;灌木林地和耕地土壤退化指数为正值。不同土地利用对土壤肥力影响不同,土壤肥力综合指数与土壤退化指数存在良好的线性关系。     

Pocono mesic till barrens in retreat: topography,fire and forest contagion effects

The Pocono mesic till barrens (PMTB) are a unique assemblage of fire-maintained shrub communities that support numerous rare species. Historically these barrens covered a large area in the vicinity of Long Pond, Pennsylvania, USA. However, due largely to regional fire suppression instituted in the early 1960s, over 70% of the area covered by barrens succeeded to fire-intolerant forest that does not support the rare species. We investigated the influence of forest proximity on barrens succession across three geomorphic types during periods of high fire frequency and fire suppression, testing the hypothesis that forest processes such as seed rain, shading, and detrital enrichment of soils enhances barrens succession through a contagion effect. Evidence of a forest contagion effect should be shown by increased rates of barrens succession with increasing proximity to the nearest forest edge. In order to detect a forest contagion effect, barrens persistence and barrens succession were modeled in proximity zones of 0-50 m, 50-100 m, 100-200 m, and greater than 200 m from the nearest forest edge. We used existing GIS data layers for fire, geomorphology, and vegetation distribution in 1938, 1963, and 1992. The layers were modified and overlain using ArcView software to determine persistence and succession rates for each unique combination of layers in each proximity zone from 1938 to 1963 (pre-fire suppression) and 1963 to 1992 (post-fire suppression). ANCOVA results indicate that proximity to the nearest forest edge significantly affected barrens persistence rates in both time periods, but succession rates were significantly affected in 1938 to 1963 only. Twenty-eight percent of the 1938 barrens succeeded to forest by 1963; 56% of the 1963 barrens became forest by 1992. Results support previous findings that barrens persistence is enhanced by increased fire frequency, and that barrens persist longer where they overlie flat glacial till than on other geomorphology types.     

OUTENIQUA — A computer model to simulate succession in the mixed evergreen forests of the southern Cape,South Africa

A succession model for mixed evergreen forests of the southern Cape, South Africa, called OUTENIQUA, was developed based on one for subtropical rain forest in New South Wales, Australia. The model simulates the regeneration, growth and mortality on a 0.04 ha plot using an individual-tree based modeling approach to forest succession. The OUTENIQUA model was tested on its ability to simulate species dynamics of the forest stand used for its development, as well as on independent data from a neighboring stand and not used for the model derivation. The model is used as a research tool to summarize published and unpublished knowledge on the southern Cape forests and to highlight aspects where knowledge is insufficient. The development of the model represents a test of an individual-tree gap model as a simulation tool for use in management and directing research in subtropical and tropical forests.     

Modeling impacts of fire severity on successional trajectories and future fire behavior in Alaskan boreal forests

Much of the boreal forest in western North America and Alaska experiences frequent, stand-replacing wildfires. Secondary succession after fire initiates most forest stands and variations in fire characteristics can have strong effects on pathways of succession. Variations in surface fire severity that influence whether regenerating forests are dominated by coniferous or deciduous species can feedback to influence future fire behaviour because of differences in forest flammability. We used a landscape model of fire and forest dynamics to explore the effects of different scenarios of surface fire severity on subsequent forest succession and potential fire activity in interior Alaska. Model simulations indicated that high levels of surface fire severity leading to a prolonged phase of deciduous forest dominance caused a reduction in landscape flammability and fewer large fire events. Under low surface fire severity, larger patches of contiguous conifer forest promoted fire spread and resulted in landscapes with shorter fire return intervals compared to scenarios of high surface severity. Nevertheless, these negative feedbacks between fire severity, deciduous forest cover, and landscape flammability were unable to fully compensate for greater fire activity under scenarios of severe climate warming. Model simulations suggest that the effects of climate warming on fire activity in Alaska’s boreal forests may be partially but not completely mitigated by changes in fire severity that alter landscape patterns of forest composition and subsequent fire behaviour.     

京津冀地区矿山排渣场植被演替规律

植被自然恢复演替过程对矿山废弃地人工辅助植被恢复设计与实施效果评价均具有重要的借鉴价值。为了探索京津冀地区矿山排渣场植被演替规律，以京津冀地区典型矿山为例，运用典型样地和样方法，在详细调查获取数据的基础上，分析矿山排渣场自然恢复50年内的植物多样性变化特征。结果表明：当年内植物多样性指数变化呈波浪状，先增加后减少，然后再增加；先锋植物为一年生草本植物，植物种群从藜→蒿草；植物种群变化可划分为6个阶段：一年生草本阶段→多年生草本阶段→灌草阶段→灌木阶段→灌木与林木混合阶段→林木阶段。可见，矿山排渣场植被自然恢复具有较强的规律性，基于植物自然演替规律，首年内宜种植一年生草本类植物，有利于促进矿山废弃地植被恢复进程。     

The impact of typhoon on post-volcanic-eruption forest landscape recovery: a study in Changbai mountain through 300 years of historic landscape reconstruction

Landscape Ecology - Study of interplay of disturbance and forest succession is key to understand forest landscape dynamics, especially under changing climate and disturbance regimes. However, most...     

Influence of forest management alternatives and land type on susceptibility to fire in northern Wisconsin,USA

We used the LANDIS disturbance and succession model to study the effects of six alternative vegetation management scenarios on forest succession and the subsequent risk of canopy fire on a 2791 km² landscape in northern Wisconsin, USA. The study area is a mix of fire-prone and fire-resistant land types. The alternatives vary the spatial distribution of vegetation management activities to meet objectives primarily related to forest composition and recreation. The model simulates the spatial dynamics of differential reproduction, dispersal, and succession patterns using the vital attributes of species as they are influenced by the abiotic environment and disturbance. We simulated 50 replicates of each management alternative and recorded the presence of species age cohorts capable of sustaining canopy fire and the occurrence of fire over 250 years. We combined these maps of fuel and fire to map the probability of canopy fires across replicates for each alternative. Canopy fire probability varied considerably by land type. There was also a subtle, but significant effect of management alternative, and there was a significant interaction between land type and management alternative. The species associated with high-risk fuels (conifers) tend to be favored by management alternatives with more disturbances, whereas low disturbance levels favor low-risk northern hardwood systems dominated by sugar maple. The effect of management alternative on fire risk to individual human communities was not consistent across the landscape. Our results highlight the value of the LANDIS model for identifying specific locations where interacting factors of land type and management strategy increase fire risk.This revised version was published online in May 2005 with corrections to the Cover Date.     

森林群落发育阶段及其效益分析——以河北省木兰林场和塞罕坝机械林场为例

为揭示森林生态、经济和社会效益的发生、发展规律,为森林经营和资源管理提供依据,根据森林群落发育和演替理论并结合木兰林场塞罕坝机械林场经营实践,对森林群落的发育阶段及森林三大效益进行了分析,提出了稳定成熟森林群落的形成可分为森林群落形成阶段、森林群落发展阶段和森林群落稳定成熟阶段。阐述了森林群落不同阶段的基本特点和群落结构的基本特征。在此基础上分析了从森林群落形成阶段到发展为稳定成熟森林群落进程中,森林三大效益产生和发展的一般规律以及它们之间的相互关系,即森林三大效益不是平行关系而是相互区别、相互联系、相互伴生的关系,它们的产生是一个从无到有、由少到多、由小到大的发展进程,特别是生态效益和社会效益,从维度上讲还是一个从单一向复杂,从单维度向多维度的发展进程,并随森林群落林龄增长而逐渐增多增强。     

间伐干扰对人工林林木生长、幼苗更新及植被多样性的影响

抚育间伐是森林经营的重要措施之一,合理的间伐可以优化林分结构,改善林下环境,提高森林生产力和稳定性。本研究以河北省塞罕坝机械林场华北落叶松人工林和樟子松人工林为对象,对比分析间伐和未间伐林分（自然保护区）中林木生长、物种多样性和天然更新的差异。结果表明,间伐区华北落叶松人工林胸径年均增长0.72 cm,比未间伐区提高53.2%;间伐区樟子松人工林胸径年均增长0.59 cm,比未间伐区提高25.5%。间伐区内Shannon-Wiener指数、Simpson多样性指数、Pielou均匀度指数和Margalef丰富度指数较未间伐区分别高出159.2%、185.3%、185.9%和108.4%。间伐区幼苗幼树的更新种类和数量明显高于未间伐区,其中,樟子松人工林间伐区幼苗幼树的更新种类和数量均高于华北落叶松人工林。可见,对自然保护区内未经营过的人工林进行适当抚育间伐对提高森林生产力、维持生物多样性和促进森林正向演替有重要作用。     

Observing succession on aspen-dominated landscapes using a remote sensing-ecosystem approach

In the North American upper Great Lakes region, forests dominated by the aspens (Populus grandidentata Michx. – bigtooth aspen, and P. tremuloides Michx. – trembling aspen), which established after late 19th and early 20th century logging, are maturing and succession will create a new forest composition at landscape to regional scales. This study analyzed the capabilities of Landsat ETM+ remote sensing data combined with existing ecological land unit classifications to discriminate and quantify patterns of succession at the landscape scale over the 4200 ha University of Michigan Biological Station (UMBS) in northern Lower Michigan. In a hierarchical approach first multi-temporal Landsat ETM+ was used with a landscape ecosystem classification to map upland forest cover types (overall accuracy 91.7%). Next the aspen cover type was subset and successional pathways were mapped within that type (overall accuracy 89.8%). Results demonstrated that Landsat ETM+ may be useful for these purposes; stratification of upland from wetland types using an ecological land unit classification eliminated confounding issues; multi-temporal methods discriminated evergreen conifer versus deciduous understories. The Landsat ETM+ classifications were then used to quantify succession and its relationship to landform-level ecological land units. Forests on moraine and ice contact landforms are succeeding distinctly to northern hardwoods (95% and 88% respectively); those on outwash and other landforms show greater diversity of successional pathways.     

Observed and modeled directional change in riparian forest composition at a cutbank edge

Lateral migrations of river meanders create transient, spatially transgressive edges where the advancing cutbank edge encroaches upon interior floodplain forest communities. This spatial movement of edge toward the forest interior should initiate directional changes in species composition within a forest plot as it is affected by a changing microclimate and hydrological regime. We found that cutbank edge and forest interior sites in an Iowa floodplain contained markedly different plant assemblages. Species commonly associated with later stages of succession dominated interior sites while cutbank edge sites favored secondary, successional species. Assuming that the cutbank edge sites once contained vegetation similar to that surveyed in the floodplain interior, the observed changes in community structure accompanying channel migration are suggestive of retrograde succession, or retrogression. To link cutbank erosional processes with retrogressional processes, we modified a computer simulation model already in use for floodplain environments. We incorporated the changing edge effects and compared model projections with the data collected from the field sites using detrended correspondence analysis. Without changes, the simulation projected a site compositionally similar to the sampled interior forest. When the changes were initiated, the simulated site progressively took on compositional characteristics similar to the riparian edge sites. Because we included only those forcing functions that would be initiated by cutbank erosion, the model supports the hypothesis that the spatially progressive edge effect results in a directional change in forest community composition analogous to retrogression. Our results demonstrate an interesting linkage between successional and fluvial-geomorphic processes and indicate that site dynamics may be controlled differently in landscapes where sites are progressively created and destroyed than where recurrent disturbances affect the same site.