京西门头沟区自然植被滞尘能力及效益研究

利用2006年夏季实地测量的植物叶片滞尘数值,得出常绿乔木、落叶阔叶乔木、灌木以及草地4种不同植物类型的平均滞尘能力,再将其与用遥感方法估算出的叶面积指数以及植被统计数据相结合,评估了门头沟区自然植被总体的滞尘能力、滞尘量与滞尘效益.结果表明: 自然植被具有明显的滞尘功能,门头沟区自然植被的年滞尘量为39.47×104 t,由此带来的滞尘效益价值为67.10×106元;灌木林和落叶阔叶林2种植被类型,是研究区自然植被滞尘能力和年滞尘量的主要组成部分;常绿乔木的滞尘时间长于其他任何植物种类,其年滞尘量与滞尘能力所占比例有所增加.      

以植被生物完整性评价梁子湖湖滨湿地生态系统健康

湖滨湿地植被是湖滨带生态系统的主要特征,以湖滨湿地植被为对象可评价湖滨带生态系统健康状况。通过对梁子湖湖滨湿地植被的详细调查,共鉴定出植物182种,隶属于52科128属,其中湿生植物147种,水生植物35种。水生植物中有20种挺水植物,6种浮叶植物和9种沉水植物。采用植被生物完整性(VIBI)方法评价梁子湖湖滨湿地生态系统健康,对21个备选指标进行筛选分析,建立了以挺水植物物种数、多年生植物物种数、外来物种百分比、香农多样性指数、植物区系质量指数FQAI、耐受性物种百分比、敏感性物种百分比为核心指标的评价体系,三分法对指标进行赋值,将梁子湖湖滨湿地划分为健康、良好、一般和较差4个等级。评价结果表明,梁子湖湖滨湿地22个调查位点中,处于健康状态的有3个位点,良好6个,共占总位点数的41%,一般和较差分别为7个和6个,共占59%。总体上看,东梁子湖和牛山湖湖滨湿地位点健康状况较好,而西梁子湖湖滨湿地差异性较大,山坡湖南部湖湾和前江大湖北部位点健康状况良好,张桥湖湖滨湿地健康状况一般,评价较差的6个位点集中在宁港湖周围和前江大湖南部沿岸。底质和人类活动如水位调控、围网养殖、放牧等是影响梁子湖湖滨湿地植被生物完整性的主要原因。     

川南山地林分变化对土壤物理性质和抗蚀性的影响

以川南天然林(TRL)及其转变成的毛竹林(MZL)、檫木林(CML)、柳杉林(LSL)、杉木林(SML)和水杉林(SSL)为对象,研究不同林分土壤物理性质和抗蚀性差异,以主成分分析法(ZCFM)和隶属函数法(LSHM)分别计算的土壤抗蚀性综合值Ⅰ(KSX-Ⅰ)和Ⅱ(KSX-Ⅱ)评价林分变化对土壤抗蚀性的影响,探索简便易行的土壤抗蚀性综合评价方法。结果表明,天然林转变为人工林后土壤物理性质和抗蚀性变差,呈现出有机质和0.25 mm水稳性团聚体含量、水稳性团聚体平均重量直径、团聚度、孔隙度及物理稳定性指数降低,而结构体破坏率、不稳定团粒指数、容重、分散率及侵蚀系数增加。各林分土壤KSX-Ⅰ和KSX-Ⅱ均呈现出TRLCMLSSLLSLMZLSML的规律变化。土壤抗蚀性指标间相关性均达到显著(p0.05)水平;土壤KSX-Ⅰ和KSX-Ⅱ之间呈显著相关关系(p0.05),且两者均与各抗蚀性指标间呈显著相关(p0.05)。说明天然林植被变化后会使土壤抗蚀性降低,影响原有植被水土保持功能,应该加强天然林及其生态功能保护;ZCFM和LSHM均可作为计算土壤抗蚀性综合值的有效方法,但考虑到计算过程的难易度,后者更简便易行。结果为土壤抗蚀性综合评价新方法的建立提供了参考。     

庐山不同森林植被类型土壤特性及其健康评价

土壤作为森林生态系统的一个重要因子,评价森林土壤健康状况对森林健康的维护经营以及森林系统功能的发挥具有重要意义。在系统调查和分析庐山8种森林植被类型土壤特性的基础上,评价指标分别从物种多样性以及不同的森林土壤特性中进行筛选,包括物种多样性系数、枯落物层厚度、腐殖质层厚度、土层厚度、容重、粘粒含量、有机质、p H值、阳离子交换量、全氮、水解氮、有效磷、速效钾、磷酸酶活性等指标,基于SPSS19.0软件对所获得数据进行差异性检验和相关分析,确定各项指标的权重,应用合适的土壤健康评分函数,将测得的指标值转换为对应指标的分值,最后通过加权综合法,计算其土壤健康指数,并对不同森林植被类型土壤健康状况进行评价。结果表明,8种森林植被类型下最终的土壤健康指数大小排序为:针阔混交林(0.78)常-落混交林(0.72)灌丛(0.69)常绿阔叶林(0.67)落叶阔叶林(0.64)竹林(0.59)马尾松林(0.53)黄山松林(0.46)。     

Structural-functional organization of lower vegetation layers in tree communities of the upper timberline ecotone in the Polar Urals

Typologically identical (dwarf birch-herb-dwarf shrub-moss) open and closed larch forests growing on the same altitudinal transect have proved to differ in the structural-functional organization of lower vegetation layers. Coverage, general species composition, and species richness of the herb-dwarf shrub layer are higher in the open forest than in the closed forest. Correlations between individual species of vascular plants weaken upon transition from the open to the closed forest. Conversely, the coverage of the lichen-moss layer increases in the closed forest, which contributes to its role as a factor of selection of vascular plant species against the background of the prevailing influence of the tree layer.     

Specific features of early stages of progressive succession in an anthropogenic landscape: An example from southeastern Belarus

Specific features of progressive succession in the vegetation of anthropogenically transformed landscapes in southeastern Belarus have been studied in permanent test plots. Using phytoindication scales proposed by Ellenberg (1974) and Tsyganov (1983), trends of changes in ecological conditions in the first years of succession have been revealed.     

Postfire succession in a forest of the cryolithozone: The example of central Yakutia

The results of studies on postfire succession in larch forests of the permafrost zone are discussed. The main directions of successional processes in burned-out areas of different ages are described. It has been shown that secondary pyrogenic successions in larch forests follow the scheme of rapid regeneration without tree species replacement and the model of succession tolerance. Groups of plant species with different life strategies and indicator species characterizing different stages of the overgrowing of burned-out areas have been identified.     

Montane Meadows as Indicators of Environmental Change

We used a time series of satellite multispectral imagery for mapping and monitoring six classes of montane meadows arrayed along a moisture gradient (from hydric to mesic to xeric). We hypothesized that mesic meadows would support the highest species diversity of plants, birds, and butterflies because they are more moderate environments. We also hypothesized that mesic meadows would exhibit the greatest seasonal and interannual variability in spectral response across years. Field sampling in each of the meadow types was conducted for plants, birds, and butterflies in 1997 and 1998. Mesic meadows supported the highest plant species diversity, but there was no significant difference in bird or butterfly species diversity among meadow types. These data show that it may be easier to detect significant differences in more species rich taxa (e.g., plants) than taxa that are represented by fewer species (e.g., butterflies and birds). Mesic meadows also showed the greatest seasonal and interannual variability in spectral response. Given the rich biodiversity of mesic montane meadows and their sensitivity to variations in temperature and moisture, they may be important to monitor in the context of environmental change     

The Vegetation of Wet Meadows in Relation to Their Land-use

Wetland biomonitoring approaches are needed to determine when changes in response to stressors are occurring and to predict the consequences of proposed land-use changes. These approaches require an understanding of shifts in biota that occur in response to land-use, data that are lacking for most kinds of wetlands. Changes in floristic composition corresponding to land-use differences at multiple scales (site to 2500 m radius) were characterized for 40 wet meadows associated with prairie glacial marshes in Minnesota (U.S.A.). In general, guild was more useful than species composition for indicating land-use impacts. Site impacts (stormwater, cultivation) and landscape disturbance (agriculture and urbanization, combined), coincide with a reduction in native graminoid and herbaceous perennial abundance (e.g., Carex lasiocarpa, Calamagrostis canadensis, Spartina pectinata). This vegetation is replaced with annuals (e.g, Bidens cernua, Polygonum pensylvanicum) in recently cultivated sites or introduced perennials (e.g., Phalaris arundinacea, Typha angustifolia) and floating aquatics (lemnids) in stormwater impacted wetlands. Ditches also reduce native perennial importance and increase perennials, but only when they are in highly impacted landscapes.     

An environmental perspective of the post-tsunami scenario along the coast of Tamil Nadu, India: role of sand dunes and forests

An endeavor to feel the pulse of a coast devastated by a powerful oceanographic event is made. Results of field investigations along Tamil Nadu seaside revealed that the tsunami of December 2004 demolished dwellings within strips ranging from 6 to 132m (average width, 41m) from the dune, and flooded up to 862m (average, 247m) from the shore. The event damaged sand dunes, ripped dune vegetation, created new water bodies and shattered high value assets. Comparatively, casuarina forests performed remarkably. Uprooting of trees was exclusively restricted to a frontal strip ranging from 5 to 25m (average width, 14m) nearest to the shore where the maximum wave run-up was 6.5m above sea level. Sand dunes in general, and casuarina forests in particular, posses an innate capacity to dissipate powerful waves. This inference is supported by (a) negligible over wash along belts characterized by high dune complexes, (b) intact villages shielded by dense forests as well as sand dunes, and (c) maximum destruction of open beach front influenced by intense human activity. In this context, the coastal regulation zone (CRZ) Notification of 1991 offers sufficient scientific validity to be endorsed. However, post-tsunami ecosystem management initiatives lack a scientific basis. Therefore, a coastal hazards policy, that considers adaptation, dune restoration and forested buffer zones, is a sustainable long-term option for Indian coasts.