Impact of riparian land use on stream insects of Kudremukh National Park, Karnataka state, India

The impact of riparian land use on the stream insect communities was studied at Kudremukh National Park located within Western Ghats, a tropical biodiversity hotspot in India. The diversity and community composition of stream insects varied across streams with different riparian land use types. The rarefied family and generic richness was highest in streams with natural semi evergreen forests as riparian vegetation. However, when the streams had human habitations and areca nut plantations as riparian land use type, the rarefied richness was higher than that of streams with natural evergreen forests and grasslands. The streams with scrub lands and iron ore mining as the riparian land use had the lowest rarefied richness. Within a landscape, the streams with the natural riparian vegetation had similar community composition. However, streams with natural grasslands as the riparian vegetation, had low diversity and the community composition was similar to those of paddy fields. We discuss how stream insect assemblages differ due to varied riparian land use patterns, reflecting fundamental alterations in the functioning of stream ecosystems. This understanding is vital to conserve, manage and restore tropical riverine ecosystems.

Greening India Mission

The Government of India has announced the Greening India Mission (GIM) under the National Climate Change Action Plan. The Mission aims to restore and afforest about 10 mha over the period 2010-2020 under different sub-missions covering moderately dense and open forests, scrub/grasslands, mangroves, wetlands, croplands and urban areas. Even though the main focus of the Mission is to address mitigation and adaptation aspects in the context of climate change, the adaptation component is inadequately addressed. There is a need for increased scientific input in the preparation of the Mission. The mitigation potential is estimated by simply multiplying global default biomass growth rate values and area. It is incomplete as it does not include all the carbon pools, phasing, differing growth rates, etc. The mitigation potential estimated using the Comprehensive Mitigation Analysis Process model for the GIM for the year 2020 has the potential to offset 6.4% of the projected national greenhouse gas emissions, compared to the GIM estimate of only 1.5%, excluding any emissions due to harvesting or disturbances. The selection of potential locations for different interventions and species choice under the GIM must be based on the use of modelling, remote sensing and field studies. The forest sector provides an opportunity to promote mitigation and adaptation synergy, which is not adequately addressed in the GIM. Since many of the interventions proposed are innovative and limited scientific knowledge exists, there is need for an unprecedented level of collaboration between the research institutions and the implementing agencies such as the Forest Departments, which is currently non-existent. The GIM could propel systematic research into forestry and climate change issues and thereby provide global leadership in this new and emerging science.

Luonnonhoitopellot maatalousympäristön luonnon monimuotoisuuden edistämisessä

Luonnonhoitopellot lisättiin uutena vapaaehtoisena toimenpiteenä maatalouden ympäristötukeen vuonna 2009. Luonnonhoitopeltoihin kuuluvat monivuotiset nurmipellot sekä niitty-, riista- ja maisemakasveilla kylvetyt pellot. Toimenpiteen avulla pyritään suojelemaan ja lisäämään maatalousympäristön luonnon monimuotoisuutta sekä muun muassa vähentämään maatalouden ravinnehuuhtoumia. Vuonna 2010 luonnonhoitopeltoja oli yli seitsemän prosenttia Suomen viljelyalasta. Luonnonhoitopeltojen ympäristövaikutusten arvioiminen ja toimenpiteen kehittäminen on tärkeää, jotta toimenpiteeseen käytettävät varat eivät valu hukkaan. Tämän tutkimuksen tavoitteena oli selvittää, millainen merkitys luonnonhoitopelloilla on maatalousympäristön monimuotoisuuden kannalta; millaiset luonnonhoitopellot ovat monimuotoisuuden kannalta arvokkaimpia; ja kuinka toimenpidettä kannattaa kehittää. Kysymyksiin pyrittiin vastaamaan tutkimalla putkilokasvilajistoa, -lajirikkautta ja kasvillisuuden rakennetta erilaisilla luonnonhoitopelloilla, sekä vertaamalla luonnonhoitopeltojen kasvillisuutta pientareiden ja niittyjen kasvillisuuteen. Maastotyö luonnonhoitopelloilla tehtiin kesällä 2010 Uudenmaan ja Pohjois-Pohjanmaan ELY-keskusalueilla. Lisäksi tutkimuslohkoista kerättiin tietoja viljelijäkyselyn kautta. Niittypellot osoittautuivat tutkimuksessa lajirikkaimmaksi luonnonhoitopeltotyypiksi, mikä selittynee lähinnä sillä, että ne kylvetään heikosti kilpailukykyisellä siemenseoksella. Nurmi- ja niittypelloilla lohkon viljavuus korreloi negatiivisesti lajirikkauden kanssa. Lajikoostumukseltaan kaikki luonnonhoitopellot eroavat toisistaan sekä maatalousympäristön puoliluonnontilaisista elinympäristöistä, ja lisäävät siten monimuotoisuutta maisematasolla. Luonnonhoitopeltojen lajisto ei ole kuitenkaan suojelun kannalta erityisen arvokasta. Toimenpiteen maatalousympäristöä rikastuttavaa vaikutusta vähentää, että tällä hetkellä valtaosa luonnonhoitopelloista on monivuotisia nurmipeltoja. Luonnonhoitopeltojen siemenseoksia kehittämällä, perustamis- ja hoitomenetelmiä tutkimalla ja neuvontaan panostamalla voidaan lisätä luonnonhoitopeltojen arvoa niin luonnon, viljelijän kuin yhteiskunnankin kannalta.

Helsingin metropolialueen maisemaekologiset muutokset vuosina 1955-2009

Landscape is shaped by natural environment and increasingly by human activity. In landscape ecology, the concept of landscape can be defined as a kilometre-scale mosaic formed by different land-use types. In Helsinki Metropolitan Region, the landscape change caused by urbanization has accelerated after the 1950s. Prior to that, the landscape of the region was mainly only shaped by agriculture. The goal of this study was in addition to describing the landscape change to discuss the factors impacting the landscape change and evaluate thelandscape ecological impacts of the change. Three study areas at different distances from Helsinki city centre were chosen in order to look at the landscape change. Study areas were Malmi, Espoo and Mäntsälä regions representing different parts of the urban-to-rural gradient in 1955, 1975, 1990 and 2009. Land-use of the maps was then digitized into five classes: agricultural lands, semi-natural grasslands, built areas, waters and others using GIS methods. First, landscape change was studied using landscape ecological indices. Indices used were PLAND i.e. the proportions of the different land-use types in the landscape; MPS, SHEI and SHDI which describe fragmentation and heterogeneity of the landscape; and MSI and ED which are measures of patch shape. Second, landscape change was studied statistically in relation to topography, soil and urban structure of the study areas. Indicators used concerning urban structure were number of residents, car ownership and travel-related zones of urban form which indicate the degree of urban sprawl within the study areas. For the statistical analyses, each of the 9.25 x 9.25 km sized study areas was further divided into grids with resolution of 0.25 x 0.25 kilometres. Third, the changes in the green structure of the study areas were evaluated. The landscape change reflected by the proportions of the land-use types was the most notable in Malmi area where a large amount of agricultural land was developed from 1955 to 2009. The proportion of semi-natural grasslands also showed an interesting pattern in relation to urbanization. When urbanization started, a great number of agricultural lands were abandoned and turned into semi-natural grasslands but as the urbanization accelerated, the number of semi-natural grasslands started to decline because of urban densification. Landscape fragmentation and heterogeneity were the most widespread in Espoo study area which is not only because of the great differences in relative heights within the region but also its location in the rural-urban fringe. According to the results, urbanization induced agricultural lands to be more regular in shape both spatially and temporally whereas for built areas and semi-natural grasslands the impact of urbanization was reverse. Changes in landscape were the most insignificant in the most rural study area Mäntsälä. In Mäntsälä, built area per resident showed the greatest values indicating a widespread urban sprawl. The values were the smallest in highly urbanized Malmi study area. Unlike other study areas, in Mäntsälä the proportion of developing land in the ecologically disadvantageous cardependent zone was on the increase. On the other hand, the green structure of the Mäntsälä study area was the most advantageous whereas Malmi study area showed the most ecologically disadvantageous structure. Considering all the landscape ecological criteria used, the landscape structure of Espoo study area proved to be the best not least because of the great heterogeneity of its landscape. Thus the study confirmed the previous results according to which landscape heterogeneity is the most significant in areas exposed to a moderate human impact.

Cross-taxon surrogacy of biodiversity in the Indian Garhwal Himalaya

Biodiversity surveys were conducted in 13, 10x50 m(2) plots located between 1400 to 3100 in abode mean sea level in a range of habitats in temperate mixed Oak and Coniferous forests through sub-alpine to the alpine grasslands in Chamoli district of Uttaranchal state in the Indian Garhwal Himalaya. Cross-taxon congruence in biodiversity (alpha-diversity and beta-diversity) across macrolichens, mosses, liverworts, woody plants (shrubs and trees) and ants was investigated, so as to examine the extent to which these group, of organisms can function as Surrogates for each other. Although woody plants provided a major substrate for macrolichens and mosses, there was no species-specific association between them. Woody plant species richness was highly positively correlated with mosses (r(2) = 0.63, P < 0.001) but the relationship, as not particularly very strong with lichens and liverworts. While there was a significant correlation in the species turnover (β-diversity) of macrolichens with mosses (r(2) = 0.21 P < 0.005). the relationship was relatively poor with the woody plants. On the other hand. negative correlations emerged in the species richness of ants with those of macrolichens, mosses and woody plants (r(2) = -0.44 P < 0.05). but most of the complementarity (turnover) relationships among them were positive, Since diversity between taxonomic hierarchies within the group was consistently significantly positively correlated in all these taxa, the higher taxonomic categories Such as genus and family may be employed as surrogates for rapid assessment and monitoring of species diversity, Although no single group other than macrolichens has emerged as a good indicator of changes in species richness in all other groups, some concordant relationships between them conform to the hypothesis that species assemblages of certain taxonomic groups could still be used as surrogates for efficient monitoring of species diversity in other groups whose distribution may further predict the importance of conserving overall biodiversity in landscapes such as the Garhwal Himalaya. (C) 2002 Elsevier Science Ltd. All rights reserved.

Contrasting fire regimes in a seasonally dry tropical forest and a savanna ecosystem in the western Ghats, India

Tropical dry forests and savannas constitute more than half of all tropical forests and grasslands, but little is known about forest fire regimes within these two extensive types of ecosystems. Forest fire regimes in a predominantly dry forest in India, the Nilgiri landscape, and a predominantly savanna ecosystem in the Sathyamangalam landscape, were examined. Remote sensing data were applied to delineate burned areas, determine fire size characteristics, and to estimate fire-rotation intervals. Belt transects (0.5 ha) were used to estimate forest structure, diversity, and fuel loads. Mean area burned, mean number of fires, and mean fire size per year were substantially higher in the Nilgiri landscape compared to the Sathyamangalam landscape. Mean fire-rotational interval was 7.1 yr in the Nilgiri landscape and 44.1 yr in the Sathyamangalam landscape. Tree (>= 10 cm diameter at breast height) species diversity, tree density, and basal area were significantly higher in the Nilgiri landscape compared to the Sathyamangalam landscape. Total fuel loads were significantly higher in tropical dry and moist deciduous forests in the Nilgiri landscape, but total fuel loads were higher in the tropical dry thorn forests of the Sathyamangalam landscape. Thus, the two landscapes revealed contrasting fire regimes and forest characteristics, with more and four-fold larger fires in the Nilgiri landscape. The dry forests and savannas could be maintained by a combination of factors, such as fire, grazing pressures, and herbivore populations. Understanding the factors maintaining these two ecosystems will be critical for their conservation.

Projected climate change impacts on vegetation distribution over Kashmir Himalayas

Despite high vulnerability, the impact of climate change on Himalayan ecosystem has not been properly investigated, primarily due to the inadequacy of observed data and the complex topography. In this study, we mapped the current vegetation distribution in Kashmir Himalayas from NOAA AVHRR and projected it under A1B SRES, RCP-4.5 and RCP-8.5 climate scenarios using the vegetation dynamics model-IBIS at a spatial resolution of 0.5A degrees. The distribution of vegetation under the changing climate was simulated for the 21st century. Climate change projections from the PRECIS experiment using the HADRM3 model, for the Kashmir region, were validated using the observed climate data from two observatories. Both the observed as well as the projected climate data showed statistically significant trends. IBIS was validated for Kashmir Himalayas by comparing the simulated vegetation distribution with the observed distribution. The baseline simulated scenario of vegetation (1960-1990), showed 87.15 % agreement with the observed vegetation distribution, thereby increasing the credibility of the projected vegetation distribution under the changing climate over the region. According to the model projections, grasslands and tropical deciduous forests in the region would be severely affected while as savannah, shrubland, temperate evergreen broadleaf forest, boreal evergreen forest and mixed forest types would colonize the area currently under the cold desert/rock/ice land cover types. The model predicted that a substantial area of land, presently under the permanent snow and ice cover, would disappear by the end of the century which might severely impact stream flows, agriculture productivity and biodiversity in the region.

The Foraging Ecology of the Mountain Long-Eared Bat Plecotus macrobullaris Revealed with DNA Mini-Barcodes

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Análisis de la flora de los pastos meso-xerófilos del Centro-Norte de España

Análisis de los pastos meso-xerófitos del centro norte de España. El objetivo es conocer la posible relación entre composición florística y los atributos de las plantas. Tratamiento de datos y analísis estadísticos que dan como resultado relaciones numéricas entre los grupos obtenidos en la clasificación y los atributos de las especies. El documento está escrito en Castellano

Stable isotopes in paleosols and origins of the Asian monsoon

The stable isotopic composition of buried soil carbonate and organic matter from northern Pakistan and Nepal can be used to reconstruct aspects of the paleoecology of riverine floodplain ecosystems over the past 17 Myr. Probable dry woodland dominated the floodplain biomass of large rivers ancestral to the modern Indus and Ganges up to 7.3 Myr. Between 7.3 and about 6 Myr, tropical grasses gradually displaced woodland and have dominated floodplain biomasses to the present. The paleovegetational transition beginning about 7.3 Myr likely signals the onset of the strongly seasonal precipitation pattern that typifies the monsoonal climate of the region today. One possible analog to the dry woodland soils of the Miocene are found under the Sal woodlands of the northern Indian subcontinent, while undisturbed modern analogs to the Plio-Pleistocene floodplain grasslands can still be found in the Chitwan area of southern Nepal.

人类活动干扰下草原温室气体地-气交换特征及碳平衡研究

放牧和开垦目前是内蒙古草原最主要的两种人类生产活动，采用静态箱一气象色谱法对这两种土地利用方式下草原主要温室气体(CH4、N20和C02)地-气交换通量进行了原位观测，同时结合草原生态系统碳循环特征对放牧生态系统碳素收支状况进行了初步探讨，首次对开垦前后内蒙古草原CH4吸收和NzO排放的季节、昼夜变化特征进行了分析研究，对不同牧压梯度下内蒙古草原碳的损失进行了估算。主要研究结果包括以下4个方面： 1．内蒙古草甸草原开垦是大气CH4的汇，开垦为农田后，土壤．植物系统吸收大气CH4的能力增强。测定期间，农田与邻近的天然草原CH4平均吸收通量为23.38和24.57 ugCm'2h．1;尽管农业活动改变了草原CH4地．气交换通量，但是通量的量级仍是由当地季节性变化的气候条件决定的，其CH4吸收通量具有强烈的季节变化规律，表现为“春秋季高，夏季低”的特点;耕作使得土壤-植物系统CH4吸收通量的季节变化趋于平缓。 2．内蒙古天然草甸草原是大气N20的源。测定期间的平均排放通量为1.922ugNm'2h．1，通量范围为-0.484~7.425 ugNm.2h．1;天然草原N20排放具有明显的昼夜变化规律和季节变化特征，排放通量出现两个高峰期，整个生长季表现为高(5月中旬)一低（5月下旬至7月中下旬）一高（7月下旬至8月中旬）一低（8月下旬至9月）的趋势;农垦增强了土壤．植物系统排放N2O的能力。观测期间平均排放通量为2.914 ugNm'2h-l，比天然草原高52%，排放通量的季节规律性减弱，整个生长季呈现波动性变化，通量变化与天然草原相比趋于平缓。 3．内蒙古冷蒿小禾草草原与天然草甸草原一样，起着CH4汇、NzO源的功 能。主要温室气体CH4、N2O和C02的地．气交换通量受水热因子控制，与温度之间存在显著相关关系，具有季节变化特征：时间尺度对于讨论不同放牧压力下甲烷通量具有重要意义，不同放牧率处理9年后，土壤吸收甲烷的能力在当地自然气候条件下没有显著变化;放牧对草原N20排放通量影响显著，依次是轻度放牧<围栏封育<中度放牧<重度放牧;放牧增大了C02排放通量，观测期间四种处理间C02通量差异显著，C02排放通量四种处理依次为：围栏封育<轻牧<重牧<中牧。 4．对内蒙古草原放牧条件下碳收支状况的研究表明，冷蒿-小禾草草原受自然条件和人为因素双重作用存在由碳库（积累碳）向碳源（释放碳）转化的可能性。

松嫩平原盐碱化草地模拟模型研究

松嫩平原盐碱化草地是我国著名的天然草场，又是东北西部绿色生态屏障，具有较高的经济价值和重要的生态意义。但是由于各种自然因素和人为因素，致使草地出现退化、沙化和盐渍化，尤其是草地盐渍化加重，生态环境日趋恶化。当地地形条件和气候要素是导致草地原生盐碱化的主要原因。而人类对草地的过度使用，如过度放牧和割草等则是导致草地快速次生盐碱化的主要原因，不仅导致土壤的退化，而且引起草地群落发生次生演替过程。在典型的次生演替过程中，常常可以出现羊革(Aneurolepidium chinense)群落、羊草和一虎尾草(Aneurotepidium chinense＆Chloris virgata)群落、虎尾草(Chloris virgata)群落、碱蓬(Suaeda glauca)群落等演替阶段。 本文试图建立一个过程模型，来模拟草地的生态学过程机理以及人类过度放牧对草地生态系统的影响。本模型包括5个部分：1）主要气候因子的模拟，2)土壤水分动态的模拟，3）土壤盐碱化动态的模拟，4）草地群落生长的模拟，5)不同放牧强度对草地生态系统的影响评价。以下将对各个部分分别描述a 在气候因子模拟子模型中，给出了影响草地生态系统主要气候园子的种类，并重点介绍了如何利用解析法计算太阳辐射，包括平地和坡地的理论可照时间，天文辐射日总量以及总辐射量。利用改进后的Penman式，模拟了全国的潜在蒸散量，与900多个气象站点的水面蒸发观测资料进行了验证，模拟结果很好。 利用面向对象技术，将土壤水分动力学模型与水分平衡模型相结合，建立了土壤水分动态的物理过程模型。模型以ld为步长，可以模拟多种土壤质地的水分动态。利用松嫩平原4中典型土壤（碳酸盐草甸黑钙土、栗钙土、碱化盐土、草甸碱土）1997年土壤湿度观测资料对模型进行了验证，效果根理想。 在水盐平衡模型和动力学模型基础上建立了物理过程模型，来模拟土壤盐碱化动态。模型以ld为步长，适合于模拟异质性强的多层土壤水盐动态。模拟了1997年羊草及碱蓬群落下的土壤盐分、碱化度、pH值动态，并与实验资料进行了比较，模拟结果可以反映土壤盐分和碱化的季节变化规律。 模型将气候要素、土壤湿度、土壤盐分浓度、碱化度和pH值作为影响草地群落生长最重要的环境因子，在土壤水分动态和盐碱化动态模型基础上，建立了过程模型来模拟以羊草(A．chinense)、虎尾草(C.virgata)、星星草(Puccinellialenuiflora)和碱蓬(S. glauca)为建群种的4种植物群落的地上生物量、地下生物量以及枯死生物量变化动态。利用吉林省长岭的气候资料和实验资料，模拟了1991年土壤湿度动态，1991年4种群落土壤盐分、碱化度和pH值变化动态，以及1991年4种群落生长动态，并分另fj利用实验资料进行了验证，模拟效果非常理想。 在此基础上，利用模型对不同放牧强度对土壤水分动态、盐碱化动态的影响进行了评价，并探讨了对群落演替和生长的可能影响。模型选择不放牧、轻牧、重牧、过牧、极牧5种放牧强度，利用模型每15天将地上生物量分别去除0%. 25%、50%、75%和90%，并且相应改变了土壤导水特性来模拟不同的放牧强度。模拟结果表明，重牧、过牧、极牧下土壤湿度显著降低，但在轻牧下土壤温度略有上升。在不放牧时，土壤以脱盐、脱碱过程为主，而轻牧下脱盐、脱碱过程则会变缓：重牧、过牧、极牧下则以盐碱化为主。．不放牧时羊草群落一直占优势，而轻牧下则被羊草一虎尾草群落替代：虎尾草可以忍受轻的盐碱，因此在重牧F取代羊草群落成为优势种;在过牧和极牧下，土壤盐碱化非常迅速，最终只有碱蓬可以忍受强度的盐碱，这时草地变为碱蓬群落或光碱斑。不放牧下草地群落生长良好，生物量最大;轻牧下，草地群落生物量保持在中等水平;而重牧、过牧、极牧下草地生物量迅速减少。通过将每年收割的生物量进行累加，可以发现轻牧下收获的生物量总量是最大的，随着放牧强度的增加，收获的生物量迅速减少，如果同时考虑到适口性的问题，则可以发现轻牧下可 以收获最多的生物量，而过牧和极牧下只能收获极少的适口性非常差的碱蓬。 模拟结果表明，过牧是导致松嫩草地次生盐碱化最重要的原因，它不仅造成草地土壤的退化，而且加速了草地群落的次生演替。适宜的放牧强度对于保护草地免受退化，保持较高的草地生产力水平至关重要。而过牧不仅降低了草地的生产力，而且严重破坏了草地环境，引起草地的迅速退化。

内蒙古退化草原对不同类型干扰的响应研究

本文结合野外调查、野外实验和模型模拟方法研究了内蒙古退化草原在继续放牧和啮齿类动物活动干扰下，植物多样性、种群空间格局、种间空间关联、小尺度鼠丘和小尺度空斑（Gap）上植被发展动态的生态响应。研究结果如下： （1）经过长期不同强度的放牧干扰后，无牧条件下植被盖度显著低于其它三个放牧（轻牧、中牧、重牧）条件下的植被盖度，而其它三个放牧条件之间的植被盖度差异不显著;无牧条件下羊草成为群落的优势种，轻牧和中牧条件下冷蒿依然是群落的优势种，这三种条件下寸草苔的种群盖度最大;重牧条件下优势种变为星毛委陵菜，并且其种群盖度最大;不同放牧退化阶段指示植物的种群盖度随放牧强度增大的变化趋势是：冷蒿为先增大后减小，而星毛委陵菜为先急剧增大，然后平缓增大，最后再急剧增大;植物多样性和均匀度指数在中牧条件下最大，在无牧条件下最小，说明中牧条件下群落的多样性最高，无牧条件下群落的多样性最小，而优势度指数的变化趋势和它们正相反。 （2）放牧对星毛委陵菜（或糙隐子草）种群空间格局有显著影响，即使在同一放牧强度下其种群在不同尺度上的空间格局存在显著差异。在小尺度上，植物种群主要呈现为集聚分布;同一放牧强度下随着尺度的增大，集聚分布趋向于随机和均匀分布;随着放牧强度的增大，物种的集聚分布消失的空间尺度缩短。 （3）不同放牧强度下，冷蒿和星毛委陵菜之间的空间关联存在显著的差异。在无牧和轻牧条件下，冷蒿和星毛委陵菜在小尺度（0-100cm）上主要呈负关联的空间关系，而在中牧和重牧条件下除了呈负关联的空间关系外，两个物种在空间上还是相互独立的。同时，放牧强度的增大缩小了负关联程度的峰值（最小值）。放牧强度越大，两物种之间的空间关系由负关联转变为相互独立的空间尺度越小（距离越短）。 （4）草原黄鼠鼠丘干扰显著降低了植物物种的丰富度（24种），同样，减少了不同功能组内的物种数，特别是多年生非禾本科草类减少的物种数最多;和周围的未受鼠丘干扰的植被比较，鼠丘上植物多样性减少了1.42，优势度减少了4.21，而均匀度增加了0.06;鼠丘上，多年生植物出现频率(0.37)大约是一年生植物出现频率(0.13)的四倍。具有高抗埋藏性的物种（寸草苔）和抗埋藏性的物种（冷蒿、冰草和糙隐子草）具有相对较高的出现频率。对于功能组来说，多年生非禾本科草类(PF, EF=0.51)具有最大的出现频率，接下来依次是多年生根茎禾草(PR, EF=0.46)、灌木和半灌木(SS, EF=0.32)、多年生丛生禾草(PB, EF=0.25)、一年生和两年生植物(AB, EF=0.13);鼠丘上，寸草苔的密度最大（244.43 个体/米2)。多年生非禾本科草类的密度(130.74个体/米2)远大于其他功能组的密度（PR，34.76个体/米2;PB，16.52个体/米2;AB，14.31个体/米2;SS，12.39个体/米2）;鼠丘上植被地上生物量(35.90克/米2)远远小于外围对照植被地上生物量(211.54克/米2)。冷蒿的地上生物量最大，其次是寸草苔。对于功能组，SS最大 (8.44克/米2) ，其次是PF (7.17克/米2)，这两个功能组的地上生物量远大于其他三个功能组的地上生物量（PR, PB和 AB分别是 3.23克/米2、1.40克/米2和2.49克/米2）。 （5）干扰产生空斑的拓殖受空斑大小和放牧历史的影响，植物拓殖空斑的方式随空斑形成后的时间而变化。空斑直径越大，其被拓殖的机会越大;具有高强度放牧历史群落中的空斑更易被植物拓殖;第一年对空斑的拓殖主要通过种子萌发;第二年，种子萌发方式（特别是一年生植物）拓殖空斑的比例有所降低，而通过地下根茎的克隆繁殖拓殖空斑的比例有所增加。

中国北方草地及东部森林季节生长格局模拟

近现代以来，由于人类对自然植被的不合理利用，导致植被退化，严重影响了我国的环境质量及社会经济的发展。因此，根据植被的净第一性生产力(NPP)制定植被资源的利用强度，依据环境承载力确定退化土地的植被恢复盖度，对于我国自然资源的合理利用及可持续的退化生态系统恢复具有重要意义，急需在区域上对NPP及最适植被盖度进行科学估计。 以我国北方草地、东部森林样带为研究对象，采用以植物群落生长与环境容纳量相平衡的基本生态学理论为基础的植物群落生理生态学模型模拟植物群落的蒸发系数(k)、叶片投影盖度(FPC)及NPP的分布状况，分析其最适盖度与NPP的空间分布及NPP的季节变化。结果表明： (1) 温性草地自东向西，青藏高原自东南向西北，植物群落3个模拟参数 k、NPP与FPC呈递减趋势。北方草地NPP的模拟值较低，仅高寒草甸和温性草甸草原的NPP均值大于2 t•hm-2•a-1，高寒草甸和高寒草原的叶片投影盖度为93%和79%。高寒草甸的3个模拟参数均最高，高寒草原FPC仅次于高寒草甸，而NPP却与温性典型草原相近，温性典型荒漠的3个参数最低。 (2) 东部森林NPP表现为从南到北逐渐减少的纬度地带性分布趋势，从最南端热带雨林季雨林的31.62 t•hm-2•a-1依次向北减少至寒温带针叶林的3.45 t•hm-2•a-1。k与FPC没有表现出递减趋势，而且变化幅度不大，分别为05-0.4和87%-77%。 (3) 高寒草甸、高寒草原、温性草甸草原、温性典型草原、温性荒漠草原、温性草原化荒漠、温性典型荒漠这7个类型草地的畜群承载力约为：5.2、2.3、3.6、2.1、1.0、0.6、0.2只羊单位•hm-2。 (4) 我国东部森林FPC大多数大于70%，可以支持密度较高的森林植被类型。北方温性草原大部分地区FPC约为50%或者更小，宜维持现有的以草本、灌木及半灌木植物为主的植被类型及生态环境功能，而不宜进行大面积的农田开垦或恢复高密度的人工植被。

黄土高原半干旱偏旱区苜蓿-粮食轮作土壤水分恢复效应

该文测定和分析了黄土高原半干旱偏旱区不同生长年限苜蓿草地以及轮作不同年限粮食作物后0～1000cm深层土壤水分变化规律。结果表明:随着苜蓿生长年限的延长,苜蓿草地土壤干层厚度逐渐增加,3年生苜蓿草地土壤干层深度达到760cm,6、7、10年生苜蓿草地土壤干层深度均超过1000cm,6年生苜蓿地1000～1500cm土层仍为干燥层,土壤平均湿度为9.68%;采用草粮轮作能明显减小苜蓿草地干层的厚度和范围,0～1000cm土壤水分较10年生苜蓿草地都有不同程度的恢复,轮作2、6、8、12和18a粮田平均土壤水分恢复速率25.2mm/a,年均累积恢复土层厚度123.1cm,0～300cm土层水分恢复程度较高,且轮作年限愈长,土壤水分恢复效果越好,轮作18a粮食作物后0～660cm土层土壤水分恢复量达到了531.1mm;苜蓿草地适宜翻耕年限为5～6a,且6年生苜蓿草地0～1000cm土壤水分恢复到当地土壤稳定湿度值需要23.8a,该地区适宜的苜蓿-粮食轮作模式为"5～6年生苜蓿→24年粮食作物"。