贵州乌江东风水库库区消落带苔藓植物区系分析

采用典型调查与路线调查相结合的方法,对贵州乌江东风水库库区消落带苔藓植物区系的物种组成、生活型、分布区类型和丰富性进行了调查和分析。结果表明:该区域共有苔藓植物18科58属101种,其中,藓类植物有16科56属99种,苔类植物有2科2属2种;优势科为灰藓科(Hypnaceae)、青藓科(Brachytheciaceae)和丛藓科(Pottiaceae),优势属为青藓属(Brahchythecium B.S.G.)、真藓属(Bryum Hedw.)和小曲尾藓属[Dicranella(Müll.Hal.)Schimp.];单属科和单种属所占比例均较高,分别占该区域苔藓植物总科数和总属数的50.0%和63.8%。该区域分布的苔藓植物生活型可分为交织型、丛集型、垫状和平铺型4类,以丛集型种数最多(48种),占该区域苔藓植物总种数的47.5%。该区域分布的苔藓植物可划分为12个分布区类型,其中,温带成分种类最多,所占比例为81.5%;热带成分所占比例仅为18.5%;中国特有种所占比例也较高,为20.7%。该区域苔藓植物的丰富性综合系数(S_i)为-0.360 8,低于相邻的六冲河下游流域。综合分析结果表明:该区域的苔藓植物多样性较为丰富,多数种类具有较强的抗逆性,且丛集型苔藓种类最多,与库区消落带的特殊生境相适应;地理成分以东亚成分和北温带成分为主,总体属温带性质,且中国特有种较多,反映出该区域苔藓植物区系的特殊性和复杂性。

南岭珍稀动物及保护现状研究

报道了湘粤交界地带南岭自然保护区珍稀动物的种类及保护现状 ,该区分布有国家级珍稀危保护动物 37种 ,占两省珍稀濒危动物 1 1 8种的 31 4% ,分隶 2 4属、 2 0科 ,其中华南虎、巨蜥、虎纹蛙濒临绝迹。

埃塞俄比亚Alatish国家公园大型哺乳动物多样性、分布及其与栖息地的联系(英文)

于2004年8月-2005年3月间研究了Alatish国家公园在雨季和旱季期间大型哺乳动物的多样性和分布。基于地形图、卫片和预调查结果,在4种生境类型中识别出37个100 km2或者更小的斑块。在4个植被类型中随机选择了11个斑块,沿随机选择的样线进行了调查,样线10 km长, 0·2 km宽,覆盖了该区域面积的20 %。使用Shannon-Wiener多样性指数、DISTANCE5·0软件以及Simpson相似性指数分析了大型哺乳动物的多样性以及分布的相似性。记录了20种体型较大的哺乳动物;河边林地在雨季和旱季都有最高的多样性,林地的多样性最低;旱季中4种类型的栖息地具有相似的分布型;由于栖息地退化不能确定物种的分布格局。联合距离取样分析揭示出,旱季和雨季大型哺乳动物的密度较低,分别为4·067只/km2和6·263只/km2。所观察的哺乳动物可分为草食动物(15 %)、游牧动物(30 %)、杂食动物(25 %)与食肉动物(30 %) 。

Structure changes and succession dynamic of the natural secondary forest after severe fire interference

The structure and dynamic succession law of natural secondary forest after severe fire interference in recent 20 years were studied by adopting the method of deducing time series from the spatial sequence of vegetation in Heihe region, Heilongjiang, China. Two typical and widely distributed forest types in the study area, namely forest type A and forest type B, were selected as study subjects. Forest type A is pure broadleaf forest or broadleaf mixed forest mainly composing of superior Betula platyphylla and Populus davidiana in the area with gradient 〈25°, while forest type B is pure forest or mixed forest composing of superior Quercus mongolica and Betula davurica in the area with gradient 〉25°. Species richness, vegetation coverage, important value, and similarity index of commtmity in different layers （Herb, shrub, small tree, and arbor layers） were investigated and analyzed for the two typical forests. The results show that after fire interference, the species richness and coverage in each layer in forest type A were higher than that in forest type B. Both for forest type A and B, with elapse of post-fire years, the species richness and coverage of herbs and shrubs showed a decline tendency, while those of arbor layer present a rising tendency. Through comparison of the important values of species in each layer and analysis of community structure changes, the dynamic process of post-fire vegetation succession for forest type A and B was separately determined. Post-fire 80 years＇ succession tendency of forest type A is B. platyphylla and Larix gmelinii mixed forest. Its shrub layer is mainly composed of Corylus heterophylla and Vaccinium uliginosum, and herb layer is dominated by Carex tristachya, Athyrium multidentatum, and Pyrola incarnate; whereas, the post-fire 80 years＇ succession of forest type B is Q. mongolica and B. davurica mixed forest. Its shrub layer is mainly composed of lespedeza bicolar and corylus heterophylla and herb layer is dominated by Carex tristachya, Asparagus densiflorus, and Hemerocallis minor.

Spatial and temporal variation of fish assemblages in a subtropical small stream of the Huangshan Mountain

Spatial and temporal variation of fish assemblages were investigated seasonally from May 2007 to February 2008 across 11 study sites in a subtropical small stream, the Puxi Stream, of the Huangshan Mountain. Along the longitudinal gradient from headwater to downstream, fish species richness and abundance increased gradually, but then decreased significantly at the lower reaches. The highest species richness and abundance were observed in August and the lowest in February. Based on analysis of similarities （ANOSIM）, fish assemblages were significantly different in spatial variation but not in temporal variation. Although differences were observed both among sites and among stream orders, the lower R value in order-variation suggested stream order was not the optimal factor explaining the spatial variation of fish assemblages. In addition, dam construction did not significantly alter fish assemblages in the sites adjacent to and immediately downstream to dams. Using cluster analysis and non-metric Multi Dimensional Scaling analysis （NMS）, assemblages were separated into three groups at a Bray-Curtis similarity value of 42%： the upper, middle and lower groups. Following analysis of similarity percentages of species contributions （SIM- PER）, shifts in occurrence or abundance of S. curriculus, Z. platypus, R. bitterling and A. fasciatus contributed most to the differences amongst the three groups. Standard Deviation Redundancy Analysis （RDA） suggested that habitat structure （such as elevation, substrate, and flow velocity） contributed to the spatial and temporal pattem of fish assemblages in the Puxi Stream. In conclusion, the fish assemblages in Puxi Stream presented significant spatial but not temporal variation. Human disturbance has perhaps induced the decrease in species diversity in the lower reaches. However, no significant change was observed for fish assemblages in sites far from and immediately downstream from low-head dams [Current Zoology 56 （6）： 670-677, 2010].

Floristic and structural analysis of the woodland vegetation around Dello Menna,Southeast Ethiopia

Floristic composition and vegetation structure were described for the woodland vegetation around Dello Menna, Bale zone, southeast Ethiopia. A total 50 （20 m ×20 m） quadrats were sampled to identify and describe plant community types, species diversity, richness and evenness and to relate the identified plant community types with some environ- mental factors and describe the population structure of woody plant species. In each quadrrat, data on species identity, abundance, height and Diameter at Breast Height （DBH） of woody plant species, altitude and slope were recorded. Vegetation classification was performed using PC - ORD software package. Sorensen＇s similarity coefficient was used to detect dissimilarities among communities. Shannon - Wiener diversity index, species richness and Shannon＇s evenness were computed to de- scribe species diversity of the plant community types. Results show that a total of 171 vascular plant species representing 53 families were re- corded. Fabaceae is the dominant family represented by 13 genera and 26 species （15%） followed by Asteraceae, Lamiaceae and Anacardiaceae with eight species each （4.6%）. Based on the results of vegetation classi- fication, three plant communities （Dalbergia microphylla community, Grewia bicolar- Acacia brevispica community, and Combretum molle- Combretum collinum community） are recognized and described. Species richness, diversity and evenness varied among the plant communities.Species richness and diversity exhibit a bell - shaped pattern along alti- tude. Species turn over among communities more or less follow altitud- inal gradients. Tukey＇s pairwise comparison of means among the plant community types shows significant variations in altitude, implying that altitude is one of the most important factors determining the distribution of plant communities. The community Dalbergia microphylla type exhibits the highest species richness and diversity. Analysis of population structure of the dominant species reveals various patterns. Future research directions and recommendations are suggested for the sustainable utilization.

Elevational diversity of arrow bamboo (Fargesia spathacea) communities on Mount Shennongjia in Central China

Altitudinal changes in species richness, species diversity, species evenness, life-form spectrum, and community structure of arrow bamboo (Fargesia spathacea) were studied within 11 plots from 1 500 m to 2 600 m asl on Mount Shennongjia in Central China. From the lowest plot (1 680 m) to the highest one (2 570 m), vascular plants declined from 30 to 7 species, following a linear model ofY=55.99-1.83X (d.f.=9,F-value=48.64,r 2=0.84,P<0.001); species diversity, reduced from 3.13 to 1.78, following a linear model ofY=4.67–0.10X (d.f.=9,F-value=22.82,r 2=0.72,P=0.001); species evenness varied from 0.83 to 0.99, but presented little relationship to the altitude (r=0.112,P=0.742). In the life-form spectra, with the increase of altitude, the percentage of annual plants (r=0.60), underground bulb perennials (r=0.40), and big trees (r=0.35) tended to increase; shrubs (r=?0.52) and middle-sized trees (r=?0.45) tended to decline; perennial grasses (r=0.04) and semi-shrubs (r=0.03) were not strongly related to the altitudinal gradient. Arrow bamboo communities could be classified into five groups: bamboo under evergreen broad-leaved forest, under deciduous broad-leaved forest, under temperate coniferous forest, under cold-temperate coniferous and mixed forest, and pure bamboo community.

Changes in tree species diversity and dominance across a disturbance gradient in Nepalese Sal (Shorea robusta Gaertn. f.) forests

Disturbance is often touted as a management tool, as moderate disturbance is believed to enhance diversity; thus an understanding of frequent and fluctuating disturbance regimes in forests and their effects on stand structure, dominance and diversity is very crucial. Here, the effects of different disturbance regimes, along a gradient, on diversity and dominance of five Shorea robusta Gaertn. f.-dominated forests were investigated in 25 one-ha plots in Nepal. A total of 67 tree species were recorded; of which 41 species were encountered in least disturbed and 10 species in beavily disturbed forest. Significant variations among forests were observed for all measures of alpha diversity. Alpha diversity measures declined linearly along a disturbance gradient while dominance increased linearly. Relative basal area of S. robusta increased as the level of disturbance increased, which in turn produced more than two-fold higher important value index in heavily disturbed forest than the least disturbed forest. All alpha diversity measures declined in an order of three with increasing relative basal area of S. robusta. The similarity in species composition between each pair of disturbed forests was generally low （Jaccard＇s similarity index 〈 57%）, suggesting a higher Beta diversity, It can be concluded that diversity of Sal forests declines with increasing magnitude of disturbance, which in turn favors a higher domi- nance of S. robusta. Controlling the population of the dominant species, mainly S. robusta, is recommended to enhance diversity and to achieve multiple-use forest management objectives.

Understory vascular plant community assembly in relation to time-since-fire and environmental variables in a Chinese boreal forest

Understanding the response of understory vegetation to fire disturbance is vital to biodiversity conservation and management of boreal forests. We surveyed understory vascular plant richness and composition, and measured related environmental variables along a toposequence within three successional stages, initial （3 years post-fire）, early （13 years post-fire） and late （〉1oo years post-fire） successional stages. Using permutation multivariate ANOVA and nonmetric multidimensional scaling, we analyzed how understory species richness and composition change as time-since-fire proceeds, and their correlative relationships with environmental variables. Species richness and composition showed significant differences among the three successional stages. Understory species richness and abundance were significantly associated with time-since-fire, topographic position, elevation and organic layer depth. Among these variables, time-since-fire had the strongest effect and topographic position was the second major factor on affecting understorycommunity assembly. In overwhelmed the effects addition, time-since-fire of soil pH in the initial successional stage and gravimetric soil moisture in early and late successional stages on understory species composition

Diversity, Endemism and Conservation of Ferns(Polypodiales) in the Mexican Mountain Component

We analyzed the distributional patterns of95 selected species of leptosporangiate ferns inhabiting the Mexican Mountain Component, using grid-cells of one geographical degree as unit areas,applying endemism indices and richness and beta diversity analyses.Distributional data were obtained from several herbaria and specialized literature.Five grid-cells appear to be important for fern species richness, as they contain 35 to 49 species.These gridcells are located in the Sierra Madre Oriental(SMO),Trans-Mexican Volcanic Belt(TMVB) and the Sierra Madre del Sur(SMS).Mean richness by latitudinal belts of one degree showed that the belts with highest values are related to the TMVB and SMS.A total of 13grid-cells were recognized as important from theperspective of endemism; most of them are located also in the SMO, TMVB and SMS.The richest gridcells coincided with one of the main centres of endemism for ferns obtained in this study, located in the convergence of the southern part of the SMO, the eastern portion of the TMVB and the northern part of the SMS, reflecting the high humidity existing on the mountain slopes facing the Gulf of Mexico.Some important grid-cells recognized from richness and endemism analyses coincide with Mexican Natural Protected Areas.The beta diversity analysis showed a low degree of similarity among grid-cells, implying a high species replacement, as the result of environmental heterogeneity occurring in the Mexican mountain systems.On the other hand, the spatial analysis suggested a pattern of phytogeographical regionalization comprising twomain areas: the Mexican Transition Zone and the Mexican Central Plateau.Ferns play an important role in the Mexican biodiversity and contributing to the beta diversity of Mexico.

Higher Species Diversity Occurs in More Fertile Habitats Without Fertilizer Disturbance in an Alpine Natural Grassland Community

Are there some relationships among species diversity and soil chemical properties of high altitude natural grasslands? Plant community composition and chemical properties of soil samples were compared to investigate the relationship between soil and species diversity, and the richness in Tibetan alpine grasslands. Results showed that species diversity was significantly positively related to soil organic matter(SOM), total nitrogen(TN),available nitrogen(AN), total phosphorus(TP),available phosphorus(AP), and available potassium(AK) in the high alpine grasslands. Margalef's species richness index was also significantly positively related to SOM, TN, AN, and TP. Most soil chemical properties showed significantly positive correlation with species diversity and Margalef's richness index.Our results suggested that higher plant species richness index and diversity occurred in more fertile soil habitats in high altitude natural grassland community. In practice, fertilization management for the restoration of degraded grassland should be conducted with reference to the nutrient levels ofnatural grassland without the additional artificial fertilizer and with higher species-diversity and richness index.

Riparian Vegetation Dynamics Across Two Different Landscapes Along the River Cauvery in the Kodagu Region of Western Ghats

Decades of commercial planting and other anthropogenic processes are posing a threat to the riparian landscapes of the Cauvery river basin, which supports a high floral diversity. Despite this, the habitats in the upstream sections of the River Cauvery are still intact, as they are located in sacred groves. To understand the dynamism of riparian forests exposed to anthropogenic pressures, the upstream stretch of Cauvery extending from Kushalanagara to Talacauvery （~102 km） was categorized into two landscapes： agro ecosystem and sacred （i.e. preserved）. The tree species were sampled using belt transects at 5 km intervals and the regeneration status of endemic species assessed using quadrats. A total of 128 species belonging to 47 families, and representing 1,590 individuals, was observed. Amongst them, 65% of unique species were exclusive to sacred landscapes. A rarefaction plot confirmed higher species richness for the sacred compared to the agro ecosystem landscapes, and diversity indices with more evenness in distribution were evident in sacred landscapes. A significant loss of endemic tree species in the agro ecosystem landscapes was found. Overall, this study demonstrates that an intense biotic pressure in terms of plantations and other anthropogenic activities have altered the species composition of the riparian zone in non-sacred areas. A permanent policy implication is required for the conservation of riparian buffers to avoid further ecosystem degradation and loss of biodiversity.

Elevational distribution of butterflies in the Himalayas: a case study from Langtang National Park, Nepal

Mountain ecosystems are relatively more vulnerable to climate change since human induced climate change is projected to be higher at high altitudes and latitudes. Climate change induced effects related to glacial response and water hazards have been documented in the Himalayas in recent years, yet studies regarding species' response to climate change are largely lacking from the mountains and Himalayas of Nepal. Changes in distribution and latitudinal/altitudinal range shift, which are primary adaptive responses to climate change in many species,are largely unknown due to unavailability of adequate data from the past. In this study, we explored the elevational distribution of butterflies in Langtang Village Development Committee(VDC) of Langtang National park; a park located in the high altitudes of Nepal. We found a decreasing species richness pattern along the elevational gradient considered here.Interestingly, elevation did not appear to have a significant effect on the altitudinal distribution ofbutterflies at family level. Also, distribution of butterflies in the area was independent of habitat type,at family level. Besides, we employed indicator group analysis(at family level) and noticed that butterfly families Papilionidae, Riodinidae, and Nymphalidae are significantly associated to high, medium and low elevational zone making them indicator butterfly family for those elevational zones, respectively. We expect that this study could serve as a baseline information for future studies regarding climate change effects and range shifts and provide avenues for further exploration of butterflies in the high altitudes of Nepal.

Assessing Conservation Values of Forest Communities in Nanda Devi Biosphere Reserve: Plant Diversity, Species Distribution and Endemicity

Present study has been conducted in a biodiversity rich Nanda Devi Biosphere Reserve between 2000-3800 m in two different forest physiognomy holding sites to analyze the structure and composition of the forest communities including richness of native, non native and endemic species,and suggest conservation values at community and reserve level.A total of 60 sites were sampled and grouped in 11 and 8 communities for two representative sites Pindari-Sunderdhunga-Kafni(PSK) and Lata-Tolma-Phagti(LTP) respectively.From the sampled sites, 451 species(11.8%, 53 trees;17.71%, 80 shrubs; and 70.51%, 318 herbs) have been recorded.In general, PSK site represented 73.6% and LTP site represented only 54.9% of the total plant species recorded in the study area.Out of total species in PSK site, native species contributed 59.6%(198spp.) and 24.7% species were endemic and near endemic.In LTP site, 66.5% species were Himalayan natives and 33.5% were endemic and near endemic.The species richness ranged from 4-23 ind ha-1(tree),3-18 ind ha-1(sapling), 5-19 ind ha-1(seedling) in PSK site and 4-18 ind ha-1(tree), 4-11 ind ha-1(sapling), 4-16 ind ha-1(seedling) in LTP site.The density ranged from 260-535 ind ha-1(tree), 145-633 ind ha-1(sapling), 1450-8170 ind ha-1(seedling) in PSK site and 599-1211 ind ha-1(tree), 70-951 ind ha-1(sapling),470-1665 ind ha-1(seedling) in LTP site.Species diversity for trees ranged from 0.73-3.37, saplings,0.64-2.67, seedlings, 0.70-2.51, shrubs, 1-2.34 and herbs, 2.02-3.21 in PSK site and 0.63-1.61, saplings,0.76-1.36, seedlings, 0.35-1.79, shrubs, 0.98-2.73 and herbs, 2.48-3.61 in LTP site.These recorded values were almost comparable with the studies conducted in sub-tropical, temperate and sub-alpine regions of the west Himalaya.In some cases the values were slightly higher than the reported values.The important communities with high conservation values have been identified based on different ecological parameters and species distribution.Among all the prioritized communities, Mixed Silver firRhododendron-Maple community in PSK site and Taxus wallichana- A.pindrow mixed community in LTP site supports maximum richness and density of native and endemic species.This study calls for development of adequate strategy and action plan for the conservation and management of habitats, species,and communities under changing climate and socioeconomic scenarios, so that sustainable utilization of the species could be ensured.

3eta Diversity of Mbuna in Lake Malawi

Molecular and field studies suggest that Mbuna have limited migration range and are restricted by habitat discontinuities especially in areas where rocky habitats are separated by stretches of sand. This study estimated regional diversity of Mbuna in Lake Malawi. The estimated fl-diversity for all sites was 114.5 Mbuna suggesting that there was high level of allopatrism for the species complex. Sympatric index was low in the two regions of southern and northern lake and the observed high-end richness strongly correlated with minimum species richness. The sympatric index for the whole lake was 0.8, with non-monotypic species complexes showing declining values of sympatric index and the decline was dependent on the geographical scale of the area covered. The northern region sites had mean habitat ranking of 84.5% while the southern sites had habitat ranking of 56.7% supporting the observation that there are more rocky habitats in the northern part of the lake than in the southern. Implications of habitat ranking are discussed in terms of species abundance and richness.

Studies on the community characteristics of major arthropods in summer maize fields

This study is to integrate pest management （IPM） of maize insect pest. The paper reports the current condition of species diversity of maize field in Nanning, Guangxi Province. All exper/mcntal materials were collected dur/ng the stages of tasseling, blister, milk, maturity and after reaping respectively from 5 plots from April to July, 2007. The Shannon-Wiener index（H）, Simpson index（H＇）, Brillouin index（J）, species evenness（E） and richness index （Dmc） were used into analysis of abundance and distribution characteristics of communities and populations of major arthropods in maize fields. Result showed that a total of 19 arthropods, belonged to 10 orders and 18 families, were obtained from maize fields. Of which there are 12 pest insects, 3 natural enemy insects, 2 spiders and 2 middle insects. All of the community diversity indices were the highest in maize fields after reaping. No significant difference was found between other 4 various stages i.t. tasseling, blister, milk and maturity stages. The results of this study will help to carry out the IPM of maize field pest insect.

The Potential Contribution of Wildlife Sanctuary to Forest Conservation: A Case Study from Binsar Wildlife Sanctuary

Forest vegetation of a protected area （Binsar Wildlife Sanctuary） in Kumaun region （west Himalaya） was analysed for structure, composition and representativeness across three different altitudinal belts, lower （1,6oo-1,8oo m a.s.1.）, middle （1,900-2,100 m a.s.1.） and upper （2,200-2,400 m a.s.1.） during 2oo9-2011 using standard phytosociological methods. Four aspects （east, west, north and south） in each altitudinal belt were chosen for sampling to depict maximum representation of vegetation in the sanctuary. Population structure and regeneration behaviour was analysed seasonally for two years to show the establishment and growth of tree species. A total of 147 plant species were recorded from the entire region of which 27 tree species were selected for detailed study. Highest number was recorded at upper （18 species）, and lowest at lower altitudinal belt （15 species）. The relative proportion of species richness showed higher contribution of tree layer at each altitudinal belt. The population structure, based on the number of individuals, revealed a greater proportion of seedling layer at each altitudinal belt. The relative proportion of seedlings increases significantly along altitudinal belts （p〈0.05） while opposite trends were observed in sapling and tree layers. The density of sapling and seedling species varied non-significantly across seasons （p〉0.05）. The density values decreased in summer and increased during rainy season. As far as the regeneration status is concerned, middle and upper altitudinal belts showed maximum number of species with fair regeneration as compared to lower altitudinal belt. Overall density diameter distribution of tree species showed highest species density and richness in the smallest girth class and decreased in the succeeding girth classes. This study suggests that patterns of regeneration behaviour would determine future structural and compositional changes in the forest communities. It is suggested that the compositional changes vis-a-vis role of ＇New＇ and ＇Not regenerating＇ species need priority attention while initiating conservation activities in the sanctuary. This study calls for exploring other less explored Wildlife Sanctuaries in the Himalaya and across the world, to achieve overall biodiversity status in these protected areas and thus to justify their role in conserving biodiversity in the region.

The Research on the Distribution, Abundance and Some Ecological Characteristics of Neuroterus Species （Hymenoptera： Cynipidae） in Oak Forest of West Azerbaijan （Iran）

Oak gall wasps （Hymenoptera： Cynipidae）, with more than 1300 species, represent one of the largest radiations of gall inducing insects. Many studies have documented galling species lists and richness, especially gall wasps, but few studies have been directed toward understanding how the gall-inducing species are locally distributed. In this survey, the oak gall wasps were collected from April to November （2009 and 2010） in West Azerbaijan of Iran. Among these collected galls, five species of oak gall wasps which belonged to the genus Neuroterus sp. were identified as： Neuroterus lanuginosus Giraud, N. numismalis Geoffroy, N. saliens Kollar, N. laeviusculus Schenck and N. quercus-baccarum Linnaeus. All of the galls in this survey are leaf galls. These galls were produced by the asexual reproduction and were collected in summer and fall seasons. The highest species richness was recorded in Ghabre-hossein and Vavan stations. Also, the highest density of gall formation was recorded at the southern direction. The multiple-sites similarity measures indicated that similarity in gall composition and community between collecting sites was generally between 0.57 and 0.90. The highest multiple site similarity was recorded between Vavan vs Rabat vs Dare-ghabr station. The authors showed that the very cold and humidity climate is not appropriate to Neuroterus species activity and the south direction is the best side for their survival.

Influence of thinning on acidic deposition in Chinese fir plantations

Acidic deposition,which is mainly caused by atmospheric pollution,is one of the global environmental problems.Thinning is an effective management to improve the tree productivity,reduce the wildfire risk and maintain a healthy forest.Since thinning may reduce the effect of acidic deposition,the effect of thinning on acidic deposition was estimated.The biomass,soil properties,pH value of runoff and groundwater in both unthinned and thinned Chinese fir plantations were measured and compared over a 5-year period(2-6 years after thinning).The results indicated that acidic deposition in the Huitong State Ecosystem Research Station was serious,and it got worse with time.Forest thinning resulted in a huge change in biomass and soil properties.During the 5-year monitoring period,biomasses of understory and litter,plant species richness,coverage of undergrowth plant layer were significantly higher in thinned site than in unthinned site.Moreover,higher soil fertility as well as lower amounts of runoff and groundwater were found in thinned site.It was suggested that thinning could improve the structure of forest,leading to restoring the effluent(runoff and groundwater) pH to the normal value.

Soil and Vegetation Seasonal Changes in the Grazing Andean Mountain Grasslands

Andean grasslands ecosystems are fragile environments with rigorous climatologic conditions and low and variable food for the grazing. The Apolobamba area is located in the Bolivian Andean Mountains. Its high grasslands provide a natural habitat for wild and domestic camelids such as vicuna(Vicugna vicugna) and alpaca(Lama pacos). The botanical diversity plays an essential role in maintaining vital ecosystem functions. The objectives of this research were to determine the seasonal changes in soil properties, to study the vegetation changes during the wet and dry seasons and the influence of soil properties and camelid densities on the vegetation in the Apolobamba grasslands. Four zones with different vicuna populations were selected to be studied. The following soil parameters were determined: total organic carbon, total nitrogen, available phosphorous, cation exchange capacity, exchangeable cations, pH and texture. The vegetation season changes were studied through botanical identification, above-ground biomass, plant cover and species richness. Results showed that some soil properties such as C/N ratio, CEC, silt and clay percentages kept stable against the seasonal changes. Generally, soil nutrients were relatively higher during the dry season in the surface and subsurface. The results did not point out the predominant vegetation growth during the wet season. The seasonal vegetation growth depended on each species. Thegood soil fertility corresponded to the highest plant cover. Soil fertility presented no influence on the above-ground biomass of the collected species. The negative influence of camelid grazing on soil properties could not be assessed. However, overgrazing could affect some plant species. Therefore, protection is needed in order to preserve the biodiversity in the Andean mountain grasslands.