Main regularities in synanthropization of different vegetation types in the Republic of Bashkortostan

The contribution of synanthropization to the anthropogenic evolution of vegetation has been analyzed by assessing its level in approximately 260 associations and communities of 31 vegetation classes in the Republic of Bashkortostan. The results show that this level is high in communities of synanthropic classes Secalietea, Chenopodietea, Artemisietea vulgaris, and Robinietea. Synanthropization of communities under the effect of human activities is also characteristic of many classes of natural vegetation, especially those of meadows, floodplain forests, and ravine-gully systems. Some communities are protected from synanthropization due to the existence of abiotic or biotic barriers to the expansion of synanthropic species (communities of high-mountain areas and zonal forests, many aquatic communities, and mountain meadows and steppes).     

Vegetation distribution on Tibetan Plateau under climate change scenario

The impact of climate change on distribution of vegetation is an important aspect in studies on the responses of ecosystems to the climate change. Particularly in the sensitive environments of the Tibetan Plateau, vegetation distribution may be significantly affected by climate change. In this research, the coupled biogeography and biogeochemistry model, BIOME4, was modified according to the features of vegetation distribution on the Plateau, and the Kappa statistic was used to evaluate the modeling results by comparing the simulated vegetation distribution with the existing 1:1,000,000 vegetation map of China. The comparison showed that modified model was appropriate for simulating the overall vegetation distribution on the Plateau. With the improved BIOME4 model, possible changes in the vegetation distribution were simulated under climate change scenarios. The simulated results suggest that alpine meadows, steppes, and alpine sparse/cushion vegetation and deserts would shrink, while shrubs, broad-leaved forests, coniferous-broad-leaved mixed forests, and coniferous forests would expand. Among these types, shrubs, alpine meadows, and steppes would change the most. The shrubs vegetation would expand toward the northwest, replacing most alpine meadows and part of steppes, and thus causing their shrinkages. Yet broad-leaved forests and coniferous-broad-leaved mixed forests demonstrated smaller changes in their distributions. For all the forest types, the area of coniferous forests would increase the most by spreading to the interior of the Plateau.     

Current state of mountain steppes in Sverdlovsk oblast

The current state and phytodiversity of mountain steppes in Sverdlovsk oblast have been evaluated, involving an inventory of several botanical and botanical-geomorphological natural landmarks in the steppe landscape. New growth localities of rare plant species have been discovered. Scientific and natureconservation significance of the surveyed mountain steppe areas has been demonstrated. A set of informative indices has been used to identify the key protection sites of steppe vegetation. Four sites are recommended for inclusion in the system of specially protected areas with the status of natural landmarks.     

Restoration of the lower reaches of the Tarim River in China

The middle and lower reaches of the Tarim River are areas of rich biodiversity and natural resources in the inland arid region of China. However, the Tarim River and its associated wetlands have been severely damaged and fragmented during the past several decades. To restore the deteriorated ecosystem and preserve the endangered riverine vegetation along the Tarim River, a project for releasing water from upper dams to the lower reaches of the Tarim River was initiated by China’s government in 2000. Between 2000 and 2005, we monitored the responses of groundwater levels and vegetation to this mitigation along nine transects spaced at mean intervals of 45 km along the river from Daxihaizi Reservoir, the source of water conveyance, to the Lake Taitema, the mouth of the Tarim River. We found that average groundwater levels rose significantly from 8 to 4 m below ground surface. Species diversity did not change during the 5-year period, but the total vegetation coverage and canopy size of some species significantly increased. The endangered tree species, Populus euphratica, started to regenerate. Our results indicated that species diversity might recover very slowly, even if the trial water release program became a permanent river management practice. Management decisions about allocating limited water supplies among competing uses in arid regions will ultimately determine whether degraded river ecosystems, such as the Tarim River, can be restored.     

The phenomenon of forest invasion to steppe areas in the Middle Urals and its probable causes

Steppes at the northern limit of their distribution are a convenient object for studying climate-induced modifications of the environment, being sensitive to regional climate changes. Over the past 46–47 years, herbaceous vegetation in the study steppe areas has been replaced by shrubs and trees. Petrophytic steppes on hilltops and stony knolls, where conditions are not favorable for tree growth, has proved to be more resistant to such changes. In these habitats, however, the influence of surrounding forest phytocenoses has also resulted in a gradual decrease in the proportions of species from the steppe and forest–steppe floras in the structure of communities and the invasion by species typical of forest vegetation.     

Vegetation dynamics and climate change on the Loess Plateau,China: 1982–2011

Monitoring the dynamics of vegetation growth and its response to climate change is important to understand the mechanisms underlying ecosystem behaviors. This study investigated the relationship between vegetation growth and climate change during the growing seasons on the Loess Plateau in China by analyzing the normalized difference vegetation index (NDVI) derived from the Land Long Term Data Record dataset from 1982 to 2011. Results showed that growing-season NDVI had increased at an annual rate of 0.0028, particularly in the semi-arid and semi-humid regions. By contrast, the NDVI first increased from 1982 to 1994 (0.0013 year^?1, P < 0.05) and then decreased from 1994 to 2011 (0.0016 year^?1, P < 0.05) in the arid region. Temperature had a positive effect on NDVI in most periods within and across seasons in the semi-humid region but had no significant effect in the arid region. Precipitation had a positive effect on NDVI in the arid region in summer and in the semi-arid region in autumn. Summer precipitation was important for autumn vegetation growth in the arid region, whereas summer temperature increased autumn vegetation growth in the semi-arid and semi-humid regions. Further analyses supported the lag-time effects of climate change on vegetation growth on the Loess Plateau. Precipitation shifts had 15- to 18-month time lag effects on vegetation growth in the three climate regions. Vegetation NDVI had a 17-month lag response to temperature in the semi-arid region. Human activities should not be neglected in analyzing the relationship between vegetation growth and climate change on the Loess Plateau.     

Reconstruction of the Holocene vegetation in the central Negev Desert,Israel, on the basis of palynological data on the Atzmaut zoogenic deposit

Zoogenic deposits are among a few promising sources of information on the history of arid ecosystems. To reconstruct the former vegetation of the Negev Desert, we performed palynological analysis of the Atzmaut zoogenic deposit that had been formed over the past 6000 years. The results made it possible to reveal seasonality in the use of this rockshelter, to reconstruct the dynamics of vegetation, and to estimate the effect of climatic changes and livestock grazing on the vegetation in the central part of the Negev Desert.     

洞庭湖流域生长季气象特旱对植被覆盖的影响

基于洞庭湖流域2000～2017年97个气象站点的综合气象干旱指数(CI)和MODIS增强型植被指数(EVI)资料,结合植被类型数据,采用最大值合成、相关分析等方法,分析了近18年来洞庭湖流域生长季(4～10月)植被(自然和人工植被)EVI与特旱强度的时空变化特征,探讨了自然植被和人工植被对特旱响应的敏感性。结果表明:在年际变化上,自然植被和人工植被区域的特旱强度最大值和EVI的最小值均出现在2011年;在季节变化上,生长季特旱强度分布为秋夏春季,自然植被EVI值明显高于人工植被,季节分布均为夏春秋季;比较而言,人工植被对特旱的敏感性高于自然植被,但两类植被对特旱的敏感性均随植被生长阶段而变化,其中两种植被EVI与特旱强度之间的最显著相关性均出现在8月;特旱强度和EVI能够很好地反映2011年春旱和夏秋连旱的时空变化过程。     

基于SPOT_NDVI的甘肃省植被覆盖变化及其与气候、地形因子的关系

植被覆盖时间序列特征体现了气候变化和人类活动对环境的影响,利用2000~2018年SPOT_NDVI并结合气象和地形数据,采用趋势分析、偏相关分析、地形面积修正等方法探究甘肃省植被覆盖的变化特征及与气候、地形的关系。研究表明：近19年来,甘肃省植被覆盖整体呈恢复状态,但低覆盖区面积仍为最大,空间分布总体呈现南高北低的状态。降水对省内植被生长总体起到促进作用,特别是黄土高原地区,植被覆盖度与降水有显著的正相关性;在南部湿润区和北部干旱区,气温对植被生长分别起到促进和抑制作用。就地形而言,海拔2 500~3 000 m、坡度大于25°的半阳坡地区最适宜植被生长。进行植被覆盖研究,有利于区域生态建设和持续性发展,同时对人地关系以及经济发展的统筹规划也有重要的理论与实际意义。     

基于时序植被指数的湖北省物候空间特征分析

湖北省地貌类型多样,植被类型丰富,也是农业大省,物候信息监测对于自然生态和农业生产具有重要意义。使用MODIS MOD13Q1 产品中的归一化植被指数数据集,运用时间序列谐波分析法重构 NDVI时序曲线,并结合土地覆被数据,采用物候特征动态阈值法获取湖北省植被物候空间分布特征,分析不同土地覆被类型的物候指标。结果表明：(1)湖北省西部山区、东南部和东北部丘陵地区,多为自然植被覆盖,且植被状况良好,NDVI最大值达到0.75以上,大部分区域NDVI最小值在0.6以上。中部江汉平原和农作物区域NDVI变化受农业耕种方式影响较大,与自然植被NDVI变化特征有所差异。(2)不同土地覆被类型物候特征各异。湖北省大部分区域的植被在2月到3月进入生长季,11月到12月结束生长,襄阳地区呈现相反的特征。耕地、裸地、水体等受人类影响较大的土地覆被类型生长季长度较短,开始时间较晚,结束较早。森林、草地、灌丛等自然植被生长季长度较长,开始较早、结束较晚。(3)物候参数由于地形地貌、地表覆被类型、人类和自然因素的影响具有显著的差异,对区域植被生态状况、不同土地覆被类型物候空间分布特点的分析,结果对于植被生态保护、植被分类、农业区划等都具有参考意义。     

“5.12”汶川地震极重灾区灾后 十年生态恢复状况评估

汶川地震发生10年后，通过对极重灾区生态系统类型解译和地面植被样方调查， GPP、LAI反演，以及对土壤有机质、全氮、全磷、全钾和速效氮、速效磷、速效钾含量的测定与分析，综合评估了极重灾区植被和土壤恢复情况。结果表明：区域生态系统总体趋于稳定向好的恢复态势。2017年的裸露地表面积虽高于震前（2007年），但相对于震后（2008年后）已有所减少。从生态系统质量上来看：GPP、LAI均值在2014年以后呈持续缓慢上升状态，反映了区域生态系统总体良好的恢复力。但是部分在地震中损坏的森林生态系统，仍未恢复到原来状态。成都平原区域部分农田转变为城镇建设用地。至2017年，地震破坏迹地植物种类明显增加。但仍以蔷薇科、菊科和禾本科等先锋物种为主，与2009年的调查结果相似。地震破坏迹地的群落结构已得到了较好的恢复。垂直分层方面，除干旱河谷区域群落结构仅草本或灌草结合1个层次外，其余区域的群落结构已经形成乔木-灌木-草本3个层次；土壤肥力状况总体上对照点优于受损点，受损点土壤肥力状况仍呈恶化状态。地震造成的土壤裸露，加速了矿化过程，短期内受损点速效营养元素含量的增加，长期来看将导致营养元素的流失，土壤肥力下降。在加强地质灾害监管，预防次生灾害的基础上，龙门山前华西雨屏一带，自然植被应坚持自然恢复为主。干旱河谷区域可以按照“因地制宜，适地适树”原则，采取适当人工恢复措施，同时注意改善土壤养分条件，促进植被恢复；城镇建设过程中应加强国土空间管控，保护基本农田。同时，应加强对生态保护红线，以及包括基本农田在内的各级各类保护地的监管。     

Assessment of vegetation β-diversity on the basis of syntaxonomy

Using the example of vegetation in four specially protected natural areas in the Southern Urals, it has been shown that its β-diversity can be estimated in two ways: from the number of syntaxa ranking from the class to the association and from the syntaxonomic spectrum, i.e., the ratio between associations of different classes. The second approach is more informative and better reflects the diversity of vegetation.     

长江源区沙化现象初步探讨

长江源区存在不同程度的沙化现象，沙地种类多样，分布广泛。沙化过程在高寒干旱的气候条件，丰富的物源条件，独特的冻土条件和为因素等综合影响下，从晚更新世末期开始，经过几次旋回一直持续到现在，对该区冻土环境、人类活动存在明显影响。     

Quantifying disturbance effects on vegetation carbon pools in mountain forests based on historical data

Although the terrestrial carbon budget is of key importance for atmospheric CO₂ concentrations, little is known on the effects of management and natural disturbances on historical carbon stocks at the regional scale. We reconstruct the dynamics of vegetation carbon stocks and flows in forests across the past 100 years for a valley in the eastern Swiss Prealps using quantitative and qualitative information from forest management plans. The excellent quality of the historical information makes it possible to link dynamics in growing stocks with high-resolution time series for natural and anthropogenic disturbances. The results of the historical reconstruction are compared with modelled potential natural vegetation. Forest carbon stock at the beginning of the twentieth century was substantially reduced compared to natural conditions as a result of large scale clearcutting lasting until the late nineteenth century. Recovery of the forests from this unsustainable exploitation and systematic forest management were the main drivers of a strong carbon accumulation during almost the entire twentieth century. In the 1990s two major storm events and subsequent bark beetle infestations significantly reduced stocks back to the levels of the mid-twentieth century. The future potential for further carbon accumulation was found to be strongly limited, as the potential for further forest expansion in this valley is low and forest properties seem to approach equilibrium with the natural disturbance regime. We conclude that consistent long-term observations of carbon stocks and their changes provide rich information on the historical range of variability of forest ecosystems. Such historical information improves our ability to assess future changes in carbon stocks. Further, the information is vital for better parameterization and initialization of dynamic regional scale vegetation models and it provides important background for appropriate management decisions.     

Decline of woody vegetation in a saline landscape in the Groundnut Basin,Senegal

Several studies have documented that vegetation in the Sahel is highly dynamic and is affected by the prevailing climatic conditions, as well as by human use of the areas. However, little is known about vegetation dynamics in the large saline areas bordering the rivers of West Africa. Combining satellite imagery, the perception of local people and botanical information, this study investigated the vegetation dynamics and the drivers of vegetation changes in Fatick Province, Senegal. Satellite images showed a change in vegetation composition, i.e., a loss of tree cover and an increase in shrub cover, herbaceous cover and tans (highly saline areas with sparse vegetation). Although the trend was the same, the three villages had different vegetation histories. A survey of the woody vegetation showed that shrubs and young trees were dominating with relatively few large trees. Local people perceived a general decline of woody plants from 1993 to 2013. Among 60 species mentioned by local people, 90 % were declining and 10 % increasing. Together the three methods documented a decrease in density and diversity of the woody vegetation, mainly influenced by salinity and land use. The large numbers of young trees indicate a potential for regeneration of some, but not all, tree species. As many tree species appreciated by local people were reported to be declining, local communities have experienced a reduction of their natural resources. Based on villagers’ recommendations for improved vegetation management, we discuss possible contributions including reforestation, desalinization and environmental protection for restoration of the vegetation.     

长江三峡张家湾遗址孢粉组合及古环境演变

长江三峡巫山地区张家湾东周一汉代古遗址文化层中含有丰富的了解粉,孢粉数据分析,为研究本区东周-汉代时期人类活动的古地理环境提供了有利的资料,根据孢粉组合的变化,可把该区地层由上到下划为三个孢粉组合带;带1（生土层）海金沙（Lygodium)一卷柏-（Seleginella)-紫萁（Osmunda)-松（Pinus)孢粉带;带2（文化层）菊科（Compositae)-毛莨科的唐僧草（Thalictrum)孢粉带;带3（文化层上部）海金沙-紫萁-水龙骨科（Polypodiaceae)-榆（Ulmus)-小芘（Berberis)-栗（Castanea)-慈菇（Sagittaria)-泽泻（Alisma)孢粉带,这种孢粉组合的差异,反映各阶段人类活动古地理环境的变化。该区古人类活动初期处于暖湿的气候,东周一汉代时期转变为温凉略干的温带落叶阔叶林-草地景观,东周-汉代后气候逐渐由于变湿,植被由草原向森林转变,同时该区经历了一次规模较大的洪水泛滥期。     

当前我国干旱半干旱地区整治与开发中的几个问题

本文根据我国当前干旱地区开发与建设中所存在的问题,针对自然资源的合理利用与环境整治如何协调,特别是沙漠与沙漠化土地的治理提出了一些原则性的看法与建议。     

Abundance of orchids on calcareous grasslands in relation to community species,environmental, and vegetational conditions

The abundance of Orchidaceae on three calcareous grasslands is studied in relation to floristic composition, environmental and vegetational factors and plant traits (ecological and life forms). The aims are: (i) to identify a group of species that is significantly correlated with the abundance of Orchidaceae or with individual species of orchids on calcareous grasslands; (ii) to study the relationship between traits associated with habitat specialisation, community life forms and the abundance of orchids; (iii) to identify the main environmental and vegetational predictors of the abundance of orchids. A shortlist of species is found to be significantly correlated with the abundance of total orchids, Orchis pauciflora and O. morio. The life forms of the community species do not show any correlation with the orchids, with the exception of Orchis pauciflora, which tends to increase in communities rich in hemicryptophytes and poor in annual species. Analyses of Orchis morio seem to suggest that it has a high level of ecological tolerance. The most important predictors of the abundance of orchids are the substrate reaction (basic) and arid grassland with low herbaceous vegetation cover (i.e. high soil reaction and luminosity values, positive correlation with the cover of lichens and rockiness, negative correlation with tree cover and herbaceous layer). The least favourable sites were the least basic and most superficial and arid sites.     

基于MODIS NDVI的攀枝花市植被覆盖变化及其驱动力#br#

攀枝花市位于金沙江与雅砻江的交汇处是长江上游生态脆弱区,也是天然林保护工程和退耕还林工程等的重点实施区。基于2001~2010年MODIS NDVI数据,以及同时期的气象数据和其他辅助数据,利用最大值合成法（MVC）、趋势分析法以及线性相关分析等方法研究了攀枝花市植被覆盖时空变化及其与气候因素和人类活动的关系。研究结果表明：攀枝花市植被覆盖整体较高,属于高植被覆盖区域,年际尺度上,植被覆盖呈上升的趋势,增长速率为0.02/10 a;从年内来看,9月NDVI达到最大值,NDVI最小值出现在3月;植被覆盖在水平空间上呈“南低北高”的分布特征,并在垂直空间上呈现出显著的差异性,研究区植被覆盖分别在海拔2 000~3 000 m、坡度30°~40°达到最大值;受水热条件的影响,阴坡（0°~45°, 315°~360°）植被覆盖高于阳坡（135°~225°）,而平地（-1°）植被覆盖度最低;就整个研究区而言,植被退化的面积与增加的面积分别占0.7%和44.4%,增加的面积远大于退化的面积;年际尺度上植被受气温的影响高于受降水的影响;大规模生态工程建设是研究区植被覆盖增加的主要驱动因素。 关键词： 植被覆盖变化;归一化植被指数;气候变化;人类活动;攀枝花市     

基于MODIS NDVI汉江中游植被时空变化及其地貌分异分析

基于2001~2015年的时间序列MODIS NDVI数据,通过逐像元线性趋势回归和回归系数计算,分析汉江中游地区植被年均NDVI变化的时空规律;通过植被时空变化的地貌分异分析,评估人类活动的影响及其空间差异。研究结果表明:汉江中游地区近15 a来,植被年均NDVI值呈现明显的波动增长趋势;植被时空变化表现出一定的地貌分异规律,平原、河漫滩、台地植被年均NDVI呈现明显的增长趋势,而丘陵、低山和中山植被年均NDVI增长趋势不明显。不同地貌类型区年均NDVI值变化受人类活动影响程度的强弱依次为:平原、台地、河漫滩、丘陵、低山、中山。人类活动是汉江中游平原区年均NDVI稳定增长的主要原因。