Functional organization of vegetation in the system of cartographic forecasting

Presented are the results from the assessment stage of forecasting-cartographic investigations into the vegetation in the Angara-Lena interfluve. An assessment is made of the main (preferred) and secondary ecological functions of vegetation within the geosystems. We demonstrate their changes with respect to native (reconstructed) vegetation.     

Vegetation stability in the system of geobotanical forecasting

Presented are the results of cartographic-prognostic investigations into vegetation by considering an example of the key area on the Lena-Angara interfluve. We examine a variety of aspects of vegetation stability for the case of geobotanical forecasting. Maps of modern and potential (regenerated) vegetation were used to compile the map of pyrogenic stability of vegetation. The map of potential vegetation with a forecast interval of 200 years was developed.     

腾格里沙漠东南缘不同生境油蒿种群的数量动态

对腾格里沙漠东南缘不同的生境条件（包括始建于1964年的人工植被区和天然植被区）下油蒿（Artemisia ordosica）种群调查取样,按照植株的体积大小分为7个龄级（Ⅰ,0~2 cm³;Ⅱ,2~5 cm³;Ⅲ,5~10 cm³;Ⅳ,10~15 cm³;Ⅴ,15~20 cm³;Ⅵ,20~30 cm³;Ⅶ,>30 cm³）,分析了种群的组成、静态生命表和存活曲线。结果表明：人工植被区油蒿种群的总体规模大于天然植被区,幼龄个体占有很高的比例;天然植被区油蒿的死亡率低于人工植被区,天然植被区Ⅰ和Ⅱ龄级油蒿种群的死亡率最高,人工植被区Ⅴ~Ⅶ龄级的油蒿种群死亡率最高;天然植被区油蒿种群的稳定性维持主要通过幼苗的更新,而人工植被区可通过幼苗的自我更新和大龄植株的自疏作用;Ⅴ龄级的油蒿个体是种群中的生存质量最佳的个体;两种生境下油蒿种群均符合Deevey Ⅱ型存活曲线。     

Cartographic assessment of the present status of vegetation in Prebaikalia for water use optimization

We bring up the issue related to the need and importance of undertaking an assessment of the present status of vegetation in Prebaikalia. The vegetation of this region has long been experiencing strong anthropogenic destructions, especially in the southern, more developed, areas. Anthropogenic impacts on vegetation continue to be enhanced thus influencing the processes of spontaneous development of vegetation and decreasing its ecological potential. Assessment of the present status of vegetation as a complex self-evolving autotrophic natural entity having its own evolutionary history of development and dynamical potential is used in reference to identifying and evaluating the degree of disturbance of its native (spontaneous) florocenotic structure. To improve objectivity of research results uses a cartographic method supported by GIS technologies. On the basis of the principles of a structural-dynamical classification of plant communities as suggested by V. B. Sochava, we compiled a universal geobotanical medium-scale (1:500 000) map for Prebaikalia. The map was generated for two purposes: inventory, i.e. identifying the typological belonging of existing plant communities in the region, and for assessment–dynamical purpose to identify the epitaxon structure of the entire vegetation cover. These efforts were accompanied by a formalized assessment of the age structure of tree stands of the region’s forest communities as well as a clear differentiation between forest and non-forest vegetation by identifying new burns and felling areas. The findings formed the basis for generating a detailed 1:500 000 map of disturbances to Prebaikalia’s vegetation displaying 11 kinds of vegetation disturbances ranging from the persisting native communities to those substituted by agrocenoses and introductions of urban settlements. A general outline of the present status of vegetation is provided as well as the main directions for nature management optimization in the region within the framework of the state ecological policy.     

植被作用下土壤干化的反馈效应及相关问题讨论

黄土高原普遍发生的植被作用下的土壤干化现象, 从一个独特角度恰当反映了环境对植 被的限制作用。由于人工林草植被不同于天然植被, 其负反馈调节机制脆弱, 这种植物生长用水 与环境供水之间的矛盾表现, 使人工林草植被生长滞缓, 稳定性下降, 甚至导致其衰亡, 并对后续 深根性植物的生长发育一般起到显著的抑制作用。但是, 后续天然植被或者浅根性植物却仍然能 够继续良好发育。显然, 植被作用下的土壤干化, 对追求一定的经济目标来说有其不利性, 但对于 防止土壤侵蚀并不一定就产生负面影响。需要根据经营目标区别对待人工林草植被的稳定性。人 工林草植被的自然化过程研究是有关生态恢复的一个有意义的命题。     

阜康绿洲-荒漠交错带荒漠植被群落稳定性

以阜康绿洲-荒漠交错带的荒漠植被为研究对象,利用样区内植被常规调查资料,改进了法国生态学家M.Godron从工业生产中发现并引入生态学研究中的稳定性测定方法,并将研究方法推广到植被群落的空间稳定性研究。根据这种方法,累积种类百分数与累积相对盖度比值越趋近于20/80群落就越稳定,在20/80这一点上是群落的稳定点。研究结果证实:从空间上看,绿洲-荒漠交错带不同植物群落稳定性不同;绿洲-荒漠交错带的荒漠植被群落稳定性受种间竞争、环境压力和干扰活动三个因素的影响,即使建群种相同的群落稳定性也会出现较大差异。     

生态水文阈值在中国沙区人工植被生态系统管理中的意义

中国北方风沙区是全球沙漠化发展和生态退化最为严重的地区之一。利用植被固沙是遏制沙化土地扩张和生态重建与恢复的主要途径,但人工植被的稳定维持是可持续性风沙治理所长期面临的挑战。作为人工植被生态系统管理的依据,对生态水文阈值的认识及界定具有重要的理论和实践意义。本文以固沙植被中人工种植的灌木和乔木（仅限东部沙区）的盖度与深层土壤水分含量互馈互调作用的长期变化为依据,基于对中国不同气候带沙区典型人工植被系统生态和水文过程的模拟,通过建立生态水文模型初步界定了不同沙区适宜于人工植被生态系统管理的生态水文阈值,对现有沙区固沙植被的生态系统管理和未来风沙区植被建设具有一定的借鉴意义。     

气候和人为因素对植被变化影响的评价方法综述

系统评价气候变化和人为因素引起的植被退化,对有效开展生态工程建设、实现生态环境的可持续发展具有重要意义。目前绝大多研究主要分析气候因素对植被变化的影响,分析气候因素和人类活动对植被变化的双重影响少有研究。本文主要介绍这一双重影响对植被变化的贡献程度的主要研究方法——定性-半定量法、回归分析法、残差趋势法、基于净第一生产力的评价方法。综述分析了气候和人为因素对植被变化驱动的主要结论,总结目前各研究方法存在的问题,提出了未来需要重点加强气候和人为因素对植被变化驱动因素的分解研究,加强模型评价和不确定性量化研究等。     

近20 a新疆南部植被覆盖度时空特征及对气候因素的响应——以塔什库尔干塔吉克自治县为例

植被覆盖度是反映生态环境质量的评价指标,掌握植被覆盖度的变化有助于实现生态文明建设与区域农牧业规划及生态环境保护。基于2001—2020年归一化植被指数（Normalization difference vegetation index,NDVI）,以耕地、林地、草地植被类型为研究对象,采用混合像元二分模型计算植被覆盖度,应用空间稳定性分析、Sen+Mann-Kendall空间趋势分析、线性回归等方法,分析塔什库尔干塔吉克自治县植被覆盖度的时空特征;同时,结合气温、降水量数据,利用Spearman相关分析、GIS空间分析等方法,分析气候因素对植被覆盖度的影响。结果表明：（1） 近20 a植被覆盖度以中植被覆盖区为主,植被覆盖度减小了4.79%。（2） 植被覆盖度的空间稳定性波动较小,以波动变化（37.3%）、中等波动变化（32.7%）为主;植被覆盖度呈显著减少和不显著减少面积分别占总面积的3.8%、54.5%。（3） 耕地、林地、草地植被状况均呈现不同程度的轻微退化,在植被覆盖度上分别减少了4.57%、6.32%、4.24%,在空间稳定性上,不显著减少分别为51.28%、54.48%、52.29%。（4） 2001—2020年耕地比林地、草地空间稳定性和退化程度更为稳定和缓慢,林地退化比耕地、草地严重。研究区植被覆盖度变化较小,呈微弱下降趋势,人类活动是影响植被生长的主要因素。     

基于文献分析的土地退化评价指标研究

中英文献综合统计,土地退化评价应用频次较高的指标有植被盖度、坡度、经济收入水平、有机质含量和土地利用类型等;土壤侵蚀应用频次较高的有植被因子、坡度、地貌类型、有机质含量和土地利用类型等;沙化有植被覆盖度、沙地占地率、土地利用类型、有机质含量、人口数量等。土地退化、土壤侵蚀和沙化遥感监测指标也集中在植被盖度、坡度、土地利用类型等指标。     

基于时间序列植被特征的内蒙古荒漠化评价

荒漠化是中国北方干旱、半干旱地区面临的主要生态环境问题。从植被特征着手,关注其年际动态变化特征,已经成为国内外荒漠化评价的发展趋势。选取遥感反演的高时间分辨率的植被降水利用率作为评价指标,利用时间序列分析方法,评价了内蒙古自治区1999-2009 年的荒漠化发展态势,并对荒漠化逆转问题进行了初步讨论。结果表明：内蒙古自治区11 年来生态环境总体趋于改善,荒漠化发展态势并不明显。其中,鄂尔多斯高原的东部至大青山南麓、大兴安岭及燕山北部余脉是内蒙古自治区生态环境改善最为明显的地区,反映出该区的植被保护政策发挥了积极的作用;荒漠化土地空间分异特征表明,降水因子和植被恢复有着密切的联系,300mm以上降水量的地区,其植被恢复能力要明显大于降水稀少的地区;干旱、极干旱地区的荒漠界限极不稳定,对荒漠化是否逆转的判断必须在特定的时间尺度,结合当年的气候条件进行综合分析。     

Paleoenvironmental reconstruction of central-western Argentina from analysis of Late-Pleistocene mammal droppings

Plant macrofossils studied in coprolites from small-sized, medium-sized and large mammals, dated by ¹⁴C to ca. 30.8–24 and 9 kybp, allowed to record changes in local vegetation and its relation with geomorphological units. Paleobotanical samples were determined using microhistological analysis. We found that plant associations and the vegetation–geomorphology relation were similar in the two periods analyzed. According to this study, the Monte plant formation would reflect certain stability during the analyzed period in arid central-western Argentina, although this does not imply the absence of variations in plant structure.     

A potential mechanism for disturbance-mediated channel migration in a southeastern United States salt marsh

Coastal salt marsh tidal creeks are thought to show less channel adjustment/movement relative to their terrestrial fluvial counterparts. We propose a mechanism for disturbance-mediated bank failure that may allow/initiate channel migration in these otherwise stable systems. The stability of tidal creeks is promoted by the extensive vegetation root structure along the banks. However, wrack mats (i.e., dead vegetation) deposited on creek banks can cause the death of below-ground vegetation leading to bare, unstable banks that may slump into the channel. We measured the frequency of bank failures associated with wrack-disturbed sites along three creeks on Sapelo Island, Georgia, USA to determine whether these sites were vulnerable to erosion. Approximately 81% of the disturbed sites showed signs of bank failure. Therefore, wrack-induced bank failure may potentially lead to channel migration in creeks previously believed to be static landscape features.     

基于SPOTNDVI的华北北部地表植被覆盖变化趋势

为分析华北北部地表植被覆盖变化趋势,探寻合理土地利用方式,基于1999年1月至2006年12月的SPOT-VEGETATION逐旬NDVI数据,采用国际通用的MVC(最大合成法)获得月NDVI值,用均值法求出年均NDVI数值。在此基础上,用一元线性回归斜率定量描述地表覆盖动态变化,以Hurst指数表示其时间依存性,利用GIS工具表征其空间格局并进行空间统计分析。研究结果表明:近8年来华北北部地表植被覆盖整体得到改善的区域比植被覆盖退化的区域面积大,得到改善的区域约占总面积的66.04%,基本不变的区域约占14.39%,退化区域约占19.57%。各种土地利用类型Hurst指数平均值均为0.5     

伊犁河谷不同植被带下土壤有机碳分布

结合2008年和2009年野外实地调查与室内分析的资料,运用方差分析等方法对伊犁河谷高山草甸、草甸草原、典型草原、荒漠草原、温性针叶林等9种不同植被条件下的土壤有机碳含量分布及其储量进行了分析估算.研究结果表明:伊犁河谷土壤有机碳含量因植被类型变化而不同.在0～50 cm土层范围,高山草甸、草甸草原土壤有机碳含量较高,其次是温性针叶林和典型草原,含量最低的是隐域植被和荒漠植被土壤.除隐域植被外,各植被类型下土壤有机碳含最基本呈随着土层深度增加而降低的,变化趋势.有机碳密度同样是高山草甸、草甸草原和温性针叶林土壤有机碳密度较高且比较相近,荒漠植被下土壤有机碳密度最低.伊犁河谷草地表层土壤有机碳含量高、密度大,因此应重视对伊犁河谷草地的保护,尤其要保护草地表层土壤以降低浅层土壤有机碳发生变化的可能性,维护土壤碳库的稳定性.     

Distribution of soil organic carbon under different vegetation zones in the Ili River Valley,Xinjiang

We analyzed and estimated the distribution and reserves of soil organic carbon under nine different vegetation conditions including alpine meadow, meadow steppe, typical steppe, desert steppe, and temperate coniferous forest and so on, in the Ili River valley, Xinjiang according to data from field investigations and laboratory analyses in 2008 and 2009. The study results show that the soil organic carbon content in the Ili River valley varies with the type of vegetation. In the 0–50 cm soil horizon, the soil organic carbon content is the highest under the vegetation types of alpine meadow and meadow steppe, slightly lower under temperate coniferous forest and typical steppe, and the lowest under the intrazonal vegetation and desert vegetation types. The soil organic carbon content shows basically a tendency to decrease as soil depth increases under various vegetation types except in the case of the intrazonal vegetation. Similarly, the soil organic carbon density is the highest and varies little under the vegetation types of alpine meadow, meadow steppe and temperate coniferous forest, and is the lowest under the desert vegetation type. Both the soil organic carbon content and density in the topsoil of meadows in the Ili River valley are high, so protecting meadows in the Ili River valley, and especially their topsoil, should be a priority so that the potential of change in soil organic carbon in the shallow soil horizon is reduced, and this means maintenance of the stability of the soil carbon pool.     

黑河下游尾闾区植物群落物种多样性与稳定性格局

黑河下游尾闾区作为西北干旱区典型的脆弱生态系统,其植物群落物种多样性与稳定性对维持该地区生态安全和可持续发展具有重要意义。以黑河下游尾闾区荒漠植被为研究对象,采用K-Means聚类,基于距河道距离及其对应的土壤含水量数据,将黑河下游尾闾区垂直于河道0—4 km区域可分为距河0—0.3 km（T_0-0.3）、0.3—1.7 km（T_0.3-1.7）和1.7—4.0 km（T_1.7-4.0）3个距离梯度,研究不同距离梯度下植物群落物种组成、多样性和稳定性特征,并进一步探讨了黑河下游尾闾区主要植物最适宜土壤水分需求。结果表明：（1）近河0—0.3 km区域以耐湿耐盐碱的草本为主,优势种为芦苇（Phragmites communis）、盐爪爪（Kalidium foliatum）、苦豆子（Sophora alopecuroides）和冰草（Agropyron cristatum）;距河道0.3—1.7 km区域出现的植物种类数目最多,以乔木为主,兼有灌木和草本,优势种为柽柳和胡杨;距河道1.7—4.0 km区域出现的植物种类数目最少,以极耐旱的灌木和亚灌木等荒漠植被为主,优势种为红砂（Reaumuria songarica）和梭梭（Haloxylon ammodendron）。（2）3个距离梯度下Simpson指数、Pielou指数、Shannon-Wiener指数和丰富度指数R均表现为距河0.3—1.7 km>0—0.3 km>1.7—4.0 km,而植物群落稳定性与物种多样性间呈现出相反的变化趋势,即群落稳定性表现为距河1.7—4.0 km>0—0.3 km>0.3—1.7 km。（3）当黑河下游尾闾区距河0—0.3、0.3—1.7 km和1.7—4.0 km区域植被最适宜土壤含水量分别为27%—31%、15%—22%和4%—7%,有利于维持该区域植物群落物种多样性与稳定性。     

The application of a remotely-sensed diversity index to monitor degradation patterns in a semi-arid, heterogeneous, South African landscape

We present a remotely-sensed degradation assessment technique based on the measurement of landscape heterogeneity (a key determinant of degradation status). The moving standard deviation index (MSDI) is derived by passing a moving standard deviation filter across the Landsat TM band 3 (red band). Degraded/unstable landscapes exhibit higher MSDI values than their undisturbed/stable counterparts. Significant differences in MSDI were detected (p<0·001) across four fence-lines which separated rangeland of contrasting condition. The relationship of the index to normalized difference vegetation index (NDVI) was tested in five different ecosystems and significant correlations were obtained in all cases (p<0·001). We propose the MSDI as a powerful adjunct to vegetation indices.     

西藏水土流失敏感性评价及其空间分异规律

以水土流失通用方程为理论基础,运用数学模型和GIS分析相结合的方法,将降水、地貌、土壤和植被因子对西藏水土流失敏感性的影响程度,划分为极敏感、相当敏感、敏感、较敏感和不敏感5个等级,并生成各单因素评价图。在Arcinfo中完成单因素图的叠加分析,得到西藏水土流失敏感性综合评价图。在此基础上,探讨了西藏特殊高原环境下的水土流失敏感性高低的分布规律及其在不同主导因子作用下的水土流失敏感性空间分异,提出了西藏水土流失治理的优先区,为水利、公路和农牧等部门进行专题规划和治理提供依据。     

基于MODIS/EVI的内蒙古高原西部植被变化

内蒙古高原西部生态环境脆弱,是全球变化的敏感地带.为了解该区域植被覆盖的时空动态变化,根据2000—2012年MODIS/EVI影像,使用趋势分析和标准差分析方法,研究了近13年内蒙古高原西部植被生长状况及其空间格局动态变化.同时,根据《1:100万植被类型图》把研究区分为荒漠区、草原区、草甸区和灌丛区,以研究不同植被类型下的EVI变化情况.结果显示:内蒙古高原西部植被覆盖退化面积大于改善面积;植被退化区主要分布在内蒙古农牧交错带北部边缘,包含乌兰察布、呼和浩特、包头等市及大通河、疏勒河、黑河等河谷地带;植被增加区域分布在河西地区、河套地区和阿巴嘎旗附近;研究区植被稳定性存在明显的地域差异,波动较高的区域位于阴山南部、祁连山南北和阿巴嘎旗,与植被覆盖退化或者增加的区域基本吻合;仅荒漠区植被覆盖水平上升,草甸、草原区植被覆盖退化严重.