为了解金沙江上游奔子栏到羊拉约130 km河段范围内干旱河谷的植被特征, 作者采用样带与典型样方相结合的方法, 对该河段进行了植物群落调查。结果显示: (1)研究区域记录到野生维管植物51科95属111种(含种下等级), 其中, 蕨类植物4科4属6种; 无裸子植物; 被子植物中双子叶植物40科71属84种; 单子叶植物7科20属21种。(2)群落物种以草本为主, 达67种, 占总物种数的60.36%; 生活型以地面芽植物为主, 占总物种数的32.43%, 矮高位芽次之, 占27.93%; 叶型以微型和小型叶为主, 微型叶有30种, 占统计总数(50种)的60%, 小型叶有11种, 占总数的22%。(3)用双向指示种分析方法可将93个样方分为5个群系。分布最广、物种丰富度最高的是小叶荆 + 小叶野丁香(Form. Vitex microphylla + Leptodermis pilosa var. microphylla)群系。(4)根据对该河谷区域的气候特点、干旱程度、植被特征(植株矮化、叶片小、植物毛被发达、植株具刺、部分植物有吸湿反应性特征等)的分析, 综合植物群落的外貌、结构、物种构成和植物形态, 可以确认金沙江上游干旱河谷植被具有亚热带荒漠植被类型的 特征。

The vegetation in dry valleys of Southwest China is characterized by unique vegetation type. Based on plant community sample data (1,339 plots) collected for 9 valleys in Gansu, Sichuan and Yunnan provinces, we used an adaptive affinity propagation method for quantitative classification, and performed an ordination using canonical correspondence analysis. Results showed that the plant communities can be divided into 7 vegetation types (savanna, succulent thicket, evergreen broadleaved thicket, warm deciduous broadleaved thicket, evergreen sclerophyllous forest, deciduous broadleaved forest, warm needle-leaved forest with 24 formations and 31 associations. The most representative vegetation type was the warm deciduous broadleaved thicket, while the most common formations were Form. Bauhinia brachycarpa (50.9%), Form. Heteropogon contortus (11.9%), Form. Bothriochloa pertusa (5.6%), Form. Vitex negundo (4.2%), Form. Eragrostis ferruginea (3.8%), Form. Dodonaea viscosa (3.4%) and Form. Pinus yunnanensis (3.3%). Mean temperature of the coldest month and precipitation seasonality are two dominant climatic factors, which limit the distribution of plant community types in the dry valleys. Savanna and succulent thicket are the dominant vegetation types in typical dry-hot valleys. Dry-warm valley are dominated by warm deciduous broadleaved thicket, evergreen sclerophyllous forest and evergreen broadleaved thicket. Warm needle-leaved forest and deciduous broadleaved forest are more adaptive to lower temperatures.

中国西南干旱河谷植被是我国西南横断山区特有的植被类型, 目前关于西南干旱河谷植被还没有整体性的群落类型划分研究。根据对甘肃、四川、云南三省九条主要河流的干旱河谷段野外调查和文献来源的1,339个植物群落样方数据, 采用自适应仿射传播聚类方法, 对我国西南干旱河谷的植物群落进行数量分类, 并采用典范对应分析方法进行排序分析。结果表明: (1)调查样方的植物群落分为7个植被型(稀树草原、肉质灌丛、常绿阔叶灌丛、暖性落叶阔叶灌丛、常绿硬叶林、落叶阔叶林和暖性针叶林), 24个群系, 31个群丛类型。暖性落叶阔叶灌丛是本植被区的代表性植被类型; 分布最广的群系为鞍叶羊蹄甲灌丛(Form. Bauhinia brachycarpa, 样方比例50.9%)、黄茅灌草丛(Form. Heteropogon contortus, 样方比例11.9%)、孔颖草灌草丛(Form. Bothriochloa pertusa, 样方比例5.6%)、黄荆灌丛(Form. Vitex negundo, 样方比例4.2%)、知风草灌草丛(Form. Eragrostis ferruginea, 样方比例3.8%)、车桑子灌丛(Form. Dodonaea viscosa, 样方比例3.4%)、云南松疏林(Form. Pinus yunnanensis, 样方比例3.3%)。(2)冬季低温和降水的季节性是限制干旱河谷植物群落分布的主要气候因子。稀树草原、肉质灌丛是典型的干热河谷植被类型; 暖性落叶阔叶灌丛、常绿硬叶林、常绿阔叶灌丛是干暖河谷植被的优势类型; 暖性针叶林、落叶阔叶林则主要在干温河谷环境占优势。

The structural differentiation of plant communities are associated with species traits, and interspecific interactions in heterogeneous environment. The comprehensive analysis of spatial variation in species assemblages may help infer processes shaping ecological communities. Based on field investigation of 116 sites and 562 sampling points in the dry valley of Jinshajiang River, combined with vegetation classification by adaptive-affinity propagation, we used Moran’s Eigenvector Maps and variation partitioning to quantify the effects of spatial and environmental factors on the community structure. The results showed that: (1) the plant communities were divided into 30 groups by Adaptive-AP, and classified into 7 vegetation types, 23 formations. Savanna (30.0%) and warm deciduous broadleaved thicket (55.7%) were the main vegetation types. (2) Mean annual temperature (MAT) and aridity index (k) are two dominant climate factors limiting the distribution of plant community types in the dry valley of Jinshajiang River. Savanna, succulent thicket and evergreen broadleaved thicket are dominant vegetation types in typical dry-hot valley. Warm deciduous broadleaved thicket and evergreen sclerophyllous forest are dominant in dry-warm valley. Warm needle-leaved forest and deciduous broadleaved forest are more adaptive to lower temperature. (3) The pure environmental fraction can explain 5.5% of the species composition variation, the pure broad-scale spatial fraction can explain 22.5% of the species composition variation, 6.6% can be explained by the fraction corresponding to broad-scale structured environment and the unexplainable part was 65.4%. Among all the factors, MAT and k indicated the critical difference among the community habitats, which has prominent impact on the change of community composition. The broad-scale spatial factors played an important role in shaping the community structure by geographic isolation.

植物群落的空间分异格局是异质生境条件下物种性状、种间相互作用等生态学过程共同作用的结果, 对其分析有助于深入理解群落构建进程。本文基于金沙江流域干旱河谷116个样点562个样方的植物群落调查数据, 采用自适应仿射传播聚类的方法进行群落数量分类, 运用莫兰特征向量地图, 和方差分解的方法对影响群落结构的空间和环境因子进行分析。结果表明: (1)自适应仿射传播聚类将金沙江干旱河谷的植物群落分为30组, 可归为7个植被型, 23个群系, 以稀树草原(30.0%)、暖性落叶阔叶灌丛(55.7%)为最主要的植被类型。(2)年均温和干燥指数是限制金沙江干旱河谷植物群落分布的主要环境因子。稀树草原、肉质灌丛、常绿阔叶灌丛是典型的干热河谷植被类型; 暖性落叶阔叶灌丛、常绿硬叶林是干暖河谷植被的优势类型; 暖性针叶林、落叶阔叶林则主要在干温河谷环境占优势。(3)纯环境因子可以解释群落物种组成变化的5.5%, 纯空间因子可以解释的物种组成变化为22.5%, 有空间结构的环境因子部分为6.6%, 未解释的部分为65.4%。在诸多环境因子中, 年均温及干燥指数的不同显示了不同群落生境的重要差异, 并显著影响到群落的分布格局。大尺度的空间因子则主要通过地理隔离对群落结构的差异产生影响。

Based on plant community data collected from dry valleys of nine major rivers in Gansu, Sichuan and Yunnan provinces of Southwest China, we divided the families and genera of the vascular plants into geographic elements of Chinese flora, and analyzed the spatial patterns. We found the flora of dry valleys of Southwest China revealed a complex composition of geographic elements with wide floristic connections, including 11 family area-types and 15 genera area-types. The ratio of tropical versus temperate floristic elements was 3.06 at the family level, and 1.77 at the genus level, showing a distinctive affinity for tropical floras, and later imprints of temperate floras. A clear floristic linkage existed between the dry valley floras and the Mediterranean, Western- and Central-Asian floras. The percentages of East Asian elements and endemic Chinese elements were below the average value in the flora found for the subtropical region in China. The Sino-Himalayan element had a value higher than that for the Sino-Japan element in the dry valley floras. The floristic affinity to the tropics weakened while affinity to temperate flora intensified moving in the region from the southwest to northeast. Linkages with the Mediterranean-Central Asian floras, and also the percentage of East Asian elements and endemic Chinese elements increased in the same direction. A boundary between the Sino-Japan type and Sino-Himalayan type was detected between the dry valley floras of Nanpanjiang River and Yuanjiang River. With respect to the genus level floristic composition of geographic elements, Nujiang River, Lancangjiang River and Yuanjiang River were separated from the other rivers, which are all upper branches of the Yangtze River. This departure indicated the impacts of the evolution of the Yangtze River, which were characterized by headward erosion, river confluences, on the characteristics of modern flora in dry valleys.

根据对云南、四川、甘肃三省九条主要河流干旱河谷的植物群落调查数据, 对我国西南干旱河谷维管束植物区系的科、属分布区类型进行划分, 并分析其地理分布格局。结果表明: (1)西南干旱河谷区的植物区系地理成分复杂, 联系广泛, 共包含11个科级和15个属级分布区类型; 总体上, 科、属两级热带/温带成分比例分别为3.06和1.77, 显示了强烈的热带区系亲缘及温带区系的后期影响; 与地中海-西亚至中亚植物区系存在一定联系; 其东亚成分和中国特有成分比例低于亚热带区系平均水平, 且中国-喜马拉雅成分比例高于中国-日本成分。(2)从西南向东北方向, 植物区系的热带性质逐渐减弱, 温带性质逐渐增强; 科、属水平区系成分与古地中海-中亚区系的相似性逐渐增强; 东亚和中国特有成分比例增加; 南盘江与元江的干旱河谷植物区系之间存在中国-日本和中国-喜马拉雅成分的分界线。(3)根据干旱河谷植物属区系成分的比例构成将怒江、澜沧江和元江与其他流域分开, 显示了长江溯源侵蚀和水系合并对西南诸河流植物区系发育的影响。

西南干旱河谷是分布于我国亚热带横断山区的隐域性河谷景观, 其环境受季风气候、岭-谷地形环境和人类开发活动的共同影响。适应于季节性干旱和垂直气候分异, 干旱河谷具有独特的植被和丰富的物种多样性资源。在过去几十年中, 干旱河谷的气候变化以增温为一致特征, 同时经历着广泛的人类活动干扰, 特别是道路建设、水利工程、矿山开发和城镇化驱动的土地利用变化, 造成了普遍的植被破坏、生境退化和生物入侵, 给乡土植物多样性资源和生态系统稳定性带来了严重威胁, 然而至今对干旱河谷生物多样性的保护仍基本属于空白。因此, 建议及时建立干旱河谷的生物多样性保护体系; 因地制宜采取退化植被修复、立体农业规划、特色植物资源利用和风景旅游开发等措施, 以维持干旱河谷生态系统的可持续性; 落实生态文明建设的相关政策, 以保障西南生态屏障的生态安全和生态服务能力。

The vegetation of the dry-hot valleys in southwestern China, especially in Yunnan, is unique as the valley bottom in a subtropical plateau and mountainous region, which is characterized by its geographic location, climate, and geomorphology. A long history of biological adaptation to the specific environmental contributes to the rarity and non-zonality rarity rarity of vegetation in these dry-hot valleys. Disturbances including land use through human activities have endangered some vegetation types in the dry-hot valleys. This paper examines the history of vegetation studies in the dry-hot valleys, and summarizes studies on flora, vegetation and land use and cover change, as well as vegetation restoration. Research of plant communities and flora have mainly focused on the classification of the community and vegetation types, the characteristics of the community, the influence of human disturbance, and the characteristics, nature and origin of the flora. The relationship between vegetation and land has mainly focused on the characteristics of soil, land use/cover change, land degradation and soil erosion. The hot spots of vegetation protection and restoration include the study of vegetation restoration objectives, functional zoning of vegetation restoration, the introduction and selection of vegetation restoration research, and evaluation of the effectiveness of vegetation restoration. We propose that more attention to be paid to the study of the prevention of natural disasters, the impacts of hydropower construction on vegetation, and in-depth vegetation monitoring and analysis of the spatiotemporal dynamics at multiple scales.

特殊的地理位置和独特的地形地貌特征组合形成了典型的干热气候环境, 在云南省亚热带高原山地河谷下部发育了一类特有的植被类型, 即干热河谷植被。干热河谷植被具有非地带性和稀有性, 以及由土地利用变化为主的人为活动干扰导致的脆弱性。本文回顾了干热河谷植被的研究历史, 分别从干热河谷的植物群落学和植物区系学、干热河谷植被与土地的关系以及干热河谷植被保护与恢复三个方面进行了总结。植物群落与区系研究主要集中于群落分类、植被分类、群落特征、人为干扰影响、区系特征、性质和起源; 植被与土地关系研究侧重于土壤特性、土地利用/覆盖变化、土地退化及水土流失状况; 植被保护与恢复的热点在植被恢复目标、植被恢复功能区划、植被恢复引种及筛选及植被恢复效益评价研究。未来在这些区域应注重自然灾害及预防、水电工程建设对植被的影响及其响应等方面的研究, 深入开展大尺度植被时空格局的监测和动态服务功能分析。