金沙江河谷特有植被丽江羊蹄甲群落特征研究

Characteristics?of?the?Bauhinia?bohniana?community,? a?unique?vegetation?in?the?Jinsha?River?Valley

关键词:  丽江羊蹄甲，干暖河谷灌丛，群落特征，物种组成，金沙江

Key words:  Bauhinia bohniana, dry warm valley shrubland, community characteristic, Species composition, Jinsha River

摘要:

干暖河谷灌丛是金沙江中游河谷的重要植被类型，丽江羊蹄甲（Bauhinia bohniana）群落是近年来发现的残存特有灌丛。目前，对河谷灌丛的研究多聚焦于干热河谷植被，缺少对干暖河谷植被群落特征和生态特征的研究，该研究采用无人机拍摄和样方法调查丽江羊蹄甲群落特征和分布现状。结果表明：（1）22个样方共记录到194种维管植物，隶属57科120属，优势科为豆科和禾本科，优势属为薹草属和卷柏属；植物区系呈热带－温带过渡性，属级热带成分占56.5%，温带成分占43.5%；种级成分以中国特有种为主，并包含金沙江干暖河谷标志种51种，反映古地中海退却与青藏高原隆升协同作用下的残遗演化和特化。（2）群落垂直结构明显，灌木层盖度30%~70%，草本层盖度10%~50%，层间层盖度1%~3%。外貌具典型旱生落叶特征，旱季枯黄稀疏，雨季返青，物候显著滞后。群落灌木层物种多样性指数大于草本层。（3）群落生活型谱以地面芽（41.2%）和高位芽植物（34.5%）为主，叶片小型化（50.5%）、纸质化（64.1%）及落叶特性突出，反映群落对干旱胁迫的趋同适应策略。群落在适应策略上与非洲萨王纳群落及地中海灌丛相似，但温带属成分较高（43.5%）体现地理过渡性。本研究对揭示金沙江河谷的历史演变，对金沙江中游的生态保护具有重要意义。

Abstract:

The dry and warm valley shrub is a significant vegetation type in the middle Jinsha River valley. The Bauhinia?bohniana scrub is a recently discovered endemic community of this type.Current research on valley shrub has largely focused on dry-hot valley vegetation, and there is a lack of research on the community and ecological characteristics of dry-warm valley vegetation. This study uses drone photography and the quadrat method to investigate the characteristics and current distribution of the Bauhinia bohniana community.The results were as follows: (1) 22 surveyed Bauhinia?bohniana community quadrats recorded 194 vascular plant species belonging to 57 families and 120 genera. Fabaceae and Poaceae are the families, while Carex and Selaginella are the dominant genera.The flora shows a tropical-temperate transitional pattern, with 56.5% tropical and 43.5% temperate genera. At the species level, Chinese endemics dominate, including 51 indicator species of the Jinsha dry-warm valleys, reflecting relict evolution and specialization driven by the Tethys retreat and the uplift of the Qinghai–Tibet Plateau. (2) The community exhibited a distinct vertical structure: shrub layer cover ranged from 30% to 70%, herb layer from 10% to 50%, and interlayer from 1% to 3%. It had a typical drought-deciduous appearance, turning sparse and yellow in the dry season and regreening in the rainy season, with a delayed phenology compared to surrounding areas.The species diversity index of the shrub layer is higher than that of the herb layer. (3)The life-form spectrum was dominated by hemicryptophytes (41.2%) and phanerophytes (34.5%). Prominent adaptive traits included a predominance of small leaves (microphylls, 50.5%), papery leaf textures (64.1%), and a deciduous habit, which indicated convergent adaptation to drought stress. The community shared adaptive strategies with African savannas and Mediterranean shrublands but had a higher proportion of temperate genera (43.5%), highlighting its transitional nature. This study is of great significance for revealing the historical evolution of the Jinsha River valley and provides a scientific basis for the ecological conservation of its middle reaches.