也论我国东部植被带的划分

Re-discussion About the Forest Vegetation Zonation in Eastern China

长期以来人们对中国东部森林区的植被带划分存在意见分歧。最近 ,宋永昌教授对这些意见分歧进行了概括 ,讨论了中国东部植被带的划分依据 ,并提出了新的划分方案。为进行交流和讨论 ,在简要回顾中国东部植被带划分的历史沿革的基础上 ,再次论及了它的划分依据 ,提出了新的划分方案。认为在中国特有的植被气候特点以及东部区域遭受长久且深刻的人为影响的现实条件下 ,中国现行的植被带划分实质上是一种近似潜在的植被带划分 ;植被本身特征 ,尤其是地带性植被特征与决定其分布的限制性气候因子作为东部植被带划分的主要依据 ,同等重要 ;物种分布是植被分带的参考依据。基于这一思想进行植被分带的通常做法是 ,根据原生植被类型或其衍生植被类型的分布 ,确定其所在分布地的限制性气候因子 ,从而建立植被气候关系 ,据此进行植被带的划分。这种处理符合植被气候关系的本质 ,在实践上又便于操作。利用业已确定的植被气候关系 ,并参考物种的分布 ,进行了中国东部植被带的划分。划分的具体指标是采用反映热量状况的温暖指数 (WI)和冬季低温的寒冷指数 (CI)以及体现干湿气候状况的水分指数 (Im)。按照这一划分方案 ,我国东部植被带从北向南依次为寒温带针叶林带 (WI <5 0℃·月 )、温带针阔叶混交林带 (5

There is a long-standing controversy about division of forest vegetation zonation in eastern China. Recently, Prof. SONG Yong-Chang has summarized the viewpoints of different authors on the division of vegetation zone, discussed the principles of the division, and proposed a new divisional system. In the present paper, based on a historical review on the division of vegetation zonation, the author reconsidered the principles of the division, and proposed a climate-vegetation relation-based divisional scheme involving the following viewpoints: (1) in reality, vegetation zonation division in eastern China is likely a kind of potential vegetation regionalization because little primary vegetation types occur in this region resulted from a long-historical human activities; (2) both characteristic of vegetation types, especially zonal vegetation types, and the climatic factor that delimits the distribution of the vegetation are coequally important in the division of vegetation zonation; and (3) as a reference information, species distribution is important in the division, but not a critical element in some cases. Based on these views, the relationships between distribution of primary vegetation types and climate conditions were analyzed, and then the vegetation-climate relation-based division for vegetation zones of eastern China was made. In the divisional scheme, warmth index (WI) and coldness index (CI) were used as thermal parameters, and moisture index (Im) as indicator of arid/humid climate. As a result, the vegetation zones in the eastern China arranged from north to south as cold-temperate conifer forest zone (WI < 50 <degrees>C.month), temperate conifer and broadleaf mixed forest zone (50 degreesC.month < WI < 90 degreesC.month), warm-temperate deciduous broadleaf woodland zone (90 degreesC.month < WI < 120 degreesC.month, - 20 < Im < 0), warm-temperate deciduous and evergreen mixed broadleaf forest zone (120 degreesC.month < WI < 135 degreesC.month, 0 < Im < 60), subtropical evergreen broadleaf forest zone (135 degreesC.month < TBI < 240 degreesC.month, Im > 60), and tropical rain and monsoon forest zone ( WI > 240 degreesC.month), respectively. In the subtropical zone, three subzones, northern, southern and western parts, were further divided on the basis of an isotherm of WI = 175 degreesC. month. The present divisional scheme is not only based on the principles mentioned above, but also incorporated with the term usage in vegetation science in China and the convenience for international scientific communications. In addition, it was emphasized that a division of dynamic vegetation zones was an increasing interest because of the changing climate and renewed vegetation information in this region.