气候变化对南极海洋性气候区土壤发生与演变的影响

IMPACT OF CLIMATE CHANGE ON GENESIS AND EVOLUTION OF SOIL IN THE MARITIME ANTARCTICA

南极海洋性气候区明显的气候变化已经对独特但脆弱的陆地生态系统构成严重影响。作为陆地生态系统中关键的环境要素之一 ,土壤的发生、发育与演化过程对气候变化同样敏感 ,其响应结果通过气候变化对成土因素的影响间接表现出来。首先 ,南极海洋性气候区日益加速的气候变暖现象导致冰川消退、地表积雪融化 ,为土壤形成与分布提供了母质与空间基础 ;同时 ,气候变暖导致自由水活动在时间和空间上的加强促进了以自由水为基础的土壤过程和冰缘地貌过程 ,对南极海洋性气候区土壤发生、发育产生深刻影响。低等植物对气温升高的响应主要表现为物种数量增加、生境拓展、群落结构演变、初级生产力与生物量提高 ,从而对土壤有机质积累过程以及土壤有机质结构与性状产生重要影响。气候变化与地壳运动等环境因素的变化对海洋脊椎动物的活动影响巨大 ,而动物活动直接影响海洋性有机质进入土壤与陆地生态系统的途径与数量 ;同时 ,动物栖息地的变迁与海岸及附近地区土壤景观演变密切相关。为了准确判断和预测一段时期内气候变化对南极海洋性气候区域土壤形成与演化影响的规模、程度与速率 ,对各种成土因素在气候变化背景下响应与反馈机制、以及与土壤过程之间相互作用机理方面的研究工作亟需开展。

Evident climate change is posing significant influences on the terrestrial ecosystems of the maritime Antarctica. As one of key elements of the terrestrial ecosystem, soil is also subjected to environmental changes. Actually, temporal variety of pedogenesis and soil development in a certain landscape is exhibited via the responses of soil forming factors to climate change. First of all, retreat of glaciers and shrink of perennial snowbank induced by climate warming provide parent materials and spatial room for soil formation and development in the maritime Antarctica. Meanwhile, melt water originating from glaciers and snow ice covers enhances temporal and spatial availability of free water, which plays all important roles both in periglacial processes and the processes within soil profiles, thus influencing soil genesis and evolution to a great degree. Climate change leads to luxuriance of lower plants, especially macroscopic plants such as lichens, mosses and algae in the maritime Antarctica, resulting in introduction of species, colonization in new habitats, increase of biomass and modification of community structures, therefore posing influences on accumulative intensity and compositions of organic matter in soils. Sea level shift and curst isostatic uplift driven mainly by climate change cause migration of the maritime vertebrates such as seals and penguins in the various spatial scales, not only leading to input change of maritime organic matter to terrestrial ecosystem and soil environment, but disturbing soil forming processes and reshaping distribution patterns of soils in the coastal areas. For a better understanding of the intensity, degree and rate of pedogenesis variation induced directly and indirectly by climate change, the detailed case studies including some long term monitoring programs in a chosen area should be conducted, focusing on the dynamics changes and feedback mechanisms of the soil forming factors under the background of climate change, and on the interactions between the changing soil forming factors and individual soil process.