Finlayson C M
Environmental Research Institute of the Supervising Scientist, GPO Box 461, Darwin, NT 0801, Australia.
Ann Bot. 2005 Sep;96(4):541-55. doi: 10.1093/aob/mci209. Epub 2005 Aug 10.
Despite the biodiversity values of the freshwater floodplains of northern Australia being widely recognized, there has not been a concomitant investment in developing the extent of knowledge of the basic functions and ecological processes that underpin the ecological character of these habitats. This review addresses the extent of our knowledge on the plant ecology of these wetlands and covers: the relationships between the climate and the hydrological regime on the floodplain; the vegetation patterns, succession and adaptation; and primary production.
Information is available on the seasonal, but less regularly on the inter-annual, dynamics of the macrophytic vegetation and its evident inter-relationship with the extent, depth and duration of inundation by seasonal flooding. The available scientifically collected information on plant distribution and relationship with the water regime could be complemented by more attention to traditional knowledge. The productivity of the vegetation is high-the dominant wetland grass species have an annual dry weight production of 0.5-2.1 kg m-2 and the surrounding riparian (Melaleuca) trees contribute litterfall of 0.7-1.5 kg (dry weight) m-2 year-1, approximately 70% due to leaf-fall. The availability of dissolved oxygen in the water is known to vary diurnally and seasonally, at least in some habitats. The importance of seasonal differences in the availability of dissolved oxygen for the growth of micro- and macrophytic vegetation has not been investigated. The seasonal distribution and growth of plant species on a few floodplains have been investigated, and maps at scales of 1:10,000 to 1:100,000 are available for these. However, only on a few occasions have longer term analyses been conducted and long-term changes in the vegetation measured and assessed. Species lists and categorization of growth strategies and forms are available and provide a basis for further ecological investigation.
Despite the large investment in managing the many pressures that have degraded the ecological character of these highly valued wetlands, the fundamental ecological processes that underpin the biodiversity values have not received the same level of attention. Further information on plant growth and the environmental factors that drive seasonal and annual changes in vegetation distribution and productivity is required to assist managers in attending to changes due to increasing invasive species and changes in fire regimes.
尽管澳大利亚北部淡水洪泛区的生物多样性价值已得到广泛认可，但在深入了解支撑这些栖息地生态特征的基本功能和生态过程方面，却未得到相应投入。本综述阐述了我们对这些湿地植物生态学的了解程度，内容涵盖：洪泛区气候与水文状况之间的关系；植被格局、演替与适应性；以及初级生产力。
关于大型植物植被的季节性动态已有相关信息，但关于年际动态的信息较少，且其与季节性洪水淹没范围、深度和持续时间之间明显的相互关系也鲜为人知。现有关于植物分布及其与水情关系的科学收集信息，可通过更多关注传统知识来加以补充。植被生产力很高——占主导地位的湿地草种年干重产量为0.5 - 2.1千克/平方米，周围河岸（千层树属）树木的凋落物产量为0.7 - 1.5千克（干重）/平方米·年，其中约70%源于落叶。已知水中溶解氧的可利用量会随昼夜和季节变化，至少在某些栖息地是这样。溶解氧可利用量的季节性差异对微型和大型植物植被生长的重要性尚未得到研究。已对一些洪泛区植物物种的季节性分布和生长进行了调查，并可获取比例为1:10,000至1:100,000的地图。然而，仅在少数情况下进行了长期分析，对植被的长期变化进行了测量和评估。已有物种清单以及生长策略和形式的分类，为进一步的生态研究提供了基础。
尽管在应对诸多使这些高价值湿地生态特征退化的压力方面投入巨大，但支撑生物多样性价值的基本生态过程却未得到同等程度的关注。需要进一步了解植物生长以及驱动植被分布和生产力季节性与年度变化的环境因素，以帮助管理者应对因入侵物种增加和火灾模式变化而导致的变化。
