九段沙湿地鸻形目鸟类迁徙季节环境容纳量

根据对九段沙湿地2005年春、秋季食物资源调查来计算迁徙期鸻形目鸟类的环境容纳量。结果表明，九段沙湿地春季食物总量为4541．20kgAFDW（去灰分干重），秋季为2279．64kgAFDW，按鸻形目鸟类有效栖息生境计算，春季鸟类可利用食物资源量为3429．03kgAFDW，秋季为1700．92kgAFDW。通过鸟类体型类群分类（根据去脂净重、基础代谢率和体长）和能量消耗模型可以得出，九段沙湿地迁徙季节总食物量理论上可维持的鸻形目鸟类最大数量约为春季350万只，秋季175万只。按有效生境计算，春季约为260万只，秋季约为130万只。考虑到食物取入率的影响，九段沙湿地实际可容纳约13～26万只鸟类。根据地理信息分析可知，高潮位期有效栖息地的缺乏可能是限制鸟类数量达到估计上限的主要原因，建议在不危害保护区生态安全的前提下，开辟一些隐蔽性强的裸地和浅水塘，以提高鸻形目鸟类对九段沙湿地资源的利用率。

Carrying capacity of shorebirds at Jiuduansha Wetland during the migratory seasons

The carrying capacity of food supply was measured in a stopover site at the Yangtze River Mouth for the migrating shorebirds during the two migratory seasons (spring and autumn). From March to April and September to October 2005, the macrobenthos resources of Jiudhansha wetland were investigated, and the most macrobenthos species in the new-formed shoal were defined as the appropriate foods for shorebirds. The results of biomass measurement showed that the total food resources were 4541.20 kg AFDW (Ash Free Dry Weight) in spring and 2279.64 kg AFDW in autumn. Another calculation was undertaken only in the available habitats (Intertidal Bare mudflat and Bulrush zones) for the shorebirds, the food resources in the available area was 3429.03 kg AFDW in spring and 1700.92 kg AFDW in autumn. Based on the classification of shorebird community (by lean weigh, basic metabolic rate and body length) and the energy depletion model, the whole food supply in Jiuduansha wetland can support 3.5 million shorebirds during spring season and 1.75 million during autumn season theoretically. The carry capacities of shorebirds in term of the available food were 2.6 million and 1.3 million during the two migratory seasons. Considering the effect of intake rate, the potential carrying capacity was 0.13-0.26 million shorebirds in the study area. The geographic information indicated that the main restrictive factor on shorebirds number in this area was the scarcity of available habitats when high tide periods rather than food supply. We recommend restoring some wading pools in the dense reed or Spartina sp. zones for shorebirds as the management strategy, by which to improve the utilization efficiency of the resources in Jiuduansha wetland for the shorebirds.