鄱阳湖浅碟湖泊沉水植物冬芽的分布及对植食水鸟的食物贡献

沉水植物的冬芽是植食性水鸟在越冬期的重要食物。鄱阳湖是长江中下游地区极为重要的水鸟越冬地,了解沉水植物冬芽的空间分布及其对越冬植食性水鸟的食物贡献可为水鸟保护提供科学依据。2012年10月和2013年4月,采用样方法调查了鄱阳湖典型蝶形湖泊(沙湖)内沉水植物冬芽的种类、密度和空间分布。调查共记录到两种沉水植物冬芽,分别为刺苦草(Vallisneria spinulosa)和罗氏轮叶黑藻(Hydrilla verticillata var.rosburghii)冬芽。10月份两种冬芽的密度分别为(9.53!1.73)个/m2和(25.78!3.97)个/m2,显著高于4月份的密度(2.52!0.91)个/m2和(4.76!1.17)个/m2(Z=3.712,P0.01;Z=5.738,P0.01);10月份两种植物冬芽的生物量(干重)分别为(3.07!0.65)g/m2和(5.43!0.75)g/m2,也显著高于4月份平均生物量(0.89!0.35)g/m2和(2.21!0.59)g/m2(Z=3.118,P0.01;Z=3.821,P0.01)。10月份罗氏轮叶黑藻冬芽密度显著高于刺苦草冬芽密度(Z=3.466,P0.01),但4月份两种冬芽密度之间无显著差异(Z=1.677,P=0.09)。丰水期(4—9月)能形成冬芽的两种沉水植物的平均水深分别为(2.63!0.15)m和(2.61!0.12)m。沙湖冬季刺苦草冬芽和罗氏轮叶黑藻冬芽是植食性水鸟的重要食物。估计水鸟越冬期在沙湖摄取两种植物冬芽约1.04×108个,共1.9×104kg。

Distribution in winter buds of submerged macrophyte and their contribution for herbivorous waterfowl in a shallow dish lake of Poyang Lake

Winter buds of submerged macrophytes are main food for herbivorous waterfowl in winter. Poyang Lake is important wintering sites for waterbirds in the Yangtze basin. Understanding the spatial distribution of winter buds and their food contribution for herbivorous waterfowl can provide scientific basis for waterfowl conservation and lake management. We studied species composition, individual density, and spatial distribution of winter buds using quadrate method in October 2012 and April 2013 in Shahu Lake, a sub-lake of Poyang Lake. Winter buds of two submerged plant species, Vallisneria spinulosa and Hydrilla verticillata var. rosburghii, were recorded. The average density of winter buds of Vallisneria spinulosa was (9.53 ± 1.73)ind/m² and of Hydrilla verticillata var. rosburghii (25.78 ± 3.97)ind/m² in October, which were also significantly higher than that in April ((2.52 ± 0.91)ind/m² for Vallisneria spinulosa and (4.76 ± 1.17)ind/m² for Hydrilla verticillata var. rosburghii)(Z=3.712, P < 0.01 and Z=5.738, P < 0.01, respectively). The average biomass of winter buds (dry weight)of Vallisneria spinulosa was (3.07 ± 0.65)g/m² and of Hydrilla verticillata var. rosburghii (5.43 ± 0.75)g/m² in October, which were significantly higher than that in April ((0.89 ± 0.35)g/m² and (2.21 ± 0.59)g/m², respectively)(Z=3.118, P < 0.01; Z=3.821, P < 0.01). The density of Hydrilla verticillata var. rosburghii winter buds was significantly higher than Vallisneria spinulosa winter buds in October (Z=3.466, P < 0.01)while there was no significant difference in the density of the two species of winter buds in April (Z=1.677, P=0.09). The average depth that suitable for the formation of winter buds of the two species of submerged plants was (2.63 ± 0.15)m and (2.61 ± 0.12)m, respectively, in flooding season (from April to September). Winter buds of Vallisneria spinulosa and Hydrilla verticillata var. rosburghii are important food for herbivorous waterfowl in Shahu Lake. It is estimated that waterfowl consumed 1.04×10⁸ ind (1.9×10⁴ kg)of the two species of winter buds in winter.