滇池大泊口水域水生植物种子库时空特征与恢复潜力

Spatiotemporal characteristics and restoration potentiality of seed banks of aquatic plants in Dabokou wetland in Lake Dianchi,southwest China

以滇池典型生态修复区--大泊口水域为研究对象,研究了富营养化高原湖泊种子库时空特征、种子库与地表覆盖水生植被及水环境的相关关系和恢复潜力.利用高密度样方原位观测与温室控制种子萌发实验相结合,基于2014-2016共3年的长期定位研究,分析湖泊平均种子库密度、分布格局及与覆盖水生植物Sorensen相似性关系,结果显示:年平均种子库形成率在20.35%~34.13%之间,种子库密度2014年为546.67粒/m^(2),2015年为826粒/m^(2),2016年为1682粒/m^(2),眼子菜科的篦齿眼子菜(Potamogeton pectinatus L.)、金鱼藻科的金鱼藻(Ceratophyllum demersum L.)等耐污种属对种子库构成和年增长率贡献较大;垂直方向上种子主要分布于深层底泥(5~30 cm).随着在时间尺度上的延长,种子库分布更为广泛,且规模越来越大(其中500粒/m^(2)以上规模的分布频率显示增多).离散系数(V/m)与Lloyd平均拥挤指数(m^(*))分析显示主要优势群丛(篦齿眼子菜等)为聚集分布,其余为均匀空间分布格局;种子库与水生植被关系评价指标Sorensen相似性系数(SC)研究显示,滇池大泊口平均SC=(0.3628±0.0265),在湖泊湿地类型和草本群落植被类型属性上处于较低水平,即显示目前植物群落演替过程发生较快,耐污先锋种属在恢复进程上占据优势生态位,而历史优势种和对水环境要求较高的物种却未能规模萌发,一定程度上揭示了高原富营养化湖泊种子库中历史优势植被可恢复性的特征及难点.

Based on long-term dynamics and recent in situ observations across three consecutive years,combined with soil seed samples and greenhouse controlled seedling-emergence methods,this study comprehensively analyzed the scale heterogeneity and spatialtemporal characteristics of seed banks under eutrophic and damaged ecosystems in Dabokou wetland,Lake Dianchi.Seventy-five soil cores were collected from sampling sites within the water area.The sites were systematically distributed using the line-transect method.Investigations were completed a total of 3 times from 2014 to 2016.Species-area relationships were then modeled for pattern detection using seed banks density and characteristics;variance/mean ratio(V/m);and Lloyd’s index of mean crowding(m^(*)).Relationships between seed banks and extant vegetation were also evaluated using Sorensen similarity coefficient(SC).Results showed that the seed density increased significantly accounting for 27.24%.Across the three year period,the mean seed bank densities were:546.67 ind./m^(2),826 ind./m^(2) and 1682 ind./m^(2),respectively for 2014,2015 and 2016.Additionally,seven species were detected from seed banks,and most of them were distributed in the deeper bottom sludge as compared to the topsoil(0-5 cm).Over the course of time,there were more and more seed banks dispersal and large-scale density amounting to a distribution frequency of 500 ind./m^(2).The seed pattern of Potamogeton pectinatus L.was aggregated while other extant vegetation was evenly distributed as indicated by aforesaid indices of pattern detection.The mean S?rensen similarity coefficient of Dabokou wetland was 0.3628,a low value for a lake wetland and herbosa-ecosystem.Overall,the succession of aquatic plant communities occurred intensely at Lake Dianchi.