农田对太子河大型底栖动物群落的影响

为研究农田对大型底栖动物的影响,以太子河南、北支为例,应用无度量多维标定分析(NMS)和典范对应分析(CCA),探讨大型底栖动物群落对农田的响应.研究发现:太子河北支物种组成以摇蚊科为主,其次是毛翅目和蜉蝣目,而積翅目相对多度较少;在南支则以蜉蝣目、積翅目和毛翅目物种为主,摇蚊科相对多度有所下降;北支主要的功能摄食类群是直接收集者和过滤收集者,刮食者和捕食者较少,撕食者几乎没有,南支各类功能摄食类群均有出现,直接收集者和刮食者较多.太子河南、北支的水温、pH值、电导、悬浮物(SS)、总溶解性固体(TDS)和总氮(TN)存在显著差异,其中北支的水温、电导和TDS显著高于南支;两条支流的水体均为弱碱性水质,南支的pH平均值高于北支;北支的SS和TN略高于南支.利用CCA开展土地利用因素对水质影响分析的总体结果表明,在河段和河流廊道尺度,农田面积比对第一轴的贡献率最高,分别为-0.76和-0.79,且水质要素-土地利用相关性在河流廊道尺度上为0.84,而在河段尺度上为0.71.对土地利用类型和物种的CCA分析可以看出,农田、河滩、居民用地方向多为耐污和中度耐污类群,且沿农田方向物种分布较少.而与此相反的,和旱田轴相反的第四象限内多为四节蜉科(如B.bicaudatus)等敏感类群.

Effects of farmland on macrobenthic community in Taizi River

To study the effects of farmland on macroinvertebrates, macroinvertebrates were collected from the north and south tributaries of Taizi River. And their response to farmland was discussed using non-metric multidimensional scaling analysis (NMS) and canonical correspondence analysis (CCA). The results show: The north tributary of Taizi River species composition mainly was Chironomidae, followed by Trichoptera and Ephemeroptera, and Hymenoptera in less relative abundance; while the south of tributary mostly were Ephemeroptera, Hymenoptera and Trichoptera, and the relative abundance of Chironomidae declined. Meanwhile, the main functional feeding groups of the north tributary were collector-gatherers and collector-filterers, scrapers and predator were less, almost no shredders; but the south tributary had various functional feeding groups, collector-gatherers and scrapers were more. There were significant differences on water temperature, pH, conductivity, suspended solids (SS), total dissolved solids (TDS) and total nitrogen (TN) between the north and south tributaries of Taizi River. Water temperature, conductivity and TDS of the north tributary were significantly higher than that of the south tributary; the water of two tributaries was all alkalescent water, and the average pH of the south tributary was higher than that of the north tributary; the SS and TN of the north tributary were slightly higher than that of the south tributary. Using CCA to carry out the land use factors impact on water quality, the result showed that farmland area ratio on the first axis of the contribution rate was highest in reach scale and river corridor scale, respectively -0.76 and -0.79; and the correlation between water quality factors and land use was 0.84 on river corridor scale and 0.71 on reach scale. From the CCA analysis between land use types and species can be seen, on the directions of farmland, beach and residential land mostly were tolerance and moderate tolerance groups, but fewer species distribution along the direction of farmland. On the contrary, in the fourth quadrant opposite of the dry land axis mostly were Baetidae (such as B.bicaudatus) and other sensitive groups.