A SURVEY OF POND LOSS IN ESSEX, SOUTH-EAST ENGLAND

被引：20

作者：

HEATH, DJ

WHITEHEAD, A

机构：

[1] Department of Biology, University of Essex, Colchester, Essex, CO4 3SQ, Wivenhoe Park

来源：

AQUATIC CONSERVATION-MARINE AND FRESHWATER ECOSYSTEMS | 1992年 / 2卷 / 03期

关键词：

D O I：

10.1002/aqc.3270020306

中图分类号：

X [环境科学、安全科学];

学科分类号：

08 ; 0830 ;

摘要：

1. Sample areas of the county were used to estimate pond loss. An extensive survey used only maps while a smaller, intensive survey combined maps with a field study. In total, 283.43 km2 were surveyed, approximately 7% of the total area. 2. Fifty-five per cent of the ponds present in 1870 had disappeared by 1960 with the greatest loss occurring between 1920 and 1960. 3. Loss of ponds in agricultural locations contributed most to this because of their high initial number and their high rates of loss. Percentage losses of large and small ponds were greater than for medium-sized ponds. 4. A field survey showed that a further 23% of a random sample of ponds shown on maps of 1960 could not be found in 1989. Overall loss rates for the period 1870-1989 are estimated to be 68.6% for the extensive area and 54.8% for the intensive area.

引用

页码：267 / 273

页数：7

共 20 条

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