The influx of potential macrofossils into Lady Lake, north Westland, New Zealand

Abstract

The influx of plant litter to a lake surrounded by forest and swamp vegetation, in Westland, was studied. The relative abundance of plant species in the vegetation was studied by sampling three sites adjacent to the sample sites for lake litter. With the exception of ground species and epiphytes there is a good qualitative representation of the forest vegetation composition in the lake litter, and for most of the very common taxa in the forests there is a good quantitative representation also. There are some discrepancies, where taxa are better represented, or less-weD represented than their abundance in the vegetation would suggest. The outstanding instance of this is the very poor representation of swamp monocotyledons and aquatic plants in the lake litter. This is attributed partly to poor preservation offoliage, and partly to over-abundance ofleafand twig detritus from trees and shrubs. Seed are not as common in the lake litter as expected and this may be due to the dilution effect and/or the sifting effect of abundant coarse leaf and twig detritus. Several different modes of entry of plant litter to the lake can be inferred, of which stream transport, direct fall, and wind-carriage seem to be the most important. Some aspects of sedimentation can also be inferred. Much more detailed study is needed before the quantitative relationships between populations of plants in the vegetation and the influx of litter to the lake are properly understood.