Geological controls on natural ecosystem recovery on mine waste in southern New Zealand |
| |
| Authors: | D Craw C G Rufaut S Hammit S G Clearwater C M Smith |
| |
| Institution: | (1) Geology Department, University of Otago, PO Box 56, Dunedin, New Zealand;(2) Department of Geosciences, Princeton University, Princeton, NJ 08544, USA;(3) Present address: Soil and Physical Sciences Group, Agriculture and Life Sciences Division, Lincoln University, PO Box 84, Canterbury, New Zealand |
| |
| Abstract: | Slopes of an abandoned waste rock at Wangaloa coal mine, south-east New Zealand, have naturally developed variable vegetation
cover over the last 40–60 years. Three distinct areas of revegetation can clearly be identified: dense cover, patchy cover,
and largely unvegetated, and the differences in revegetation success are directly related to the physical properties of different
rock types making up the waste rock substrate. The colonizing plants have become established in largely unweathered rock with
essentially no soil development. Quartz gravel and siltstone waste rock are the two principal rock types forming substrates
for revegetation. The quartz gravel has clasts up to 3 cm, and was derived from the coal-bearing sequence. Siltstone was largely
derived from a Quaternary loess cap on the coal mine area. These two substrates have similar mineral contents, and this mineral
material provides the low level of available nutrients. However, there is little difference in nutrient status or trace element
load of the different substrates, and differences in cohesion, moisture content, and proportion of quartz pebbles control
revegetation success. Finer grained matrix has been flushed from quartz gravel waste rock by rain water, leaving a dry surface
armour layer of quartz pebbles. This surface layer inhibits plant establishment, so quartz gravel waste rock remains largely
unvegetated. Erosion creates deep rills, and steep surfaces creep downslope. In contrast, full vegetation cover was established
on the siltstone waste rock that was cohesive and did not erode. Patchy revegetation was localized by siltstone in mixed quartz
gravel and siltstone substrate. Invertebrate diversity and distribution were closely linked to the spatial patterns of revegetation.
The rate of revegetation and ecosystem recovery was primarily dependent on the proportion of siltstone waste rock in the last
dumped truck load. A quartz pebble content <15% is optimal for plant establishment. |
| |
| Keywords: | Natural revegetation Waste rock Coal Mine Plants Invertebrates |
| 本文献已被 SpringerLink 等数据库收录！ |
|
