Threat and response: A decade of decline in a regionally endangered rainforest palm affected by fire and introduced animals
journal contribution
posted on 2023-05-19, 04:27authored byLiddle, DT, Barry BrookBarry Brook, Matthews, J, Taylor, SM, Caley, P
The wild population of the palm Ptychosperma macarthurii near Darwin, in monsoonal northern Australia, is regionally endangered and provides a focus to illustrate a range of issues pertinent to conservation of rainforest habitat. Surveys in 1990 found that several populations exhibited a polarised size class structure typified by large adults and small juvenile plants. Over the following decade, in the absence of wildfire and in a period of reduced disturbance from introduced buffalo (Bubalus bubalis), cattle (Bos indicus) and pig (Sus scrofa), sufficient small juvenile plants survived and grew so as to infill the intermediate size classes. Three stage (bifid, juvenile and adult) transition matrix models characterised the population as declining under all observed conditions (intrinsic rate of increase: unburnt + few animals 0.9850; unburnt + many animals 0.9584; burnt <1 year 0.8737; burnt 1-2 years 0.9146; burnt >2 years 0.9937). In the absence of fire, simulations conducted to explore management options revealed a positive rate of increase with exclusion of introduced animals. With only partial introduced animal control or supplementation with juvenile plants, the median rate of increase remained negative. The regional population is at risk by more frequent and more intense fire due to the invasion of exotic grass species and land use changes in the catchment which result in an increased drying of the rainforest habitat. Ongoing decline is the most likely outcome in the absence of effective management intervention.
History
Publication title
Biological Conservation
Volume
132
Pagination
362-375
ISSN
0006-3207
Department/School
School of Natural Sciences
Publisher
Elsevier Sci Ltd
Place of publication
The Boulevard, Langford Lane, Kidlington, Oxford, England, Oxon, Ox5 1Gb
Rights statement
Copyright 2006 Elsevier Ltd.
Repository Status
Restricted
Socio-economic Objectives
Assessment and management of freshwater ecosystems