A cross-scale approach for abundance estimation of invasive alien plants in a large protected area
Date
2013
Journal Title
Journal ISSN
Volume Title
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Abstract
Efficient management of invasive alien plants requires robust and
cost-efficient methods for measuring the abundance and spatial structure of inva-
sive alien plants with sufficient accuracy. Here, we present such a monitoring
method using ad hoc presence-absence records that are routinely collected for
various management and research needs in Kruger National Park, South Africa.
The total and local abundance of all invasive alien plants were estimated using the
area-of-occupancy model that depicts a power-law scaling pattern of species
occupancy across scales and a detection-rate-based Poisson model that allows us
to estimate abundance from the occupancy, respectively. Results from these two
models were consistent in predicting a total of about one million invasive alien
plant records for the park. The accuracy of log-transformed abundance estimate
improved significantly with the increase of sampling effort. However, estimating
abundance was shown to be much more difficult than detecting the spatial structure
of the invasive alien plants. Since management of invasive species in protected
areas is often hampered by limited resources for detailed surveys and monitoring,
relatively simple and inexpensive monitoring strategies are important. Such data
should also be appropriate for multiple purposes. We therefore recommend the use
of the scaling pattern of species distribution as a method for rapid and robust
monitoring of invasive alien plants in protected areas. Not only do these approaches
provide valuable tools for managers and biologists in protected areas, but this kind
of data, which can be collected as part of routine activities for a protected area,
provides excellent opportunities for researchers to explore the status of aliens as
well as their assemblage patterns and functions.
Description
Keywords
Invasive plants, Kruger National Park, Opuntia stricta, Lantana camara, Optimum monitoring strategy
Citation
Hui, C., Foxcroft, L.C., Richardson, D.M. & MacFadyen, S. (2013) A cross-scale approach for abundance estimation of invasive alien plants in a large protected area. In: L.C. Foxcroft, D.M. Richardson, P. Pysek & Genovesi. eds. Plant Invasions in Protected Areas: Patterns, Problems and Challenges, pp. 73-88. Springer, Berlin. ISBN: 978-94-007-7750-7.