Lantana camara L. (Verbenaceae) invasion along streams in a heterogeneous landscape
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Streams are periodically disturbed due to flooding, act as edges between habitats and also facilitate the dispersal of propagules, thus being potentially more vulnerable to invasions than adjoining regions. We used a landscape-wide transect-based sampling strategy and a mixed effects modelling approach to understand the effects of distance from stream, a rainfall gradient, light availability and fire history on the distribution of the invasive shrub Lantana camara L.(lantana) in the tropical dry forests of Mudumalai in southern India. The area occupied by lantana thickets and lantana stem abundance were both found to be highest closest to streams across this landscape with a rainfall gradient. There was no advantage in terms of increased abundance or area occupied by lantana when it grew closer to streams in drier areas as compared to moister areas. On an average, the area covered by lantana increased with increasing annual rainfall. Areas that experienced greater number of fires during 1989–2010 had lower lantana stem abundance irrespective of distance from streams. In this landscape, total light availability did not affect lantana abundance. Understanding the spatially variable environmental factors in a heterogeneous landscape influencing the distribution of lantana would aid in making informed management decisions at this scale.
KeywordsFire history invasive plant Mudumalai rainfall gradient seasonal streams seasonally dry tropical forest
We thank the Forest Department of Tamil Nadu state for granting us permission to conduct this study and the Ministry of Environment and Forests, India, for funding this study. We thank field assistants M Bomman, Kunmari, Alan and Bantan for help with data collection. Rainfall maps were generated by Sandeep Pulla and Nandita Mondal. All rainfall data and fire data from 1989–2004 were collected by CM Bharanaiah, HS Dattaraja and HS Suresh. Fire data post 2004 was collected and collated into a landscape-wide fire frequency map by Nandita Mondal.
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