Mapping invasive species Lantana camara in a high diversity tropical ecosystem of Western Ghats, India

Niphadkar, Madhura (2016) Mapping invasive species Lantana camara in a high diversity tropical ecosystem of Western Ghats, India. Doctoral thesis, Manipal University, Ashoka Trust for Research in Ecology and the Environment (ATREE).

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Abstract

Species that spread uncontrollably in areas beyond their natural ranges are termed invasive alien species. These species are an increasingly widespread problem, adversely affecting all kinds of ecosystems in the world today. Their impacts range from community-level changes in species composition, to changes in soil nutrient characteristics, alterations in disturbance regimes, and negative impacts on ecosystem services such as disruption of the hydrological balance. Prevention and timely control of invasion by alien species is therefore an imperative for conservation of native ecosystems and biodiversity. Repeated observations and monitoring are a means to understanding their behaviour better in order to facilitate action for management. While regular field surveys are a useful means of monitoring invasion on the ground, the time taken and resources required for large area field surveys are often prohibitive. Remote sensing (hereafter RS) is a valuable tool to detect and monitor invasion in large landscapes. In this thesis I consider RS as a methodology to monitor invasion by first reviewing and summarizing existing literature, and later focusing on a single invasive alien plant species — Lantana camara (henceforth Lantana) — in a highly biodiverse mixed forest ecosystem in the Western Ghats of India. I first did a comprehensive review of literature on RS applications to mapping invasion (Chapter 2). I began by studying the various life-forms for which, and habitats wherein, RS has proved an effective tool for detecting invasion, listing the sensors that were most effective. I found that invasion has been recorded from almost all kinds of habitats across the globe, and RS methods have been used in these habitats to detect or map invasive species, from areas with dense tree cover to those with sparse vegetation. Invasion mapping in tropical forests is more challenging than temperate forests, due to the diversity and complexity of the tiered tropical forests, and advanced technology such as use of LiDAR or RADAR, as well as fine spatial and spectral resolution sensors were the way to facilitate detection. Among invasive plant life-forms that could be detected efficiently by RS methods, those that formed large dominant canopies or contiguous stands were most easily detected, since discriminating them from the background was comparatively easier. I then looked into plant traits that were most easily detectable from RS data, grouping them into three trait groups — phenological, structural and physiological — to identify those traits that are appropriate tools for monitoring invasion. Plant phenology traits have been easier to map due to long term and repeated RS data availability. While structural traits in the vertical as well as lateral or horizontal dimension have been tapped for invasion detection, physiological trait mapping has only been restricted to a few studies where it is possible to distinguish the amounts of nitrogen or moisture content in the canopy. This review also touched upon the area of predictive modelling using known data records, which is a newly emerging tool for monitoring. A collaborative approach among plant ecologists, RS scientists, simulation modelers, and land managers would facilitate advancement of methods to monitor and combat invasion in an era of global change. I next focused on trying to understand ground-based and over-the-canopy approaches to studying invasion using a focal species, Lantana camara (hereafter, Lantana). This shrub, a Central American native, is notorious for its invasive behaviour across the globe, and has been reported to have invaded several habitat types across India. The Western Ghats biodiversity hotspot is a region of extreme significance for conservation of biodiversity. While Lantana has been reported as an aggressive invader in several locations in the Western Ghats, the Biligiri Rangaswamy Temple Tiger Reserve (BRT TR) has undergone recent systematic long-term observational studies on the species’ spread, making in-depth investigations possible in this location. This tiger reserve is a protected area with very high biodiversity and comprises several forest types, predominantly deciduous; almost the entire BRT TR has been invaded by Lantana to varying extents.

Item Type: Thesis (Doctoral)
Additional Information: Copyright of this article belongs to the author, Manipal University, Ashoka Trust for Research in Ecology and the Environment (ATREE)
Subjects: B ATREE Students Thesis and Dissertations > L Students Thesis
Divisions: ATREE Students Thesis and Dissertations > Students Thesis
Depositing User: The Library Officer
Date Deposited: 10 Sep 2019 10:33
Last Modified: 10 Sep 2019 10:33
URI: http://eprints.atree.org/id/eprint/657

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