Ecological Impacts of Visitor Use, Aconcagua Provincial Park, Argentina
Total Page：16
File Type：pdf, Size：1020Kb
Ecological Impacts of Visitor Use, Aconcagua Provincial Park, Argentina Author Barros, Ana Agustina Published 2014 Thesis Type Thesis (PhD Doctorate) School Griffith School of Environment DOI https://doi.org/10.25904/1912/2676 Copyright Statement The author owns the copyright in this thesis, unless stated otherwise. Downloaded from http://hdl.handle.net/10072/366504 Griffith Research Online https://research-repository.griffith.edu.au Ecological Impacts of Visitor Use, Aconcagua Provincial Park, Argentina Ana Agustina Barros, B.Sc., M.Sc. Submitted in the fulfilment of the requirements of the degree of Doctor of Philosophy Griffith School of Environment Science, Environment, Engineering and Technology Griffith University, Australia September 2013 STATEMENT OF ORIGINALITY This work has not previously been submitted for a degree or diploma at any university. To the best of my knowledge and belief, the thesis contains no material previously published or written by another person except where due reference is made in the thesis itself. Ana Agustina Barros ii ABSTRACT Protected area managers often face the challenge of conserving biodiversity while at the same time providing tourism and recreational opportunities for visitors. Popular nature based activities in more remote mountain protected areas include sightseeing, hiking and mountaineering. There are often commercial services provided to support these activities including pack animals for transport and campsite services. These, along with general visitor use, can result in a range of ecological impacts on soils, vegetation, wildlife and aquatic systems. In mountain ecosystems, impacts on vegetation are particularly important as alpine plants often have limited capacity to recover from damage due to the short growing season and poor soils. While a range of impacts from visitor use have been documented in alpine ecosystems in the Northern Hemisphere, there is limited research in the Southern Hemisphere. This is particularly true for the Andes, even though they account for 13% of the world’s mountains and are increasingly popular destinations for hiking and mountaineering. Prior to this thesis, for example, there was only one Masters thesis that assessed visitor impacts in the highest protected area in the Southern Hemisphere, Aconcagua Provincial Park in the dry Andes of Argentina, despite the Park receiving over 33,000 visitors per year. Impacts of visitor use on vegetation in this Park and other protected areas in the dry Andes is of particular concern as visitor use tends to be concentrated in the few areas where vegetation is found. This includes concentrated visitor use of alpine steppe vegetation (29.5% of the Park) and alpine meadows (0.4%) in Aconcagua Park. This thesis assesses the ecological impacts of increasing visitor use of Aconcagua Provincial Park, including impacts on vegetation. To determine which environmental impacts from visitor use are likely to be occurring in the Park, a desktop assessment at the landscape scale supported by Geographical Information Systems was conducted by integrating data on visitation, infrastructure and biophysical features of the Park with the recreation ecology literature. Visitors only used 2% of the Park, but use was focused in areas with vegetation including alpine meadows. Likely impacts varied based on the types of activities, amount of use and the altitudinal zone. Impacts on water resources were likely to be more severe in campsites in the high alpine zone, while impacts on terrestrial biodiversity were likely to be more severe in the low and intermediate alpine zones. iii These results highlight how protected areas, in particular those with limited resources, can use desktop assessments to determine the likely types and locations of visitor impacts through the integration of data sets available in some protected areas, including detailed data from visitor permits. A rapid assessment method was used in the field to examine actual visitor impacts in the most intensively used 237 ha of the Park close to the entrance. The area of vegetation loss due to a network of informal trails was determined by mapping the total extent (length and width) of trails and other infrastructure. This infrastructure resulted in the loss of 9% of the vegetation in this area with the remaining vegetation extensively fragmented. A new rapid visual assessment method was then used to assess the level of disturbance from off trail use based on the amount of dung, and obvious signs of grazing, trampling and soil movement from machinery. Based on the level of damage identified using this method at 102 randomly located plots off trail, it appears that a further 82% of the area was impacted by visitor use. The level of damage based on the visual categories was also found to closely reflect the results from a more detailed vegetation survey of the same 102 plots. This rapid visual method could be modified and used to determine the ecological condition of areas of high use as part of longer term monitoring programs in this Park and other protected areas including identifying priority areas for management. To quantify and compare the response of alpine meadows to trampling by pack animals and hikers, a manipulative experimental design was used in a meadow site subjected to a range of trampling intensities (none, 25, 100 and 300 passes) for the two activities. As expected, pack animals caused more damage to vegetation than hikers. Differences in vegetation cover between activities were only apparent at the highest number of passes due to the apparent resistance to trampling of one of the dominant sedges, Carex gayana. Other measures of damage, including plant height and the cover of the sedge Eleocharis pseudoalbibracteata, were apparent at low or moderate usage by pack animals. Based on the research in Aconcagua and the few other experimental studies comparing these two activities, it appears that while pack animals often cause more damage than hikers, differences in impacts depend in part on the vegetation parameters measured, the intensity of use and the vegetation type. Given that the highest number of passes applied in this experiment is similar to current levels of use per day during peak visitation, the results highlight the importance of limiting these types of visitor use of alpine meadows. iv To examine the potential benefits of excluding grazing by pack animals over one growing season in the spatially limited alpine meadows, twenty pairs of exclosures and unfenced quadrats were established in three high altitude meadows. Vegetation responded rapidly to the removal of grazing. After one growing season plant height was twice as high, above ground biomass increased by 30% and the cover of grasses was greater in ungrazed quadrats compared to grazed quadrats. Thus short term exclusion of grazing by pack animals could be used to restore important vegetation attributes of these meadows, including plant height and productivity, potentially increasing habitat quality for native wildlife in the Park. To determine the distribution and diversity of weeds in the Park, and if they are associated with visitor disturbance, data on the location of weeds were obtained from vegetation surveys in this thesis and from previous surveys. Weed diversity and cover was low compared to other mountain regions, probably reflecting differences in climate and the limited historical use of Aconcagua by people prior to being declared a Park. Most weeds were limited to areas disturbed by visitor use, but two common environmental weeds, Taraxacum officinale and Convolvulus arvensis, were also found invading relatively undisturbed native vegetation. The results highlight that even isolated protected areas can be susceptible to weed invasions with visitor use and that strategies should be implemented to reduce further spread of weeds in the Park. The research in this thesis contributes to the limited information currently available for the Andes about visitor impacts, including on alpine plant communities of high conservation value and limited distribution. Current visitor use of Aconcagua already damages vegetation, with the amount of damage influenced by the type of activity, the amount of use and the distribution of use. Parts of the methods used here can be adapted to other protected areas to monitor and manage visitor impacts, including the desktop assessment to determine likely ecological impacts across a protected area, and, on the ground, visual assessment methods used to categorize off trail disturbance. The results also highlight the importance of managing increased visitation in remote mountain protected areas including regulating multiple uses of trails and minimizing grazing by pack animals. Given the importance of the Andes, more recreation ecology research in the region is required. While this thesis demonstrates that the results from other mountain regions are relevant to the Andes, research within the Andes is critical for the conservation of these important mountain ecosystems. v TABLE OF CONTENTS ABSTRACT ............................................................................................................................. iii TABLE OF CONTENTS .......................................................................................................... vi LIST OF TABLES .................................................................................................................... ix LIST OF FIGURES .................................................................................................................