Terer T.,Vrije Universiteit Brussel |
Muasya A.M.,University of Cape Town |
Higgins S.,Lake Naivasha Riparian Association |
Gaudet J.J.,Ecology Consultant |
Triest L.,Vrije Universiteit Brussel
Aquatic Botany | Year: 2014
Drawdown-flooding cycles occur commonly in many water bodies and influence plant succession in many ways including the expansion of macrophytes through seedling recruitment. We investigated a regeneration event of Cyperus papyrus in Lake Naivasha and documented seed production, seedling recruitment, zonation progression, dispersal and establishment in relation to evidence from genetic relatedness between seedlings and mature stands using microsatellite loci. Seed estimate counts in five papyrus umbels reached high values between 98,000 and 337,000. The drawdown drying phase led to desiccation accompanied by cracking of mudflat soils, and the oxidation and demise of littoral aquatic plants. Reflooding led to distinct zones of young papyrus and hygrophilous ephemerals. In the final flooding phase when the lake reached normal water levels, hygrophilous ephemerals died off while papyrus survived. Young floating papyrus mats dispersed through wind and wave action joined existing mature stands or spread into formerly unoccupied shoreline areas.Microsatellite analysis of seedlings in the drawdown zone and a neighboring stand of mature and juvenile shoots reveals high overall gene diversity (Ho. = 0.476, He. = 0.576, A. e= 2.8) reflecting an underlying sexual reproduction. A large overlap of genotypes was found in seedling and parent stands indicating a single gene pool. A total of 40 alleles were observed across 3 life stages (clonal juvenile, mature and seedlings), however, more private alleles and higher allelic diversity were detected in seedlings than in the parent individuals, showing their contribution to an increase in the local gene pool. Fine-scaled spatial genetic structuring was detected at about 100. m distance in parent stands for both juvenile and mature life stages indicating a potential influence caused by local seed rain. © 2014 Elsevier B.V.
Barros A.,Griffith University |
Gonnet J.,Ecology Consultant |
Pickering C.,Griffith University
Journal of Environmental Management | Year: 2013
There is limited recreation ecology research in South America, especially studies looking at informal trails. Impacts of informal trails formed by hikers and pack animals on vegetation and soils were assessed for the highest protected area in the Southern Hemisphere, Aconcagua Provincial Park. The number of braided trails, their width and depth were surveyed at 30 sites along the main access route to Mt Aconcagua (6962ma.s.l.). Species composition, richness and cover were also measured on control and trail transects. A total of 3.3ha of alpine meadows and 13.4ha of alpine steppe were disturbed by trails. Trails through meadows resulted in greater soil loss, more exposed soil and rock and less vegetation than trails through steppe vegetation. Trampling also affected the composition of meadow and steppe vegetation with declines in sedges, herbs, grasses and shrubs on trails. These results highlight how visitor use can result in substantial cumulative damage to areas of high conservation value in the Andes. With unregulated use of trails and increasing visitation, park agencies need to limit the further spread of informal trails and improve the conservation of plant communities in Aconcagua Provincial Park and other popular parks in the region. •There is a lack of recreation ecology research in South America.•Impacts on vegetation and soils from informal trails were examined in the Andes.•Trampling resulted in reductions in vegetation cover, soil loss and changes in composition.•Impacts were greater in alpine meadows than steppe vegetation. © 2013 Elsevier Ltd.