Ecological and Evolutionary Impacts of Harvesting the Himalayan Snow Lotus (Saussurea Laniceps Maxim. and Saussurea Medusa Hand.-Mazz.). PDF Download

Author: Wayne Law
Publisher:
ISBN: 9780549070269
Category :
Languages : en
Pages : 154

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Book Description
Harvesting plants has obvious effects on the fitness of the individuals that are harvested, but can also have effects on the population dynamics and on the evolution of the species. This dissertation examines the ecological and evolutionary responses of plant populations due to increased harvest intensity using a favored species of Snow Lotus, Saussurea laniceps, and a less desired sister species, S. medusa. By using theories of ecology and evolution I quantify the effects of plant removal and demonstrate how this can lead to more accurate predictions about sustainable management. First, by conducting interviews with Tibetan doctors and local area botanists, I identify S. laniceps and S. medusa as a valuable part of the local culture that is threatened by increasing demands. Despite differences in conservation priorities of Tibetan doctors and botanists, both parties consistently identify Snow Lotus as useful and threatened. Next, using herbarium specimens and present day individuals, I uncover a negative trend in plant size indicating that preferential harvest of larger individuals has lead to a decrease in plant stature. This has resulted in smaller S. laniceps plants in high harvest areas, compared to plants in low harvest areas. Following theories of ecology indicating that decreasing plant density leads to decreased pollination success, I determine the breeding system, pollination ecology, and level of pollen limitation for both species. I find that both species require bumblebee pollinators for reproduction, and that seed production of S. medusa is significantly limited by pollen receipt, a factor which, when combined with high harvesting, could quickly lead to population decline. Finally, by incorporating plant size, harvesting intensity and environmental stochasticity into matrix models, I provide insight into differences in population growth rates for different sites, leading to more accurate predictions of sustainable harvests. The results provide new information about the population effects of pollen limitation and harvesting on monocarpic species, flowering once and then dying in the lifecycle of the plant, and the evolution of traits within harvested populations; these findings will help with future development of strategies that protect the Snow Lotus from going extinct.