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Restoration of overgrazed environments in semi-arid Chaco (Argentina) using facilitation: studying germination requirements to grow nurse plants

María Fernanda Martínez Gálvez

University of Kentucky

Arid and semiarid environments are one of the largest ecosystems in the world; between 10-20% of these lands are heavily degraded affecting 250 million people. In Argentina, Copo National Park protects 118118 ha of semiarid Chaco forest and five families are living there. These people live on traditional livestock management in “puestos” (groups of houses, farmyards and artificial water sources), but these activities are poorly controlled. In the puestos, livestock concentrate around water sources and the grazing pressure on the environment is excessive; as a result gaps are generated. In order to recover the functionality of these degraded ecosystems, restoration ecology is needed. One strategy to restore overgrazed ecosystems is using facilitation relationships; by using the shadow of an adult plant (nurse plant) a favorable microsite is created (more humidity and low temperatures) which can protect early successional plant species. To reintroduce new nurse plants species, we need to grow new individuals using seeds from similar environments and close to the disturbed area. In order to optimize seedling emergency and the number of individuals obtained to be used in restoration programs, we must know the germination requirements of the plant species and if they present some kind of dormancy. Germination requirements include seeds requirements of light and temperature; while dormancy refers to germination impediments when the environmental conditions are not the optimum for seedling survival. In the case of tropical dry forests, dormancy occurs in seeds of 76% of the species, and physical dormancy is the most common class of dormancy. We have studied the germination requirements of five potential nurse plants species in semi-arid Chaco forest and only two species reached 80% of germination. In order to figure out the best treatments to improve the germination of those potential nurse plants species from Chaco forest in Argentina further studies must be done. The objective of this project is to study the germination ecology of potential nurse plants species from Chaco forest in Argentina; to achieve this objective I will work in the laboratory of Plant Ecology leaded by Dr. Carol Baskin at Kentucky University. Specifically I will: (1) analyze germination and dormancy breaking data of potential nurse plants from Chaco forest in Argentina of experiments already performed at Salta National University; (2) perform a light requirement experiment and a physiological dormancy breaking treatments to increase the germination percentages of seeds of potential nurse plants from Chaco forest in Argentina; and (3) create a germination protocol to germinate seeds of potential nurse plants from Chaco forest in Argentina.

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