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New Mexico State University (2014)

Evapotranspiration of mixed riparian vegetation after removal of dense saltcedar in an arid environment

Santillano, Ernesto

Titre : Evapotranspiration of mixed riparian vegetation after removal of dense saltcedar in an arid environment

Auteur : Santillano, Ernesto

Université de soutenance : New Mexico State University

Grade : Master of Sciences (MS) Civil Engineering 2014

In the arid southwestern United States, large riparian areas have been overgrown by non-native saltcedar plant (Tamarix spp.). Resource managers seek to manage the non-native plant to reduce evapotranspiration for water salvage, restore native riparian vegetation, encourage diversity of plant species, improve wildlife habitat, and for aesthetic reasons. Studies on the consumptive use (or evapotranspiration) of saltcedar along riparian regions, and their impact on local and regional hydrologic budgets have long been a concern. In this study, the consumptive use of a riparian area where a monotypic stand of saltcedar was partially cleared by mechanical plowing and vegetated with native riparian plants was investigated. The cleared site was seeded with a mixture of native riparian vegetation in an arid environment along the Middle Rio Grande at Bosque del Apache National Wildlife Refuge (Bosque NWR). According to the March 2010 Rio Grande Habitat Restoration Project Report from the US Fish and Wildlife, native vegetation comprised approximately 93% of the established woody vegetation on the plowed site ; approximately 25% consisted of Salix exigua and Salix gooddingii, 46% Populus deltodes, and 22% two Baccharis species. The saltcedar management effort was led by Bosque NWR to control saltcedar as well as encourage ecological diversity and the health of the riparian forest. Plowing of the dense saltcedar began in late 2005 and was completed in 2006. Evapotranspiration (ET) of the site was measured at the plowed (North Bosque) and non-plowed (South Bosque) locations for several years (2005, 2006, 2007, 2010, 2011 and 2013) ; the plowed site was initially overgrown by dense saltcedar. ET was measured using a one-propeller eddy covariance (OPEC) technique in the energy budget method, where ET was determined as a residual in the energy budget. The results show a trend of ET for the periods before, during, and after plowing of saltcedar at the site. In 2006, when saltcedar was completely cleared, ET difference between the plowed and dense saltcedar during the growing season reached a maximum of 499 mm (Residual Variance = 9.43 mm²). The difference in ET between the sites decreased as the vegetation at North Bosque continued to grow and become dense. By 2011, a difference in ET (North Bosque - South Bosque) during the growing season (231 days) was only 47 mm (Residual Variance = 0.44), and in 2013 the difference was -11 mm (Residual Variance = 0.61 mm) ; exceeding ET of dense saltcedar (-ve sign). Reduction in ET reached a minimum level five years after revegetation. Based on this study, replacing dense saltcedar with the Middle Rio Grande mixed native riparian vegetation as described above will not reduce ET depletion losses in the long-term.

Sujets : Evapotranspiration—New Mexico—Bosque del Apache National Wildlife Refuge. Riparian areas—Management. Invasive plants—New Mexico—Bosque del Apache National Wildlife Refuge. Saltcedar

Présentation (NMSU Library)

Page publiée le 12 février 2016, mise à jour le 24 décembre 2019