Biology ETDs

Kimberly Fike

Publication Date

7-1-2015

Abstract

1. Anthropogenic-induced river intermittency is an increasing global concern with far-reaching ecological consequences. Cessation of flow outside of a rivers natural regime can have cascading effects on aquatic and terrestrial community composition and structure. Water abstraction during summer months often leaves the Rio Grande below Isleta Diversion Dam dry. This research investigates differences in hydrology, riparian vegetation, and arthropod communities within the Rio Grande floodplain, known locally as the 'bosque,' between perennial and intermittent reaches of the river. 2. Despite the high degree of interannual variability, a spatio-temporal analysis of stream discharge revealed a trend of declining flow in both reaches throughout the study period. The intermittent reach showed between 15 — 210 days per year with recorded discharge values low enough to be potential riverbed drying events. An increasing trend of low flow and no flow events was seen for the period of record. 3. The floodplain bordering the perennial reach throughout Albuquerque is dry and disconnected from the river due to the high degree of river incision, which rarely has overbank floods. The groundwater table in the perennial reach is significantly deeper than in the intermittent reach, but is more responsive to higher flows. The intermittent reach is less incised because it flows through an aggrading section of the river, leading to more overbank and seep flood events despite the annual drying events. 4. Vegetation cover and plant species diversity were significantly greater within the intermittent reach of the Rio Grande. Plant species richness was significantly greater in the sites adjacent to the perennial reach. Community composition varied among reaches with significantly more native shrub and tree species found throughout the perennial reach. Significantly more exotic trees, weeds, grasses (native annual, native perennial) and forbs (native annual, exotic annual, native perennial), and sedges were found throughout the intermittent reach. 5. Significantly greater abundance of arthropods, including indicator groups Carabidae, Tenebrionidae, and Isopoda, were found in the southern sites adjacent to the intermittent reach of the river. Functional groups were dominated by detritivores within both reaches. There was no significant difference between reaches for herbivores, ants, or predator arthropod species.

Project Sponsors

Bosque Ecosystem Monitoring Program

Language

English

Keywords

River, Drying, Intermittent, Hydrology, Vegetation, Arthropods

Document Type

Thesis

Degree Name

Biology

Level of Degree

Masters

Department Name

UNM Biology Department

First Committee Member (Chair)

Eichhorst, Kim

Second Committee Member

Stone, Mark

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