Historical Analysis of Riparian Vegetation Change in Response to Shifting Management Objectives on the Middle Rio Grande

Abstract

Riparian ecosystems are valuable to the ecological and human communities that depend on them. Over the past century, they have been subject to shifting management practices to maximize human use and ecosystem services, creating a complex relationship between water policy, management, and the natural ecosystem. This has necessitated research on the spatial and temporal dynamics of riparian vegetation change. The San Acacia Reach of the Middle Rio Grande has experienced multiple management and river flow fluctuations, resulting in threats to its riparian and aquatic ecosystems. This research uses remote sensing data, GIS, a review of management decisions, and an assessment of climate to both quantify how riparian vegetation has been altered over time and provide interpretations of the relationships between riparian change and shifting climate and management objectives. This research focused on four management phases from 1935 to 2014, each highlighting different management practices and climate-driven river patterns, providing unique opportunities to observe a direct relationship between river management, climate, and riparian response. Overall, we believe that management practices coupled with reduced surface river-flows with limited overbank flooding influenced the compositional and spatial patterns of vegetation, including possibly increasing non-native vegetation coverage. However, recent restoration efforts have begun to reduce non-native vegetation coverage.

Land Use, anthropogenic disturbance, and riverine features drive patterns of habitat selection by a wintering waterbird in a semi-arid environment

“…Additionally, the interaction between channel width and mean bank vegetation height influenced roosting habitat selection. A narrower channel width, which is more incised and has reduced lateral flows, supports more woody vegetation [ 15 ] and in turn can have higher mean bank vegetation heights which decreased relative probability of use ( Fig 5 ). Relative probability of using a location within the Rio Grande for roosting also increased as distance from bridges increased ( Fig 6 ).…”

“…Historically, the Rio Grande was a highly dynamic river system marked by frequent pulses of flooding within the floodplain creating a wide and braided river channel interspersed with sandbars, wetlands, and wet meadows [ 15 , 92 ], an ideal collection of high quality habitat features for sandhill cranes and many other wildlife. Presently, however, the historic flow regime of the Rio Grande has been substantially altered, creating narrower and incised channel morphology, and sedimentation loads that have allowed establishment of invasive woody vegetation such as Tamarisk [ 15 , 93 ]. Much of this change owing to human alteration of the natural hydrology, a deeper water table, and regional drought [ 94 ], has eliminated important riverine habitat once used by sandhill cranes [ 92 ].…”

“…Unfortunately, the MRGV is a basin facing increased imperilment by way of human population growth compounded by impacts of climatic fluctuations. Long-term perturbations facilitated by changes in land use, high demands placed on limited water resources, introduction of invasive species, and human-modification of the natural hydrological regime has made it harder to simultaneously fulfill the needs of humans and wildlife [ 5 , 15 ]. These environmental stressors have substantially changed both physiognomy and function of the MRGV and raised concern for the persistence of some fish and wildlife species [ 16 – 19 ].…”

“…Drought, flood control, water diversion or damming, and human water consumption have drastically altered the natural hydrology of the Rio Grande [ 15 ], influencing habitat availability for sandhill cranes. Transition away from grain-based crops, an important dietary component for wintering sandhill cranes [ 38 ], have likely influenced the availability and quality of food resources [ 39 , 40 ].…”

Assessing Riparian Vegetation Condition and Function in Disturbed Sites of the Arid Northwestern Mexico

“…Moreover, previous work suggests that water management practices could potentially modify the structure and function of key ecosystems in arid environments [3,[8][9][10]. In this sense, recent studies describe how groundwater depth restricts the establishment of riparian vegetation in watersheds located in arid environments of central Sonora (northwestern Mexico), particularly in vegetation on different sites along the river by field sampling.…”