The Long-term Development of Wetland Plant Communities with Water Deliveries in a Created Wetland in the Desert Southwest

In the middle of the Rio Grande, valuable wetlands and riparian areas have been replaced by urban and agricultural land, as well as the channelization of the river along the US-Mexico border. The Rio Bosque wetlands were constructed in El Paso, TX to mitigate the loss of these habitats. Unfortunately, these wetlands faced issues with water availability until 2016, when they began to receive the resource more frequently. Vegetation was allowed to establish naturally over time in response to winter water deliveries (2005–2014) and summer water deliveries (2016-7). This study investigated how changes in water delivery influenced the plant community development over more than a decade of restoration activities. We observed that water depth was an important predictor of increasing the relative frequency and cover of wetland plants, as well as macrophyte diversity. An NMDS ordination showed a transition of the vegetation community from limited water years to more regular water availability. The plant community changed from one dominated by upland plants, including invasive tumbleweed ( Salsola tragus ), to one dominated by tolerant, competitive wetland plants ( Lemna spp and Polygonum lapathifolium ). Deeper areas had a greater proportion of wetland plants, while facultative wetland plants occurred on the edges of ponds. In general, this 12-year study has helped to understand how the Rio Bosque ecosystem has changed after more regular water availability and will assist managers in tracking the future recovery and restoration of this valuable desert wetland.