Zapata Bladderpod and Prostrate Milkweed Landscape Ecology, Seed Dispersal, Pollinators, and Border Fence Mitigation Active
USGS is studying how the current border fence designs or positions in the Lower Rio Grande Valley, Texas, impact seed dispersal and pollinator movement across the border.
The Science Issue and Relevance: The U.S.-Mexico border fence and associated road construction may create a landscape barrier to seed dispersal and pollinators critical to the reproductive success of plant species listed as threatened or endangered under the U.S. Endangered Species Act. This project will focus on the landscape flow of threatened and endangered seeds and pollinators across the border wall with respect to the direction of wind as well as border fence and road characteristics. The purpose of these studies will be to determine if any of the current border fence designs or positions in the Lower Rio Grande Valley, Texas, better support seed dispersal and pollinator movement across the border.
Methodology for Addressing the Issue: Seed and wind traps were placed at Arroyo Ramirez (Fig. 1), Arroyo Morteros, and Cuellar Tract in the Lower Rio Grande Valley National Wildlife Refuge, Texas, in January-February 2023. The traps were placed in positions to capture seeds moving across the trap's surface both by surface water flow and wind near Zapata bladderpod and prostrate milkweed populations. Insect visitors of threatened and endangered species were netted. We made observations on the ability of potential insect pollinators to cross the border wall and associated construction.
Future Steps: The findings of these studies will inform proposed approaches for the mitigation of threatened and endangered plant species for the consideration of the U.S. Fish and Wildlife Service. For example, if the movement of the seeds or pollinators are hindered by border fence or associated activities, then managers might decide to manually move seeds or plants across the barrier to increase genetic flow. If historical seed banks of threatened and endangered species represent a seed source whose germination requirements are not met, future management might focus on creating a natural disturbance or other environments for recruitment success.
USGS is studying how the current border fence designs or positions in the Lower Rio Grande Valley, Texas, impact seed dispersal and pollinator movement across the border.
The Science Issue and Relevance: The U.S.-Mexico border fence and associated road construction may create a landscape barrier to seed dispersal and pollinators critical to the reproductive success of plant species listed as threatened or endangered under the U.S. Endangered Species Act. This project will focus on the landscape flow of threatened and endangered seeds and pollinators across the border wall with respect to the direction of wind as well as border fence and road characteristics. The purpose of these studies will be to determine if any of the current border fence designs or positions in the Lower Rio Grande Valley, Texas, better support seed dispersal and pollinator movement across the border.
Methodology for Addressing the Issue: Seed and wind traps were placed at Arroyo Ramirez (Fig. 1), Arroyo Morteros, and Cuellar Tract in the Lower Rio Grande Valley National Wildlife Refuge, Texas, in January-February 2023. The traps were placed in positions to capture seeds moving across the trap's surface both by surface water flow and wind near Zapata bladderpod and prostrate milkweed populations. Insect visitors of threatened and endangered species were netted. We made observations on the ability of potential insect pollinators to cross the border wall and associated construction.
Future Steps: The findings of these studies will inform proposed approaches for the mitigation of threatened and endangered plant species for the consideration of the U.S. Fish and Wildlife Service. For example, if the movement of the seeds or pollinators are hindered by border fence or associated activities, then managers might decide to manually move seeds or plants across the barrier to increase genetic flow. If historical seed banks of threatened and endangered species represent a seed source whose germination requirements are not met, future management might focus on creating a natural disturbance or other environments for recruitment success.