德州大學奧斯汀分校整合生物學系教授富勒（Norma Fowler）和凱特（Tim Keitt）的研究，2日刊登於同儕評閱的《生態與環境前線》（Frontiers of Ecology and the Environment）期刊。
美國國會剛通過決議，聖安娜國家野生動物保護區（Santa Ana National Wildlife Refuge）免築邊界牆，但也提出許多其他聯邦土地上蓋邊界牆的新建議，總計好幾公里，大部分位於下大河谷國家野生動物保護區（Lower Rio Grande Valley National Wildlife Refuge）。
A border wall between the United States and Mexico threatens to harm endangered Texas plants and animals and cause trouble for the region’s growing ecotourism industry, warn conservation biologists, led by a pair of scientists from the University of Texas at Austin.
In a letter published today in the peer-reviewed journal “Frontiers of Ecology and the Environment,” Norma Fowler and Tim Keitt, both professors in the Department of Integrative Biology at UT Austin, examine what would happen if more of Texas’ roughly 1,200 miles of border with Mexico were to be walled off, contributing to habitat destruction, habitat fragmentation and ecosystem damage.
Other states have shorter borders than Texas has and more barriers already in place; in Texas, there are walls along only 100 miles of the border with Mexico.
President Donald Trump has made construction of a border wall a signature issue of his presidency. On Sunday Trump linked his proposal to build such a wall to ongoing NAFTA trade negotiations with Mexico and Canada.
Congress just exempted the Santa Ana National Wildlife Refuge from the border wall project, but many miles of new barriers are proposed to be built on other federal lands, most of which are part of the Lower Rio Grande Valley National Wildlife Refuge.
“Up to now, the wall has either gone through cities or deserts. This is the Rio Grande we’re talking about here. It’s totally different,” Fowler said. “We have high biodiversity because of the river and because Texas extends so far south. I and other Texas biologists are very concerned about the impact this will have on our rich natural heritage.”
Based on a scientific literature review of 14 other publications, including some that looked at effects of existing walls and fences on the border, the authors outlined concerns about the proposed wall, including habitat destruction and degradation caused by the construction of the wall and the roads on either side of the wall.
The ocelot, a small native wildcat listed as an endangered species, has already suffered from severe habitat loss. The Texas Parks and Wildlife Department estimates there are no more than 120 left in Texas, and scientists worry that the wall would further deplete their numbers.
With habitat fragmentation, the wall could cut off ocelot and black bear populations in Texas and Mexico from other members of their species, leaving some populations too small to persist.
Of particular concern, write Fowler and Keitt, is damage to Tamaulipan thornscrub, a once abundant but now rare ecosystem in South Texas. Many South Texas organisms depend on this ecosystem, but it is disappearing as cities, farms and ranches move in.
The living things that depend on it would lose access to some of the last remaining patches in Texas if the wall were built, Fowler said.
Plants would be damaged if the pollinators and seed-dispersing animals that they depend on could not cross the barrier.
Because the wall will probably not be built in the flood plain of the Rio Grande, it will have to be set back from the river, sometimes by more than a mile. This has the potential to damage the valuable riparian forest ecosystem along the river, cutting off organisms that need to get to the river and preventing people from accessing several wildlife refuges along the river used for ecotourism.
Scientists also expressed concern about the border wall project being exempt from environmental review requirements.
“Negative impacts could be lessened by limiting the extent of physical barriers and associated roads, designing barriers to permit animal passage and substituting less biologically harmful methods, such as electronic sensors, for physical barriers,” the letter states.
Based in Tucson, Arizona, near that state’s border with Mexico, the Center for Biological Diversity shares these concerns, saying the border wall planned by President Trump would be “a tragedy for the region’s diverse wildlife and people, as well as its rugged and spectacular landscapes.”
It would “destroy thousands of acres of habitat and halt the cross-border migration of dozens of animal species,” the Center warns as it fights the proposed wall in the courts, in Congress and in border communities.