Invading species can extinguish native plants despite recent reports

Seed Daily via SPX: Ecologists at the University of Toronto and the Swiss Federal Institute of Technology Zurich (ETH Zurich) have found that, given time, invading exotic plants will likely eliminate native plants growing in the wild despite recent reports to the contrary.

A study published in Proceedings of the National Academy of Sciences (PNAS) reports that recent statements that invasive plants are not problematic are often based on incomplete information, with insufficient time having passed to observe the full effect of invasions on native biodiversity.

"The impacts of exotic plant invasions often take much longer to become evident than previously thought," says Benjamin Gilbert of U of T's Department of Ecology and Evolutionary Biology (EEB) and lead author of the study. "This delay can create an 'extinction debt' in native plant species, meaning that these species are slowly going extinct but the actual extinction event occurs hundreds of years after the initial invasion."

Much of the debate surrounding the threat posed to biodiversity by the invasions of non-native species is fueled by recent findings that competition from introduced plants has driven remarkably few plant species to extinction. Instead, native plant species in invaded ecosystems are often relegated to patchy, marginal habitats unsuitable to their nonnative competitors....

Crows on a cross at Pere Lachaise cemetery in Paris, with an invasive ailanthus in the background, shot by jphilipg, Wikimedia Commons via Flickr,  under the Creative Commons Attribution 2.0 Generic license

Emerging consensus shows climate change already having major effects on ecosystems and species

US Geological Survey: Plant and animal species are shifting their geographic ranges and the timing of their life events – such as flowering, laying eggs or migrating – at faster rates than researchers documented just a few years ago, according to a technical report on biodiversity and ecosystems used as scientific input for the 2013 Third National Climate Assessment.

The report, Impacts of Climate Change on Biodiversity, Ecosystems, and Ecosystem Services, synthesizes the scientific understanding of the way climate change is affecting ecosystems, ecosystem services and the diversity of species, as well as what strategies might be used by natural resource practitioners to decrease current and future risks. More than 60 federal, academic and other scientists, including the lead authors from the U.S. Geological Survey, the National Wildlife Federation and Arizona State University in Tempe, authored the assessment.

"These geographic range and timing changes are causing cascading effects that extend through ecosystems, bringing together species that haven't previously interacted and creating mismatches between animals and their food sources," said Nancy Grimm, a scientist at ASU and a lead author of the report.

...Another key finding is the mounting evidence that population declines and increased extinction risks for some plant and animal species can be directly attributed to climate change. The most vulnerable species are those already degraded by other human-caused stressors such as pollution or exploitation, unable to shift their geographic range or timing of key life events, or that have narrow environmental or ecological tolerance. For example, species that must live at high altitudes or live in cold water with a narrow temperature range, such as salmon, face an even greater risk due to climate change.

"The report clearly indicates that as climate change continues to impact ecological systems, a net loss of global species’ diversity, as well as major shifts in the provision of ecosystem services, are quite likely," said Michelle Staudinger, a lead author of the report and a USGS and University of Missouri scientist....

Snow geese at Sacramento National Wildlife Refuge, shot by Brocken Inaglory, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported licence