Despite Reports to the Contrary, Invasive Plants will Cause Natives to go Extinct

Credit: James Cornwell

Native plants on a California reserve. Most natives are on mounding islands where they are trying to hang on. Once the mycorrhizal network grid system within the chaparral plant community has been replaced by a bacterial one, this actually favours the invasive annual weeds which thrive in such an environment. The California natives simply cannot compete. Sadly, it's not just the ignorant activities of the early cattle ranching pioneers who deliberately made an irresponsible business decision to alter the chaparral & oak woodland landscape to a grassland-scape using foreign grass species from Europe to feed more cattle than the land could support, but also the irresponsible actions today by what should be educated & informed Forestry Officials utilizing bad science to control mega-fires through a  proven flawed method called prescribed burns that have actually exacerbated the problem causing invasive weeds to spread rapidly. There is a war raging across the planet to stop the invasive species  from other countries from invading other lands. There is no country or region of the planet which has not been effected. For example, for all you south-westerners who demonize the Tamarisk for destroying 10s of 1000s of acreage of riparian habits in your desert regions, you should know that your beloved Mesquite is a horrible  invasive species in Asia and Africa where Tamarisk comes from. Both trees are wonderful plants in the correct balanced setting, but put the blame where it really belongs, on human idiocy, not the plants. Agribusiness in the United States had the bright idea years ago to bring Tamarisk over to the desert regions to create windbreaks. In their ignorance they never once utilized their powers of observation to consider the actual resources available around them that nature creates natural barriers like the Mesquite Mounds which could have been replicated by the constructing of large berms running for miles along fields and/or along roads and railway right-of-ways with various native mesquites, palo verdes ironwoods, etc. 

 

Southern Xinjiang Railway
windbreak

The example of utilizing a berm next to a railroad by use of heavy equipment has been done in China as the photo to the right proves. Extend this further back and plant with southwest natives and an artificial Mesquite dune could have been created for further height next to the Coachella Valley Southern Pacific or Interstate 10 right-of-ways. But it's the Mesquite from the southwest that has ruined the landscape in Africa and India where it has spread like an invasive weed, thanks to the bright idea of the United Nations (another inept made made organization). Here is what the Invasive Species Council based in Australia had to say on this matter.

"Aid agencies face pressure to provide quick solutions to long-term problems, so they recommend plants that thrive on degraded lands - in other words, plants with the attributes of weeds," Mr Low said today.

"Mesquite, a prickly firewood tree heavily promoted by the Food and Agriculture Organization of the United Nations, is now causing great suffering in Africa, where it is invading farmland and national parks."

"Sudan has passed a law to eradicate it, and Kenya and Ethiopia have declared it a noxious weed," Invasive species Biologist Tim Low said.

Lately I've noticed, in the face of Climate Change and Global Warming alarm, that there are a number of movements out there trying to downplay the dangers of change and invasive species as not being all that bad and we should accept the inevitable. We should learn to live with these consequences and adapt to the change. That is bunk. I'll never except human stupidity and make excuses and concessions for it. There has even been an attempt to downplay the bad role that invasives will play in destroying native species from their traditional habitats. Yet a new study came from the University of Toronto, shedding light on the reality of the serious situation and exposing the falsehood of that propaganda. 

http://media.utoronto.ca/media-releases/arts/invading-species-can-extinguish-native-plants-despite-recent-reports/

TORONTO, ONTARIO - 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 & 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 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 plants to extinction. Instead, native plant species in invaded ecosystems are often relegated to patchy, marginal habitats unsuitable to their non-native competitors. 

 However, Gilbert and co-author Jonathan Levine of ETH Zurich say that it is uncertain whether colonization and extinction dynamics of the plants in marginal habitats will allow long-term native persistence. - "Of particular concern is the possibility that short term persistence of native flora in invaded habitats masks eventual extinction," says Levine. 

 The researchers conducted their research in a California reserve where much of the remaining native plant diversity exists in marginal areas surrounded by invasive grasses. They performed experiments in the reserve and coupled their results with quantitative models to determine the long term impacts of invasive grasses on native plants. 

"Invasion has created isolated 'islands of native plants' in a sea of exotics," says Gilbert. "This has decreased the size of native habitats, which reduces seed production and increases local extinction. It also makes it much harder for native plants to recolonize following a local extinction." 

"Our research also allows us to identify how new habitats for native flora could be created that would prevent extinction from happening. These habitats would still be too marginal for invaders, but placed in such a way as to create 'bridges' to other habitat patches," says Gilbert. 

The findings are reported in the paper "Plant Invasions and Extinction Debts" in PNAS Early Edition this week. The research is supported by funding from the Natural Sciences and Engineering Research Council of Canada and the Packard Foundation. -

Credit: James Cornwell

Once again take note of the Chaparral islands which were referred to in the above article. Many of these chaparral islands also contain a native type of bi-colored sunflower called "Tidy Tips" which are also endangered as seen here in yellow on those mounds. This is the beautiful green time of year in California chaparral country. The lush looking meadows are however mostly made up of annual non-natives which will dry up and turn brown in summer. It's these plants which burn like gasoline during mega-fire season and it's generally the chaparral which gets the blame. Modern government mismanagement practices and policies have made this spread of invasives far worse as the latest article.

Image - Maureen Glimer

Tamarisk, helpful to settlers, can be a pest in the long run

Many long time native Californians will remember this plant from the old days when they were once plentiful. The flower is called "Tidy Tips" (Layia platyglossa) and they were heavily growing on Rattlesnake Mountain in El Cajon when I was growing up as a kid in the 1960s. Unfortunately there is not a single plant existing up there any longer. I know because when I visited California in 2011, I made a deliberate attempt to look for it. What I remember most about the thick patches of them which grew interspersed with California Buckwheat & Coastal Sagebrush which also contained some Sea Lavender, was the biodiversity of insects, especially the butterflies population varieties which were very heavy. They too are now gone.

Credit: Me!!!

The beautiful bicoloured "Tidy Tips" were always thick and dense at the top of this street where that SUV is now parked, all the way halfway up this mountain. The yellow you now see is a mix of non-native Mustard, Star Thistle, Foxtail grasses and so forth. Other than the coastal sage scrub, most annual wild flowers are long gone, including the Blue Bells which use to sprout the next spring after a brushfire. Above that parked SUV is a naturalized Palo Verde Tree which volunteered from a seed source of a 50 year old Palo Verde tree to the far left of the SUV, but which is out of the picture. I'll give that one a pass.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Further references:

http://www.vcstar.com/news/2008/oct/08/tamarisk-helpful-to-settlers-can-be-a-pest-in/

http://www.pnas.org/content/early/2013/01/04/1212375110.abstract