I was reading one of my California Native Grasslands Association newsletters and I ran across an article regarding Italian ryegrass (Lolium multiflorum) and it's increasing dominace in the California Central Valley's grasslands. CA has plenty of problems with invasive grasses and forbs but the creeping dominance of this particular grass is quite interesting and like most invasive species poses more than a few problems to our health, economy and biodiversity. I won't go into specifics as I am assuming most here do not find grasses very interesting but there are a few facts about Italian ryegrass: Native to Europe, it was possibly imported to the U.S. in the 1700s (Hendry 1931). Populations have increase significantly over the last decade on the order of 32%-63% (Weiss 1999, 2002)(varies depending on annual precipitation and other factors). "Non-native grasses cost Californians between $400 million and $1 billion per year in missed work, medication, and Kleenex (Andeson 2005). Ryegrass is an adundant and potend allergen (Pollart et al. 1988; Spangenberg et al. 200) and is likely to be responsible for a significant portion of the grass pollen allergies in CA." Effectively out competes native grasses and reduces biodiversity as well as native forbs (wildflowers and such). Is great forage for livestock Nitogen is often a limiting factor in vegetative growth, at least in the non-legumes, and the deposition of nitrogen (various forms of nitrogen) on vegtation and soils has been shown to increase growth and vigor of Italian ryegrass. Thus ""nitrogen "fertilization" of the soil by automobile air pollution is strongly implicated as the cause of ryegrass' invasion of serpentine soils in the South Bay and Peninsula. At Jasper Ridge, Edgewood, and sites in San Jose, Weiss has shown that various forms of nitrogen deposited on plants and soils at much higher levels in areas with bad air pollution problems (Weiss 1992, 2002)." Experiments by other Standford University researchers have demonstrated that nitrogen fertilization can rapidly turn a study plot form forb-dominated to grass-dominated, and that ryegrass in particular, grows quickly and vigorously with nitrogen fertilization. It appears that over many years, air pollution has added enough nitrogen to the soil that a threshold has been crossed, allowing Italian ryegrass to flouish even in harsh soils like serpentine. This is just another example of why burning fossil fuels is a bad idea for a multitude of reasons. There are many reasons one could provide to just about anybody who claims they don't see a problem with it no matter what their favorite political flavor. Be it the loss of biodiversity and native species (including rare species), reduced precipitation, negative health effects, structural damage, warfare, national stability, economics etc., the costs associated with fossil fuel burning are high. We all know this in one or more forms but I feel it is best to be aware of as many negatives as you can so when you run into one of the naysayers, you have plenty of reasons to give them and maybe one of them will hit home and change their minds in the long run.... For more information of the loss of native pollinators and the costs to society look here: http://www.xerces.org/wp-content/up...bill-programs-for-pollinator-conservation.pdf
Nitrogen deposition in arid regions has also been shown to make invasive species better competitors. Some friends at UC Riverside are working on that.
Interesting... so the nitrogen is derived from NOx compounds then? Washed out by precipitation? Or soot?
Biogeoclimatic zones are shrinking and shifting with the weather changes, and many native species no longer 'feel at home'. They simply can't migrate as fast as the weather patterns are changing. The plants we keep as well-cared-for 'pets' in our gardens may well continue to thrive, but most species aren't that lucky. Aside from doing our best to weed out the invasive interlopers, what else can we do to support native species?
Aye, that is the general consensus it seems. Combine this with a changing climatic regime like Hyo stated and we are mixing things all up. In an article from 2006 that I found on the CA.gov site, air pollution from motor vehicles was also implicated in the reduction of precipitation in the Sierra Nevada due to the formation of very small but numerous rain nuclei. The moisture that collects on these smaller than normal particles never reaches a mass high enough to fall due to gravity and instead continue to flow over the Sierra Nevada western slope and beyond, taking precious rain/snow with it. This has serious implications for the future of California and it's water resources. I cannot find a link to the old paper (althought I have it saved on my hard drive. Here is a newer paper but at 133pages I have not read it yet so I am not 100% sure the conclusions are the same. AIRCRAFT MEASUREMENTS OF THE IMPACTS OF POLLUTION AEROSOLS ON CLOUDS AND PRECIPITATION OVERTHE SIERRA NEVADA
The amount is varaible but fundamentally it is not possible to prevent the formation of some nitrogen oxides during combustion in a nitrogen/oxygen atmosphere. Some of those become nitric acid in the atmosphere, other times the reactive N gases attach to airborne particles. Both are washed outed by rain, or less efficiently, by snow. Less efficiently only means a larger and more dilute 'footprint'. They all come back down somewhere. The highest reported N deposition regions are downwind of dense pig operations, e.g., Netherlands, but their it' s ammonia not oxidized N. All forms affect N cycling through the biota. We have a lot to learn still about industrial/dense population effects on ecosystems! The aerosols are a whole 'nother story. dependig on their size, chemistry and height in the atmosphere, they can increase or decrease rain and heat trapping and a bunch of things. Little wonder that even the best available climate models still choke on aerosols.
Without a doubt! I trying to get one of our preserves involved in a study that is looking at soils and how they differ in their services (C storage, N retention, water infiltration and storage, erosion control, etc.) in restored vs. unrestored patches. Valerie Eviner ( Department of Plant Sciences at UC Davis) is leading this study. I'm hoping that we can set up an additional test plot that would aid in that study. It's really interesting stuff. Well, considering you do the same type of work I know you're very familiar with it.
Since ecosystems change over time naturally a lot of us in the protection and/or restoration field are not overly concerned with reproducing a landscape from a particular point in time. We do strive to restore native species that work in the specific location and will contribute to the overall biodiversity, ecosystem health (and the associated ecosystem services they provide us with) and resiliency to overcome small to catestrophic changes. Things like land transformation (Habitat destruction) in the form of development or agriculture are the largest contributors to the decline of ecosystems and biodiversity. It is the first letter in the acronym HIPPO). One way you can help native species that have lost habitat is to create more habitat for them, even if it is in your own front/back yard. Plant species that are native to your area and you will help foster other associated species (insects, birds, mammals, fungi, bacteria, etc.) and you may reduce the amount of yard maintainence required as well as reducing water and nutrient inputs. The Sierra Nevada Alliance put out a great "Yard & Garden" landscaping book which details many natural landscaping ideas that work in the Sierra Nevada regions. I would check with your local Resource Conservation District if you have one or something similar to see if there is such a guide book or information packet that works for you. The one I mentioned above can be downloaded for free if you would like to read it to get an idea of how to plan your landscaping upgrades.
I'm looking forward to xeriscaping our front garden. It's kentucky blue grass, which makes no bloody sense at all in CO. I want to add a lot of native plants and flowers as well as vegetables and fruits (we get way better sun in the front than in the back). I'd like us to grow more of our own food and each year we take a few more steps towards expanding our production. The girls love helping out and they will learn a bit while having fun so it's a great win-win-win for us. Xeriscaping will have a noticable payback in terms of water bill too, so there are several upsides.
Less mowing and less fertilizer too! You'll have to take pics and start a thread for it my friend. I want to watch it progress.
