[APWG] WATER quality Contaminant reduction by ecosystems Re: Nutrient and stormwater release

[Wayne Tyson]

Marc:



I have worked on this issue for decades (more than three). It is a lot simpler than it might appear, but there are crucial considerations. A lot of effort has been put into studies about marginal differences between species, sub-populations (and even bio-engineered species, f' gawd's sake!), but much of it is much ado about very little, when the effort could be allocated to higher-priority work. Statistically, there's usually so much background noise that the differences, if you will excuse the expression, "wash." N and P sequestration "happens," and this is not a variable you can do much to change--in itself. But you certainly can design a project to balance, to the maximum extent feasible by using various tricks. One of the big problems is "seasonality," for example, the variations in uptake of N and P. I think annual averages are often a "cop-out." That is, it's an easy way to show/cover up "acceptable" reductions as "the best that can be done" when, in fact, much more could be done. Hint: the bottom line is how much difference the TOTAL output into the receiving body is reduced. What also counts is peaks of variation in performance that can have significant effects at significant times (e.g. at crucial points in reproductive cycles). 



Theoretically  speaking, water and nutrients, all things being equal (such as the presence of available water in the root zone) control biomass, up to the potential for each site. All this should be determined for each site and set of conditions (where there are significant differences), and the design is pretty much dictated by the load (and its variations) against the "treatment" capacity. Overloading, at least seasonally, is the primary reason why such systems fail to meet expectations. Big loads=big areas, but there are ways to engineer higher effective capacities for smaller areas. 



A bigger "problem" (the problem is not in the set of conditions, but in the response to them) is that natural areas do not always have optimal conditions for maximizing treatment effectiveness. This can mean that in some places, for example, site geology is favorable (e.g. strata are bedded toward the waterway at the right depth) but in other places it is unfavorable (e.g., percolation into a water-table). In the latter cases, engineered systems may be required to avoid wasting resources on good intentions and "intuitive certainties." A project that isn't based on good evidence on all of the relevant and substantial considerations required to demonstrate feasibility should not be funded. Evidence AND performance that are quantified within a reasonable range of maximums to minimums, are ESSENTIAL. Beware of consultants bearing fancy proposals! Be on the lookout for substance, particularly in input/output standards and require a large performance bond (based on highly specific limitations on blaming God and Nature, etc. for failure to function as promised--of course where true imponderables are accepted by both parties, some flexibility might be tolerable, but ONLY for DEMONSTRATION project. Demonstration projects, on smaller, but reasonably representative scales, should be considered ESSENTIAL. No theoretically-based project should ever be done without REAL EVIDENCE. Generalities are cheap, and not worth whatever you pay for them. At some point, failure to perform should probably rise to the level of fraud, but it's sometimes difficult to distinguish from incompetence, however well-intentioned or slickly packaged and spun. 



Someday, taxpayers and other funders are going to get wise to these issues, and errors and emissions insurance rates, not to mention lawsuits, are likely to descend upon the heads of those who fail to deliver. 



As to "native" vs alien species, many alien species can, in lab "experiments" especially, show higher levels of nutrient removal (presuming this is what you mean by your statement) than "natives." High nutrient availability can increase alien vegetation, but this can be mitigated to some extent by ensuring the development of a diverse ecosystem, even on engineered (with competent ecologists, not the engineers, calling the shots) projects. (I developed an "ecologically engineered" system many years ago, but the slick-talking big "firms" could always out-BS me.) Some natives can also shift to higher nutrient-uptake forms (hybridization), and sometimes such can be found "spontaneously" occurring on comparable disturbed sites. Certainly the data you seek might serve to provide some ball-park figures to indicate differences in species "performance" under lab conditions, but that is rarely equivalent to the long-term, passive, self-maintaining sequestration system required. The problem is that such data can be misleading, perhaps more so, than useful. Context, including time and change projections, is "everything." 



I should add that, while N and P are serious pollutants, projects should also be designed for the removal or transformation of other pollutants as well, and sometimes that requires a higher level of pre-treatment or consideration/incorporation of, for example, microbial species and adsorption. 



But the bottom remains: For a given input level of contamination, there is a given output level of "contamination," and the latter always should be demonstrated to be feasible over the life of the project, as defined and approved by the parties. No amount of "authoritative" statistical references can predict actual performance to any meaningful degree. 

 

Sorry this went on so long; I actually left a lot out. 

 

Best regards,

WT

 

----- Original Message ----- 
From: <ialm at erols.com>
To: <APWG at lists.plantconservation.org>
Sent: Monday, January 04, 2010 5:38 AM
Subject: [APWG] Nutrient and stormwater release


Regarding: 

"Native plants provide food and shelter for birds, butterflies and other
desirable wildlife. Many help to enrich the soil. Their root systems help
rainfall percolate into the soil, reducing erosion and runoff. This
improves water quality." on the Wild Ones web site and similar statements
on other web sites, I am looking for actual statistical studies that give
percent increase in nutrients such as Nitrogen and Phosphorus, sediment, or
storm water run-off in mono-cultural patches or plots of non-native
invasive plants in natural areas compared to native plant plots in a
bio-diverse ecosystem. This will help folks get funding under the new 
grants to protect the Chesapeake Bay and other watersheds. We have such
information for Microstegium but need it for other species. Best regards.

Marc Imlay
anacostia Watershed Society





--------------------------------------------------------------------
mail2web LIVE - Free email based on Microsoft® Exchange technology -
http://link.mail2web.com/LIVE




_______________________________________________
PCA's Alien Plant Working Group mailing list
APWG at lists.plantconservation.org
http://lists.plantconservation.org/mailman/listinfo/apwg_lists.plantconservation.org

Disclaimer
Any requests, advice or opinions posted to this list reflect ONLY the opinion of the individual posting the message.


--------------------------------------------------------------------------------



No virus found in this incoming message.
Checked by AVG - www.avg.com 
Version: 8.5.432 / Virus Database: 270.14.124/2599 - Release Date: 01/04/10 08:24:00
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.plantconservation.org/pipermail/apwg_lists.plantconservation.org/attachments/20100104/beadbf7c/attachment.html>