Trees in the riparian zone (Trees and water resources).

A.J. Glauber madrona at
Tue Sep 30 01:30:15 EST 1997

A complex answer to a complex question.

Yes, some types of trees do use relatively high amounts of water (e.g.
willows, cottonwoods, etc.). However, vegetation in channels or
floodplains slow the flow of water, instead of conveying higher flows
quickly downstream (often too quickly to be handled by
stormwater-discharge or filtration systems).

Riparian wetlands (including forested) provide many beneficial services
to the ecosystem and to human devleopment. For example, wetlands: (1)
act as "filters", removing many contaminants from water, including
heavy metals, and storing them in saturated conditions that may not be
bioavailable; (2) minimize the impact of flooding, by providing storage
capacity for high waters; and (3) provide habitat to a plethora of
wildlife species at varying times in their life histories.

In my job as a restoration ecologist, I have countless projects that
involve developing mitigation and restoration plans to offset the
unintended effects of dredging, channelization, and/or vegetation
removal. The impacts to both the ecosystem and public works are
staggering. In the San Francisco Bay Area, voters have just approved
over $200,000,000 to come up with ways of restoring the Sacramento-San
Joaquin Delta that is faces catestrophic decline both in terms of biota
(numerous endangered fish species and aquatic habitats), water supply
(heavily engineered water distribution systems based on levees,
dredging, canals, pumping, etc), water quality (decimation of wetlands
coupled with increase in polution from agriculture, non-point sources,
etc.),  and various other factors. 

So, let's think before we act! There are ways to accomodate both humans
and the world beyond that can save countless dollars and quandries in
the not-too-distant-future.

In <342852D6.632 at> at writes: 
>av08 at wrote:
>>    The controversy of Trees and Water, especially within the
Riparian zone.
>>    There are some who allege that all trees should be cleared from
>>    banks of streams and rivers as this will increase water flow;
>>    use the water).    This is a hot issue in South Africa and the
>>    Government has even made suggestions of introducing a rainfall
>>    interception tax on forestry areas in general.
>>    Others again say that trees in the riparian zone are necessary to
>>    conserve the eco-system, reduce errosion and filter the water.
>>    I would be intersted in hearing your views on the matter - WHO is
>>    and WHO is WRONG.
>>    Harold
>I agree with the other posts, then there is the aspect of
>Pytoremediation where all plant material will break down organic
>contaminats in the ground and surface water.
>I find the propensity to dredge all waterways a bad thing to for the
>above reason.
>as for evaporative loss in irrigaton and potable aquiducts arid
>governments would do good to enclose them. 
>Here in wisconsin it is an old practice to plant a willow down slope
>from a septic system.

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