BIOPLAN POSTING 2001-6-9
BIOPLAN POSTING 2001-6-9
"David Duthie" <David.Duthie@unep.org>
Sent by: owner-bioplan@undp.org
06/13/01 11:01 AM
bioplan
"David Duthie" <David.Duthie@unep.org>
Dear BIOPLANNERS,
Hard on the heels of reports that diversity increases ecosystem services
function in experimental grassland systems comes another - this time
for
experimental wetland systems.
The paper which appeared in Nature 7th June 2001 is as follows:
ENGELHARDT, Katharina A. M., & Mark E. RITCHIE (2001) Effects
of
macrophyte species richness on wetland ecosystem functioning and services.
Nature 411:687-689.
and can be access electronically at:
http://www.nature.com/nlink/v411/n6838/abs/411687a0_fs.html if
you have a
subscription. Alternatively, contact me (david.duthie@unep.org)
if you
wish to see a full copy of the report.
As in the grassland study, the experiments only involve the manipulation
of
four wetland macrophyte species in experimental mesocosms, but do provide
clear evidence that diversity promotes biomass production and nutrient
retention, an important ecosystem service of wetlands.
The advice to manage for diversity in wetlands by mimicking the natural
disturbance regime is hardly new, but serves as a reminder that
laissez-faire management of small natural (or semi-natural) systems
will
not suffice in landscapes that are increasingly human-influenced.
A summary of the results is pasted below.
Best wishes
David Duthie
(david.duthie@unep.org)
**************************************
WETLANDS SHOW STRENGTH IN DIVERSITY
LOGAN, Utah, June 7, 2001 (ENS) - The more diverse a wetland,
the better
it can serve as a natural water purifier, new research suggests.
Wetlands are both an important source of food for humans and natural
water
purifiers. Researchers have discovered that the more species of rooted,
submerged aquatic plants - also known as macrophytes - a wetland ecosystem
contains, the better able it is to perform these functions.
Katharina Engelhardt and Mark Ritchie of Utah State University
in Logan,
manipulated the diversity of four different aquatic plant species in
experimental ponds. As species richness increased, so did the total
combined biomass of macrophytes and algae - and therefore the ponds'
ability to support animal life, they found.
The ponds were also better at retaining polluting nutrients such
as
phosphorus. These experiments suggest that wetlands should be managed
through human disturbance to prevent competitive species from dominating
the ecosystem.
For example, the researchers learned that the presence of a plant
species
known as crisped pond weed was associated with increased amounts of
algae
in the experimental ponds. The algae helps to absorb phosphorus, preventing
the nutrient from running downstream where it could cause more dangerous
algal growth such that associated with the notorious Gulf of Mexico
"dead
zone."
Because crisped pond weed cannot always compete with other wetland
plant
species, it could be lost from wetlands that are not managed to maintain
diversity. The loss of this plant could reduce the wetland's algal
content,
and therefore its ability to filter out phosphorus from polluted runoff.
"Our results imply that management practices that maintain the
diversity
of aquatic macrophytes in wetlands, such as sustaining or restoring
a
natural disturbance regime, to prohibit exclusion of less competitive
species, may sustain ecosystem functioning and promote the services
of
those wetlands to humans," the researchers conclude.
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