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Pond management Pond management
Data Natuurpunt Data Natuurpunt (last 15 years)(last 15 years)::
Management of > 200 ponds in Flanders Management of > 200 ponds in Flanders (preliminary results)(preliminary results)
33%
21%
34%
9%
1%2%
Pond management Pond management Data Natuurpunt Data Natuurpunt (last 15 years)(last 15 years)::
Creation of 1049 new ponds in Flanders Creation of 1049 new ponds in Flanders Regionaal LandschapRegionaal Landschap
Provinciale domeinenProvinciale domeinen
NatuurpuntNatuurpunt
Agentschap Natuur & BosAgentschap Natuur & Bos
Provinces & MunicipalitiesProvinces & Municipalities
Private personsPrivate persons
… …
Pond management Pond management
Dredging (sludge removal): often used management techniqueDredging (sludge removal): often used management technique
Dredging needed Dredging needed silting up silting up
What is the effect of dredging?What is the effect of dredging?
Tommelen pond complex: Case studyTommelen pond complex: Case study
Management - dredging Management - dredging
Ponds in Tommelen dredged in October 2008
MOVIE(see website Pondscape: www.pondscape.be)
Case study: managementCase study: management
Physical & chemical variablesPhysical & chemical variables (nutrients, turbidity, oxygen, ...) (nutrients, turbidity, oxygen, ...)
MorphologyMorphology (depth, surface area, …) (depth, surface area, …)
Different organism groupsDifferent organism groups* Bacteria* Bacteria * Macroinvertebrates * Macroinvertebrates * Diatomea * Diatomea * Amphibians* Amphibians * Phytoplankton* Phytoplankton * Vegetation* Vegetation* Zooplankton* Zooplankton
Sampling:Sampling:- Spring & summer 2007 & 2008 - Spring & summer 2007 & 2008 pre-dredgingpre-dredging
- Spring & summer- Spring & summer 2009 2009 post-dredgingpost-dredging
Dredging in 2008 Dredging in 2008 effect in 2009? effect in 2009?
Management - dredging Management - dredging
Effect dredging on environmental factors?Effect dredging on environmental factors?
After dredging:After dredging: Higher suspended matterHigher suspended matter Higher chlorophyll concentrationsHigher chlorophyll concentrations
More open waterMore open water (also independent of ditch)(also independent of ditch)
Could affect communities Could affect communities
Effect of ditch on environmental factors?Effect of ditch on environmental factors?
Before dredging: Before dredging: Less vegetation and higher Less vegetation and higher conductivityconductivity
After dredging:After dredging: No effect of ditchNo effect of ditch
So effect of ditch is partly ‘filtered’ out due to dredgingSo effect of ditch is partly ‘filtered’ out due to dredging
Management - dredging Management - dredging
Effect dredging on macroinvertebrates?Effect dredging on macroinvertebrates?
Number of taxaNumber of taxa Total diversityTotal diversity
Spring 2007 Spring 2007 (pre-dredging)(pre-dredging) 21.5 +- 6.821.5 +- 6.8 5454
Spring 2008 Spring 2008 (pre-dredging)(pre-dredging) 20.1 +- 4.420.1 +- 4.4 5454
Spring 2009 Spring 2009 (post-dredging)(post-dredging) 9.4 +-9.4 +- 3.33.3 3434
Less taxa after managementLess taxa after management (also independent of ditch)(also independent of ditch)
Mostly rare taxa disappear after managementMostly rare taxa disappear after management
Ditch no effect on taxon richnessDitch no effect on taxon richness
Management - dredging Management - dredging
Effect dredging on macroinvertebrates?Effect dredging on macroinvertebrates? DREDGING
2007 2008 2009C C C
D = dredgingD D
Taxon Richness
20
10
C = control
CC D
Management - dredging Management - dredging
Ponds dredged in the mid-90’s: difference with other ponds?Ponds dredged in the mid-90’s: difference with other ponds?
Current macroinvertebrate communities: no significant effectCurrent macroinvertebrate communities: no significant effect
Current environmental features: no significant effectCurrent environmental features: no significant effect
No proof for longterm negative No proof for longterm negative effect on macroinvertebrate effect on macroinvertebrate communitiescommunities
Reduction of macroinvertebrate richness right after dredging Reduction of macroinvertebrate richness right after dredging
Reduction of richness probably recovers after a few yearsReduction of richness probably recovers after a few years
Before managementBefore management Year after management Year after management
Management - macroinvertebratesManagement - macroinvertebrates
High beta diversity in Tommelen:High beta diversity in Tommelen:
Conserving only a few ponds is not sufficient Conserving only a few ponds is not sufficient
Rare species seem mostly affected immediatly after dredging:Rare species seem mostly affected immediatly after dredging:
Do not dredge all ponds in an area at the same timeDo not dredge all ponds in an area at the same time
Spread management over several yearsSpread management over several years
Management - macroinvertebratesManagement - macroinvertebrates
Multiscale survey
125 ponds in Belgium & Luxembourg125 ponds in Belgium & Luxembourg
Hierarchical designHierarchical design
Reveal spatial scales Reveal spatial scales of of pond biodiversitypond biodiversity
Samples taken & being analysedSamples taken & being analysed
- Physical & chemical variables - Physical & chemical variables
- Morphology- Morphology
- Different organism groups- Different organism groups
Age effect
Effect age on communities Effect age on communities Important information for creation of new pondsImportant information for creation of new ponds
Age classes: Age classes: 0-5 years0-5 years
5-10 years5-10 years
10-25 years10-25 years
> 25 years> 25 years
Samples taken (83 ponds)Samples taken (83 ponds)
- Physical & chemical variables- Physical & chemical variables
- Morphology- Morphology
- Different organism groups- Different organism groups
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