Embed Size (px)
Citation preview
Kolonisation in fen ponds
Judith Sarneel
Utrecht University
Dramatic decrease of typical fen
species
Water quality improved
Why are there no new
colonisation events?
Chara Stratiotes Menyanthes
Colonisation1. Propagules entering the water
2. (long)distance dispersal by water
3.deposition
4b.Germination and establishment
5.Clonal expansion
>6 floating fen
4a.Incorporation in the seedbank
ZZZZ
Dispersal: What is mechanism, what are the effects?
Main wind direction
SouthWest
Isolated ponds
currents by wind
hydrochory => wind driven
p=0.006
Lee, SWWind, NE
exposure
Nov-06 Feb-07 may-07 Aug-07 Nov-07
0
4000
8000
12000
Dia
spo
res
pe
r m
at
Wind direction
N N N N N
Lee, SWWind, NE
exposure
But:
Azza, et al 2007
The desired species typically grow in sites sheltered from the wind, whereas the majority of seeds are transported to exposed banks.
Glyceria maxima
Mentha aquatica
Comarum palustris
Calla palustris
Berula erecta
Can this difference be explained by differences in germination and establishment?
0
10
20
30
40
50
4 8 12 16Time (wk)
see
dlin
gs
At first more seedlings at downwind sites =>light
Later on, highest numbers at lee, upwind sites
Steeper decrease at NE banks =>waves
SW NE
1. Propagules entering the water
2. (long)distance dispersal by water
3.deposition
4b.Germination and establishment
5.Clonal expansion
>6 floating fen
4a.Incorporation in the seedbank
ZZZZ
1. Propagules entering the water
2. (long)distance dispersal by water
3.deposition
4b.Germination and establishment
5.Clonal expansion
1. Propagules entering the water
2. (long)distance dispersal by water
3.deposition
4b.Germination and establishment
5.Clonal expansion
>6 floating fen
4a.Incorporation in the seedbank
ZZZZ
WIND
Waves
Clonal expansion
Under which circumstances do species colonise the water from the bank?
What is the effect of eutrophication on the colonisation of fen ponds?
We will relate all kinds of environmental variables
(chemical, morphological, management)
To:The colonised distance as measured in the field
AprilJuniMeiJuliSeptemberJuni 2006Sept 2007
Mesocosm experiment with different nutrient treatments to water and peat
