TY  - JOUR
A1  - Gemeinholzer, B.
A1  - May, F.
A1  - Ristow, Michael
A1  - Batsch, C.
A1  - Lauterbach, D.
T1  - Strong genetic differentiation on a fragmentation gradient among populations of the heterocarpic annual Catananche lutea L. (Asteraceae)
JF  - Plant systematics and evolution
N2  - In landscapes which are predominately characterised by agriculture, natural ecosystems are often reduced to a mosaic of scattered patches of natural vegetation. Species with formerly connected distribution ranges now have restricted gene flow among populations. This has isolating effects upon population structure, because species are often confined by their limited dispersal capabilities. In this study, we test the effects of habitat fragmentation, precipitation, and isolation of populations on the genetic structure (AFLP) and fitness of the Asteraceae Catananche lutea. Our study area is an agro-dominated ecosystem in the desert-Mediterranean transition zone of the Southern Judea Lowlands in Israel. Our analysis revealed an intermediate level of intra-population genetic diversity across the study site with reduced genetic diversity on smaller scale. Although the size of the whole study area was relatively small (20 x 45 km), we found isolation by distance to be effective. We detected a high level of genetic differentiation among populations but genetic structure did not reflect spatial patterns. Population genetic diversity was correlated neither with position along the precipitation gradient nor with different seed types or other plant fitness variables in C. lutea.
KW  - AFLP
KW  - Heterocarpy
KW  - Population structure
KW  - Precipitation gradient
KW  - Asteraceae
Y1  - 2012
U6  - https://doi.org/10.1007/s00606-012-0661-1
SN  - 0378-2697
VL  - 298
IS  - 8
SP  - 1585
EP  - 1596
PB  - Springer
CY  - Wien
ER  - 
TY  - JOUR
A1  - Guo, Tong
A1  - Lohmann, Dirk
A1  - Ratzmann, Gregor
A1  - Tietjen, Britta
T1  - Response of semi-arid savanna vegetation composition towards grazing along a precipitation gradient-The effect of including plant heterogeneity into an ecohydrological savanna model
JF  - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog
N2  - Ecohydrological models of savanna rangeland systems typically aggregate plant species to very broad plant functional types (PFTs), which are characterized by their trait combinations. However, neglecting trait variability within modelled PFTs may hamper our ability to understand the effects of climate or land use change on vegetation composition and thus on ecosystem processes. In this study we extended and parameterized the ecohydrological savanna model EcoHyD, which originally considered only three broad PFTs (perennial grasses, annuals and shrubs). We defined several sub-types of perennial grasses (sub-PFTs) to assess the effect of environmental conditions on vegetation composition and ecosystem functioning. These perennial sub-PFTs are defined by altering distinct trait values based on a trade-off approach for (i) the longevity of plants and (ii) grazing-resistance. We find that increasing grazing intensity leads to a dominance of the fast-growing and short-lived perennial grass type as well as a dominance of the poorly palatable grass type. Increasing precipitation dampens the magnitude of grazing-induced shifts between perennial grass types. The diversification of perennial grass PFTs generally increases the total perennial grass cover and ecosystem water use efficiency, but does not protect the community from shrub encroachment. We thus demonstrate that including trait heterogeneity into ecosystem models will allow for an improved representation of ecosystem responses to environmental change in savannas. This will help to better assess how ecosystem functions might be impacted under future conditions. (C) 2016 Elsevier B.V. All rights reserved.
KW  - Plant functional types
KW  - Trait heterogeneity
KW  - Rangeland management
KW  - Precipitation gradient
KW  - Livestock
KW  - Ecosystem functioning
Y1  - 2016
U6  - https://doi.org/10.1016/j.ecolmodel.2016.01.004
SN  - 0304-3800
SN  - 1872-7026
VL  - 325
SP  - 47
EP  - 56
PB  - Elsevier
CY  - Amsterdam
ER  -