TY  - JOUR
A1  - Kolk, Jens
A1  - Naaf, Tobias
A1  - Wulf, Monika
T1  - Paying the colonization credit
BT  - converging plant species richness in ancient and post-agricultural forests in NE Germany over five decades
JF  - Biodiversity and conservation
N2  - Massive historical land cover changes in the Central European lowlands have resulted in a forest distribution that now comprises small remnants of ancient forests and more recently established post-agricultural forests. Here, land-use history is considered a key driver of recent herb-layer community changes, where an extinction debt in ancient forest remnants and/or a colonization credit in post-agricultural forests are being paid over time. On a regional scale, these payments should in theory lead toward a convergence in species richness between ancient and post-agricultural forests over time. In this study, we tested this assumption with a resurvey of 117 semi-permanent plots in the well-studied deciduous forests of the Prignitz region (Brandenburg, NE Germany), where we knew that the plant communities of post-agricultural stands exhibit a colonization credit while the extinction debt in ancient stands has largely been paid. We compared changes in the species richness of all herb layer species, forest specialists and ancient forest indicator species between ancient and post-agricultural stands with linear mixed effect models and determined the influence of patch connectivity on the magnitude of species richness changes. Species richness increased overall, but the richness of forest specialists increased significantly more in post-agricultural stands and was positively influenced by higher patch connectivity, indicating a convergence in species richness between the ancient and postagricultural stands. Furthermore, the richness of ancient forest indicator species only increased significantly in post-agricultural stands. For the first time, we were able to verify a gradual payment of the colonization credit in post-agricultural forest stands using a comparison of actual changes in temporal species richness.
KW  - Herb layer
KW  - Land-use history
KW  - Land-use legacy
KW  - Long-term change
KW  - Resurvey
KW  - Temperate forest
Y1  - 2016
U6  - https://doi.org/10.1007/s10531-016-1271-y
SN  - 0960-3115
SN  - 1572-9710
VL  - 26
SP  - 735
EP  - 755
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Naaf, Tobias
A1  - Wulf, Monika
T1  - Traits of winner and loser species indicate drivers of herb layer changes over two decades in forests of NW Germany
JF  - Journal of vegetation science
N2  - Questions
 What are the most likely environmental drivers for compositional herb layer changes as indicated by trait differences between winner and loser species?
 Location
 Weser-Elbe region (NW Germany).
 Methods
 We resurveyed the herb layer communities of ancient forest patches on base-rich sites of 175 semi-permanent plots. Species traits were tested for their ability to discriminate between winner and loser species using logistic regression analyses and deviance partitioning.
 Results
 Of 115 species tested, 31 were identified as winner species and 30 as loser species. Winner species had higher seed longevity, flowered later in the season and more often had an oceanic distribution compared to loser species. Loser species tended to have a higher specific leaf area, were more susceptible to deer browsing and had a performance optimum at higher soil pH compared to winner species. The loser species also represented several ancient forest and threatened species. Deviance partitioning indicated that local drivers (i.e. disturbance due to forest management) were primarily responsible for the species shifts, while regional drivers (i.e. browsing pressure and acidification from atmospheric deposition) and global drivers (i.e. climate warming) had moderate effects. There was no evidence that canopy closure, drainage or eutrophication contributed to herb layer changes.
 Conclusions
 The relative importance of the different drivers as indicated by the winner and loser species differs from that found in previous long-term studies. Relating species traits to species performance is a valuable tool that provides insight into the environmental drivers that are most likely responsible for herb layer changes.
KW  - Acidification
KW  - Browsing pressure
KW  - Climate warming
KW  - Disturbance
KW  - Long-term change
KW  - Oceanic distribution
KW  - Seed longevity
KW  - Specific leaf area
Y1  - 2011
U6  - https://doi.org/10.1111/j.1654-1103.2011.01267.x
SN  - 1100-9233
VL  - 22
IS  - 3
SP  - 516
EP  - 527
PB  - Wiley-Blackwell
CY  - Malden
ER  -