@article{NaafWulf2012,
  author    = {Naaf, Tobias and Wulf, Monika},
  title     = {Plant community assembly in temperate forests along gradients of soil fertility and disturbance},
  series = {Acta oecologica : international journal of ecology},
  volume    = {39},
  journal   = {Acta oecologica : international journal of ecology},
  number    = {2},
  publisher = {Elsevier},
  address   = {Paris},
  issn      = {1146-609X},
  doi       = {10.1016/j.actao.2012.01.009},
  pages     = {101 -- 108},
  year      = {2012},
  abstract  = {Plant community assembly from a regional pool is largely driven by two mechanisms: environmental filtering and niche partitioning, which result in trait convergence or divergence, respectively. Although empirical evidence for both assembly mechanisms exists, the environmental conditions and traits where each of the two assembly patterns is prevalent remain unclear. We studied community assembly mechanisms in herb layer communities of temperate forest patches in NW Germany, looking at distributions of competitive and reproductive traits along gradients of soil fertility and disturbance. We also examined how community assembly patterns changed over a time span of two decades. Canopy height converged toward taller species with increasing soil fertility and increasing light availability. Most reproductive traits diverged with an increasing degree of disturbance and with increasing fertility. Comparisons over time indicated that disturbance events induced the coexistence of species with different reproductive strategies and also selected for tall species as a result of enhanced competitive pressure. Our study demonstrates that in accordance with existing hypotheses, competitive traits (e.g., canopy height) can be convergent in favorable environments. However, this convergence is associated with a divergence of traits related to other challenges (e.g., reproduction), indicating that true functional redundancy within communities does not exist. Moreover, our study shows that the expected divergence of reproductive traits at disturbed sites can be accompanied by a convergence of other traits (e.g., canopy height), indicating that several assembly mechanisms can operate simultaneously.},
  language  = {en}
}
@article{NaafWulf2012,
  author    = {Naaf, Tobias and Wulf, Monika},
  title     = {Does taxonomic homogenization imply functional homogenization in temperate forest herb layer communities?},
  series = {Plant ecology : an international journal},
  volume    = {213},
  journal   = {Plant ecology : an international journal},
  number    = {3},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {1385-0237},
  doi       = {10.1007/s11258-011-9990-3},
  pages     = {431 -- 443},
  year      = {2012},
  abstract  = {Biotic homogenization, the decrease in beta diversity among formerly distinct species assemblages, has been recognized as an important form of biotic impoverishment for more than a decade. Although researchers have stressed the importance of the functional dimension to understand its potential ecological consequences, biotic homogenization has mostly been studied at a taxonomic level. Here, we explore the relationship between taxonomic and functional homogenization using data on temperate forest herb layer communities in NW Germany, for which taxonomic homogenization has recently been demonstrated. We quantified beta diversity by partitioning Rao's quadratic entropy. We found a general positive relationship between changes in taxonomic and functional beta diversity. This relationship was stronger if multiple functional traits were taken into account. Averaged across sites, however, taxonomic homogenization was not consistently accompanied by functional homogenization. Depending on the traits considered, taxonomic homogenization occurred also together with functional differentiation or no change in functional beta diversity. The species shifts responsible for changes in beta diversity differed substantially between taxonomic and functional beta diversity measures and also among functional beta diversity measures based on different traits. We discuss likely environmental drivers for species shifts. Our study demonstrates that functional homogenization must be explicitly studied as an independent phenomenon that cannot be inferred from taxonomic homogenization.},
  language  = {en}
}