@article{NottebrockEslerSchurr2013,
  author    = {Nottebrock, Henning and Esler, Karen J. and Schurr, Frank Martin},
  title     = {Effects of intraspecific and community density on the lifetime fecundity of long-lived shrubs},
  series = {Perspectives in plant ecology, evolution and systematics},
  volume    = {15},
  journal   = {Perspectives in plant ecology, evolution and systematics},
  number    = {3},
  publisher = {Elsevier},
  address   = {Jena},
  issn      = {1433-8319},
  doi       = {10.1016/j.ppees.2013.03.003},
  pages     = {150 -- 161},
  year      = {2013},
  abstract  = {Intra- and interspecific density dependence has profound consequences for plant population and community dynamics. In long-lived plants, however, lifetime patterns and mechanisms of density dependence are difficult to study. Here, we examine effects of intraspecific and community density on the lifetime fecundity of two long-lived shrub species from South African Fynbos: Protea repens (animal-pollinated, hermaphroditic) and Leucadendron rubrum (wind-pollinated, dioecious). Both species are serotinous, retaining seeds in cones until fire kills the mother plant. We measured lifetime fecundity as the product of cone number, proportion of cones that are not damaged by predation and seed set (fertile seeds per intact cone). Intraspecific and community densities were quantified by counting individuals of target species and all Proteaceae in small- and large-scale neighbourhoods (10 m and 50 m radius) around each focal individual. Additionally, we determined the age and size of focal individuals. We found that lifetime fecundity of the wind-pollinated L rubrum is density independent. In contrast, the lifetime fecundity of the animal-pollinated P. repens increases with large-scale intraspecific density and shows a hump-shaped relationship to large-scale community density. Community density has a hump-shaped effect on seed set (probably through partial absence of generalized pollinators at low and competition for pollinators at high densities) and negatively affects cone number per individual. For both species, plant age decreases seed set while increasing lifetime fecundity. The qualitative differences in the density dependence of lifetime fecundity may arise from differences between animal and wind pollination. In particular, interactions with generalized animal pollinators may cause community-level Allee effects with profound consequences for the future dynamics of long-lived plant populations and communities.},
  language  = {en}
}
@inproceedings{GaertnerNottebrockFourieetal.2012,
  author    = {Gaertner, M. and Nottebrock, Henning and Fourie, H. and Privett, S. D. J. and Richardson, D. M.},
  title     = {Plant invasions, resilience, economics, and restoration - can fynbos pay for alien management?},
  series = {South African journal of botany : an international interdisciplinary journal for botanical sciences},
  volume    = {79},
  booktitle = {South African journal of botany : an international interdisciplinary journal for botanical sciences},
  number    = {3},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0254-6299},
  pages     = {186 -- 186},
  year      = {2012},
  language  = {en}
}
@article{GaertnerNottebrockFourieetal.2012,
  author    = {G{\"a}rtner, Mirijam and Nottebrock, Henning and Fourie, Helanya and Privett, Sean D. J. and Richardson, David M.},
  title     = {Plant invasions, restoration, and economics perspectives from South African fynbos},
  series = {Perspectives in plant ecology, evolution and systematics},
  volume    = {14},
  journal   = {Perspectives in plant ecology, evolution and systematics},
  number    = {5},
  publisher = {Elsevier},
  address   = {Jena},
  issn      = {1433-8319},
  doi       = {10.1016/j.ppees.2012.05.001},
  pages     = {341 -- 353},
  year      = {2012},
  abstract  = {Restoration is gaining importance in the management of plant invasions. As the success of restoration projects is frequently determined by factors other than ecological ones, we explored the ecological and financial feasibility of active restoration on three different invaded sites in South Africa's Cape Floristic Region. The aim of our study was to identify cost-effective ways of restoring functional native ecosystems following invasion by alien plants. Over three years we evaluated different restoration approaches using field trials and experimental manipulations (i.e. mechanical clearing, burning, different soil restoration techniques and sowing of native species) to reduce elevated soil nutrient levels and to re-establish native fynbos communities. Furthermore we investigated the possibility of introducing native fynbos species that can be used for sustainable harvesting to create an incentive for restoration on private land. Diversity and evenness of native plant species increased significantly after restoration at all three sites, whereas cover of alien plants decreased significantly, confirming that active restoration was successful. However, sowing of native fynbos species had no significant effect on native cover, species richness, diversity or evenness in the Acacia thicket and Kikuyu field, implying that the ecosystem was sufficiently resilient to allow autogenic recovery following clearing and burning of the invasive species. Soil restoration treatments resulted in an increase of available nitrogen in the Acacia thicket, but had no significant effects in the Eucalyptus plantation. However, despite elevated available soil nitrogen levels, native species germinated irrespective whether sown or unsown (i.e. regeneration from the soil seed bank). Without active introduction of native species, native grasses, forbs and other shrubs would have dominated, and proteoids and ericoids (the major fynbos growth forms) would have been under-represented. The financial analysis shows that income from flower harvesting following active restoration consistently outweighs income following passive restoration, but that the associated increase in income does not always justify the higher costs. We conclude that active restoration can be effective and financially feasible when compared to passive restoration, depending on the density of invasion. Active restoration of densely invaded sites may therefore only be justifiable if the target area is in a region of high conservation priority.},
  language  = {en}
}