The Influence of Gaps on Tree Regeneration: A Case Study of the Mixed Lime-Hornbeam (Tilio-Carpinetum Tracz. 1962) Communities in the Białowieża Primeval Forest. Bobiec, A. 55(3):441–455.
The Influence of Gaps on Tree Regeneration: A Case Study of the Mixed Lime-Hornbeam (Tilio-Carpinetum Tracz. 1962) Communities in the Białowieża Primeval Forest [pdf]Paper  abstract   bibtex   
Tree stand regeneration in ten natural gaps, ranging in size from 250 to 1610 m[²], and three artificial clearings of 650.1150 m[²] was compared to the undergrowth in the adjacent stands representing mesic lime-hornbeam (Tilio-Carpinetum Tracz. 1962) assemblages of the Białowieża Primeval Forest. The purpose of the study was to find how gaps influence the tree regeneration in such forests, regarding sapling density and composition. Most of the gaps were formed by the decline of groups of spruce (Picea abies (L.) Karst.) trees. In the largest openings spruce logs contributed to more than 80\,% of the volume of fallen trees. Having four times higher all saplings density and eight times higher tall saplings (h$>$ 1.3 m) density, comparing to the canopy-sheltered undergrowth, gaps play an important role of successful tree regeneration centres. Pioneering, intolerant species such as birch (Betula pendula Roth), aspen (Populus tremula L.), goat willow (Salix caprea L.), rowan (Sorbus aucuparia L.), and alder (Alnus glutinosa L.), regenerate almost solely in gaps. The gap size had no influence on the gap-filler composition. The most successful gap-fillers, both in small and large gaps were tolerant species: hornbeam (Carpinus betulus L.) and lime (Tilia cordata Mill.). Spruce, the third dominant canopy species of the neighbouring stands was absent in the gap-filling regeneration. The study showed that under the current environmental conditions only hornbeam reveals a continuous mode of regeneration giving it a big competitive advantage both under canopy and in gaps. Other species, including lime, oak (Quercus robur L.) as well as pioneering birch and aspen seem to regenerate in a discrete and irregular manner. It was hypothesised that their regeneration depends on ephemeral opportune circumstances occurring at the initial phase of gap filling, such as presence of layering fresh logs, sprouting stumps and roots, spots of exposed mineral material, as well as inaccessibility to browsers. Artificial openings, created by forestry operations, considerably differ from natural gaps, mimicking a 'catastrophic mode' of dynamics, quite uncommon in the observed forest assemblages, favouring abundant regeneration of pioneering species. Further research necessary to explain important structural and dynamic characteristics of natural stands should address the following questions: - overall gap size structure; - mechanisms determining successful regeneration of less competitive and intolerant species; - history of the gap dynamics (dendrochronology) and its future development (modelling); - average rate of disturbance and turnover time in Tilio-Carpinetum; - minimal conservation area.
@article{bobiecInfluenceGapsTree2007,
  title = {The Influence of Gaps on Tree Regeneration: A Case Study of the Mixed Lime-Hornbeam ({{Tilio}}-{{Carpinetum Tracz}}. 1962) Communities in the {{Białowieża Primeval Forest}}},
  author = {Bobiec, A.},
  date = {2007},
  journaltitle = {Polish Journal of Ecology},
  volume = {55},
  pages = {441--455},
  issn = {1505-2249},
  url = {http://pje.miiz.waw.pl/article/ar55_3_02.pdf},
  abstract = {Tree stand regeneration in ten natural gaps, ranging in size from 250 to 1610 m[²], and three artificial clearings of 650.1150 m[²] was compared to the undergrowth in the adjacent stands representing mesic lime-hornbeam (Tilio-Carpinetum Tracz. 1962) assemblages of the Białowieża Primeval Forest. The purpose of the study was to find how gaps influence the tree regeneration in such forests, regarding sapling density and composition. Most of the gaps were formed by the decline of groups of spruce (Picea abies (L.) Karst.) trees. In the largest openings spruce logs contributed to more than 80\,\% of the volume of fallen trees. Having four times higher all saplings density and eight times higher tall saplings (h{$>$} 1.3 m) density, comparing to the canopy-sheltered undergrowth, gaps play an important role of successful tree regeneration centres. Pioneering, intolerant species such as birch (Betula pendula Roth), aspen (Populus tremula L.), goat willow (Salix caprea L.), rowan (Sorbus aucuparia L.), and alder (Alnus glutinosa L.), regenerate almost solely in gaps. The gap size had no influence on the gap-filler composition. The most successful gap-fillers, both in small and large gaps were tolerant species: hornbeam (Carpinus betulus L.) and lime (Tilia cordata Mill.). Spruce, the third dominant canopy species of the neighbouring stands was absent in the gap-filling regeneration. The study showed that under the current environmental conditions only hornbeam reveals a continuous mode of regeneration giving it a big competitive advantage both under canopy and in gaps. Other species, including lime, oak (Quercus robur L.) as well as pioneering birch and aspen seem to regenerate in a discrete and irregular manner. It was hypothesised that their regeneration depends on ephemeral opportune circumstances occurring at the initial phase of gap filling, such as presence of layering fresh logs, sprouting stumps and roots, spots of exposed mineral material, as well as inaccessibility to browsers. Artificial openings, created by forestry operations, considerably differ from natural gaps, mimicking a 'catastrophic mode' of dynamics, quite uncommon in the observed forest assemblages, favouring abundant regeneration of pioneering species. Further research necessary to explain important structural and dynamic characteristics of natural stands should address the following questions: - overall gap size structure; - mechanisms determining successful regeneration of less competitive and intolerant species; - history of the gap dynamics (dendrochronology) and its future development (modelling); - average rate of disturbance and turnover time in Tilio-Carpinetum; - minimal conservation area.},
  keywords = {*imported-from-citeulike-INRMM,~INRMM-MiD:c-13506713,carpinus-betulus,forest-regeneration,poland,tilia-spp},
  number = {3}
}
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