Abstract
Species responses to disturbance (mortality of dominant individuals within a community) influence many aspects of that ecological community. To trace the responses of vegetation to one particular type of disturbance, I sampled vegetation in 250 canopy gaps in 1976/1977, 1983, and 1990/1991. These gaps were located in three sites in the southern Appalachians of eastern North America: Great Smoky Mountains National Park, Walker Cove Research Natural Area, and Joyce Kilmer Wilderness Area. Each gap was sampled thrice for sapling composition (stems ≥1 cm in diameter at breast height). Additional measurements included the extension growth of border trees into the gap, recent mortality rates of border trees, deterioration rates of gap makers that had been standing dead in earlier samples, and the composition of understory plots. The mean extension (branch) growth of border trees was 12 cm/yr, with slower growth by longer branches. Gap makers that had been tall stumps tended to deteriorate, although 35% stayed intact over the 14 yr of the study. Border-tree mortality averaged 0.60%/yr, with higher rates for larger stems and with much interspecific variation. Stem density of saplings in gaps increased during the first sampling interval and decreased during the second as self-thinning counteracted increased establishment. Basal area increased during both sampling intervals. The death of border trees increased basal area per unit gap area. The four main species (Acer saccharum, Tsuga canadensis, Fagus grandifolia, and Halesia carolina) showed different patterns of correlation to gap size and age. Species in general showed more correlations with gap age for the first sample than afterwards; gap size was more consistently related to species importance. Species patterns also were affected by the presence or absence of border-tree mortality. The stands studied seem nearly at equilibrium. Some small changes are likely to occur, but the species present dominated all size classes: gap saplings, border trees, other canopy trees not related to gaps, and understory saplings. Species differed in their relative growth rates in the understory and in gaps of different sizes. Species also differed in their survival rates in the understory and in the canopy.
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Claims 17
Claim · model-written summary
Mean extension (branch) growth of border trees was 12 cm/yr.
Verbatim
e0“The mean extension (branch) growth of border trees was 12 cm/yr”
Claim · model-written summary
Extension growth of border trees was slower for longer branches.
Verbatim
e0“The mean extension (branch) growth of border trees was 12 cm/yr, with slower growth by longer branches”
Claim · model-written summary
Gap makers that had been tall stumps tended to deteriorate, although 35% stayed intact over the 14 yr of the study.
Verbatim
e0“Gap makers that had been tall stumps tended to deteriorate, although 35% stayed intact over the 14 yr of the study”
Claim · model-written summary
Border-tree mortality averaged 0.60%/yr.
Verbatim
e0“Border-tree mortality averaged 0.60%/yr”
Claim · model-written summary
Border-tree mortality was higher for larger stems and varied much among species.
Verbatim
e0“Border-tree mortality averaged 0.60%/yr, with higher rates for larger stems and with much interspecific variation”
Claim · model-written summary
Stem density of saplings in gaps increased during the first sampling interval.
Verbatim
e0“Stem density of saplings in gaps increased during the first sampling interval”
Claim · model-written summary
Stem density of saplings in gaps decreased during the second sampling interval as self-thinning counteracted increased establishment.
Verbatim
e0“Stem density of saplings in gaps increased during the first sampling interval and decreased during the second as self-thinning counteracted increased establishment”
Claim · model-written summary
Basal area increased during both sampling intervals.
Verbatim
t0“TREE”
e0“Basal area increased during both sampling intervals”
Claim · model-written summary
The death of border trees increased basal area per unit gap area.
Verbatim
e0“The death of border trees increased basal area per unit gap area”
Claim · model-written summary
Acer saccharum, Tsuga canadensis, Fagus grandifolia and Halesia carolina showed different patterns of correlation to gap size and age.
- Taxon
- Acer saccharum, Tsuga canadensis, Fagus grandifolia, and Halesia carolina
Acer saccharum
Fagus grandifolia
Tsuga canadensis
Halesia carolinae0 - Treatment
- gap size and agee0
- Outcome
- different patterns of correlatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The four main species (Acer saccharum, Tsuga canadensis, Fagus grandifolia, and Halesia carolina) showed different patterns of correlation to gap size and age”
Claim · model-written summary
Species showed more correlations with gap age for the first sample than afterwards.
Verbatim
e0“Species in general showed more correlations with gap age for the first sample than afterwards”
Claim · model-written summary
Gap size was more consistently related to species importance.
Verbatim
t0“TREE”
e0“gap size was more consistently related to species importance”
Claim · model-written summary
Species patterns were affected by the presence or absence of border-tree mortality.
Not reportedDirection
Verbatim
e0“Species patterns also were affected by the presence or absence of border-tree mortality”
Claim · model-written summary
The stands studied seem nearly at equilibrium.
Verbatim
e0“The stands studied seem nearly at equilibrium”
Claim · model-written summary
The species present dominated all size classes: gap saplings, border trees, other canopy trees not related to gaps, and understory saplings.
Verbatim
e0“the species present dominated all size classes: gap saplings, border trees, other canopy trees not related to gaps, and understory saplings”
Claim · model-written summary
Species differed in their relative growth rates in the understory and in gaps of different sizes.
Not reportedDirection
Verbatim
e0“Species differed in their relative growth rates in the understory and in gaps of different sizes”
Claim · model-written summary
Species differed in their survival rates in the understory and in the canopy.
Not reportedDirection
Verbatim
e0“Species also differed in their survival rates in the understory and in the canopy”