Abstract
Vegetation change in the Great Smoky Mountains fol lowing balsam woolly ade lgid-caused mortality of Fraser fir has inc luded deve lopment of a dense Rubus canadens is s hrub layer . Many fir seedlings have persisted in the forest understory , but the possible effects of Rubus on their annual growth have not been intens ive ly studied . This study had two objectives : ( 1 ) to determine i f s igni ficant associations exist among density and shoot growth of Fraser f i r seedlings , density/biomass of Rubus canadens is , canopy closure , and soi l chemical parameters , and ( 2 ) to determine the effects of removal of aboveground Rubus stems on fir seedling shoot growth . Eighty 1 x 1 m plots were used on Mount Col lins , Great Smoky Mountains National Park , to characterize the unders tory habitat of Fraser fir seedlings . Terminal and lateral shoot lengths of the 1 9 8 3 1 9 8 7 growth were measured on fir seedlings . Seedlings were class i fied according to substrate type , surface type , substrate form , presence of ade lgid damage , and age . Soil samples were taken for analyses of pH , potassium , phosphorus , and calcium . Overstory composition was characteri zed with prism plots . Fourteen 2 x 2 m plots were es tablished to determine e f fects of Rubus removal on fir seedling growth , herbaceous cover , shrub/seedling counts , and soil parameters . i i i Rubus canadens is dens ity was highest on the southwes t f acing s lope and lowest o n the northeastfacing s lope of Mount Collins . Fraser fir seedling density was highest on the northeastfac ing s lope and lowest on the southwest f acing s lope . The Spearman rank corre lation between Rubus dens ity and f i r seedling density was 0 . 3 7 6 ( P < 0.0 1 ) ; a graph of these data showed variabi lity in fir dens ity to decrease with increas ing Rubus density . Most years of fir termina l shoot growth showed positive as sociations with Rubus density ( 0 . 3 0 9 0 . 3 9 6 , P < 0 . 0 1 ) ; a graph of these data showed no pronounced relationship . Rubus dens ity and biomass were s igni ficantly correlated with soil phosphorus and potassium concentrations . All years of termina l shoot growth of f i r seedlings measured showed positive as soc iations with soil pH and potass ium concentration . Most f i r seedlings were �2 5 em tall . Only 3 8 % were <5 years old . More seedlings than expected occupied dead wood substrates , and more than expected were found on bryophyte covered surface s . More than 25% of seedlings showed ade lgid damage ; ade lgid damage was more prevalent among seedlings �5 years old . Most seedlings showed a trend of increasing gains of terminal shoot growth over previous ye ars of growth . Remova l of Rubus s tems produced no signif icant effect on fir seedling shoot growth over one season . No Rubus removal effects were found on any other understory var iable iv measured ; Rubus itself responded to removal by rapid appearance and growth of new stems . Large seasonal changes in bryophyte cover and red spruce seedling dens ity ( from germination ) occurred , but the se changes were not affected by Rubus removal . Germinal Fraser f i r seedlings are scarce and are not like ly to appear in large numbers unle ss existing understory firs reach reproductive age . inhibit establishment of fir seedlings . Rubus appears to Fir shoot growth doe s not appear to be assoc iated with Rubus dens ity or biomass . Fir shoot growth trends are probably consequences o f normal growth patterns and recovery from adelgid infestation .
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Claims 14
Claim · model-written summary
Rubus canadensis density was highest on the southwest-facing slope.
Verbatim
e0“Rubus canadens is dens ity was highest on the southwes t”
Claim · model-written summary
Fraser fir seedling density was highest on the northeast-facing slope.
Verbatim
e0“Fraser fir seedling density was highest on the northeastfac ing s lope”
Claim · model-written summary
Rubus density and Fraser fir seedling density were positively rank-correlated (Spearman 0.376, P < 0.01).
- Taxon
- Fraser Fir Seedlingst0
- Outcome
- f i r seedling densitye0
- Direction
- increaseinferrede0
- Value
- 0 . 3 7 6e0
RubusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Spearman rank corre lation between Rubus dens ity and f i r seedling density was 0 . 3 7 6 ( P < 0.0 1 )”
t0“Fraser Fir Seedlings”
Claim · model-written summary
In most years terminal shoot growth of fir seedlings was positively associated with Rubus density (coefficients 0.309 to 0.396, P < 0.01).
- Taxon
- Fraser Fir Seedlingst0
- Outcome
- fir termina l shoot growthe0
- Direction
- increaseinferrede0
- Value
- 0 . 3 0 9 0 . 3 9 6e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Most years of fir termina l shoot growth showed positive as sociations with Rubus density ( 0 . 3 0 9 0 . 3 9 6 , P < 0 . 0 1 )”
t0“Fraser Fir Seedlings”
Claim · model-written summary
Rubus density and biomass were significantly correlated with soil phosphorus and potassium concentrations.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rubus dens ity and biomass were s igni ficantly correlated with soil phosphorus and potassium concentrations”
Claim · model-written summary
In all measured years, terminal shoot growth of fir seedlings was positively associated with soil pH and potassium concentration.
Verbatim
e0“All years of termina l shoot growth of f i r seedlings measured showed positive as soc iations with soil pH and potass ium concentration”
t0“Fraser Fir Seedlings”
Claim · model-written summary
Only 38% of the fir seedlings were younger than 5 years.
Verbatim
e0“Only 3 8 % were <5 years old”
t0“Fraser Fir Seedlings”
Claim · model-written summary
More fir seedlings than expected occupied dead wood substrates.
Verbatim
e0“More seedlings than expected occupied dead wood substrates”
t0“Fraser Fir Seedlings”
Claim · model-written summary
More than 25% of seedlings showed adelgid damage.
Verbatim
e0“More than 25% of seedlings showed ade lgid damage”
t0“Fraser Fir Seedlings”
Claim · model-written summary
Most seedlings showed a trend of increasing gains in terminal shoot growth over previous years.
Verbatim
e0“Most seedlings showed a trend of increasing gains of terminal shoot growth over previous ye ars of growth”
t0“Fraser Fir Seedlings”
Claim · model-written summary
Removal of Rubus stems had no significant effect on fir seedling shoot growth over one season.
- Taxon
- Fraser Fir Seedlingst0
- Treatment
- Remova l of Rubus s temse0
- Outcome
- fir seedling shoot growthe0
- Direction
- no_changeinferrede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Remova l of Rubus s tems produced no signif icant effect on fir seedling shoot growth over one season”
t0“Fraser Fir Seedlings”
Claim · model-written summary
Rubus responded to stem removal by rapid appearance and growth of new stems.
- Outcome
- rapid appearance and growth of new stemse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rubus itself responded to removal by rapid appearance and growth of new stems”
Claim · model-written summary
Large seasonal changes in bryophyte cover and red spruce seedling density occurred and were not affected by Rubus removal.
- Taxon
- red spruce
Picea rubense0 - Treatment
- Rubus removale0
- Outcome
- seasonal changes in bryophyte cover and red spruce seedling dens itye0
- Direction
- no_changeinferrede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Large seasonal changes in bryophyte cover and red spruce seedling dens ity ( from germination ) occurred , but the se changes were not affected by Rubus removal”
Claim · model-written summary
Fir shoot growth does not appear to be associated with Rubus density or biomass.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fir shoot growth doe s not appear to be assoc iated with Rubus dens ity or biomass”
t0“Fraser Fir Seedlings”