Gap-phase regeneration in longleaf pine wiregrass ecosystems

Brockway, Dale G.; Outcalt, Kenneth W.

doi:10.1016/s0378-1127(97)00308-3

Cited by 135 publications

(126 citation statements)

References 52 publications

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“…In higher latitude on the northern hemisphere a high relative PAR-intensity on the northern edge of a gap and a low relative PAR-intensity on the southern part of a gap can be found (Canham et al 1990). In contrast to relative PAR, assuming a distance dependency of fine root density distribution (Ammer and Wagner 2005;Zerihun et al 2007), root density is constant in a particular distance to the gap edge (Brockway and Outcalt 1998;Ammer and Wagner 2002;Müller and Wagner 2003). However, while in the controlled factorial experiment no significant correlation between relative PAR and SW values was observed, a weak but significant correlation was given in the field experiment between relative PAR and IRI although we carried out the investigation using gaps.…”

Section: Discussionmentioning

confidence: 96%

Evaluation of different approaches for modelling individual tree seedling height growth

Wagner¹,

Madsen

Ammer

2009

Trees

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We compared different approaches for modelling height growth of individual beech seedlings in a controlled factorial experiment as well as in field data from naturally regenerated beech seedlings under the canopy of overstorey mature beech trees. Several competition indices, a model of overstorey fine root density, relative photosynthetically active radiation (PAR) values, and soil water values were used in these approaches. In the factorial experiment relative PAR and soil water content were measured and used for the prediction of seedlings height growth. In the field experiment this was done by using relative PAR and estimated fine root biomass as a surrogate for below ground resource availability. The latter approach was compared with a model where we used various competition indices representing the impact of overstorey trees on beech seedlings. Our results suggested that (1) models which combine resource based growth functions are suitable for the prediction of individual height growth of beech seedlings. Resource based models offer the opportunity to investigate on the independent multiplicative effect of irradiance and water supply and their interactions on tree seedlings. It was (2) shown that a combined model could be used not only to predict individual height growth of beech seedlings in a controlled experiment but also in the field. The model parameters of a pure light response function for the controlled factorial experiment are comparable to those obtained in the field study. The results showed (3) that the precision of predicting beech seedlings height growth is comparable between the model types tested within this study. Approximately half of the observed variation in seedlings relative height growth rate could be explained. However, the simple competition index approach provides no information on the environmental factors constraining tree seedlings growth; whereas the multiplicative combined models can be used to get a better understanding of growth dynamics in the field.

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Section: Discussionmentioning

confidence: 96%

Evaluation of different approaches for modelling individual tree seedling height growth

Wagner¹,

Madsen

Ammer

2009

Trees

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“…In the experimental plots, C and N concentrations were higher near the trunk where litter accumulation and forest floor depth are generally greater [19,51,52]. Indeed, Varner et al [22] reported that without fire, litter from pines and hardwoods could accumulate as deep as 25 cm near the trunk of large trees.…”

Section: Soil Gradientmentioning

confidence: 95%

“…Trees can create gradients in soil moisture [4][5][6], temperature [7,8], texture [9], carbon (C) and nutrient accumulation and turnover [10][11][12], understory species composition through spatially distinct effects via litter accumulation [1,12,13], stemflow and throughfall [14,15], light and precipitation interception [16][17][18] and root distribution [8,19].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Restoration Treatments on the Spatial Variability of Soil Processes under Longleaf Pine Trees

Lavoie

Mack

Hiers

et al. 2012

Forests

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Abstract:The objectives of this study were to (1) characterize tree-based spatial patterning of soil properties and understory vegetation in frequently burned ("reference state") and fire-suppressed longleaf pine forests; and (2) determine how restoration treatments affected patterning. To attain these objectives, we used an experimental manipulation of management types implemented 15 years ago in Florida. We randomly located six mature longleaf pine trees in one reference and four restoration treatments (i.e., burn, control, herbicide, and mechanical), for a total of 36 trees. In addition to the original treatments and as part of a monitoring program, all plots were subjected to several prescribed fires during these 15 years. Under each tree, we sampled mineral soil and understory vegetation at 1 m, 2 m, 3 m and 4 m (vegetation only) away from the tree. At these sites, soil carbon and nitrogen were higher near the trunk while graminoids, forbs and saw palmetto covers showed an opposite trend. Our results confirmed that longleaf pine trees affect the spatial patterning of soil and understory vegetation, and this patterning was mostly limited to the restoration sites. We suggest frequent burning as a probable cause for a lack of spatial structure in the "reference state". We attribute the presence of spatial patterning in the restoration sites to accumulation of organic materials near the base of mature trees.

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“…A gap was defined as any opening with a diameter of at least 24 m measured between the bases of living non-lightning affected trees. This distance was chosen to represent a true gap because this is the threshold where probability of successful longleaf regeneration markedly increases in sandhills habitat of this region (Brockway and Outcalt, 1998).…”

Section: Data Collection and Analysesmentioning

confidence: 99%

Lightning, fire and longleaf pine: Using natural disturbance to guide management

Outcalt

2008

Forest Ecology and Management

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The importance of lightning as an ignition source for the fire adapted longleaf pine (Pinus palustris) ecosystem is widely recognized. Lightning also impacts this system on a smaller scale by causing individual tree mortality. The objective of this study was to determine mortality due to lightning and other agents in longleaf stands on the Ocala National Forest in central Florida and to quantify lightning ignited fire. Mortality from lightning was also tracked in longleaf stands on the Savannah River Site in South Carolina. Lightning killed more trees than any other agent with a mean mortality of nearly 1 tree/3 ha/yr in Florida and 1 tree/8 ha/yr in South Carolina. The probability of a tree being struck by lightning increased as a function of tree height at both sites, i.e. lightning preferentially removed the largest trees from the stand. In addition lightning strikes were clumped within stands, sometimes killed multiple trees with a single strike, and often hit trees on the edge of existing gaps. The combination of these processes means gaps suitable for regeneration within longleaf stands are created quite rapidly. This information provides guidelines for the development of selection harvest systems based on this natural disturbance. Although lightning activity was greatest during the summer months in Florida and most fires occurred in June, the probability of a strike causing a fire was highest in February to May. Published by Elsevier B.V.

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Gap-phase regeneration in longleaf pine wiregrass ecosystems

Cited by 135 publications

References 52 publications

Evaluation of different approaches for modelling individual tree seedling height growth

Evaluation of different approaches for modelling individual tree seedling height growth

The Effect of Restoration Treatments on the Spatial Variability of Soil Processes under Longleaf Pine Trees

Lightning, fire and longleaf pine: Using natural disturbance to guide management

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