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Dryad

Data for: Hardwoods influence effect of climate and intraspecific competition on growth of woodland longleaf pine trees

Cite this dataset

Bigelow, Seth et al. (2023). Data for: Hardwoods influence effect of climate and intraspecific competition on growth of woodland longleaf pine trees [Dataset]. Dryad. https://doi.org/10.5061/dryad.mcvdnck3d

Abstract

Longleaf pine woodlands of the North American Coastal Plain are proposed to be resilient to climate change impacts, but little is known about changes in limiting factors to longleaf pine growth as climate has changed in the late 20th and early 21st centuries. Moreover, the role that neighborhood trees play in the context of climate change remains largely unexplored. We used static and moving-window tree-ring and climatic analyses to measure the effects of climate on longleaf pine growth at a site in southwest Georgia, USA. We then performed maximum likelihood analysis to examine the influence of neighboring hardwoods on the response of longleaf pine growth to the joint effects of competition and climate. Analysis of climate data from local stations in southwest Georgia over six decades indicated that mean air temperature decreased until the late 20th century and then began to rise, and that the variability of spring and summer precipitation has increased. Tree ring and climate analyses indicated longleaf pine radial growth is sensitive to precipitation and air temperature, and that the strength of correlation of longleaf pine growth to summer air temperature and summer precipitation increased since the 1950s. Likelihood models, which were applied over a shorter (23-year) period and explicitly incorporated competition, did not support a link between summer temperature and growth but did indicate summer precipitation increased growth. Furthermore, basal area of neighboring hardwoods was correlated with greater pine growth per millimeter of precipitation. Basal area of neighboring longleaf pine negatively affected the growth of conspecific trees; the presence of hardwoods increased the competitive effect when basal area of neighboring pine trees was low (<10 m2 ha-1) but decreased the competitive effect when basal area of neighboring pine trees was high (≥ 10 m2 ha-1). These results suggest that retention or recruitment of hardwood trees when restoring longleaf pine woodlands may contribute to increased ability to withstand dry summers and may help to allay concerns of managers that retention of hardwoods will unduly affect the growth of residual mature longleaf pines.

Methods

Increment cores were extracted from >100 mature longleaf pine trees ('target trees') in 32 clusters which included mature oaks. Tree neighborhoods were mapped to 20 m around target trees. Weather data from 1950 were obtained from www.ncdc.noaa.gov/cdo-web/ from 4 Division 7 stations with close-to-complete record of Temperature and Precipitation.

Tree cores were prepared with standard methods and analyzed for sensitivity to temperature and precipitation using static and moving window approaches. Long-term tree growth data from the study site (proprietary data not included with these data sets) were used to estimate the sizes of neighboring trees back to 1994. Maximum likelihood methods were used to detect intra-specific competition (pines), and the influence of oaks on longleaf intra-specific competition. A prescribed fire record was used to detect the influence of fire on radial growth rate.

Usage notes

The R statistical computing software is required to run the programs and process files associated with submission, along with packages bootRes, data.table, dplR, and likelihood

Funding

University of Florida

The Jones Center at Ichauway