DOI: 10.5061/dryad.mcvdnck3d
title: Data for: Hardwoods influence effect of climate and intraspecific competition on growth of woodland longleaf pine trees

description: 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 (&lt;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.
description: Increment cores were extracted from &gt;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.
description: 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