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Geographic Variation in Longleaf Pine: Improving Deployment of Seed Source to Site

 
A wider geographic range in longleaf seed sources is now available for planting, including montane sources.  Given the substantial effort underway to restore longleaf pine throughout its native range, more information on site adaptability and the subsequent need for deployment of specific sources to different sites to increase survivability and growth is needed.  Juvenile and mature longleaf pine have been shown to be sensitive to drought and over the next 25 to 50 years, temperatures and the frequency of extreme weather events in the southeastern U.S. are predicted to increase.  These conditions combined with high runoff may reduce the amount of moisture captured and available for tree growth.  Therefore, information on variability in adaptability of different seed sources to drought is also needed to match seed source to site and ensure long-term success of restoration plantings. 

We are collecting preliminary data on seedling variation in drought tolerance, physiological processes, biomass allocation, growth and disease resistance in nine longleaf seed sources generously provided by the International Forest Company.  This study will identify important variables to examine in out-planting studies in addition to standard attributes such as survival, duration of grass stage and brown-spot resistance.  We are seeking support to implement field trials using different seed sources planted in replicated studies in as many sites and states as funding permits.  Please contact Lisa Samuelson if you are interested in supporting this new endeavor to improve longleaf pine restoration!

 

 

 

 

 

 

 

 

 

Temperature and Drought Responses in Longleaf, Slash and Loblolly Pine: Comparative Adaptation to Climate Change

Understanding the impact of climate change on southern pine species is important in assessing potential climate change impacts to southern Coastal Plain forests.  Potential changes in temperature and precipitation patterns may influence growth of mature longleaf pine, loblolly pine, and slash pine stands in order to provide better predictions for future climate change effects on southeastern forests.  The objectives of this study are to: 1) determine if longleaf pine is better adapted to predicted rising temperatures than loblolly pine and slash pine by measuring in situ photosynthetic temperature optima in mature trees and 2) compare in situ diurnal patterns in net photosynthesis, stomatal conductance, water use efficiency, and leaf water potential under varying soil moisture conditions and between species to assess drought tolerance.

An existing research site, located within the USDA Forest Service Harrison Experimental Forest near Saucier, MS in the DeSoto National Forest will be used for this study.  The site is located 32 km north of Gulfport, MS.  The site was established in 1960 by the Forest Service for growth and genetics studies on longleaf, slash, and loblolly pine.

 

Are Longleaf Pine Forest Carbon Sinks?

  • Global climate change and the accumulation of carbon dioxide in the atmosphere can be mitigated by the proper management of soils and forests through carbon sequestration.
  • Longleaf pine forests and soils sequester large quantities of carbon because of long timber rotations and temperate climate conditions.
  • The objective of the project was to examine how forest structure influences the rate of soil respiration to better understand forest management effects on carbon pools.
  • Soil respiration was examined in response to:
    1. basal area,
    2. live, dead, coarse, and fine root biomass,
    3. woody debris in the soil,
    4. soil charcoal mass,
    5. litter depth and litter mass,
    6. downed woody debris,
    7. aboveground biomass in woody species,
    8. environmental conditions,
    9. and estimated percent ground cover.

 

 

 

 

 

 

 

 

 

Structure and Diversity of Longleaf Pine (Pinus palustris Mill.) Forest Communities in the Mountain Longleaf National Wildlife Refuge, Northeastern Alabama

  • The Mountain Longleaf National Wildlife Refuge (MLNWR) has significant acreage of young and old growth mountain longleaf pine.
  • The MLNWR has a lack of historical information, therefore, data are needed on forest structure and fuel loads in the Refuge.
  • The objectives of the project were to:
    1. establish permanent monitoring plots in the Refuge,
    2. document herbaceous and woody vegetation,
    3. and measure biodiversity, forest structure, and fuel loads in longleaf communities with varying fire and management histories.
  • Results:
    1. Without hardwood control or fire, hardwood encroachment and high duff layers are significantly inhibiting longleaf pine regeneration and development of native herbaceous and grass cover.
    2. Only 17 of 48 plots had longleaf pine regeneration.
    3. Future monitoring is needed to track regeneration success in response to management activities.

  • Funding provided by the National Fish and Wildlife Foundation (NFWF).

 

 

 

 

 

 

 

 

Relationship Between Foliar dgr13C and Hydraulic Pathway Length in Pinus palustris

Because of the importance of hydraulic architecture in understanding physiological differences between small and large trees, we tested the hypothesis that foliar δ13C increased with aboveground flow-path length in longleaf pine (Pinus palustris Mill.) trees of varying age and size at two sites in the lower Coastal Plain.  This species offered a unique opportunity to examine variability in foliar δ13C in relation to pathway length because of the open, will-mixed canopy in savanna-like stands and concentration of foliage in splayed tufts on branch ends.  At both sites, models with total flow-path length (bole + branch) explained 78-81% of the variation in foliar δ13C, and a full model with separate slopes and intercepts for each tree was required.  Branch flow-path length was highly correlated with foliar δ13C and the models accounted for 76-88% of the variation in foliar δ13C, and a reduced model with one slope was suitable for each site.  Flow-path length was not as well correlated to foliar N path length indicates the need for mechanistic studies to better understand the role of hydraulic resistance in controlling leaf-level physiology within the canopy and amount different size longleaf pine trees.