Croatan Long Term Soil Productivity (LTSP) Study


The Croatan National Forest Long Term Soil Productivity study site is part of an internationally coordinated study whose objectives are to:

  • Measure the interactions of soil and site disturbance on long-term productivity.
  • Validate USDA Forest Service soil quality monitoring standards and develop effective monitoring techniques for evaluating the long-term impacts of management practices.
  • Understanding how soil and site disturbances affect the fundamental processes controlling productivity.


The Croatan LTSP site is a 3 x 3 factoral split-plot design, replicated in 3 blocks. The main effects are 3 levels of organic matter removal and 3 levels of soil compaction. The split-plot effect is competition control, usually in the form of chemical herbicide. In addition, 1 treatment plot per block represents an ameliorated treatment of bedding and fertilizing. View the Croatan LTSP map.

Past Research and Measurements

  • pre and post treatment bulk density measurements
  • pre and post treatment plant community descriptions
  • Measurements of nitrogen and phosphorus mineralization by treatment
  • Soil microarthropod abundance
  • Monthly apical bud growth
  • Soil moisture using time domain reflectometry (TDR) probes
  • Soil strength using penetrometer
  • Needle carbohydrate and nutrient concentrations
  • Root growth

Current Measurements and Studies

  • Weather conditions
  • Tree height growth
  • Crown length and diameter
  • Diameter at breast height
  • Bulk density measurements at the 10th growing season
  • plant community descriptions at the 10th growing season
  • Whole tree planted pine bimass at the 10th growing season
  • Soil nutrients at the 10th growing season
  • Nitrogen forms
  • Soil CO2 efflux
  • Rotting log decomposition
  • Litter decomposition


Other LTSP Site Locations: