National Park Service

Gulf Coast Network (GULN)

Terrestrial Vegetation Monitoring

Big Thicket National Preserve
Big Thicket National Preserve

GULN Vegetation Classification & Mapping Inventory Reports

GULN Coastal Dynamics Monitoring Protocol Summary

There are currently no other documents or reports concerning this topic.

Diversity of Terrestrial Vegetation

A number of vital signs related to the diversity of terrestrial vegetation found within network parks were ranked as high priority for the network. These specific vital signs include non-native vegetation, salt marsh communities, riparian communities, forest health, and terrestrial vegetation. Ecologically speaking, vegetation comprises the foundation for most terrestrial ecosystems, and the status and function of vegetation components are central to the function of these systems. Changes in vegetation parameters can serve as useful indicators of changes in ecosystem function. From a resource-management perspective, vegetation comprises a highly-valued set of resources that are subject to impact from both natural and anthropogenic forces; thus vegetation is a central focus for management attention and effort.

The goal of this protocol is to develop a landscape-scale approach to monitoring the diverse vegetation communities across the network, using a common methodology. To a large degree, the general questions about vegetation status and trend may be effectively answered using data about the sizes, shapes, heights, densities, distribution patterns and locations of plants within vegetation units. I n general, quantifiable changes in canopy heights, densities, structural heterogeneity, etc., are indicative of a system or community or population conditional change. For example, changes in plant height and size correspond to growth, changes in canopy density may indicate stress and pest damage, while spacing and distribution can indicate coverage change and stand/patch condition.


Parks Where Protocol will be Implemented

  • Big Thicket National Preserve (BITH)
  • Gulf Island National Seashore (GUIS)
  • Jean Lafitte
    National Historical Park and Preserve (JELA)
  • Natchez Trace Parkway (NATR)
  • Padre Island National Seashore (PAIS)
  • Palo Alto Battlefield National Historical Park (PAAL)
  • San Antonio Missions National Historical Park (SAAN)
  • Vicksburg National Military Park (VICK)

Specific Monitoring Questions and Objectives to be Addressed by the Protocol

Some of the specific monitoring questions that will be addressed by this protocol include

  • What is the current status, based on physical characteristics (distribution, coverage, canopy height, and density descriptions) of selected vegetation units on sampled parks?
  • How are the physical characteristics (canopy properties and in-canopy distribution) of selected vegetation units changing over time in patches on sampled parks?
  • What is the current major species composition and per-species distribution in selected vegetation units in selected units or patches on sampled parks?
  • How are major species composition and per-species distribution changing in selected vegetation units on sampled parks? Is relative abundance shifting? Are formerly key or dominant taxa declining, and if so, what is replacing them?
  • What are the current distributions and area coverage of selected vegetation units on sampled parks?
  • How are distributions and area coverage of selected vegetation units changing, in terms of area-covered and specific point and boundary locations, over time on sampled parks?

Some of the specific monitoring objectives that will be accomplished

  1. Quantitatively describe (structural and derived major species composition, relative abundance and distribution) the current condition of selected vegetation units on sampled parks.
  2. Quantify the type, magnitude and rate of changes occurring in structural (and/or major species composition and distributions, as appropriate) properties in selected vegetation units on sampled parks. Relate these reported changes to changes in vegetation condition or status (i.e., is it evidence of plant or stand stress, plant pest infection, and changes in recruitment?)
  3. Using GIS, quantify and map the changes detected in area-covered, dimensions and locations of selected vegetation units on sampled parks. Aside from within-patch or unit conditional changes, the other salient question for many parks will be whether selected vegetation units are shifting in patch sizes and/or actual location on parks- such as in the case of spreading invasive species areas.

Basic Approach used in the GULN Vegetation Protocol

The vegetation protocol consists of two general sampling elements

  1. Technology-based sampling to detect structural change in a park's vegetation over time
  2. A targeted ground-truth survey-based sampling to provide biological correspondence to support the technology-based monitoring.

Technology-based Sampling

Technology-based sampling will use an airborne lidar (Light Detection And Ranging) system. Data are collected in a fly-over sampling event on a selected park at a specified season and state-of-foliation. The lidar data are geospatially explicit and link to a park's GIS layers with GPS locations. Consequently, structural vegetation metrics will be explicitly spatially linked to other biological data, such as bird and herpetofauna communities. Details on the USGS EAARL lidar sensor, lidar-based vegetation metrics, and vegetation delineation methodologies.

Lidar data are processed using an auto-classification modeling routine which results in a set of multi-variate, 3-dimensional structural patches that represent the sampled vegetation. Each patch belongs to one statistically-distinct class, and has a location and boundary enclosing a recognizable area on the park's landscape. Detection of structural change is via a two-level comparative analysis of lidar models acquired at different times. Level-1 analysis detects changes in the whole-park model. Level-2 analysis is based on the detailed examination of patch and within-patch changes seen at locations specified by park management. Following identification of patches that have experienced structural change, a detailed ground-truth evaluation to reveal explicit biological changes will be performed on changed patches selected for further analysis by park managers. Monitoring will consist of repeating lidar data-collection, modeling, and comparative analysis to detect changes in the size, location, dimension, and class of patches seen on a park's data set.


Ground-truth surveys

Ground-truth surveys identify major species composition, distribution, status, and abundance, and are based on standard plant ecological field methods.

  1. a biological description of patches of management interest
  2. assessment of biological change in a patch which has shown detectable structural change in model analysis. Ground-truthing will be performed as needed to assess detected change in given patches. For example, a park may elect to assess a patch which exhibits statistically significant change to determine whether the change is of interest. Detected structural changes may indicate species-composition change, the onset of a forest pest, results of a management activity such as fire, or storm-related damage.

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