It didn't look like much: a patch of overgrown vegetation tucked behind a maintenance building, partly hemmed in by a tall fence topped with barbed wire — more a job for a landscaping crew than for scientists. But the vegetation team from the Southeast Coast Inventory and Monitoring Network (SECN) saw a plot full of good data.
A vegetation plot at Ocmulgee Mounds National Historical Park, May 2021. SECN photos / Mark Hynds
Why vegetation
Ocmulgee Mounds National Historical Park, in Macon, Georgia, is best known for its cultural riches — it preserves the site of a Native American settlement complex from before European arrival. But in a fast-growing urban area, its natural resources matter too. It is one of 15 parks where the network monitors plant communities, a key measure of ecosystem health: changes in vegetation reflect stresses such as extreme weather, disease, invasive species, fire and changing land use, and plants provide the structure and food other species depend on.
Choosing and laying out the plot
A pilot program began at the park in 2011, with more monitoring in 2014 and 2017. The spring 2021 visit was the first under the network's updated protocol of 2019.
- Where: plot locations were generated by random stratified sampling across the park's habitat types — Coastal Plain alluvial forests and Coastal Plain upland forests — with vegetation maps used to size the sample to each habitat's acreage.
- Checking: SECN botanist Forbes Boyle and biological technician Elizabeth vetted each computer-chosen plot: could it be reached safely? Did it straddle habitat types, fall on private land, or include roads, trails or mown lawn?
- Getting there: some plots take a hard hike or a boat ride. This one meant parking in the next-door lot and following a GPS to the center.
- Layout: each plot is a 20-meter square divided into four 10 × 10-meter modules — like a foursquare court — marked out with fiberglass tape, chaining pins and rebar.
Measuring the diameter of a smaller tree. SECN photo / Mark Hynds
What they record
The monitoring sets out to answer: how many species grow in the park's main habitats, and how do native, non-native and invasive species compare? Which plants are most common, and are there rare ones? What is the balance of woody species among canopy trees, saplings and seedlings? And are there stresses that could harm these plant communities?
| Task | How |
|---|---|
| Site | characteristics, plus signs of disturbance — recent or past fire, deer browsing, hog damage, heavy windthrow. New plots also get landform and soil data |
| Photos | two from opposite sides, plus a 360° camera at the center, starting due north — so managers can "visit" the plot from the office, and visitors can see places they can't reach |
| Species | Forbes lays out measuring sticks to make small nested quadrats in two corners of each module, in a set pattern so no two sampled corners touch, then records every plant on his knees, named according to Alan Weakley's 2020 Flora of the Southeastern United States. Knowing what's there reveals invasive species |
| Canopy | a spherical densiometer turns how much sky the leaves block into a number. High canopy closure means a dim forest floor; low closure can signal disturbance such as wind or pest damage |
| Stand height | a clinometer measures three co-dominant trees, giving the volume of live trees to compare with dead trees and fallen wood |
| Woody stems | every tree, shrub and vine, living or standing dead (if leaning no more than 45° from vertical); dead trees get a decay class and snag height. A tree map shows every stem for future teams |
| Tree condition | codes for crown position (full sun to fully shaded), vigor (healthy to functionally dead), dieback (1–100% of the crown), and any damage from pests or pathogens |
| Classification | the plot is matched to the closest U.S. National Vegetation Classification association |
Outlining a nested subplot, and recording the species inside it. SECN photos / Mark Hynds
Checking canopy cover. SECN photo / Mark Hynds
Fuel for fire
Dead plant material isn't part of the living community, but it tells how much could burn. Fuel is sampled along three 25-meter transects from the plot center — one due north, the others at 135° and 225° — with the slope of each measured.
| Fuel | What it is | How it's measured |
|---|---|---|
| Coarse woody debris | fallen trees and branches over 8 cm across that cross the transect | diameter and decay class — from "hard when kicked" to "falls apart when stepped on" |
| Fine woody debris | pieces under 8 cm, sorted into 1-hour (0–0.64 cm), 10-hour (0.64–2.54 cm) and 100-hour (2.54–8.1 cm) fuels | counted along the transects, from the top of the duff up to 2 m |
| Litter and duff | litter: twigs, dead grass, fresh leaves and needles; duff: the layer between litter and soil | depth, measured with a trowel and ruler at set points |
Measuring fire fuels with help from park staff. SECN photo / Mark Hynds
The big picture
The team set up and sampled eight plots at the park — four in alluvial forest and four in upland forest. A baseline report will cover species diversity and abundance of trees, shrubs, vines and herbaceous plants, woody stem measurements, disturbances and threats, landforms and soils, and fuel loads — so park managers can make informed decisions about the park's natural resources.
Sources
Based on "Vegetation Monitoring at Ocmulgee Mounds NHP," Southeast Coast Inventory and Monitoring Network, National Park Service; a work of the United States government in the public domain. The article gives the technician's surname as both "Rico" and "Reno," so only her first name is used; its flag positions along the fuel transects don't match its sampling points, so neither is given. Rewritten in hubnx's own words.
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许可协议： CC0 1.0（公有领域） · 改编自 www.nps.gov
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