1. PAST AGRICULTURAL LAND USE HAS PERSISTENT EFFECTS ON CONTEMPORARY PLANT GROWTH
INTRODUCTION
• Over one-third of the Earth's surface has been altered by
anthropogenic land-cover changes, specifically conversion to
agriculture
• Conversion to agriculture has affected soil characteristics and
reduced plant community diversity
• Longleaf pine savannas in the Southeastern U.S. are an
endangered ecosystems that has been reduced to less than 3%
of the original area
• Prescribed burning and canopy thinning are key drivers of
understory composition and are used to restore understory
richness in post-agricultural sites
• Carphephorous bellidifolius is a plant species of conservation
concern, which we use to provide an estimate of restoration
success in response to canopy thinning, land-use history, and
prescribed fire.
HYPOTHESES
H1: There will be an increase in productivity of C.
bellidifolius from thinned vs. unthinned sites and in the
remnant vs. post-agricultural sites.
H2: Prescribed burning will increase the productivity of
C. bellidifolius.
KEY FINDINGS
LITERATURE CITED
ROBERTA DONALDSON, PHIL HAHN, DR. JOHN ORROCK
DEPT. OF ZOOLOGY, UNIVERSITY OF WISCONSIN, MADISON, WI 53706
RESULTS
•Biomass was greatest in the thinned
remnant patches with no history of
agricultural land use
•More light is able to reach the understory
due to thinning, which increases plant
growth
•Soil conditions are more suitable for plant
growth in remnant plots as opposed to the
post-agricultural plots.
•Fire has a positive effect on plant
productivity in the thinned and burned plots.
•Fire reduces woody encroachment which
can shade plants
•Period of high resource availability after
burning allows for increased growth
•Our results suggest that canopy thinning
with regulated burns are an effective
restoration technique
•This technique could be used in savannas
around the world to promote the restoration
of plant communities and reverse negative
anthropogenic effects
METHODS
• Study site: Savannah River Site in South Carolina, USA.
• 16 two ha patches were selected that contained both post-
agricultural and remnant habitats. These patches received a
factorial combination of mechanical canopy thinning (thinned or
unthinned).
• We transplanted four seedlings of C. bellidifolius in each patch
in 2012.
• The Forest Service conducted a
prescribed burn in four of the 16
sites in Spring 2013
• The plants were harvested
in September of 2013, dried, and
weighed for total biomass.
A) Overview of the experimental design at the Savannah River Site.
Past land use for each patch was either remnant or post-agricultural;
canopy was either thinned or unthinned. View from B) an unthinned
patch and C) a thinned patch. Note the woody encroachment (B) and
the sparse pine savanna (C).
Thinning increased biomass but the
effect of land use depended on
whether the plot was thinned or not
(F=4.13, p=.047)
There was a greater difference in
biomass production within thinned
patches that were burned compared
to not burned (F=23.28, p<.001 )
EXPERIMENTAL DESIGN
Brudvig LA, Damschen EI. 2011. Land-use history, historical connectivity,
and land management interact to determine longleaf pine woodland understory
richness and composition. Ecography 34:257-266.
Catling PM, Kostiuk B. 2010. Successful Re-establishment of a Native
Savanna Flora and Fauna on the Site of a Former Pine Plantation at Constance
Bay, Ottawa, Ontario. Canadian Field-Naturalist 124:169-178.
Rhemtulla JM, Mladenoff DJ, Clayton MK. 2007. Regional land-cover
conversion in the US upper Midwest: magnitude of change and limited recovery
(1850-1935-1993). Landscape Ecology 22:57-75.
0
0.5
1
1.5
2
2.5
Unthinned Thinned
Biomass(g)
Fire
No Fire
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Unthinned Thinned
Biomass(g)
Remnant
Post-Agriculture
ACKNOWLEDGEMENTS
Special thanks to Justin Chenevert for his helpful feedback and guidance with
writing my paper. I would also like to acknowledge the Writing Center, my peer
reviewer, and my weekly meeting group for their advice and helpful criticisms.
CANOPY THINNING AND
LAND USE
CANOPY THINNING AND FIRE