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Disturbance & Ecology of Coastal Plain Forests
with a focus on Longleaf Pine
Dr. Steve Jack
Conservation Ecologist and Applied Forest Scientist Joseph W. Jones Ecological Research Center
Disturbance Ecology
• Develop understanding of what is “natural” for a given location and forest type
Disturbance Ecology
• Develop understanding of what is “natural” for a given location and forest type
• For disturbance should consider: – Frequency – Scale – What is left after disturbance
EXAMPLE: Natural Variation in Disturbances (based on ca. 20 studies; Seymour et al 2002)
1
Interval between Disturbances (at the same point on the landscape) - years
Con
tiguo
us A
rea
Dis
turb
ed a
nd R
egen
erat
ed -
ha
Severe Fire and Wind
100 1000 10000 0.0001
0.001
0.01
0.1
1
10
100
1000
10000
Natural Canopy Gaps
100-year return interval
Range =
.001 - .1 ha
Natural Disturbance Agents
In southeast many things can cause disturbance: – Wind – Lightning – Insects – Disease – Water – Fire
Natural Overstory Disturbance
More common sources in longleaf forest result in small scale disturbance – Lightning (more prevalent on xeric sites) – Competition (more prevalent on hydric
sites) – Wind (more prevalent on hydric sites) – Beetles/root rot – Fire
From Palik and Pederson (1996)
Suppression
DBH class (cm)
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70
Perc
enta
ge o
f tot
al p
opul
atio
n0
10
20
30
40
Unknown
0
4
8
12
16
Lightning
02468
10121416
Wind
0
4
8
12
16
Live
0
2
4
6
8
10
Mortality (trees ha-1 5 yr-1)
0 2 4 6 8 10 12
Num
ber o
f plo
ts
0
4
8
12
16
20
24
28
Mortality (m2 ha-1 5 yr-1)
0.0 0.2 0.4 0.6 0.8 1.0
Conceptual Longleaf Model
from Michener et al. 1996
Natural Disturbances
In longleaf forests result in: • Perpetual forests with multiple age classes • Continuous fuels through time and across
space – supports fire • Variable density and spacing (heterogeneity) • Advance regeneration seedling pools in
more open areas
Fire in Coastal Plain Forests
Role of Fire
• Maintain early successional state • Reduce fuel accumulations • Affects structure and function
– Reduced or absent midstory – Species rich ground cover – Nutrient cycling
Day 1 3 months
1 year
3 years
10 years
30 years
Fire and Biodiversity
Fire is the overriding feature that sustains the biodiversity of the longleaf pine ecosystem – Frequent – Continuous over
time
Diverse Ground Cover Community
Diverse Faunal Community
Longleaf Pine Prior to European Settlement
Longleaf Communities - Montane
Longleaf Communities - Sandhills
Longleaf Communities - Mesic
Longleaf Communities - Flatwoods
Longleaf – Wide Ecological Amplitude
• High water use efficiency – tolerates droughts, extensive root system
• Overstory trees can survive short-duration flooding
• Unique regeneration habit – tolerates fire, drought-tolerant once established
• Associated understory species have similar characteristics
• Resistant to pests, disease, physical damage • FIRE adapted (required?) species
Management at Ichauway
With Predicted Climate Change …
• What factors will change, and how will the changes affect the forest? – Altered precipitation patterns? – Elevated average temperatures? – More severe weather events? – More wildfires? Reduced use of Rx-fire?
• What forest types will be best adapted to the
“new” (and changing?) conditions?
Disturbance Frequency & Extent with Climate Change
from Michener et al. 1996
Catastrophic flooding
Droughts
Hurricanes & Tropical Storms
Heard from Experts
Hurricanes & Tropical Storms
Hurricanes & Tropical Storms
Hurricane Damage
Hurricane Damage
Hurricane Damage
• Southern MS Katrina Damage • Two 20 year old plantations, each with stands of
loblolly, slash and longleaf
Species Type of Hurricane Damage (%)
None Snapped Leaning Blown Over
Loblolly 16.3 75.9 5.7 2
Slash 52.4 38.1 7.8 1.7
Longleaf 64 8.9 16.9 10.2
Source: MS Forestry Commission
Flooding Events
Drought Response
• Large effects on regeneration – Seedling survival – Seed production
• Cumulative effects on overstory – Decreased vigor – Increased susceptibility to pests
• Ability to burn, mortality following fires
Changes in Fire Regimes
Changes in Fire Regimes
Forest Responses to These Changes?
• Fire-maintained longleaf forests may be in best position to continue under altered climate
• But what about other forest types that are more common on the landscape?
Mixed Pine – Hardwood Forests
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