Nantahala Pisgah NF Plan Process - Natural Range of Variation Gary Kauffman National Forests in NC Ecologist 1
NRV Plan Directives indicate must contain plan components, including standards or guidelines, that maintain or restore composition, structure, ecological processes, and connectivity of plan area ecosystems in a manner that promotes their ecological integrity. When developing plan components, the Interdisciplinary Team shall consider the role of the natural range of variation. Each Ecozone has a Natural Range of Variability that is described by: Composition (veg. type) Structure (Open vs. Closed) Disturbance (Age- Early, Mid, Late, Old) 2
Defining Natural Range of Variation Determine appropriate ecozones Correlate Landfire biophysical setting (BPS) modeled vegetation units with ecozones Review other local Landfire modeling examples in Southern Apps Develop age and successional classes for Nantahala/Pisgah Determine appropriate disturbance regimes (type and frequency) for each separate BPS Run state and transition simulation models (STSMs) for each separate BPS; incorporate variability for all disturbance regimes Define a geographic area for BPS models 3
1 Dry-Mesic Oak Ecozone Desired Conditions 4 The overstory consists of oak and other deciduous hardwood canopy trees. Aggressive native tree species, such as red maple and white pine, are present but not dominant. Shrub densities, primarily deciduous species, range from 25 to 50 percent. A diverse herbaceous layer occurs within open canopy sites while a sparser layer occurs within closed canopy sites. Grasses are dispersed and evident within fire-maintained sites. Young forest is represented, 5-7 percent of the landscape, across this ecozone. Potential old-growth conditions, from 50-61 percent of the landscape, are present in amounts that support species diversity. With the older closed-canopy forest, a mosaic of different size openings are dispersed throughout providing structural and age class diversity. Greater than half of the old-growth class, representing 28-33 percent of the landscape, is open canopy. A greater portion of the landscape supports open canopy forest, 48-59 percent, compared to closed canopy forest, 36-45 percent. Open canopy conditions are distributed across all age classes. Wildland fire occurs across this ecozone at intervals ranging from 14-20 years. Periodic burns regenerate the dominant oak species. Table 8. Dry-Mesic Oak Forest Age and Structural Classes Age/Structural Classes Young Mid Closed Mid Open Late Closed Late Open OG Closed OG Open 2 3 Age (years) 0-15 16-75 16-75 76-130 76-130 130+ 130+ Landscape % 5-7 7-9 13-17 7-8 7-9 22-28 28-33 4
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Environmental modeling Uses digital terrain data (elevation, aspect, slope, etc.) to approximate environmental gradients (moisture, temperature, fertility) to define types of environment Uses Plant Associations (Dry Oak, Rich Cove, Spruce-Fir, etc.) to name the types of environment Determines relationships between Plant Associations and digital terrain data at known locations and extrapolates to unknown locations: Model = a mathematical approximation of reality 7
Ecological Systems / Zone modeling Known Location (point) 10m 10m Spatial Data Layers (DTMs) Elevation Aspect Slope Ave. annual precipitation Relative slope position Geology (+ 24 others) f(x) statistical function* Maxent 8
Determination of Final Ecozones by combining various model zones; merged types with similar plant diversity EcoZones 1 Nant-Pisgah Acres Nant-Pisgah Percent Spruce-Fir 16600 2% Changes Northern Hardwood 53920 5% includes slope and cove types High Elevation Red Oak 38640 4% Acidic Cove Forest 240940 23% combine acidic cove and mixed oak rhododendron tpes Rich Cove Forest 189140 18% Mesic Oak 186200 18% includes slope, cove and rich types Dry Mesic Oak 105990 10% Dry Oak 59680 6% Pine-Oak Heath 101280 10% Shortleaf Pine-Oak heath 44450 4% Floodplain 2640 0.3% includes evergreen and deciduous types Combine low elevation mixed pineoak and pine types combine alluvial and large floodplain types 1 Third Approximation Southern App Model 9
Plant Communities in Southern Appalachian Landscape Spruce-Fir Grassy Bald Beech Gap High Elevation Red Oak Northern Hardwood Northern Hardwood Pine-Oak/ Heath Mesic Oak Mesic Oak Dry-Mesic Oak Dry-Mesic Oak Shortleaf Pine-Oak Floodplain Forest 10
Spruce-fir High Elevation Red Oak High Elevation > 4200 Feet 10% of Nantahala & Pisgah NFs Northern Hardwood 11
Mid Elevation: 2300-4200 Feet Acidic Cove 85% of Nantahala & Pisgah NFs Rich Cove Pine- Oak/Heath Dry Oak Dry-Mesic Oak Mesic Oak 12
Low Elevation < 2300 Feet Shortleaf Pine Forest 5% of Nantahala & Pisgah NFs Floodplain Forest 13
1 Dry-Mesic Oak Ecozone Desired Conditions 4 The overstory consists of oak and other deciduous hardwood canopy trees. Aggressive native tree species, such as red maple and white pine, are present but not dominant. Shrub densities, primarily deciduous species, range from 25 to 50 percent. A diverse herbaceous layer occurs within open canopy sites while a sparser layer occurs within closed canopy sites. Grasses are dispersed and evident within fire-maintained sites. Young forest is represented, 5-7 percent of the landscape, across this ecozone. Potential old-growth conditions, from 50-61 percent of the landscape, are present in amounts that support species diversity. With the older closed-canopy forest, a mosaic of different size openings are dispersed throughout providing structural and age class diversity. Greater than half of the old-growth class, representing 28-33 percent of the landscape, is open canopy. A greater portion of the landscape supports open canopy forest, 48-59 percent, compared to closed canopy forest, 36-45 percent. Open canopy conditions are distributed across all age classes. Wildland fire occurs across this ecozone at intervals ranging from 14-20 years. Periodic burns regenerate the dominant oak species. Table 8. Dry-Mesic Oak Forest Age and Structural Classes Age/Structural Classes Young Mid Closed Mid Open Late Closed Late Open OG Closed OG Open 2 3 Age (years) 0-15 16-75 16-75 76-130 76-130 130+ 130+ Landscape % 5-7 7-9 13-17 7-8 7-9 22-28 28-33 14
Landfire is a nation-wide database that in part describes vegetation dynamics, including structure and disturbance regimes, for 1000 plus ecosystems, known as Biophysical Settings (BpS). Biophysical Settings (BpS) represents vegetation that may have been dominant in former times with less human intervention. Map units are defined by Nature Serve (NatureServe.org) Ecological Systems, a nationally consistent set of mid-scale ecological units. BpS are dynamic, can be regionally updated with more accurate information 15
Bridge from BpS to review of existing modeling effort Correlated BpS with the 11 ecozones. Rich Cove and Acidic Cove were combined in a single BpS given similar landscape position and disturbance history Examined three regional modeling efforts north zone Cherokee NF, Warwoman watershed on Chattahoochee NF, and southern Apps overall Within separate models observed variation in number of structural-age (s-classes), wide variation in percent particularly for oak types Decided to include old growth for all BpS models Decided to document a range per individual s-class 16
Added old growth classes for all models, these varied from 6-7 classes per model Calibrated age classes based on dominate tree species growth, the density of tree species, and changes in grass, shrub, and species dominance. Old growth ages typically used data from Region 8 Old Growth Guidance Ecozones Age Class Early Mid Late Old Growth Spruce-Fir 0-35 36-70 71-120 120+ High Elevation Red Oak 0-20 21-70 71-130 130+ Northern Hardwood 0-15 16-75 76-130 130+ Cove (Rich or Acidic) 0-10 11-100 101-140 140+ Mesic Oak 0-10 11-80 81-130 130+ Dry-Mesic Oak 0-15 16-75 76-130 130+ Dry Oak 0-20 21-70 71-100 100+ Pine-Oak heath 0-20 21-70 71-130 130+ Low Elevation pine 0-15 16-70 71-100 100+ Floodplain 0-10 11-100 101-140 140+ 17
1 Dry-Mesic Oak Ecozone Desired Conditions 4 The overstory consists of oak and other deciduous hardwood canopy trees. Aggressive native tree species, such as red maple and white pine, are present but not dominant. Shrub densities, primarily deciduous species, range from 25 to 50 percent. A diverse herbaceous layer occurs within open canopy sites while a sparser layer occurs within closed canopy sites. Grasses are dispersed and evident within fire-maintained sites. Young forest is represented, 5-7 percent of the landscape, across this ecozone. Potential old-growth conditions, from 50-61 percent of the landscape, are present in amounts that support species diversity. With the older closed-canopy forest, a mosaic of different size openings are dispersed throughout providing structural and age class diversity. Greater than half of the old-growth class, representing 28-33 percent of the landscape, is open canopy. A greater portion of the landscape supports open canopy forest, 48-59 percent, compared to closed canopy forest, 36-45 percent. Open canopy conditions are distributed across all age classes. Wildland fire occurs across this ecozone at intervals ranging from 14-20 years. Periodic burns regenerate the dominant oak species. Table 8. Dry-Mesic Oak Forest Age and Structural Classes Age/Structural Classes Young Mid Closed Mid Open Late Closed Late Open OG Closed OG Open 2 3 Age (years) 0-15 16-75 16-75 76-130 76-130 130+ 130+ Landscape % 5-7 7-9 13-17 7-8 7-9 22-28 28-33 18
Examined frequency of disturbance types for each BpS model for each s-class Data was incorporated from literature, previous determinations, and discussion with experts. Included Disturbance Frequency for following major types Fire - Surface, mixed, and sever Wind including hurricanes and downbursts Hoar Frost-Ice Severe Rain Events Insect Outbreaks Diseases Flooding Models were examined relative to all other models. Given the lack of historical data and the uncertainty on frequencies, there was greater emphasis placed on reviewing all models together ensuring frequencies for individual BpS units were realistic based on landscape exposure, topography, etc. 19
Disturbance Ecology Young Mid Mid Closed Mid Open Late Open Old Growth Open Late Closed Old Growth Closed 20
Disturbance Frequency By Ecozones in Western North Carolina Ecozones Disturbances POH SLP Dry Oak Dry-Mesic Oak Mesic Oak HERO SF NHwd Cove Flood Min Surface Fire 3 2 5 14 18 11 100 50 50 Max Surface Fire 15 12 20 20 25 20 500 250 350 Average Surface Fire 5 5 10 15 20 15 333 100 200 Min Mixed Fire 20 20 25 80 80 50 600 500 400 400 Max Mixed Fire 100 100 100 250 250 100 2000 1000 1000 1000 Average Mixed Fire 50 50 60 100 100 70 1000 602 500 500 Min Replacement Fire 30 30 25 200 100 100 600 500 500 200 Max Replacement Fire 300 500 500 500 500 500 2000 1000 1500 1000 Average Replacement Fire 150 200 250 300 350 350 1000 602 1000 612 Min Wind/Weather 100 100 70 150 150 40 100 120 200 120 Max Wind/Weather 300 333 333 400 400 300 333 500 500 250 Average Wind/Weather 150 150 100 200 250 100 150 200 300 150 Min Extreme Wind/Ice 100 80 100 100 Max Extreme Wind/Ice 300 400 500 700 Average Extreme Wind/Ice 250 250 333 500 Min Insect/Disease 60 70 70 100 100 70 50 80 100 100 Max Insect/Disease 200 200 200 400 400 300 333 350 400 400 Average Insect/Disease 100 125 125 200 250 125 100 200 250 250 Min Flooding 50 Max Flooding 400 Average Flooding 120 * all frequencies in years POH = Pine-Oak/Heath SLP = Low Elevation Pine HERO = High Elevation Red Oak SF = Spruce-Fir NHwd = Northern Hardwoods Cove = Acidic or Rich Flood = Floodplain 21
Modeling Developed models with state and transition simulation software Each model ran for 1000 years with 100 simulations All models were non-spatial Model results for broader spatial scale Models do not provide compositional distribution Structural diversity does not define gap size -- simply defines open habitat as less than 60 % canopy cover Results with greater open forest (young and woodlands) in drier ecozones compared to moist ecozones High elevation models more open based on more frequent storm impacts 22
Ecozones POH SLP Dry Oak Dry-Mesic Mesic HERO SF NHwd Cove Flood S-Classes Early 14 9 12 6 4 13 19 7 5 8 Mid-Closed 2 4 5 8 15 15 17 22 31 44 Mid-Open 37 35 14 16 11 17 1 2 2 2 Late-Open 26 25 7 9 6 15 1 1 1 1 Late-Closed 2 2 3 8 10 9 17 15 10 12 OG-Open 18 23 43 30 19 22 2 3 2 OG-Closed 1 2 16 24 37 9 44 50 51 31 23 Total Closed 5 8 24 40 62 33 78 87 92 87
Young Forest lower range upper range NP Acres Pine-oak 11 11140.25 19 19242.25 101275 Shortleaf 8 3556.08 13 5778.63 44451 Dry Oak 9 5370.93 22 13128.94 59677 Dry-Mesic Oak 5 5299.55 7 7419.37 105991 Mesic Oak 4 7445.24 5.5 10237.21 186131 HERO 14 5409.18 18 6954.66 38637 Spruce-Fir 14 2324.56 17 2822.68 16604 Northern Hardwood 5 2696.2 7 3774.68 53924 Cove 4 17203.24 5 21504.05 430081 Floodplain 6 158.4 8 211.2 2640 5.8% 60603.63 8.8% 91073.67 1039411 Varies from 4-5% to 14-18 depending on ecozone 24
Old Growth Closed lower range upper range NP Acres Pine-oak 0.5 506.375 3 3038.25 101275 Shortleaf 0.5 222.255 4 1778.04 44451 Dry Oak 5 2983.85 16 9548.32 59677 Dry-Mesic Oak 22 23318.02 28 29677.48 105991 Mesic Oak 27 50255.37 34 63284.54 186131 HERO 6 2318.22 10 3863.7 38637 Spruce-Fir 36 5977.44 45 7471.8 16604 Northern Hardwood 40 21569.6 50 26962 53924 Cove 46 197837.3 54 232243.7 430081 Floodplain 22 580.8 30 792 2640 29.4% 305569.2 36.4% 378659.9 1039411 Lower amount in drier fire adapted types compared to mesic types 25
Old Growth Open lower range upper range NP Acres Pine-oak 11 11140.25 26 26331.5 101275 Shortleaf 16 7112.16 29 12890.79 44451 Dry Oak 40 23870.8 57 34015.89 59677 Dry-Mesic Oak 28 29677.48 33 34977.03 105991 Mesic Oak 20 37226.2 25 46532.75 186131 HERO 18 6954.66 26 10045.62 38637 Spruce-Fir 12 1992.48 16 2656.64 16604 Northern Hardwood 11 5931.64 14 7549.36 53924 Cove 0 0 0 0 430081 Floodplain 9 237.6 13 343.2 2640 11.9% 124143.3 16.9% 175342.8 1039411 Higher amounts in more fire adapted drier types 26
18 County area, about 4.8 million acres, surrounding Nantahala Pisgah NFs Has spatial variability Large enough to be statistically robust for larger landscape 27
Current vegetation condition process: Nantahala/Pisgah NFs Spatial Data Layers Ecozones Stand Age (FSVeg) Early succession from fire (Imagery) Canopy cover (LiDAR) RULES From BpS Models, (type, age, canopy) = existing s-class map Age/Structural Classes Young Mid Closed Mid Open Late Closed Late Open OG Closed OG Open Age (years) 0-15 16-75 16-75 76-130 76-130 130+ 130+ Landscape % 2 27 3 55 4 8 1 = existing S-class distribution 28
STRUCTURAL DIVERSITY: having a mix of seral stages and forest conditions present, in appropriate amounts, to ensure long-term habitat diversity and productivity ESTIMATED DEPARTURE equals DESIRED CONDITION (PNV) minus EXISTING CONDITION (FSVeg) Below low end of range = deficit Above high end of range = surplus 29
The Planning Directives state: If past conditions relative to the natural range of variation are not appropriate, practical, possible, or desirable approaches The ID Team should design plan components based on a general scientific and ecological understanding of the conditions that would sustain key ecosystem characteristics and sustain at-risk species using factors such as: representativeness, redundancy, habitat associations of particular species, disturbance dynamics, observed conditions in reference 30
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109 Patches 56 Nantahala NF 53 Pisgah NF Range 2-32,500 acres 36 Patches > 2500 acres 19 Patches > 5000 acres 19 Patches represent 75% of Landscape A 32
All 11 Ecozones represented Cove, Mesic Oak, Dry Oak all within 1% Greatest variability Dry- Mesic Oak (6% vs 10%) Shortleaf Pine, Spruce-Fir, Northern Hardwoods, Pine Oak/Heath vary by 2-3% Steeper Slopes Landscape A (16% vs 11%) High elevation types greater representation, Low elevation types less representation 33
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NRV can provide perspective from historical conditions NRV provides an understanding of processes that drive ecosystem change Models make logical sense compared to each other, varies by ecozone Landscape Patch A does provide for larger patches where a mosaic of natural disturbance can occur Landscape Patch A does provide representation in ecozones Landscape Patch A does incorporate species and unique habitat diversity 35
I survived the (s)class Wars on the Nantahala & Pisgah 36