Nantahala Pisgah NF Plan Process - Natural Range of Variation. Gary Kauffman National Forests in NC Ecologist

Transcription

1 Nantahala Pisgah NF Plan Process - Natural Range of Variation Gary Kauffman National Forests in NC Ecologist 1

2 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

3 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

4 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 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 percent of the landscape, is open canopy. A greater portion of the landscape supports open canopy forest, percent, compared to closed canopy forest, percent. Open canopy conditions are distributed across all age classes. Wildland fire occurs across this ecozone at intervals ranging from 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) Landscape %

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7 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

8 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

9 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 % Changes Northern Hardwood % includes slope and cove types High Elevation Red Oak % Acidic Cove Forest % combine acidic cove and mixed oak rhododendron tpes Rich Cove Forest % Mesic Oak % includes slope, cove and rich types Dry Mesic Oak % Dry Oak % Pine-Oak Heath % Shortleaf Pine-Oak heath % Floodplain % 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

10 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

11 Spruce-fir High Elevation Red Oak High Elevation > 4200 Feet 10% of Nantahala & Pisgah NFs Northern Hardwood 11

12 Mid Elevation: Feet Acidic Cove 85% of Nantahala & Pisgah NFs Rich Cove Pine- Oak/Heath Dry Oak Dry-Mesic Oak Mesic Oak 12

13 Low Elevation < 2300 Feet Shortleaf Pine Forest 5% of Nantahala & Pisgah NFs Floodplain Forest 13

14 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 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 percent of the landscape, is open canopy. A greater portion of the landscape supports open canopy forest, percent, compared to closed canopy forest, percent. Open canopy conditions are distributed across all age classes. Wildland fire occurs across this ecozone at intervals ranging from 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) Landscape %

15 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

16 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

17 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 High Elevation Red Oak Northern Hardwood Cove (Rich or Acidic) Mesic Oak Dry-Mesic Oak Dry Oak Pine-Oak heath Low Elevation pine Floodplain

18 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 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 percent of the landscape, is open canopy. A greater portion of the landscape supports open canopy forest, percent, compared to closed canopy forest, percent. Open canopy conditions are distributed across all age classes. Wildland fire occurs across this ecozone at intervals ranging from 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) Landscape %

19 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

20 Disturbance Ecology Young Mid Mid Closed Mid Open Late Open Old Growth Open Late Closed Old Growth Closed 20

21 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 Max Surface Fire Average Surface Fire Min Mixed Fire Max Mixed Fire Average Mixed Fire Min Replacement Fire Max Replacement Fire Average Replacement Fire Min Wind/Weather Max Wind/Weather Average Wind/Weather Min Extreme Wind/Ice Max Extreme Wind/Ice Average Extreme Wind/Ice Min Insect/Disease Max Insect/Disease Average Insect/Disease 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

22 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

23 Ecozones POH SLP Dry Oak Dry-Mesic Mesic HERO SF NHwd Cove Flood S-Classes Early Mid-Closed Mid-Open Late-Open Late-Closed OG-Open OG-Closed Total Closed

24 Young Forest lower range upper range NP Acres Pine-oak Shortleaf Dry Oak Dry-Mesic Oak Mesic Oak HERO Spruce-Fir Northern Hardwood Cove Floodplain % % Varies from 4-5% to depending on ecozone 24

25 Old Growth Closed lower range upper range NP Acres Pine-oak Shortleaf Dry Oak Dry-Mesic Oak Mesic Oak HERO Spruce-Fir Northern Hardwood Cove Floodplain % % Lower amount in drier fire adapted types compared to mesic types 25

26 Old Growth Open lower range upper range NP Acres Pine-oak Shortleaf Dry Oak Dry-Mesic Oak Mesic Oak HERO Spruce-Fir Northern Hardwood Cove Floodplain % % Higher amounts in more fire adapted drier types 26

27 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

28 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) Landscape % = existing S-class distribution 28

29 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

30 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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32 109 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

33 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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35 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

36 I survived the (s)class Wars on the Nantahala & Pisgah 36