2009 AAG Professional Presentation
How do rural land uses, and land use conversions, influence biodiversity and the biotic landscape of the Southern Appalachians? Across the Southern Appalachians, rural environments are undergoing dramatic land use change. A common trend is the conversion of agricultural land to exurban development. However, organic farming is also an increasingly popular alternative land use to conventional agricultural production. We examined landscape structure, habitat and plant diversity in a rural mountain setting in western North Carolina at multiple spatial scales. Specifically, we compared two differing land uses, organic agriculture (4 farms) and exurban development (4 subdivisions), at the landscape, site, and habitat scales. At the landscape (4 squared-km sampling window) and site scales, we delineated discrete habitat patches in ArcGIS, by on-screen digitizing of 6-inch resolution aerial photography. Patches were classified into 8 land use categories (built, paved, crop fields, water, riparian, forested, field/woodlot, and shrub). Landscape- and site-level patch structure and composition were analyzed using Patch Analyst to compare the land uses, and patch heterogeneity, size, connectivity and diversity of farms and subdivisions. At the habitat scale, we documented plant species composition and cover in 100 squared-meter plots within each habitat patch. We compared plant species composition and diversity among patch types and between farms and subdivisions. By combining GIS analysis with field data collection, this research provides an understanding of how rural land use affects biotic diversity.
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Multi-scale Effects of Land Use Conversion on Southern Appalachian Landscapes
1. Multi-scale Effects of Land Use
in a Rural and Exurban
Landscape within the Southern
Appalachians
Stephanie Smith & Gabrielle Katz
Appalachian State University, Boone NC
2. Rural & Exurban Landscape
! Agricultural and low density housing
! Heterogeneous setting (Benton et al. 2003, Weibull et al.
2003)
" Complex landscape structure and diverse habitat matrix
! Human interaction effects to the natural
surroundings
! Alters the landscape
! Impacts
" soil structures, hydrologic systems, atmospheric
composition
" biotic diversity and habitat fragmentation
3. Study Setting
! Western mountains of
North Carolina Elevation
! Watauga & Ashe Counties High : 5923
Low : 1339
! Mountainous landscape
! steep slopes
! diverse land uses
! Land use change
! rural ! exurban
! developable land is highly
desired
4. Research Question
! How does land use conversion from
agriculture to exurban affect the
landscape structure of the Southern
Appalachians?
6. Study Design
! Multi-scale analysis
using ArcGIS!
! landscape scale
" 2 km2 surrounding each site
! site scale
" land area of each farm and
subdivision
! patch scale
" plant species richness
7. Methods
! ArcGIS!
! 6 in. aerial photography
! min zoom, 1:1,500
! 8 habitat patch types
" forested,
built/landscaped,
field/woodlot, crop,
shrub, riparian, water,
& paved
! manually digitized each
habitat patch at every
site Ñ
8. Methods
! ArcGIS!
! 6 in. aerial photography
! min zoom, 1:1,500
! 8 habitat patch types
" forested,
built/landscaped,
field/woodlot, crop,
shrub, riparian, water,
& paved
! manually digitized each
habitat patch at every
site
9. Methods
! ArcGIS!
! 6 in. aerial photography
! min zoom, 1:1,500
! 8 habitat patch types
" forested,
built/landscaped,
field/woodlot, crop,
shrub, riparian, water,
& paved
! manually digitized each
habitat patch at every
site
10. Methods
! ArcGIS!
! 6 in. aerial photography
! min zoom, 1:1,500
! 8 habitat patch types
" forested,
built/landscaped,
field/woodlot, crop,
shrub, riparian, water,
& paved
! manually digitized each
habitat patch at every
site
11. Methods
! ArcGIS!
! 6 in. aerial photography
! min zoom, 1:1,500
! 8 habitat patch types
" forested,
built/landscaped,
field/woodlot, crop,
shrub, riparian, water,
& paved
! manually digitized each
habitat patch at every
site
13. Statistical Analysis
! Each site was then analyzed within Patch Analyst
(Rempel et al. 1997) and Fragstats (McGarigal and Marks, 1994)
(landscape & site scale)
! landscape metrics and diversity indices
" patch richness, mean patch size, mean patch fractal
dimension, edge density, shannon’s diversity &
evenness indices
" percent area for each patch type
14. Landscape Scale
Percent Area by Patch Type
100%
80%
% Paved
% Built
60% % Water
% Riparian
% Crop
40% % Field
% Shrub
% Forested
20%
0%
F1 S1 F2 S2 F3 S3 F4 S4
F = Farms; S = Subdivisions
15. Site Scale
Percent Area by Patch Type
100%
80% % Paved
% Built
% Water
60%
% Riparian
% Crop
40% % Field
% Shrub
% Forested
20%
0%
Farms Subdivisions
16. Results
Farm and Subdivisions Patch Comparisons
Site Measure Site Type Mean Patc
Mean Patch Number Mean Patch Size
Patch Number Farm 37.00
35 4 Mea
Subdivision 73.00
30 Mean Patch Size (ha) Farm 1.58
3 Edg
Subdivision 0.77
25
Edge Density Farm 597.57
20 AWM
Hectares
Subdivision 885.52
2
15 AWMP Fractal Dimension Farm 1.38
Sha
Subdivision 1.46
10 1
Shannons Diversity Index Farm 1.07
5 Sha
Subdivision 1.23
0
0 Shannons Evenness Index Farm 0.60
AW=
Farms Subdivisions
Farm Subdivisions Farms Subdivisions
Farm Subdivisions Subdivision 0.74
F1, S1 F2, S2 F3, S3 F4, S4
AW=area weighted; AWM=area weighted mean
F1, S1 F2, S2 F3, S3 F4, S4
17. Results
Farm and Subdivisions Patch Comparisons
Site Measure Site Type Mean
Patc
Edge Density Area Weighted Mean
Patch Fractal Dimension Patch Number Farm 37.00
1200 1.55 Subdivision 73.00 Mea
Mean Patch Size (ha) Farm 1.58
1000
1.5
Subdivision 0.77 Edg
800 Edge Density Farm 597.57
1.45
Meters/Hectare
Subdivision 885.52 AWM
600
AWMP Fractal Dimension Farm 1.38
1.4
400 Subdivision 1.46 Sha
Shannons Diversity Index Farm 1.07
1.35
200
Subdivision 1.23 Sha
0 1.3 Shannons Evenness Index Farm 0.60
Farm Subdivisions Farm Subdivisions AW=
Subdivision 0.74
F1, S1 F2, S2 F3, S3 F4, S4
F1, S1 F2, S2 F3, S3 F4, S4 AW=area weighted; AWM=area weighted mean
18. Results
Farm and Subdivisions Patch Comparisons
Shannon’s Diversity Index Shannon’s Evenness Index Site Measure Site Type Mean
Patc
2 1 Patch Number Farm 37.00
Subdivision 73.00 Mea
1.6 0.8 Mean Patch Size (ha) Farm 1.58
Subdivision 0.77 Edg
1.2 0.6 Edge Density Farm 597.57
Subdivision 885.52 AWM
0.8 0.4
AWMP Fractal Dimension Farm 1.38
Subdivision 1.46 Sha
0.4 0.2
Shannons Diversity Index Farm 1.07
Subdivision 1.23 Sha
0 0
Shannons Evenness Index Farm 0.60
Farm Subdivisions Farm Subdivisions
AW=
F1, S1 F2, S2 F3, S3 F4, S4 F1, S1 F2, S2 F3, S3 F4, S4 Subdivision 0.74
AW=area weighted; AWM=area weighted mean
19. Conclusion
! How does land use conversion from agriculture to
exurban affect the landscape structure of the Southern
Appalachians?
! Heterogeneous landscape
" high levels of patch richness, diversity and evenness
! Change in overall landscape structure
" greater degree of fragmentation within subdivisions
" smaller patches and more complex shapes
" agricultural land is being converted to developed
instead of forested area
" high amount of forested within both land uses
" tradeoffs between patch types
" crop/field ! built
20. Acknowledgements
! Funding: NC Beautiful
! Participants: Creeksong Farm, Maverick Farms, ASU Farm,
Watauga River Farms, Laurel Mtn, The Glen at Mast Gap,
Shulls Farm, Riverside Homes
! Research Assistance: Appalachian State University
Department of Geography and Planning, Gabrielle Katz, Chris
Badurek, Michael Denslow, Chris Kaase, Sarah Moncelle