Ma. Spetich et al., SPATIAL AND TEMPORAL RELATIONSHIPS OF OLD-GROWTH AND SECONDARY FORESTS IN INDIANA, USA, Natural areas journal, 17(2), 1997, pp. 118-130
We examined the spatial pattern of forests in Indiana to (1) determine
the extent, connectivity and percent edge of all forests; (2) examine
the change in connectivity among these forests if all riparian zones
were replanted to forest or other native vegetation; (3) determine the
location, spatial dispersion, and percent edge of current old-growth
forest remnants; (4) predict future changes in area and spatial distri
bution of old-growth forests based on current land management plans of
public agencies; and (5) discuss biological implications of different
edge widths, patch sizes, and spatial configurations of forests in In
diana. To achieve this, we produced a map of forested riparian zones u
sing a Geographic Information System (GIS) buffering function and deve
loped GIS models to predict locations of potential old-growth forests
on lands designated in public agency management plans as preserves or
unmanaged forests. A proximity index (PX) was used as a quantitative m
easure of effective connectivity of forest patches. PX values ranged f
rom 0 to nearly 3,000, where a value of 0 is affectively isolated and
a value of 3,000 is very well connected, For the 9,508 patches and 2,0
26,716 ha of all forests in both Indiana and the surrounding area, the
average PX was 19.49. Adding a 200-m forest buffer to both sides of a
ll nonforested riparian areas resulted in a decreased number of fragme
nts to 3,634 and an increase of 1,724,664 ha of forest (the buffer). A
20-m buffer would add 172,466 ha of forest. The PX was not used to an
alyze riparian areas because it was not appropriate for the dendritic
pattern formed when riparian areas were revegetated. Total area of old
-growth forests greater than or equal to 4 ha held in public trust in
Indiana is 362 ha divided among 19 forests. An additional 8 sites grea
ter than or equal to 4 ha in private ownership contain 215 ha. Most ol
d-growth forests are isolated within an agricultural matrix. The perce
ntage of old-growth forest areas located within 40 m, 200 m, 400 m, an
d 600 m of a nonforest edge were 23%, 75%, 89% and 93% respectively. P
X values for all 19 old-growth sites were 0, implying that they are ve
ry isolated sites. If current public forest management plans are follo
wed, the area and number of old-growth forests will increase and their
relative isolation will decrease. Potential future old-growth forests
consisted of 137 patches and 82,520 ha with an average PX of 1.8. Of
this amount 27,297 ha were within Hoosier National Forest purchase bou
ndaries but are currently in private ownership.