A topographic index to quantify the effect of mesoscale landform on site productivity

Abstract

Landform is related to environmental factors that affect site productivity in mountainous areas. I devised a simple index of landform and tested this index as a predictor of site index in the Blue Ridge physiographic province. The landform index is the mean of eight slope gradients from plot center to skyline. A preliminary test indicated that the index was significantly associated with slope position and three classes of landform (ridge, slope, and cove). In a test with data from four locations, site index of yellow-poplar (Liriodendrontulipifera L.) was significantly correlated with landform index for each location (r = 0.45–0.65). Landform index and two other topographic variables together accounted for 31 percent of the variation in yellow-poplar site index throughout the Blue Ridge province. Landform index is a conveniently measured site variable that may be useful in various forestry-related applications, including multivariate analysis of the distribution and composition of forest vegetation.

Stand age and habitat influences on salamanders in Appalachian cove hardwood forests

“…COVEHA was defined as the area with an LFI > 0.24 (bighly sheltered sites), or 0.25 > LFI > 0.15 and PSS < -0.025 (less sheller&, but concave sites) at each study stand. meshold values for LFI and PSS were d e t e~n e d based on prior experience of one of the authors (Odom, 1996) and others (McNab, 1993(McNab, , 1996 in using these indices to quantify topogfapby in the southern Appalachians. To compuk COVE=, the total area defined as "cove" within 1 km of each study site was summed using proximity and overlay functions in ~r c~i e w~ spatial Analyst, BASAL was calculated using a 10-factor handheld prism (mZ ha-') at each drift-fence may and averaged across each stand (Grosenbaugh, 1952), as it is not a pmicularly meaningful fine-scaled, microhabiitat variable.…”

Effect of topography on tree species composition and volume of coarse woody debris in an Oriental beech (Fagus orientalis Lipsky) old growth forests, northern Iran

“…Instead of using descriptive categories (such as ridge, midslope, and valley), we quantified land form as a land form index (LI) by calculating the mean slope from the plot center to the topographic horizon every 45 degrees (8 total measurements) around the plot center using clinometer and compass (McNab 1992, Rubino & McCarthy 2003). The eight measurements were then averaged to obtain a single LI value for each plot.…”

“…The use of the land form index (LI, dimensionless) instead of descriptive categories (ridge, mid-slope, valley) facilitated statistical analyses and avoided classification problems. In fact, using this index the effects of distance and height of landforms are compensated, e.g., a low, nearby ridge and ta high, distant ridge could have the same effect on LI, though obviously their ecological influence could differ (McNab 1992).…”

Landform Analysis Using Terrain Attributes. A Gis Application on the Island of Ikaria (Aegean Sea, Greece)

“…In particular, landform classification has been proved a valuable processing tool for studies related to archaeology, ecology, agriculture, forestry, rural planning, hazards, etc. (Ho and Umitsu, 2011;Hoersch et al, 2002;Macmillan et al, 2003;Martin-Duque et al, 2003;Mcnab, 1993;Verhagen and Dragut, 2012).…”