THE LATITUDE-ELEVATION RELATIONSHIP FOR SPRUCE-FIR FOREST AND TREELINE ALONG THE APPALACHIAN MOUNTAIN CHAIN

Spruce-fir forests extend along the Appalachian Mountains of eastern North America from 35-degrees to 49-degrees-N. This montane vegetation differs from boreal spruce-fir forest in that it is dominated by Picea rubens, has a higher vascular species richness, has wind, rather than fire, dominated dynamics, and has a mean annual temperature above 2-degrees-C. Using field reconnaissance, remote sensing, and literature review we described and modeled the latitude-elevation relationship for Appalachian spruce-fir. The elevation of the spruce-fir/deciduous forest ecotone decreases from 1,680 m at 35-degrees-N to 150 m at 49-degrees-N, while the elevation of treeline (spruce-fir/tundra ecotone) decreases from 1,480 m at 44-degrees-N to 550 m at 55-degrees-N. Linear regressions gave latitude-elevation relationships of -100 m/l-degrees Latitude for the spruce-fir/deciduous forest ecotone and -83 m/l-degrees Latitude for treeline. These values compare to literature reports of -54 to -230 m/l-degrees Latitude and are most similar to values reported from eastern Asia. The latitude-elevation relationship for mean July temperature (-94 to -121 m/l-degrees Latitude) was more similar to the slopes of these ecotones than is the slope for mean annual temperature (-170 to -220 m/l-degrees Latitude). The spruce-fir/deciduous forest ecotone was correlated with a mean July temperature of approximately 17-degrees-C. Treeline was correlated with a mean July temperature of approximately 13-degrees-C.