The Upland Forest Continuum in Northern New Jersey

Abstract

Quantitative data on trees, saplings and tree seedlings were taken from 60 acceptably homogeneous upland stands on a wide variety of geological substrata and topographic positions throughout northern New Jersey, partly to test the applicability of a unidimensional continuum in a heterogeneous environment. The strong negative correlation between stand altitude and continuum index could not be ascribed to altitude alone because rich calcareous soils were found at low altitides while poor, shallow soils from more resistant rocks were found at higher elevations. Species diversity was greatest in forests on limestone substrata. Although Quercus species were found as leading species in 54 of the 60 stands, sapling data showed that in these forests as a whole succession is leading from dominance by oaks to dominance by Tsuga canadensis or by Acer saccharum, the association between these two species being weak. Though useful as a tool for the study of vegetation, a linear continuum was not applicable to the forests of northern New Jersey; they appear to conform to a pluridimensional continuum. It is concluded that the Clementsian concept of climax, as a process, is in no way degraded by the concept of the continuum, either linear or pluridimensional.