Identifying forest stand types using pollen from forest hollows

Abstract

Methods of interpreting pollen assemblages in sediment were examined using surface samples from 66 small forest hollows in Michigan and Wisconsin. All canopy trees in the surrounding 50 m were measured to provide detailed information about the source vegetation of each surface pollen assemblage. Basal area of trees in each forest sample was used to classify them into six stand types: hemlock-dominated, sugar maple/hemlock mixed, sugar maple-dominated, and ash-, oak-, and pine-dominated stands. Various statistical procedures were tested to learn which was most successful in sorting the pollen assemblages into appropriate vegetation groups. Two ordination techniques – detrended correspondence analysis (DCA) and canonical variate analysis (CVA) – give similar overall results, although CVA more successfully separated assemblages from hemlock stands from those of sugar maple-dominated stands. Squared chord distance,0.05 also successfully identified samples from the same forest type. After stand dominants have been identified from pollen assem blages using multivariate methods, a further determination of stand composition is sometimes possible using ratios of pollen counts of individual taxa. Ratios can be calibrated by comparison with species abundances around surface samples. For instance, ratios of pine to hemlock pollen can indicate the abundance of pine within a stand dominated by hemlock, whereas pine pollen percentages alone are affected by variable abundance of other species.

A Paleoecological Perspective on Wetland Restoration

“…For example at the smallest scale, Calcotte (1995) and others have demonstrated that the fossil pollen recovered from small isolated wet areas within a forest or small basin can give a stand-scale view of vegetation (Sugita 1994). In this setting, local pollen contributes about 45-50% of the pollen input to small forested hollows in mixed hardwood conifer forests, which is enough to characterize the contributions of the major plant taxa that grew within about 50-100 m of the sample point (Calcotte 1995(Calcotte , 1998Sugita 1994). Thus, pollen studies conducted in basins of differing sizes may afford an opportunity to study changes in both local and regional vegetation and the response of local vegetation to different environmental forcing factors (Schauffler and Jacobson 2002).…”

Modern pollen and its ecological relationships with the tropical deciduous forests of central Uttar Pradesh, India

“…However, because of uncertainties in pollen dispersal and deposition such as pollen production, dispersal ability and basin size, the pollen assemblage does not necessarily correspond the vegetation composition (Davis & Goodlett 1960;Whitehead & Tan 1969;Kennedy et al 2005). Thus, analysing modern pollenÀvegetation relationships has been one of the most effective ways to interpret fossil pollen data (Webb et al 1981;Bradshaw & Webb 1985;Calcote 1998;Wilmshurst & McGlone 2005;Xu et al 2005). The present approach is based on the assumption that the same vegetation types have the same pollen assemblage, provided that the vegetation composition and distribution are the same.…”

Searching for ancient forests: A 2000 year history of land use in northeastern French forests deduced from the pollen compositions of closed depressions

“…In small sedimentary basins under a closed canopy, however, the pollen produced by nearby trees growing (local vegetation) is well represented (Chen, 1988;Sugita, 1994), but the information may not be representative of the larger forested area. Numerous palaeo-ecological investigations have used small forest hollows to study stand-level vegetation changes over centennial to millennial timescales (Calcotte, 1998;Parshall and Calcote, 2001 Closed depressions (CD) are common features of many oakbeech-hornbeam forests in the low altitudes of northeastern France, Germany (Barth et al, 2001), Luxembourg (Herault and Thoen, 2008) and Belgium (Gillijns et al, 2005;Vanwalleghem et al, 2006aVanwalleghem et al, , 2006bVanwalleghem et al, , 2008. In these small (10-30 m in diameter) closed wetlands, mostly supplied by rainwater, pollen grains are trapped in the sediment perfectly preserved (Etienne et al, 2010;Hannon et al, 2000;Lindbladh and Bradshaw, 1995;Ruffaldi et al, 2007).…”