Vegetation structure and pollen source area

Abstract

In this paper we use a simulation approach to explore the effect of variation in taxon parameters and landscape patterning on relevant source area of pollen. We use the Prentice-Sugita model, assume constant atmospheric conditions and basin morphology, and take a reductionist approach to explore the behaviour of pollen dispersal and deposition in a simple landscape scenario. Individual factors within the scenario (pollen fall speed, relative pollen productivity, size of basic unit in the landscape mosaic, patch size, rarity of individual taxa and overall number of taxa present in the landscape) are varied while all other parameters are kept constant. thus pennitting exploration of the role of different components of the system. These simulations suggest that, for basins of given size under fixed atmospheric conditions, the relevant source area of pollen is primarily an expression of the patterning of the different vegetation elements within the landscape. This has important implications for the interpretation of palaeoecological records and reconstruction of past environments. Reconstruction, especially quantitative reconstruction, requires some estimate of past relevant source area of pollen. If, as our results suggest, vegetation patterning is an important determinant of this, then it must also be taken into account when attempting to reconstruct past vegetation communities.

Evaluating the effect of flowering age and forest structure on pollen productivity estimates

“…Thus, extrapolation from the woodland patch-size versus RSAP in Switzerland and Estonia to the size of forest patches in Brandenburg may explain the large RSAP obtained. This example shows the dependency of RSAP on the patch size (Bunting et al 2004;Hellman et al 2009) for the selected lakes and indicates large effective patch size for the region investigated here.…”

“…The full dataset has a lake size distribution with a stronger skew to the right but yields a similar RSAP. It is most likely that the result is in fact due to the distribution of vegetation types and forest species in the study area, which is a well-known factor controlling the size of the RSAP (Sugita et al 1999;Bunting et al 2004;Nielsen and Sugita 2005;Hellman et al 2009). Soil substrate, and therefore nutrient and water availability in north-east Germany are linked to the glacial geomorphology of the area.…”

Pollen source areas of lakes with inflowing rivers: modern pollen influx data from Lake Baiyangdian, China

“…As the outline of Lake Baiyangdian is crescentic, we estimated the lake radius as half of the maximum lake width in the sampling area (4125 m). Wind speed is usually assumed to be constant in many studies (Sugita, 1994;Sugita et al, 1999;Broström et al, 2004;Bunting et al, 2004), but changes in modeled wind speed have obvious influence on model outputs (e.g. Mazier et al, 2008).…”

Vegetation Dynamics at the Upper Reaches of a Tropical Montane Forest are Driven by Disturbance Over the Past 7300 Years

“…In addition, other disturbance indicators, including Chenopodiaceae and over-represented pollen and spore types, increased in abundance. These disturbance indicators were likely not growing on site, but became increasingly over-represented in pollen assemblages because of a more open forest increasing the frequency of longer pollen transport distances (e.g., Bunting et al, 2004). This change in the fire regime altered the understory community but did not affect the composition of cloud forest tree taxa over the long term, except for modest increases in the tree Myrsine at the onset of an intensified fire regime (Appendix Fig.…”