Modern pollen assemblages from grazedvegetation in the western Pyrenees, France: a numerical tool for more precise reconstruction of past cultural landscapes

Abstract

To cite this version:Florence Mazier, Didier Galop, Cécile Brun, Alexandre Buttler. Modern pollen assemblages from grazed vegetation in the western Pyrenees, France: a numerical tool for more precise reconstruction of past cultural landscapes. Holocene, SAGE Publications, 2006, 16 (1) Abstract: Modern pollen assemblages from grazed vegetation in the Pyrenees Mountains (France) were studied with the aim of providing a calibrated model for reconstructing past pastoral activities. The modern analogues were selected to cover the major gradients of grazing pressure and degree of openness. The vegetation was surveyed by means of the synusial integrated method, assessing the structure and the patchiness of the pastoral phytoceonoses. A correlative model (Redundancy analysis) was devised relating 61 modern pollen spectra with 37 explanatory vegetation and land-use variables. It was shown that wooded, open grazed and nitrophilous sites are clearly separated from one another and that the model can be simplified using three relevant vegetation types as explanatory variables: dry heathland, semi-open oak forest and overgrazed community, respectively related to gradients of openness, soil richness and grazing pressure. When reconstructing past pastoral activities with fossil pollen spectra, it is important to consider scale-dependent influences of plant species. Low frequencies of well-dispersed taxa such as Artemisia, Chenopodiaceae, Plantago lanceolata and Plantago major/media must be interpreted with care since they reflect more regional, rather than local, input into the pastoral landscape. In contrast, the simultaneous occurrence of Asteroideae, Cichorioideae, Cirsium-type, Galium-type, Ranunculaceae, Stellaria-type and Potentilla-type pollen is clearly related to grazing on a local scale. Calculation of Davis indices also shows that Cichorioideae, Galium-type and Potentilla-type indicate the very local presence of the corresponding plants. These pastoral plant indicators may have a limited geographical validity, ie, mountainous regions with crystalline bedrock, which may indeed also provide the framework for the application to fossil spectra of the modern pollen/vegetation/land-use models presented here.

Are pollen records from small sites appropriate for REVEALS model-based quantitative reconstructions of past regional vegetation? An empirical test in southern Sweden

“…''Open land'' has the stronger explanatory power in all RUNS 1-5, which is a common feature of the results from numerical analyses of pollen data with a strong gradient in values of non-arboreal pollen (NAP) (or arboreal pollen AP), axis one generally contrasting pollen assemblages with high NAP (or low AP) with pollen assemblages with low NAP (or high AP) (e.g. Gaillard et al 1994;Mazier et al 2006). The ''site size'' either is not significant or has a very low explanatory power.…”

Modern pollen assemblages from surface lake sediments in northwestern China and their importance as indicators of vegetation and climate

“…Numerous studies (e.g., Wright et al, 1967;Gaillard et al, 1992;Sugita, 1994;Cour et al, 1999;Davis, 2000;Shen et al, 2006;Ma et al, 2008;Zhao and Herzschuh, 2009;Herzschuh et al, 2010;Lu et al, 2011;Fall, 2012;Zheng et al, 2013;Tian et al, 2014) have been conducted to understand the relationship of modern pollen assemblages with contemporary vegetation and climate. Modern pollen assemblages are mainly collected from airborne pollen collectors (e.g., Cour et al, 1999;Giesecke et al, 2010), moss polsters (e.g., Hicks and Birks, 1996;Mazier et al, 2006), topsoils (e.g., Xu et al, 2009;Zhang et al, 2010) and surface lake sediments (e.g., Herzschuh, 2007;Seppa et al, 2004). However, the four types of pollen traps always yield different pollen assemblages even if they are collected from the same site (e.g., Fall, 1992;Wilmshurt and McGlone, 2005a;Lisitsyna et al, 2012;).…”

Palynological perspectives on vegetation survey: a critical step for model-based reconstruction of Quaternary land cover

“…This is not to say that the minor taxa are not interesting, but their value is largely as indicator taxa rather than as sources of reconstruction of the broad structure of the vegetation composition (e.g. providing information about intensity and moisture levels in pasture areas, not about the proportion of the landscape dominated by grassy communities; see Behre, 1981;Gaillard et al, 1994;Hjelle, 1998Hjelle, , 1999aMazier et al, 2006Mazier et al, , 2009. The major taxa are defined as the dominant taxa in recent and past vegetation/landscape.…”