A Review of Relative Pollen Productivity Estimates From Temperate China for Pollen-Based Quantitative Reconstruction of Past Plant Cover.

Furong Li,Yuecong Li,Huishuang Mu,Wei Shen,Yahong Zhang,Panpan Zhang,Marie-José Gaillard,Shengrui Zhang,Qinghai Xu,Jingyao Lu,Qiaoyu Cui,Jie Li,Mairi J Bunting

doi:10.3389/fpls.2018.01214

Abstract

Model-based quantitative reconstruction of past plant cover in Europe has shown great potential for: (i) testing hypotheses related to Holocene vegetation dynamics, biodiversity, and their relationships with climate and land use; (ii) studying long term interactions between climate and land use. Similar model-based quantitative reconstruction of plant cover in China has been restricted due to the lack of standardized datasets of existing estimates of relative pollen productivity (RPP). This study presents the first synthesis of all RPP values available to date for 39 major plant taxa from temperate China and proposes standardized RPP datasets that can be used for model-based quantitative reconstructions of past plant cover using fossil pollen records for the region. We review 11 RPP studies in temperate China based on modern pollen and related vegetation data around the pollen samples. The study areas include meadow, steppe and desert vegetation, various woodland types, and cultural landscapes. We evaluate the strategies of each study in terms of selection of study areas and distribution of study sites; pollen- and vegetation-data collection in field; vegetation-data collection from satellite images and vegetation maps; and data analysis. We compare all available RPP estimates, select values based on precise rules and calculate mean RPP estimates. We propose two standardized RPP datasets for 31 (Alt1) and 29 (Alt2) plant taxa. The ranking of mean RPPs (Alt-2) relative to Poaceae (= 1) for eight major taxa is: Artemisia (21) > Pinus (18.4) > Betula (12.5) > Castanea (11.5) > Elaeagnaceae (8.8) > Juglans (7.5) > Compositae (4.5) > Amaranthaceae/Chenopodiaceae (4). We conclude that although RPPs are comparable between Europe and China for some genera and families, they can differ very significantly, e.g., Artemisia, Compositae, and Amaranthaceae/Chenopodiaceae. For some taxa, we present the first RPP estimates e.g. Castanea, Elaeagnaceae, and Juglans. The proposed standardized RPP datasets are essential for model-based reconstructions of past plant cover using fossil pollen records from temperate China.

Highlights

Pollen-based quantitative reconstructions of past plant cover may be required to answer specific questions related to past vegetation changes and/or the interactions between plant cover, humans, and climate
In most studies performed in Europe and elsewhere, the strategy has been to assume that a maximum of 15 to 20 taxa will be appropriate for Extended R-Value (ERV)-model analysis and, 30 to 40 sites were used for collection of pollen and vegetation data in field (e.g., Broström et al, 2008; Mazier et al, 2012). (iii) Theoretically, the most reliable estimate of relative pollen productivity (RPP) using the ERV model should correspond to the RPP value obtained for the distance from the pollen sample corresponding to the radius of the relevant source area of pollen (RSAP)
Relative pollen productivity (RPP) of plant taxa is one of the key parameters required for quantitative reconstruction of vegetation abundance using the Landscape Reconstruction Algorithm (LRA; Sugita, 2007a,b) or the Multiple Scenario

Summary

Introduction

Pollen-based quantitative reconstructions of past plant cover may be required to answer specific questions related to past vegetation changes and/or the interactions between plant cover, humans, and climate. The cover of tree versus herb vegetation at a continental to global scale can roughly be estimated using biomization (e.g., Davis et al, 2015) and pseudo-biomization (e.g., Fyfe et al, 2015), it has been shown by comparison of satellite-derived with pollen-based estimates of tree cover in e.g., northern Asia that pollen-inferred tree cover is often too high for most tree categories, largely due to long-distance transport of pollen (Tarasov et al, 2007) These methods cannot provide details on the respective proportions of plant taxa, plant groups such as conifers, broad-leaved trees, and herbs, or land units such as forest, grassland, and cultivated land. A relatively large number of RPP estimates have been produced in Europe using this method (see reviews by Broström et al, 2008; Mazier et al, 2012; Bunting et al, 2013) and northern America (e.g., Calcote, 1995; Commerford et al, 2013)

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