A survey of modern pollen and vegetation along a south–north transect in Mongolia

Abstract

Aim This modern pollen‐rain study documents the spatial and quantitative relationships between modern pollen and vegetation in Mongolia, and explores the potential for using this relationship in palaeoclimatic reconstructions. Location East‐central Mongolia. Methods We collected 104 pollen surface samples along a south–north transect across five vegetation zones in Mongolia. Discriminant analysis was used to classify the modern pollen spectra into five pollen assemblages corresponding to the five vegetation zones. Hierarchical cluster analysis was used to divide the main pollen taxa into two major groups and seven subgroups representing the dry and moist vegetation types and the main vegetation communities within them. Results Each vegetation zone along the transect can be characterized by a distinctive modern pollen assemblage as follows: (1) desert zone: Chenopodiaceae–Zygophyllaceae–Nitraria–Poaceae pollen assemblage; (2) desert‐steppe zone: Poaceae–Chenopodiaceae pollen assemblage; (3) steppe zone: Artemisia–Aster‐type–Poaceae–Pinus Haploxylon‐type pollen assemblage; (4) forest‐steppe zone: Pinus Haploxylon‐type–Picea–Artemisia–Betula, montane forb/shrub and pteridophyte pollen assemblage; and (5) mountain taiga zone: Pinus Haploxylon‐type–Picea–Poaceae–Cyperaceae, montane forb/shrub and Pteridophyte pollen assemblage. Main conclusions Based on the ratio between the major pollen taxon groups and subgroups, we propose two pollen–climate indices that represent the precipitation and temperature conditions in the study region. When plotted along our south–north transect, the moisture indices (M) and temperature indices (T) mimic the regional gradients of precipitation and temperature across Mongolia very closely. These pollen–climate indices can be used for palaeoclimatic reconstruction based on fossil pollen data.

Pollen Evidence of a Humid Mid-Holocene Climate from Bahar Nuur, Inner Mongolia

“…The Pinus pollen has most likley probably been transported by wind from the pine-dominated forest-steppes. It is apparent that the Pinus pollen is over-represented in the pollen spectra, confirming the widely-reported over-representation of Pinus pollen in the semi-arid and arid regions of China and Mongolia [18].…”

A late Eocene palynological record of climate change and Tibetan Plateau uplift (Xining Basin, China)

“…Although Pinus can be transported over long distances (> 1000 km) other conifers such as Picea are much less prone to transport (Lu et al, 2008;Zhou and Li, 2011) and are therefore a good proxy for regional palaeoaltitude especially when found in such high percentages. Pinus pollen can have occurrences of up to 10-50% in the palynological assemblages of deserts and steppe-deserts, where pine trees are absent, as the result of long-distance transport by wind (Ma et al, 2008). However, the abundance of Picea is more significant as Picea pollen distribution in present environments strongly dwindles at any distance from the spruce forests (Lu et al, 2008;Zhou and Li, 2011).…”

“…In the modern deserts of northwestern China, where these taxa presently occur, annual rainfalls of less than 100 mm are measured which makes these among the most arid regions in the world (Sun and Wang, 2005). Ephedra and Nitraria have slightly different ecological ranges; Ephedra prefers aridity (semi-desert) while Nitraria is a relatively more humid steppe/desert taxon (Xi and Sun, 1987;Cour et al, 1999;Sun and Wang, 2005;Jiang and Ding, 2008;Ma et al, 2008;Li et al, 2009;Zhao and Herzschuh, 2009). According to Li et al (2005) the Nitraria/Ephedra (N/E) ratio is below 1 in typical desert communities and above 1 in steppe-desert environments suggesting that the ratio of these taxa may be used as a measure of relative humidity in this dry environment.…”

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

“…2). These taxa typically have low pollen productivities compared to trees, the grains are comparatively large and therefore have a short aerial transport distance (Cerealia fall speeds are estimated at 0.060 m s À1 and Zea mays fall speeds around 0.100 m s À1 , Sugita et al, 1999), and Poaceae grains also have relatively poor pollen preservation (Ma et al, 2008;Zheng et al, 2008). These facts mean that these communities would be expected to be under-represented in a pollen record relative to the scrub and woodland vegetation of the Taihang Mountains which will probably have the effect of reducing the aerial contribution to the lake pollen record relative to the fluvial component.…”