Surface pollen deposition in a modern woodland–steppe ecotone in the southeastern edge of the Inner Mongolia Plateau, situated between the deciduous broadleaved forest zone and the steppe zone in Asia, has been investigated. The following pollen and spore groups can be classified according to the relationship between surface pollen and plant community: (1) pollen group representing the whole study region: Artemisia, Betula, Chenopodiaceae, Polygonaceae and Plantago; (2) pollen group representing a vegetation zone: Pinus; (3) pollen and spore group representing a certain community type: Quercus, Picea, Ostryopsis, Corylus and spores; and (4) pollen group having a low representation: Ulmus, Gramineae, Leguminosae and Compositae. According to the pollen composition in each vegetation zone, four vegetation zones of the investigated area could be characterized by the following combinations of pollen types: (1) woodland zone: Betula–Pinus-Artemisia; (2) woodland–grassland zone: Betula-Artemisia; (3) woodland-steppe zone: Artemisia-Betula-Chenopodiaceae; and (4) steppe zone: Artemisia-Chenopodiaceae. Some ratios of various pollen types have been proved to be better at indicating the vegetation gradient than single pollen types. For example, C=A (Chenopodiaceae=Artemisia), A=B (Artemisia=Betula) and AP=NAP (Arboreal pollen=Non-Arboreal Pollen) show distinctly the gradient from the woodland zone to the steppe zone. This investigation has a future application for the reconstruction of Holocene vegetation and climate history in the investigated area. Various pollen combinations can be used as 'indicator units' for the diagnosis of vegetation types from fossil pollen analysis. Some problems of the interpolation of vegetation from fossil pollen data in the semi-arid area have also been discussed. High Artemisia pollen value do not indicate an Artemisia-dominated steppe vegetation due to the under-representation of Gramineae pollen. Plantago pollen in semi-arid and arid area can hardly be regarded as an indicator of human interference.

Pinus tabulaeformis is an endemic species in northern China. The northern edge of its distribution corresponds to the northern margin of the monsoon climate. Several stands of Pinus tabulaeformis beyond its major range of distribution were found on the southeastern edge of the Inner Mongolia Plateau. Phytosociological analysis shows that the community structure, species composition and regeneration ability of Pinus trees in these stands are quite different from those within its continuous range of distribution. This paper presents palynological evidence to explain how and when these remnant communities were formed. Pinus tabulaeformis entered the study area in the mid-Holocene as the summer monsoon intensified, and declined when the summer monsoon weakened. Climatic change was the driving factor for the migration of Pinus tabulaeformis. It might be supposed that the competition between pine and oak forest during the mid-Holocene warm period also affected the immigration of pine. The remnant stands of Pinus tabulaeformis were apparently favored by the microhabitat of the sandy soils in valleys when the climate became drier. The remnant stands of Pinus tabulaeformis help stabilize the stand dunes. The protection of these stands is an important task of natural conservation in the study area.

The vegetation of the woodland-steppe transition in southeastern Inner Mongolia, where the East Asian monsoon climate reaches its northwestern edge, is described and analysed in this paper. The communities are classified in a phytocoenological way. 12 major types of woodland, shrubland, meadow, fen, open woodland and steppe are differentiated and described according to 133 relev

Discriminant functions link vegetation zones and surface pollen along the woodlandsteppe ecotone in northern China. These links were utilised to reconstruct palaeovegetation using fossil pollen data from four lake sediment sites within the ecotone. Holocene movements of the vegetation zones were derived from the above results and were interpreted as the results of climatic, topographic and edaphic factors. This study shows that climatic change was the driving factor for ecotonal movement, but that the positions of vegetational zones were nevertheless controlled by topographical and edaphic conditions, and consequently boundaries between different vegetational zones responded individualistically. Copyright