To assess the reliability of arboreal phytoliths for differentiating vegetation types in temperate forest regions, we systematically analysed arboreal leaf phytoliths from 72 arboreal plants and 49 modern soils from three forest types in northeast China. The arboreal leaf phytolith production and morphotypes were highly variable between species. The arboreal leaf phytolith assemblages could clearly distinguish between broadleaf and coniferous species, but they were much less successful in differentiating broadleaved trees into subtaxa. Coniferous leaf morphotypes were successfully used to differentiate coniferous trees into families and subtaxa, especially in the Pinaceae. Two diagnostic broadleaved and six coniferous phytolith morphotypes were recognized within the modern soil beneath forest ecosystems. These arboreal phytoliths comprised up to 10–15% of the total soil phytoliths, and were dominated by coniferous types. Arboreal phytolith concentrations and phytolith assemblages in the soils fluctuated substantially amongst the three forest types. Soil arboreal phytolith assemblages were successfully used to differentiate samples from Larix mixed forest, broadleaf forest and Pinus koraiensis mixed forest. In addition, the arboreal index quantitatively distinguished the three forest types, with B/BE values <0.4 for Larix mixed forest samples, values from 0.4 to 0.6 for broadleaf forest samples, and values from 0.6 to 0.9 for P. koraiensis mixed forest. Thus, our surface soil arboreal phytolith assemblages and arboreal index are a useful reference for differentiating forest ecotypes, and they also provide reliable analogues for arboreal phytoliths from palaeoecological contexts in temperate forest regions.

We investigated the phytolith assemblage characteristics and preservation of soil phytoliths in nine soil types at 83 sites in northeast China. The results indicate that the phytolith assemblages from the nine soils are similar, particularly in terms of the content of the dominant short cell phytoliths, and elongate and lanceolate phytoliths. The phytolith indexes of aridity and water stress (Iph and Fs, respectively) have been proven to be effective in the temperate zone, and we find that values of Iph and Fs higher than 0.45 and 0.24, respectively, are characteristic of meadow steppe. However, there are differences in phytolith indexes amongst the different soil types. In addition, the preservation characteristics of phytoliths in different soil types are different, with phytolith preservation in zonal soils being better than in azonal soils. Morphotypes such as rondel, bilobate, lanceolate, blocky, tabular and bulliform are well preserved in the studied soils; however, other morphotypes, such as microhair, conical epidermal, silicified stomata and epidermal, are poorly preserved. Morphotypes such as saddle, trapeziform sinuate and elongate are moderately well preserved in the soils. The preservation characteristics of the same type of phytolith differ between the soil types. Thus, there are differences in the preservation of soil phytoliths amongst different soil types, which needs to be considered when soil phytoliths are used to produce quantitative palaeoenvironmental reconstructions.