Response of phytoliths in Phragmites communis to humidity in NE China

Leaves of Phragmites communis were collected from five sampling sites distributed across three climatic zones in NE China, each zone representing a different level of humidity. A total of 4372 phytolith particles were counted from the leaves and classified into six types. The types of phytoliths are saddle, lanceolate, bulliform, and rondels, elongated, favose. Phytoliths in P. communis are sensitive to change in humidity. The main types from the five sampling sites are identical. The proportion of saddle phytoliths is greater than other phytoliths types. However, the quantity of phytoliths in P. communis differs markedly across the five sampling sites. In Shalan, Changchun, and Changling, the corresponding proportions of the saddle type are 28.1%, 25.4%, and 37.6%. In samples representing the aquatic, seasonal waterlogged, and mesic sampling sites from Nanhu Lake in Changchun, the corresponding proportions for saddle phytoliths are 32.6%, 20.6%, and 23.0%. The size of phytoliths, tested by CA, VA and PCA, to some extent indicates that the humidity is the main factor affecting the phytoliths. In Shalan, Changchun, and Changling, as humidity decreases, the phytoliths grow larger. In Nanhu Lake, as humidity decreases, the phytoliths grow smaller. The result reveals that phytoliths in P. communis are both sensitive to temperature and humidity. For regional research, temperature is the most important factor in the formation of phytoliths. Lanceolate phytoliths are sensitive to habitat change, and the saddle phytoliths are also sensitive to regional differences. Compared with the long cell phytoliths, short cell phytoliths as a proxy indicator of paleoclimate are more convincing. Overall, the results confirm that humidity is one of the dominant variables controlling the formation of phytoliths, which provides a new thinking for palaeoenvironmental reconstruction.