Floristic complexes on landslides of different age in Central Yamal, West Siberian Low Arctic, Russia

Accurate ground-based datasets are important for correct interpretation of remote sensing data. West-Siberian Arctic has been exposed to rapid land-cover and land-use changes during the last 50 years. Cryogenic landslides are important disturbing agents in the region, especially in the central part of the Yamal Peninsula. Different succession stages in the recovery of cryogenic landslides are described at the example of 4 model ones formed respectively in 1989, in the middle of 1970s, in late 1950s or early 1960s and an ancient landslide back scarp dated with radiocarbon method as ca 1000 year old. Botanical survey was performed in 1991 and repeated in 2012, phytosociological study on the same landslides and their surroundings was performed in 1997-2002. Correlation between different syntaxa, age and morphological element of landslide is shown. Both projective cover and species composition change gradually on young and old landslides, though vegetation on the ancient ones did not change during the last 20 years. Pioneer communities on Yamal landslides are dominated by grasses (Deschampsia borealis, Puccinellia sibirica, Calamagrostis holmii, Poa alpigena ssp. colpodea, Dupontia fisheri). Proportion of various species differs both between years and different sections of the shear surface. Carex glareosa indicating saline deposits was recorded on landslides of all stages. Mosses play important role in the recovery and formation of organic horizon on the young landslides. Geochemical properties of the groundwater were analyzed and correlation of different communities with different levels of mineralization of groundwater is shown. Vegetation allows estimate the age of younger landslides and indicates the sites of possible ancient detachment.