A small mud clast ("mc" in Fig. 6a) at the base of the overlying silt penetrates into the massive sand without disturbance of the lower boundary of the sand.
The vegetational disturbance and sand movement were probably triggered by a climatic change to cooler conditions.
During two years (2003 2004), 133 dune patches between Nieuwpoort Belgiumm) and Bray-Dunes (France) varying in area, connectivity, eolian sand dynamics and trampling disturbance were sampled for five focal species: two spiders (Alopecosa fabrilis and Xysticus sabulosus), two butterflies (Issoria lathonia and Hipparchia semele) and one grasshopper (Oedipoda caerulescens).
Other potential causes for the martin's decline include the disturbance of sand bars in the rivers, and the construction of dams (which flood the area upstream and change the water flow downstream), deforestation, and increasing conversion of its habitat to agriculture.
Despite these dominant effects of elevation and habitat, the amount of sand accretion or loss (disturbance) at each site also had a significant effect on the plant community structure, which has implications for the effects of climate change.
What triggers germination is unknown, and seedlings have also arisen from areas disturbed by sand mining, sometimes growing in higher concentrations than before the disturbance.
Since the measurement of shear modulus is very sensitive to soil disturbance, especially for sand, determination of the stiffness of soil in the field is more reliable than in laboratory tests on sampled specimens.
Other potential causes for the species' decline include the disturbance of riverine sand bars, the construction of dams which flood the area upstream and alter the downstream hydrology, deforestation, and increasing conversion of its habitat to agriculture.
Understanding the effects of the disturbance caused by sand accretion or erosion on dune plant communities will help to elucidate the mechanisms by which global climate change can affect areas such as barrier islands, sandy bars and spits.
Oil sands mining is a major disturbance to boreal landscapes in north-eastern Alberta, Canada.
