Surface movement and deformation characteristics due to high- intensive coal mining in the windy and sandy region

As China＇s energy strategy moving westward, the surface movement and deformation characteristics due to high-intensive coal mining in the windy and sandy region become a research hotspot. Surface movement observation stations were established to monitor movement and deformation in one super-large working face. Based on field measurements, the surface movement and deformation characteristics were obtained, including angle parameters, subsidence prediction parameters, etc. Besides, the angle and subsidence prediction parameters in similar mining areas are summarized; the mechanism of surface movement and deformation was analyzed with the combination of key stratum theory, mining and geological conditions. The research also indicates that compared with conventional working faces, uniform subsidence area of the subsidence trough in the windy and sandy region is larger, the trough margins are relative steep and deformation values present convergence at the margins, the extent of the trough shrink towards the goaf and the influence time of mining activities lasts shorter; the overlying rock movement and breaking characteristics presents regional particularity in the study area, while the single key stratum, thin bedrock and thick sand that can rapidly propagate movement and deformation are the deep factors, contributing to it.

Patterns of leaf N:P stoichiometry along climatic gradients in sandy region, north of China

Aims Biological and environmental factors determine geographic patterns of plant nutrient stoichiometry jointly.Unraveling the distribution pattern and the potential drivers of nutrient stoichiometry is therefore critical for understanding the adaptive strategies and biogeochem-istry cycling.Aimed to determine how leaf nitrogen(N):phosphorus(P)stoichiometry is linked to biological and environmental factors,we investigated the patterns of psammophyte leaf N:P stoichiometry in sandy region,northern China,and the potential factors affecting leaf N:P stoichiometry were explored.Methods Based on 10 m×10 m quadrates survey,the leaves of 352 dominant psammophyte samples belonging to 167 species were collected cross a 3000 km east-west transect in sandy environments,north-ern China.The samples were further classified into the following groups on the basis of plant life forms and functional groups(pho-tosynthesis pathways and nitrogen fixation).The structural equation modeling was employed to clarify the importance of biological and environmental factors on leaf N:P stoichiometry.Important Findings Generally,the higher leaf N and P concentrations,but lower N:P ratio were found in psammophyte compared with other ecosystems.Mean annual temperature(MAT)influenced the leaf N,P concentra-tions negatively,while mean annual precipitation(MAP)did posi-tively.MAP played greater influence on leaf N,P concentrations than MAT did.MAP affected leaf N,P concentrations directly or indirectly through phylogeny,while MAT only shown direct effect on leaf N concentration.The psammophyte was more limited by N,rather P,in sandy region of northern China.These results suggest that phylogeny of psammophyte and climate jointly influence leaf N:P stoichiometry,and the results could be helpful in modeling bio-geochemical nutrients cycling in vulnerable ecosystems like sandy environment.