Spatiotemporal Variation of the Microclimatic Factors at Pit and Mound Microsites in Windthrow Area of the Spruce-fir Forest and Their Relationships with Soil Temperature Diurnal Variation of Tree Pollen Concentration and Its Relation to Microclimate Factors on Hard Ground Surface in Beijing Urban Area Time lag effect between poplar’s sap flow velocity and microclimate factors in agroforestry system in west Liaoning Province.