Study On Microclimate Characteristics And Soil Physical Properties Of The Broad-leaved Korean Pine Forest Gaps

Based on broad-leaved Korean pine forest gaps in Xiao Xing'an Mountains, and themicroenvironmental heterogeneity of illumination, soil temperature and soil physical propertieswere analyzed by classical and geographical statistical method during growing season, andthen the microclimate among different size gaps, bare ground and understory was compared.The results showed as follows:The spatial heterogeneity features of illumination and soil surface temperature in varyingdegrees were shown in the broad-leaved Korean pine forest gap, and displayed a differentvariation trend at different stages during growing season. The spatial variation degree ofillumination in different months presented single-peak changing tendency over time; except themedium variation in some individual months, the spatial heterogeneity of autocorrelation ofillumination and soil temperature in the forest gap was the main part of the total, and possessedgreater variation. The higher values of illumination and soil surface temperature were found onthe northwest-north-east of the gap in a day, and the soil temperature was also affected. Thedistributions of illumination and soil surface temperature were complicated to different extentduring growing season, and the edge effects were significant.The total and autocorrelation spatial heterogeneity of soil physical properties in top soillayer were greater than that in lower soil layer in the broad-leaved Korean pine forest gap. Thespatial. heterogeneity of autocorrelation was the main part of the total. The mutual effectsbetween variation functions of autocorrelation spatial heterogeneity of soil physical propertiesin top soil layer were smaller than that in lower soil layer. The autocorrelation spatialheterogeneity of soil moisture in top soil layer was greater than that in lower layer duringgrowing season except in August; the total spatial heterogeneity of soil moisture in the samelayer and structural proportion showed definite rules within growing season. As for the spatialdistribution of soil physical properties in forest gap, the medium-level and low-level patcheswere dominant in different soil layers, but relatively higher level patches only distributed in topsoil layer.The high-level patches of soil moisture occupied the top soil layer in June, but low-levelpatches also did that, the area of high-level patches was less than that of other level patches inother months; this trend was especially significant in July and August. The low-level patchesoccupied lower soil layer in all months during growing season, but high-level patches rarelyoccurred in the forest gap.The diurnal and growing seasonal variations of illumination, soil surface and airtemperature showed single peak change trends in the forest gaps of different size and control in broad-leaved Korean pine forests. In a day, the highest data occurred at noon in all observationlocations; during growing season, their maximum data happened in the forest gaps and bareground in July; but they did in understory in June. In most of time, the illumination, soilsurface and air temperature gradually decreased with forest canopy closing. The air relativehumidity was higher early in the morning and late in the evening, but lower at noon in a day;and showed single peak change trends during growing season; its maximum data appeared inthe middle of growing season, but its minimum data happened in the early period and lateperiod of growing season, and it increased with forest canopy closing. The precipitation andtimes of rainfall decreased with forest canopy closing. During growing season, the prevailingwind directions of bare ground, large and middle gaps were southwest, but those of small gapand understory were south, and the speed of wind decreased with forest canopy closing.