云冷杉林风倒区坑丘微立地微气候因子时空变化及其与土温的关系

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

为了揭示云冷杉林生长季坑丘微立地上微气候因子的时空变化以及PPFD、RH、SWC与不同深度Ts的相关性。2013年7—9月在小兴安岭谷地云冷杉林风倒区1．50hm2的固定样地内，测定所有35对坑丘微立地（丘顶、丘面、坑底、坑壁）的光量子通量密度（PPFD）、空气相对湿度（RH）、地表土壤温度（Ts0）、5cm和10cm深度的土壤温度（Ts5和Ts10），以及0～7．6cm、0～12cm和0～20cm土壤含水量（SWC1、SWC2和SWC3）等微气候因子，并将完整立地（未受掘根干扰的完整林地）设为对照样地。比较5个不同微立地微气候因子的月变化以及PPFD、RH以及SWC对土壤温度（Ts）的影响。结果表明：7-9月，坑丘微立地（丘顶、丘面、坑底、坑壁）的月均脚和％均为7月〉8月〉9月，月均RH以及Ts5和Ts10均为8月〉7月〉9月，月均SWC均为8最大；7—8月不同微立地月均PPFD大小顺序均为丘顶〉丘面〉坑底〉完整立地，9月却为丘顶〉丘面〉完整立地〉坑底〉坑壁；7—9月，各微立地Ts0大小顺序均为丘顶〉丘面〉完整立地〉坑壁〉坑底，而5cm和10cm均为丘顶〉丘面〉坑壁〉完整立地〉坑底；月均RH和月均SWC均为坑底〉坑壁〉完整立地〉丘面〉丘顶；7月丘顶的PPFD最大，为736．11μmol·m-2·s-1，完整立地最小，为25．46μmol·m-2·s-1，丘顶乐最Ts，为26．29℃，坑底以最低，为5．13℃；浅层SWC大于较深层的，最大SWC出现在8月的坑底，为51．58％。相同微立地（丘顶、坑底、完整立地）PPFD与浅层瓦的相关性大于较深层的土壤，Ts0与PPFD呈正相关，与RH呈负相关。

An investigation was conducted in a 1.5 hm2permanent plot in the windthrow area of Picea asperata and Abies nephrolepis forest in Xiaoxing＇ an Mountains to measure the microclimatic factors of photosynthetic photo flux density（ PPFD）, relative air humidity（ RH）, the soil temperature of surface（ Ts0 ）, the depth of 5 cm （ Ts5 ） and 10cm （Ts10） , soil water content at the depth of 0 ~7.6 cm （SWC1）, 0 ~ 12 cm（SWC2） and 0 ~20 cm（SWC3 ） on 35 pairs of pit and mound microsites （mound top, mound face, pit bottom, pit wall） from June to September in 2013. The intact site （intact forest floor undisturbed by uprooting） was set up as the controls. The monthly varia- tions of the microclimatic factors on 5 different microsites and the impacts of PPFD, RH, and SWC on Ts were com- pared. The results showed that： from July to September, both mean monthly PPFD and Ts0 in pit and mound mi- crostes ranked in the decreasing order of July 〉 August 〉 September, but the monthly mean RH, Ts5 and Ts10de- creased in the order of August 〉 July 〉 September, the monthly mean SWC decreased in the order of August 〉 September 〉 July; from July to the August, the monthly mean PPFD was listed in the decreasing order of mound top 〉 mound face 〉 pit bottom 〉 intact forest floor, but in September, it changed in the order of mound top 〉 mound face 〉 intact forest floor 〉 pit bottom 〉 pit wall; from July to September, the monthly mean Ts0 decreased in the order of mound top 〉 mound face 〉 intact forest floor 〉 pit wall 〉 pit bottom, but that ofTssand Ts10 were in the order of mound top 〉 mound face 〉 pit wall 〉 intact forest floor 〉 pit bottom, both the monthly mean RH and SWC was in the order of pit bottom 〉 pit wall 〉 intact forest floor 〉 mound face 〉 mound top; in July, the PPFD at mound top was the highest （736.1μmol . m-2 . s-1） and the lowest in intact forest floor （25.46 μmol . m-2 .S -1 ）, the Ts at mound top was the highest （26.29 ℃ ） and the lowest in pit bottom （5.13℃） ; the SWC in shallow soil layer was larger than that in deep soil layer, the SWC was the highest in pit bottom （51.58%） on Au- gust. The correlation between PPFD in the same microsite and Ts in shallow soil layer was larger than in deep soil layer. There was positive correlation between Tsoand PPFD, but negative correlation between Tso and RH, respec- tively.