【作者】 李轶涛；

【导师】 余新晓；

【作者基本信息】 北京林业大学 ， 水土保持与荒漠化防治， 2014， 博士

【摘要】 水分由土壤进入森林植物体内,通过茎杆到达叶片,再从气孔以水汽的形式扩散到空气边际层,最后参与大气的湍流交换,形成相互作用且动态统一的连续系统,即土壤-植被-大气连续体(Soil-Plant-Atmosphere Continuum),简称SPAC.由于研究方法和观测手段的不足,过去这一研究一直以农田生态系统为主,对于高大、复杂多样的森林生态系统研究较少。本研究主要以北京山区典型人工林为研究对象,依托国家林业局首都圈森林生态系统定位观测研究站,对该地区典型森林生态系统进行长期定位观测。通过分析SPAC各界面之间的能量交换和SPAC系统内水分传输及其驱动机制：(1)北京地区典型森林生态系统热量平衡各项都与净辐射有相同的日变化特征,一般表现为净辐射>潜热通量>显热通量>土壤热通量。生长季生态系统所接受的净辐射绝大部分用于潜热交换和显热交换,非生长季净辐射绝大部分用于潜热交换。潜热通量占净辐射的比例8-9月逐渐下降,9月上旬下降最快,而潜热通量和土壤热通量的比例9-10月逐渐上升,反映了植被生命活动能力的季节变化。在非生长季时土壤是森林生态系统的热源之一,热量由土壤向上传递。而生长季时则相反,是热能汇。年平均土壤热量为-1.48w/m2,说明年尺度上,土壤也是森林生态系统的热源。(2)各林分土壤容重除了侧柏外都随土层深度增加而增加。平均土壤容重排序为：侧柏林>油松林>刺槐林>栓皮栎林。针叶林的土壤渗透能力要明显高于阔叶林。土壤入渗过程用蒋定生公式拟合的效果最佳。通过逐步回归分析表明,土壤入渗率与土壤初始含水量和非毛管孔隙度关系最密切。通过相关分析得出土壤日蒸发量与相对湿度、降水量与呈负相关,而与VDP、太阳辐射与土壤日蒸发量呈正相关关系。通过CCA的自动前向选择对影响土壤水分因子进行排序,其影响大小的顺序为降雨量>土壤热通量>土壤水势>大气温度>大气湿度。这一排序结果表明长时序的土壤水分变化最主要的影响因素是降水量,其次热能是土壤水分传输的重要影响要素。(3)北京山区林分树种树干液流速率均呈典型的单峰变化趋势。四个树种的树干液流速率都为晴天>阴天>雨天。侧柏、油松、刺槐和栓皮栎的树干液流速率与气温、相对湿度、太阳辐射和VDP四个环境因子都达到了0.01水平上显著相关,其中与太阳辐射的相关性都最高。四个树种生长季的总蒸腾量存在很大差异,总蒸腾量排序为侧柏(428.71mm)>油松(329.30mm)>栓皮栎(311.82mm)>刺槐(263.05mm)。相同树种林分生长季内各月的蒸腾量也各不相同,总体来说,5、6月份的蒸腾量相对较小,7、8、9三个月份的林分蒸腾量相对较高(4)多年降雨资料表明北京地区10年间降雨量变化较均匀,无明显波动。北京地区季节降雨特征为：降雨量季节差异很大,其中夏季降雨量最大,平均降雨量达到302.7mm,占年均降雨量的64%。主要降雨类型为小雨(0-10mm)降雨场次达60场,占了总降雨场次的67.4%,但其对降雨总量的贡献率却并不是最大的,仅占17.1%。研究区场降雨雨强特征：降雨强度受控于降雨量与降雨历时,89场降雨的平均降雨强度介于0.02-37.16mm/h之间。(5)根据实测及文献资料调整参数后的COUP model可以较好的应用于研究区。采用R2和均方根误差来评价模型的模拟效果,COUP model可以较好的对土壤水分动态和植物蒸散进行模拟。林分蒸腾及林冠截留是重要的水分输出项,林分蒸腾在各个林分中均占到50%以上,林冠截留占有的比例也在15%以上,土壤蒸发在这个水量平衡过程中也占有一定的比例,而地表径流计枯落物截持占用的比例较小。枯落物层截留分配比例均在1%以下,地表径流分配比例均在3%左右。更多还原

【Abstract】 As the main structure of the terrestrial ecosystem, the forest ecosystem cover approximately30%of the terrestrial surface. Through the exchange of energy and matter between soil and atmosphere, the forest ecosystem profoundly influenced and shaped the terrestrial ecosystem. The relationship between forests and water is the core direction of the study of forest ecology and soil and water conservation. Water move from the soil into the forest canopy through stalks, then evaporate in the form of water vapor into the air marginal layer, and finally participate in the exchange of atmospheric turbulence. The formation of a unified continuous interaction and dynamic system, namely soil-vegetation-atmosphere continuum (SPAC).In this study, research mainly focus the forest plantation of Beijing mountainous area. Relying on the State Forestry Administration metropolitan Forest Ecosystem Research Station, the area of forest ecosystems typical positioned for long-term observation. By analyzing the energy exchange between the interface and the SPAC SPAC each water transfer system and its drive mechanism, this study made following conclusions:(1) In the non-growing season when the soil is one of the heat of forest ecosystems, the heat is passed up from the soil. And when the growing season, by contrast, is a heat sink. The yearly mean soil heat was-1.48w/m2, the instructions on-year scale, the soil is one heat source of forest ecosystem. Soil heat flux, especially the soil surface heat flux is closely related to the net radiation, soil heat flux in the study area and the regression equation for net radiation. Indicating that the soil heat flux greatly affected by the net radiation, may be due to the higher forest canopy, making a greater proportion of net radiation reaches the earth’s surface, soil heat flux outside influence by more intense. Use of net radiation to soil heat flux is an effective way.(2) Beijing regions typical forest ecosystems are associated with the heat balance of the net radiation has the same diurnal variation, the relationship between the number of generally expressed as net radiation> latent heat flux> sensible heat flux> soil heat fluxes. Growing season ecosystem net radiation received by the majority for latent heat exchange and sensible heat exchange, rather than the growing season, the vast majority of net radiation for latent heat exchange. Latent heat flux ratio of net radiation decreased from August to September, the fastest decline in early September, while the proportion of latent heat flux and soil heat flux gradually increased from September to October, reflecting the seasonal changes in vegetation life activity.(3) Species stands with soil infiltration law has some differences, the size of initial infiltration rate is sort of cork oak forest> side Berlin> pine forest> locust forest, steady infiltration rate of side order of magnitude Berlin> pine forest> locust forest> cork oak forest, sorting average penetration rate and the total amount of permeate side of the Berlin> pine forest> locust forest> cork oak forests, soil infiltration capacity in general seems to be significantly higher than the coniferous forest broadleaf forest. By stepwise regression analysis showed that soil infiltration rate initial soil moisture and non-capillary porosity has the closest relationship.(4) Through the automatic selection of the former CCA to factors affecting soil moisture sort order of magnitude of the impact of rainfall> soil heat flux> soil water> air temperature> atmospheric humidity. This sort results show that soil moisture change the timing of the long main factor is rainfall, followed by heat is an important factor affecting soil moisture transfer.(5) based on the measured and literature after COUP model adjustment parameters can be appropriate applied to the study area. R2and root mean square error using simulation to evaluate the effect of the model, COUP model can appropriate soil moisture and plant transpiration dynamics simulation.更多还原