Radiative exchange, near-surface temperature and soil water of forest and cropland in interior Alaska
Radiative exchange, near-surface temperature and soil water of forest and cropland in interior Alaska
复制标题
阿拉斯加内陆森林和农田的辐射交换、近地表温度和土壤水
DOI：
10.1016/s0168-1923(97)00071-3
复制
发表时间：
1998
影响因子：
6.2
通讯作者：
B. Sharratt
中科院分区：
文献类型：
--
作者：
B. Sharratt
1980 年代初，阿拉斯加农业产业的扩张导致砍伐了 5 万公顷的北方森林。然而，人们对砍伐北方森林对地表能量交换过程的影响知之甚少。这项研究评估了阿拉斯加州三角洲章克申附近的北方森林和草地的辐射和热交换、温度和土壤水。这些地点相距 5 公里，位于几乎平坦的冲积阶地上。草地于 1978 年被清理，并于 1985 年左右播种。在这两个地点都安装了传感器，用于测量 1991 年 9 月至 1993 年 4 月的反照率、净辐射、地表热通量、近地表温度和土壤含水量。草地反照率的季节变化（0.19 至 0.85）比森林（0.08 至 0.18）更为明显。与草地相比，森林的净辐射在夏季高 20%，在冬季低 20%。在草原和森林生长季节，地表加热分别消耗了 13% 和 6% 的净辐射。草原区0.5米深度土壤温度为-14℃至10℃，森林区0.5米深度土壤温度为-2.5℃至0.5℃。与森林土壤相比，草地土壤更加干燥，含水量季节变化也更大。当含水量超过孔隙度时，0.3-0.6 m 深度的森林土壤中出现明显的冰透镜体。这项研究表明，砍伐林地将减少辐射的净吸收，但会加剧亚北极地区的土壤加热和干燥。
The expansion of the agricultural industry in Alaska during the early 1980's allowed for clearing 50 000 ha of boreal forest. Little is known, however, about the impact of clearing boreal forest on surface energy exchange processes. This study assessed radiative and heat exchange, temperature and soil water at boreal forest and grassland sites near Delta Junction, AK. The sites, located 5 km apart, were on a nearly level alluvial terrace. The grassland site was cleared in 1978 and seeded to grass in about 1985. At both sites, sensors were installed to measure the albedo, net radiation, surface heat flux, near-surface temperatures and soil water content from September 1991 to April 1993. Seasonal variations in albedo were more apparent for grassland (0.19 to 0.85) than for forest (0.08 to 0.18). Net radiation over forest was 20% greater during the summer and 20% smaller during winter compared with grassland. Surface heating consumed 13 and 6% of net radiation during the growing season at the grassland and forest sites, respectively. Soil temperatures at the 0.5-m depth ranged from −14 to 10°C at the grassland site and from −2.5 to 0.5°C at the forest site. The soil at the grassland site was drier and exhibited greater seasonal variation in water content compared with the soil at the forest site. Ice lenses were apparent in the forest soil at a depth of 0.3–0.6 m as the water content exceeded the porosity. This study suggests that clearing forest land will reduce the net absorption of radiation, but enhance soil heating and drying in the subarctic.