栓皮栎水源林林木耗水尺度扩展方法研究

Single trees sapwood scattering style and diameter classes diurnal water consumption rhythm were studied in a 48 years old Quercus variabilis stand at the east hill slope, located in the Forest Research Station of Beijing Forestry University in the water conservation area in Beijing (39°54′N, 116°28′E). Results showed that relation between trees sapwood area and diameter at breast height (DBH) was significant. Single trees daily water consumption ascended as DBH and sapwood area increased, and related significantly. Daily water consumption of different diameter class in September ascended steeply from the early morning and got the peak around 11:00 pm, and then descended till 18:00 when it got the valley slowly. Three-dimension model of daily-accumulated water consumption was acquired by scaling-up method from the typical Richards model and characteristic parameters of daily stand water consumption course were calculated from modulated Richards equation derivative: W d-it-j=(-7.147+1.174 d-i)[1-(-3 025.937+d 2.175 i)e (-0.011t-j)] 1/(1-d 0.242 i)(R=0.985 8).

无灌溉造林树种耗水特性的研究

采用无灌溉造林的方法,依据水量平衡技术与Penman-Monteith方程,研究干旱地区造林树种沙棘、梭梭、紫穗槐和锦鸡儿的蒸腾耗水规律、林木需水量、林木系数及林木水分亏缺量。结果如下:4种灌木在生长期内的蒸腾速率皆为双峰型,沙棘、锦鸡儿和紫穗槐的峰值出现时间一致。梭梭的峰值出现在10∶30和16∶30左右。各树种阳坡的蒸腾速率>阴坡的蒸腾速率。4种灌木中紫穗槐的耗水量最大,阳坡与阴坡的耗水量分别为173.4 mm和134.86 mm,梭梭的耗水量最小。干旱地区各树种生长期内的林木系数有所不同,5月份的阴坡梭梭林木系数最小为0.16,7月份阳坡紫穗槐林木系数最大为1.33。紫穗槐的水分亏缺量最大、沙棘次之,梭梭水分亏缺最小。所以梭梭为最适树种,紫穗槐为干旱地区较难生存、生长的树种。

林木蒸腾耗水量测算方法的比较与应用

本文简述了林木蒸腾耗水的概念、研究价值和研究进展,从实测法和估测法的角度,综述了林木蒸腾耗水量的主要测算方法,对比了各方法的优缺点、适用性、局限性、应用现状以及适用尺度。本研究认为:实测法可应用于多种空间尺度耗水量的测定,估测法常应用于大空间尺度蒸散量的测算。实测法是估测法的基础,因此应对实测法的测定结果进行合理的质量控制与评价,为校正估测法的估算结果提供数据基础。不管是同一大空间尺度还是不同空间尺度,实测法和估测法的结合能够提高蒸散量测算结果的准确性。提升复杂下垫面和恶劣气候环境下大空间尺度林木蒸散量的测算精度将成为未来的研究热点与难点。随着科学技术的不断进步,现有的测定装置和测算方法将被改进,精确测定林木蒸腾耗水量的新方法也将随之诞生。