旷野风速对林网内风速分布及防风效能的影响

为了揭示旷野风速对农田林网内风速分布及防风效能的影响,通过空间多点实地观测,利用传统统计分析、Surfer软件、地统计学等方法对3种风速(5.4,7.2和10.3m/s)条件下的林网内风速分布及防风效能进行了分析。结果表明,3种旷野风速下主林带的背风面均形成一个较大范围的降风区;3种旷野风速下林网平均降低风速效能为26.1,23.3和25.7%,平均有效防护面积比为50.8%,41.7%和47.7%,林网的总体防护效能在风速为5.4m/s时为最大,风速为7.2m/s时为最小;3种不同旷野风速下林网风速空间变异函数均可以较好地拟合为球状模型,3种旷野风速下网格内风速块金值与基台值的比值较小,均小于25%,林网内风速均具有强烈的空间自相关性。旷野风速对林网内风速分布及防风效能的影响比较复杂,并不是单一的随着风速的增大而增大或减小,受林带结构及疏透度的影响较大。

Influence of Desert Wind Velocity on Wind Velocity Distribution in Forest and Windbreak Effect

In order to explore the influence of the desert wind velocity on wind velocity distribution in forest and windbreak effect, this article observed in multi points, using traditional statistical analysis, surfer software, geostatistics and other methods to analysis wind velocity distribution in forest and windbreak effect when the desert wind velocity is 5.4, 7.2 and 10.3 m/s. The results showed that the leeward side of primary forest formed a wind down district under all 3 kinds of desert wind velocity; The average wind velocity reduced by forest is 26.1%,23.3% and 25.7% under 3 kinds of desert wind velocity. The average effective protection area ratio is 50.8%, 41.7% and 47.7%. The overall effectiveness of forest protection is maximum with a wind speed of 5.4 m/s and minimum with a wind speed of 7.2 m/s; forest wind velocity spatial variability functions under 3 kinds of desert wind velocity can be a good fit as a spherical model, the ratio of nugget to sill under 3 kinds of desert wind velocity is small, and all were less than 25%, and forest wind velocity has a strong spatial autocorrelation. The influence of the wind velocity of desert on wind velocity distribution in network of forest and windbreak effect is complex, it does not increase or decrease with desert wind velocity but strongly influenced by forest structure and porosity.