Pinus patula Growth Areas and Yield Estimation

Of the three major species of pines grown commercially in South Africa, viz. Pinus taeda, P. elliottii and P. patula, the latter is in many respects the least tolerant of the three. For optimal growth, Pinus patula requires a MAP > 950 mm. Mean annual temperatures should ideally be > 13 degree Celsius but < 18 degree Celsius. P. patula is highly susceptible to Sphaeropsis sapinea after hail damage (Smith, 1998). It is, however, least prone to damage by snow because of the hanging nature of its needles. Pinus patula generally require a minimum soil depth of 0.7 m, but this can be relaxed to 0.6 m when clay content exceeds 35 percent.

Climatically optimum growth areas for Pinus patula have been defined in the ICFR`s Forestry Toolbox (Kunz, 2004), by mean annual precipitation (MAP) and mean annual temperature (MAT). This figure also shows the climatic conditions under which sub-optimum growth would take place because conditions may be too cold and snow may cause damage, or too dry with either occasional or more frequent droughts occurring, or because the trees may become diseased under hot and wet conditions. Optimum and sub-optimum growth areas of P. patula were mapped by applying these criteria to the one arc minute (1` x 1` of a degree latitude/longitude) databases of MAP (Lynch, 2004) and MAT (Schulze and Maharaj, 2004) for South Africa.

在南非商业化种植的三大松树品类中，即火炬松（Pinus taeda）、湿地松（Pinus elliottii）与展松（Pinus patula），展松在诸多方面的耐受能力为三者最弱。
展松的最优生长条件为：年平均降水量（Mean Annual Precipitation, MAP）需大于950毫米，理想年平均气温范围为13摄氏度至18摄氏度之间。展松在遭受雹害后，极易感染松枯梢病菌（Sphaeropsis sapinea）（Smith, 1998）。但由于其针叶呈下垂状，展松受雪害的概率则为三者最低。展松通常要求最低土壤厚度为0.7米，但若土壤黏土含量超过35%，该要求可放宽至0.6米。

ICFR的林业工具箱（Kunz, 2004）已基于年平均降水量（MAP）与年平均气温（Mean Annual Temperature, MAT），明确了展松的气候适宜生长区。该工具箱中的图表同时展示了展松次适宜生长的气候条件：当环境过冷易引发雪害、环境过干导致偶发或频发干旱，或是高温高湿环境下树木易染病时，均属于次适宜生长区间。研究人员将上述判定标准应用于南非的1弧分（纬度/经度1'×1'）分辨率年平均降水量数据库（Lynch, 2004）与年平均气温数据库（Schulze and Maharaj, 2004），绘制出了展松的适宜与次适宜生长区分布图。