Pinus elliottii Growth Areas and Yield Estimation

Pinus elliottii a native of the southern USA also goes by the name of slash pine. It is an evergreen conifer with very long needles, an extensive root system and a moderate taproot (Hill, 2001). P. elliottii is the hardiest of the three main species of pine grown in South Africa (the other two being P. patula and P. taeda) and produces a relatively hard, durable wood which, because of its high resin content, however, limits its marketability (Smith, 1998). Normally planted in pits, it is weed sensitive (Smith, 1998).

Climatically optimum growth areas for Pinus elliottii have been defined in the ICFR`s Forestry Toolbox (Kunz, 2004), by mean annual precipitation (MAP) and mean annual temperature (MAT), as illustrated in This figure also shows the climatic conditions under which suboptimum growth would take place because conditions may at times be too cold and damage from snow occurs, or because occasional drought may occur. Optimum and sub-optimum growth areas of P. elliottii 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. Using Smith`s (1994) rule based approach and considering only his climatic criteria and not soil or management factors, Pinus elliottii yield estimates were done.

湿地松（Pinus elliottii）原产于美国南部，又名slash pine。它是一种常绿针叶树，具有极长的针叶、庞大的根系和中等发达的主根（Hill，2001）。湿地松（P. elliottii）是南非种植的三种主要松树中最耐寒的品种（另外两种为展叶松P. patula和火炬松P. taeda），其木材相对坚硬耐用，但因树脂含量较高，市场推广受到限制（Smith，1998）。该树种通常采用穴植方式种植，且对杂草较为敏感（Smith，1998）。

湿地松的气候最适生长区已在ICFR的林业工具箱中通过年平均降水量（mean annual precipitation, MAP）和年平均气温（mean annual temperature, MAT）进行了定义（Kunz，2004）；该图还显示了次适生长的气候条件，包括偶尔出现的低温积雪危害或干旱。通过将这些标准应用于南非年平均降水量（MAP，Lynch，2004）和年平均气温（MAT，Schulze and Maharaj，2004）的1角分（纬度/经度各1分）数据库，绘制出了湿地松（P. elliottii）的最适及次适生长区域。采用Smith（1994）的规则化方法，仅考虑其气候标准（未纳入土壤或管理因素），对湿地松的产量进行了估算。