Magnitude and duration of growth and wood quality responses to phosphorus and nitrogen in thinned Pinus radiata in southern Western Australia
Magnitude and duration of growth and wood quality responses to phosphorus and nitrogen in thinned Pinus radiata in southern Western Australia
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西澳大利亚州南部间伐辐射松的生长幅度和持续时间以及木材质量对磷和氮的反应
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发表时间：
2003
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通讯作者：
I. Dumbrell
中科院分区：
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作者：
J. McGrath;B. Copeland;I. Dumbrell
研究了疏伐后第一代辐射松（Pinus radiata D.）唐种植园在前本土森林网站在西澳大利亚州南部。在施肥后10年内，使用高达360 kg P ha−1和540 kg N ha−1的析因P x N试验来监测树木生长。主要的不足是P，因为没有响应N在没有P的情况下。没有N的应用程序的响应P的幅度是有限的，最佳的P应用程序是低于当N被应用。磷、氮配施效果最佳。在施用后的前4年，在最佳的P和N比例下，断面积增加量增加了86%。在施氮量最高时，对氮素的反应最长可达4年。对P的反应持续了10年，尽管在此期间结束时，P的反应在较低的速率下降。这种下降的增长和浓度的下降，在土壤中的碳酸氢盐和HCl提取的P表明，在这种红土，P的可用性下降随时间推移。在研究的10年中，施肥导致木材增加了100 m3 ha−1，并将周期性年增量从16 m3 ha− 1增加到26 m3 ha−1。施氮降低了木材密度的生长响应的N的持续时间，但木材密度保持在结构级木材所需的最低密度以上。施肥对干形没有不利影响，因为锯材和小锯材的体积比例没有变化。由于原木直径的增加，原木从较小且因此价值较低的类别（小锯材原木）移动到较大且价值较高的类别（锯材原木），增强了对肥料的响应值高于总体积的增加。
Summary The responses to phosphorus (P) and nitrogen (N) following thinning were investigated in a first-rotation Pinus radiata D. Don plantation on an ex-native forest site in southern Western Australia. A factorial P x N trial with up to 360 kg P ha−1 and 540 kg N ha−1 was used to monitor tree growth for 10 y after application of fertiliser. The primary deficiency was P, as there was no response to N in the absence of P. Without the application of N the magnitude of the response to P was limited, and the optimum P application was lower than when N was applied. The optimum response was achieved by combined applications of P and N. In the first 4 y after application there was an 86% increase in basal area increment at the optimum rate of P and N. The response to N lasted a maximum of 4 y at the highest rate of N application. The response to P continued for 10 y, although the response at the lower rates of P declined towards the end of this period. This decline in growth and the decline in concentration of both bicarbonate-and HC1-extractable P in the soil indicated that, on this lateritic soil, P availability declined overtime. Fertiliser application resulted in an extra 100 m3 ha−1 of wood over the 10 y of the study, and increased the periodic annual increment from 16 to 26 m3 ha−1. Nitrogen application reduced wood density for the duration of the growth response to N, but the wood density remained above the minimum density necessary for structural- grade wood. Fertiliser had no detrimental effect on stem form, as the proportion of the volume classified as sawlog and small sawlog was unchanged. The movement of logs from a smaller and hence lower- value category (small sawlog) to a larger, higher-value category (sawlog) due to an increase in log diameter, enhanced the value of the response to fertiliser above the increase in total volume.