The conventional stake test is widely used to evaluate wood durability. The test monitors the deterioration level observed on stakes partially inserted into the ground. The test results are conventionally expressed as the relationship between the mean deterioration level and exposure periods. Durability is compared between the stake groups based on the test results; however, there is no scientific basis for the comparison. To include a scientific basis to the conventional stake test, we applied survival analysis to it. Four stake groups were subjected to deterioration at three sites for 7 years. The deterioration levels were monitored according to the conventional procedure, and survival analysis was applied to the monitored data. The Kaplan–Meier curves plotting the survival probabilities against the exposure periods indicated that the durability of the test stakes of Japanese cedar heartwood is higher than those of Japanese cedar sapwood. However, it was also demonstrated that the durability ratio between Japanese cedar heartwood and sapwood was strongly dependent on the test sites. It was also revealed that the durability of the heartwood portion did not differ significantly among Japanese cedar, Japanese cypress, and Japanese larch. These results were verified using the modified Gehan–Wilcoxon test.

中文翻译：

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通过桩测试和生存分析比较木材的自然耐久性

传统的桩测试被广泛用于评估木材的耐久性。该测试监测在部分插入地面的桩上观察到的恶化水平。测试结果通常表示为平均劣化水平和暴露时间之间的关系。根据测试结果比较权益组之间的耐久性；然而，这种比较没有科学依据。为了给传统的权益测试提供科学依据，我们对其进行了生存分析。四个支联会在三个地点遭受了长达 7 年的恶化。按照常规程序监测恶化水平，并对监测数据应用生存分析。Kaplan-Meier 曲线绘制的存活概率与暴露时间的关系表明，日本雪松心材测试桩的耐久性高于日本雪松边材。然而，也证明了日本雪松心材和边材之间的耐久性比在很大程度上取决于测试地点。还表明，在日本雪松、日本柏和日本落叶松之间，心材部分的耐久性没有显着差异。使用改进的 Gehan-Wilcoxon 检验验证了这些结果。还发现，杉木、柏树和落叶松的心材部分的耐久性没有显着差异。使用改进的 Gehan-Wilcoxon 检验验证了这些结果。还发现，杉木、柏树和落叶松的心材部分的耐久性没有显着差异。使用改进的 Gehan-Wilcoxon 检验验证了这些结果。