Provenance variations in stem productivity of 30-year-old Japanese larch trees planted in northern and central Japan are associated with climatic conditions in the provenances
<p>An association between provenance variations in growth performance of the Japanese larch (<i>Larix kaempferi</i>) and climatic conditions in the provenances has been found in the natural distributional range in central Japan. To verify whether this association differs in northern Japan, outside of the original habitats, we examined stem productivity of 30-year-old trees planted in three test sites in the Nagano Prefecture in central Japan and three test sites in the Hokkaido Prefecture in northern Japan. The trees originated from 25 provenances throughout the whole range of the natural distribution. Stem-productivity variances of interactions between the test sites and provenances were relatively small. Provenance correlations in the stem productivity among most of the tests sites were positive. Climatic conditions in the provenances and test sites were summarized as two indices: a gradient of warmth and drought (higher temperature and less precipitation at lower elevations) and a cline of climatic seasonality (from the northwestern to southeastern sides of the Japanese mainland, with decreasing and increasing seasonal variations in temperature and precipitation, respectively). The maximum stem productivity among the provenances was frequently observed at both extremities of the warmth/drought gradient and on the southeastern side of the climate-seasonality cline. These associations were detected in test sites in both central and northern Japan. These findings suggest similar provenance variations in growth performance of the Japanese larch among different growing environments in Japan.</p
