Environmental variation and forest dynamics in the terrestrial regions around the Sea of Okhotsk

我们在俄罗斯堪察加半岛建立了3-5年前不同演为阶段的3个北方针叶林，对不同演为阶段的树木(cajanderi落叶松（Larix cajanderi）、白桦（Betula platyphylla）进行了重新测量（树干直径、树高、死亡率、招募、光合作用、叶绿素荧光）。每公顷落叶松幼苗数几乎与演替阶段无关。落叶松的光合速率高于桦木。落叶松光合系统的光氧化胁迫程度（因低温和/或低降水而放大）小于桦木。随着演替的进行，桦木的出苗率高于落叶松，但死亡率高于落叶松。同时，桦树在无性系生长时，在母树干基部产生了大量的树干吸盘。这些结果表明，桦在演替早期具有优势的繁殖和生存策略，而落叶松在演替后期具有优势的繁殖和生存策略。因此，我们认为落叶松可以成为堪察加北部森林的优势种，而桦树则可以在堪察加森林火灾等大规模扰动后形成低温、低降水等胁迫条件下的早期演替林。

We made re-measurements (stem diameter, tree height, mortality, recruitment, photosynthesis, chlorophyll fluorescence) of trees (Larix cajanderi, Betula platyphylla), in the three boreal forests with different successional stages in Kamchatka, Russia, that we established 3-5 years before. The number of Larix seedlings per ha was almost constant irrespective of successional stage. The photosynthetic rate of Larix was higher than that of Betula. The degree of photooxidative stress in the photosynthetic system (which is magnified by low temperature and/or low precipitation) was smaller in Larix than in Betula. Betula produced a larger number of seedlings than Larix but the mortality rate got higher than Larix as succession proceeded. At the same time, Betula produced a large number of trunk suckers at the base of the mother trunk as clonal growth. These results suggest that Betula has advantageous reproductive and survival strategies at the early-successional stage, while Larix has those at the late-successional stage. Therefore, we conclude that Larix can be a dominant species in the Kamchatka boreal forest while Betula can form an early-successional forest under stressful conditions (low temperature, low precipitation) after large-scale disturbance such as forest fire in Kamchatka.