| The distribution of some dominant species include Larix sibirica, Pinus sibirica, Picea obovata, and Abies sibirica in the Kanas National Nature Reserve, where were the best preserved and the most typical taiga forest, but also an important resource base and biological gene bank. It was important to mainting terrestrial ecosystem balance, protecting environment, and developing economic utilization and ecological value. In this paper, the soil respiration of four typical forest types (L. sibirica, P. obovata, P. sibirica and Betula pendula) was measured by LI-8100 soil respiration auto-measurement system from June to September in 2012 and 2013, respectively. Based on the measured data, spatial and temporal variation in soil respiration and its influence factors were analysed. The results showed that:(1) The diurnal variation of soil respiration rate of all 4 kinds of forest was unimodal curve. The daily maximum respiration rate of all 4 kinds of forest was 1.63,1.57,1.60, and 2.19 μ mol·m-2·s-1, respectively. The mean respiration rate of all 4 kinds of forest was (1.41 ±0.25), (1.39±0.09), (1.40±0.24), and (1.97±0.45) μ mol·m-2·s-1, respectively.(2) The seasonal change of soil respiration rate of the all 4 kinds of forest was unimodal curve from June to September, too. The monthly mean value of soil respiration rate was 0.72-3.34 μmol·m-2·s-1. The maximum value of respiration rate was in July, and the minimum was in June. There were significant difference among soil respiration in different month (p<0.05). The soil respiration rate variation coefficient (CV) of he all 4 kinds of forest was 19.76%～55.35%.(3) With the altitude increasing, the soil respiration rate of four typical forest types (L. sibirica, P. obovata, P. sibirica and B. pendula) decreased gradually, and the value at 1600 m were the highest, respectively to 1.79,1.56,2.00, and 2.43 μ mol·m-1·s-1. But the soil respiration of L. sibirica and P. obovata forest at 1600 m were significantly higher than that at 1700 m and 1800 m.While with the altitude increasing, the soil respiration of P. sibiricaand and B. pendula forest declined significantly (p<0.05).(4) At the same altitude, there are differences between four typical forest types in the value of soil respiration, and soil respiration rate of B. pendula higher than other forest types (p<0.05). Among them, at altitude of 1600 m, the order of soil respiration rate of four typical forest types was that:B. pendula> P. sibirica> L. sibirica>P. obovata. At altitude of 1700 m, the order was that:B. pendula> P.sibirica> P. obovata> L. sibirica. And at altitude of 1800 m, the order was that:B. pendula> P. obovata> L. sibirica> P. sibirica.(5) During process of freezing and thawing alternation, the soil respiration rate of L. sibirica and P. obovata changes were divided into three stages. The soil respiration was relatively low and stable in first stage. And the soil respiration was significant increase in the second stage, with a significant reduction (p<0.05). In the third satge, soil respiration was maintained at a high level, close to the value of the growing season. During the process, the trends in soil temperature and soil respiration were same, both of which showed a significant exponential relationship (p<0.05).(6) The cumulative contribution of soil respiration rate of soil temperature and soil moisture of four typical forest types were respectively 95.647%,94.056%,92.14% and 82.333%. But the soil bulk density of soil respiration contribution rate was between 4.353 %～17.667%. The soil temperature and soil respiration rate of each forest type showed a highly significant correlationship (p<0.01), and soil moisture and soil respiration rate was significantly correlated (p<0.05).(7) Using two-factor model linear and exponential-power refers to the results of two-factor model of soil respiration and soil temperature and soil moisture fitting showed that the exponential model and linear models were able to fit well in soil temperature, soil moisture and soil respiration relations, and the value of R2 was between 0.914～0.993. The results showed that the soil respiration in different forest types had higher influence by the changes of relatively soil temperature and humidity. |
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