| Several typical forest types in Xiaoxing’an Mountain and northeastern China are the primary mixed broadleaved-Korean pine forest (KY), valley spruce-fir forest (YL), selective cutting of mixed broadleaved-Korean pine forest (ZF), secondary birch forest (BH), Dahurian arch plantation (RL) and Korean pine plantation (RHS). We used the trenching-plot and infrared gas exchange analyzer to measure and compare soil respiration (Rs) and related environmental factors for six forest types. We examined spatial and temporal variation of soil respiration and Rs components (autotrophic respiration, RA; heterotrophic respiration, RH) were quantified of six forest types. The results showed that:Soil respiration and its components displayed obvious seasonal dynamics, with maximum values in summer and minimum values in the early and late growing season. Soil respiration and its components were significantly positively correlated to soil temperature in all forest types, but showed varying correlations to soil moisture and its interactions with soil temperature. Soil moisture and its interactions with soil temperature were significantly correlated to ln(RS) in valley spruce-fir forest, Dahurian larch plantation and Korean pine plantation (P<0.05), were significantly correlated to In(RH) in all forest types except Dahurian larch plantation (P<0.05) and were not significantly correlated to ln(RA) in all forest types (P>0.05). Furthermore, soil temperature, soil moisture and their interactions could explain62.6—82.6%and66.6—89%of seasonal variation of RS and RH.Q10of RS for mixed broadleaved-Korean pine forest, spruce-fir forest, selective cutting of mixed broadleaved-Korean pine forest, secondary birch forest, Dahurian larch plantation and Korean Dine plantation was:2.46,2.56,2.39,2.48,2.01and2.01, respectively. Q10of RA was significantly higher than that of RH in all forest types, the results showed that RA is more sensitive to temperature.The average Rs in growing season of each forest type was in sequence of:YL> ZF> BH> RL> RHS> KY, were3.519μmolCO2·m-2·s-1,3.159μmolCO2·m-2·s-1,3.121μmolCO2·m-2·s-1,2.556μmolCO2·m-2·s-1,2.416μmolCO2·m-2·s-1and2.226μmolCO2·m-2·s-1, respectively. The average RH was in sequence of:YL> BH> RL> RHS> ZF> KY. The average RA was in sequence of:YL> ZF> RL> BH> KY> RHS. After human disturbance and operation of primary mixed broadleaved-Korean pine forest, the average Rs in growing season increased in various degree. The order of average RA and RH of six forest types were different, which indicating that RH and RA are probably driven by different mechanisms. Contribution of RA to RS(RC) was29.19%,33.36%,40.13%,27.05%,34.36%and23.71%in mixed broadleaved-Korean pine forest, valley spruce-fir forest, selective cutting of forest, secondary birch forest, Dahurian larch plantation and Korean pine plantation, respectively. The standard deviation (SD) of Rs showed the similar seasonal pattern with soil temperature, The mean SD of Rs for the six forest types was0.93μmolCO2·m-2·s-1between late June and early September was greater than that (0.38μmolCO2·m-2·s-1) in the early and late growing season. The coefficient of variation (CV) of Rs and for the six forest types did not have a clear seasonal pattern, that varied from14.75%to39.59%. The SD and CV of Rs among collars averaged1.29μmolCO2·m-2·s-1and43.59%, significantly greater than those (0.6μmolCO2m·2s-1,21.3%) among plots (P<0.001), highlighting the significance of finer-scaled heterogeneity in Rs. CV (54.31%,54.08%and48.07%) of Rs among collars in mixed broadleaved-Korean pine forest, selective cutting of forest and secondary birch forest were greater than those (36.65%,34.32%and34.1%) in valley spruce-fir forest, Dahurian larch plantation and Korean pine plantation (P<0.05). Because of the difference of the original forest vegetation and human disturbance and operation of primary mixed broadleaved-Korean pine forest, spatial variability of soil respiration were different. And soil moisture could explain about15.8—33.5%of spatial variation of soil respiration within each forest type except mixed broadleaved-Korean pine forest. |
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