Dynamic Characteristics Of Dissolved Organic Carbon In Natural Forest Succession And Planted Forest In Greater Khingan Mountains Region

Dissolved organic carbon（DOC）is the most active part of soil carbon pool.Studying the dynamics of DOC in natural forest succession and plantation growth is of fundamental significance for understanding the northern forest carbon cycle.In this paper,the representative forest succession sequence and plantations of different ages after fire were selected in Genhe Forestry Bureau of Greater Hinggan Mountains,Inner Mongolia,by using the method of space instead of time.DOC concentration was collected and measured.The distribution characteristics of DOC in different layers during natural forest succession and plantation growth were studied,and the effects of slope position,month pair and Fe,Mg and pH on DOC were analyzed.Influence.The main conclusions are as follows:（1）The distribution characteristics of DOC in all layers of natural forest succession stage were as follows:rainfall<0-30 cm soil layer<organic matter layer<penetrating rain<instemflow;and the distribution characteristics of DOC in all layers of plantation growth were as follows:rainfall<0-30 cm soil layer<penetrating rain<organic matter layer<instemflow.Variance test showed that DOC concentration in runoff of Larch trunk was significantly higher than that of birch（P<0.05）,while DOC concentration in penetrating rain of shrub and grass was significantly lower than that of larch forest and birch forest（P<0.05）.（2）With the succession process,DOC concentration in osmotic water of organic layer and 0-30 cm soil leakage increased first and then decreased,and the mixed forest of Betula platyphylla and Larix gmelinii reached the maximum.The DOC concentration in osmotic water of organic layer of different age plantations showed as follows:50-year-old Larix gmelinii forest>39-year-old Larix gmelinii forest>29-year-old Larix gmelinii forest,but there was no significant difference in 0-30 cm soil leakage.（3）In the process of natural forest succession and plantation growth,DOC concentration in of organic matter layer and 0-30 cm soil layer leakage was higher in downhill than in uphill,but there was no significant difference between mid-slope and uphill.（4）The maximum DOC concentration in the instemflow of Betula platyphylla and Larix gmelinii in natural forest appeared in July and the minimum appeared in September.The overall variation trend of DOC concentration in the permeable water of organic matter layer and 0-30 cm soil leakage leakage was the highest in June,decreased in July and August,and increased again in September.（5）The overall trend of DOC concentration in instemflow,organic matter layer and 0-30 cm soil leakage leakage osmotic water in plantation was that the maximum value appeared in June,decreased in July and August,and increased in September,but the minimum value of DOC concentration in 29a larch forest organic matter layer osmotic water appeared in September,and the maximum value of DOC concentration in 50 a larch organic matter layer osmotic water was in July.（6）The correlation analysis showed that the DOC concentration of each layer was positively correlated with Fe³⁺and Mg²⁺,and the Mg²⁺concentration was higher than that of Fe³⁺;the DOC concentration of each layer was negatively correlated with the pH value,only the DOC in instemflow was significantly correlated;the average pH value in rainfall outside the forest was 5.93.