Evaluation of the Water Conservation Function of Different Forest Types in Northeastern China

Water conservation is an important function of forest ecosystems, but it is still unclear which forest types function best in this regard. We investigated the water conservation function indicators including the water-holding rate of branches and leaves (BLwr), water-holding capacity of litter (L-wc), water absorption rate of litter (L-wr), soil infiltration rate (I-r), soil and water content (SWC), soil water storage (SWS), and soil organic matter (SOM) accumulation of five forest types (Larix gmelinii forests, Pinus koraiensis forests, Robinia pseudoacacia forests, Pinus tabulaeformis forests, and mixed forests) and evaluated them using the gray correlation method (GCM). The results indicate that the BLwr of five stands in the study area varied from 18.3% to 33.5%. The SWC and SWS of the R. pseudoacacia stand were 13.76% and 178.9 mm, respectively, which was significantly higher than that of the other stands (p < 0.05). The SOM was similar for the R. pseudoacacia (0.23%), mixed forest (0.22%), and L. gmelinii (0.22%) sites. The BLwr, L-wc, L-wr, SWC, and SWS values of broad-leaved tree species were higher than those of the mixed species, followed by those for coniferous tree species. Soil infiltration rate followed the order L. gmelinii > P. koraiensis > mixed forest > P. tabulaeformis > R. pseudoacacia. Based on our results, the R. pseudoacacia stand had the highest water conservation ability, while the lowest performance was found for the P. tabuliformis site. This suggests that, in order to enhance the water conservation function of forests in northeastern China, the focus should be on the establishment of R. pseudoacacia forests.