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

Abstract

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 (BL wr ), 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 BL wr , 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.Sustainability 2019, 11, 4075 2 of 13 scale of small watersheds, albeit with complex calculations [16,17]. The Gray correlation method is widely used as a relatively simple and reliable analysis method [18]. The results of this method are accurate and can be used to analyze the development trend of a system. In addition, there is no requirement in terms of sample number, and a typical distribution law is not needed because the amount of calculations is relatively low [19][20][21].The mountainous area of Eastern Liaoning is a typical seasonal dry area in China. Precipitation is unevenly distributed (about 70% of precipitation occurs in June-September), with serious water shortage [22]. Against the background of a warming climate, these water shortages will be aggravated, restricting the water conservation function of vegetation in this area [22]. Only by adapting to this arid environment, plants can maintain their ecological benefits and functions. Larix gmelinii, Pinus koraiensis, Robinia pseudoacacia, Pinus tabulaeformis, and mixed forests are widely distributed in the eastern Liaoning Mountains [22]. After long-term natural selection and co-evolution, they have shown a strong ecological adaptability. However, we do not know which forest type has the highest water conservation capacity, making it necessary to compare these forests, incorporating global climate change data....

Response of the Water Conservation Function to Vegetation Dynamics in the Qinghai–Tibetan Plateau Based on MODIS Products

“…The evaluation of the water conservation function of an ecosystem is a popular and difficult issue in ecosystem service research [4]. Currently, most research on the water conservation function of vegetation has used field investigation and sample plot setting methods to prove that there is a certain relationship between vegetation types and water conservation functions [19], and the results of this article are consistent with the results of these previous studies. In this study, long time series RS data are used to determine that the LAI of vegetation and water conservation is not a simple linear relationship.…”

“…The research shows that there are significant differences in the water conservation capacity of different biome types. However, other researchers have used field survey methods to explore the differences in water source functions between different types of biome and obtained the best type of biome in terms of water conservation functions, providing important scientific evidence for the protection of regional water conservation functions [19]. Currently, the methods used to evaluate the water conservation functions of ecosystems mainly include the water balance method, precipitation storage method, comprehensive water storage capacity method, soil water storage method, canopy interception surplus method and multi-factor regression method.…”

The Water Storage Function of Litters and Soil in Five Typical Plantations in the Northern and Southern Mountains of Lanzhou, Northwest China

“…The gray correlation method is a relatively simple and reliable approach because it has no requirement on sample number and low computation and does not follow typical distribution rules [28][29][30]. It is, therefore, widely used in studies on forest soil and water conservation capacity [16].…”

“…After 0.08, 0.25, 0.5, 1, 1.5, 2, 3, 4.5, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24 h, the litter was taken out and excessive water was removed. The samples were weighed, then oven-dried at 65 • C to constant weight, then weighed again to determine the water holding capacity [16]. The calculation formula is as follows:…”

“…In general, the water conservation ability and maximum water holding capacity of the litter layer were stronger in the mixed forests than in the coniferous and broad-leaved forests and were closely related to the accumulation of forest litter and local climate [13]. The soil water storage was greater in the mixed forest than in the pure forest and was closely related to the different soil physical and chemical properties in the different forest types [14][15][16].…”