| Management strategy of northeastern forests changed after implementing natural forest protection project. At this background, taking several regional and typical forests as study subject, the influence of management strategy on stand structure, community diversity and ecological services function was studied by combing field investigation method with laboratory test. At the same time, water conservation function of typical forests in Da and Xiao Xing’an Mountains was analyzed and compared. Furthermore, optimal allocation of water conservation forests of small watershed in Da and Xiao Xing’an Mountains was selected based on analytic hierarchy process.Firstly, comparing with water conservation function of typical forests in Da and Xiao Xing’an Mountains, we got the results:(1) the rate of forest canopy interception in Da Xing’an Mountains was higher than which of Xiao Xing’an Mountains, especially grasses Xing-an larch forest had the highest capacity of interception. The rate of five shrub forest canopy interception varied in 11.99%～24.86%, with filbert brush having the biggest interception capacity which was no significant difference to arboreal forest in the same stand. (2) Maximum water holding capacity of litter in Xiao Xing’an Mountains varied from 578.03% to 747.22%, which of cuckoo birches was highest, and followed by Larch birch mixed forests, Korean pine plantation, Mongolian oak forest, mongolica plantations and fraxinus mandshurica forest, orderly. Maximum water holding capacity of litter in Da Xing’an Mountains varied from 25.66 to 136.82 t/hm2; effective water capacity varied from 17.17 to 67.00 t/hm2, which of larch plantation was highest, and followed by grasses larch forest, rhododendron larch forest, oak larch forest and Mongolian oak forest.(3) The effective soil water capacity of six typical forests in Xiao Xing’an Mountains varied in 234.66～438.56 t/hm2, with natural manchurian ash being highest capacity; the effective soil water capacity of typical forests in Da Xing’an Mountains varied in 340.00～632.15 t/hm2, with cuckoo birches being highest capacity of water conservation; (4) Comparing with water conservation capacity of 16 types of forest and shrub forest from Da and Xiao Xing’an Mountains, we found that, in Da Xing’an Mountains region, comprehensive water conservation function was higher, and reflected in forest canopy interception and litter water-holding capacity; in Xing’an Mountains region, water conservation function mainly reflected in maximum water capacity of soil layer, shrub forest had higher water conservation function by improving effective water capacity of soil layer.Secondly, we analyzed the hydrological characteristics and soil erodibility of close-to nature-Larch artificial pure forests and mixed forests by investigating the bringing layer, litter layer and soil layer, in Maoershan experimental forest farm. Results showed that:(1) the standing crop of shrub layer and herbal standing crop varied from 0.51 to 0.73t/hm2, and from 0.20 to 0.62 t/hm2, respectively, maximum water capacity varied in 2.31-4.97t/hm2, with Phellodendron amurense Rupr and Larix mixed forests biggest for above three indexes. (2) The accumulated mass of litter was between 6.23 and 9.13t/hm2, and Fraxinus mandschurica Rupr and Larix mixed forests was the biggest. The order of maximum water capacity of four forests gradually decreased from Fraxinus mandschurica Rupr and Larix mixed forests (53.50t/hm2) to Phellodendron amurense Rupr and Larix mixed forests (47.82t/hm2),to pure larch stands (45.02t/hm2), to larch walnut Chinese catalpa mixed forests (36.64/hm2). Fraxinus mandschurica Rupr and Larix mixed forests had the biggest effective retaining content (23.94t/hm2). (3)The maximum soil water-holding capacity varied between 2927.74 and 3454.31t/hm2, Larix pure forest was the biggest. The order of soil maximum water capacity of four forests gradually decreased from Phellodendron amurense Rupr and Larix mixed forests (282.24t/hm2), to pure larch stands (275.83t/hm2),to larch walnut Chinese catalpa mixed forests (219.05t/hm2), to Fraxinus mandschurica Rupr and Larix mixed forests (143.01t/hm2). (4)Through ternary plot of soil structure we can concluded that, in the surface soil (0-20 cm), soil structure of Fraxinus mandschurica Rupr and Larix mixed forests was more closer to the ideal structure, mainly by increasing the proportion of solid phase and reducing the liquid proportion. (5) During soil layer of 0～10 cm, the hydrostatic disruption rate Fraxinus mandschurica Rupr and Larix mixed forests was smallest (2%～4%). Soil aggregate of water stability index of four kinds of forests was significantly difference (P< 0.05), with the range of 0.85～0.97, and Fraxinus mandschurica Rupr and Larix mixed forests had the lowest soil erodibility (0.97). (6)Within 0-20 cm soil layer,2～5 mm of dry sieve aggregate was dominant Fraxinus mandschurica Rupr and Larix mixed forests could significantly increase soil water stable aggregate bigger than 0.25 mm, reduce the aggregate damage risk, the PA0.25 of the other three forests deceased gradually from pure larch stands to Fraxinus mandschurica Rupr and Larix mixed forests, and to Phellodendron amurense Rupr and Larix mixed forests. (7) K value of four kinds of forest soil was calculated through the EPIC evaluation model and ranged between 0.294 and 0.337, Fraxinus mandschurica Rupr and Larix mixed forests showed lowest erodibility (0.294). Based on the integrated results, we incoluded that pure larch stands had the potential water conservation capacity, Phellodendron amurense Rupr and Larix mixed forests had biggest capacity of water holding, Fraxinus mandschurica Rupr and Larix mixed forests had lowest erodibility.Next, we analyzed the intermediate cutting management measures effects on white birch forest, Mongolica forest and larch forest, by investigating their stand structure, biodiversity of the shrub layer and herb layer, litter mass and water-holding capacity, physical properties of soil layer and water conservation capacity, in A Muer forestry administration of Da Xing’an mountains Results showed that:(1) traditional intermediate cutting promoted growth of diameter and height. After traditional intermediate cutting, the stand density of white birch forest decreased by 50%, average height increased by 0.4m, average diameter increased 1.5cm, consequently, the volume of stand did not decline. Excessive thinning increased average diameter And height of natural larch forest, and volume decreased with increasing thinning intensity; (2) after intermediate cutting, the species richness index and Shannon-Wiener index of shrub layer and herb layer in white birch forest dramatically decreased, vegetation species also decreased accordingly. (3) Intermediate cutting could affect the mass and distribution of litter:after intermediate cutting, the little mass of white birch forest, Mongolica forest decreased by 20% and 13.27%, respectively; secondary thinning on natural larch forest reduced litter mass significantly. (4) The composition of little contributed to litter water capacity differently, fallen leaves was predominant in white birch forest litter composition, maximum water holding capacity of undecomposed leaves was 2.58-3.65 times of dead branch, which of decomposed leaves was 1.27-2.92 times of dead branch; the litter composition of Mongolica forest and larch forest were also fallen leaves. The water hold capacity of leaves was highest, and followed by bark, dead branch, cone orderly. (5) Intermediate cutting improve soil physical properties, bulk density decreased significantly and non capillary porosity increased obviously after intermediate cutting treatments.Furthermore, optimal allocation of water conservation forests of small watershed in Da Xing’an Mountains was selected based on analytic hierarchy process:the proportion of Mongolian oak forest is 24.86%, the proportion of cuckoo larch forest is 16.30%, and the proportion of Oak wood larch forest is 44.49%, the proportion of cuckoo birches is 10.88%, the proportion of herbage larch forest is 3.47%. Based on the optimal allocation pattern, the water conservation capacity of studied watershed was improved by 135,562 ton, with increasing by 7.0% comparing to the situation without optimal allocation, which revealed that optimal allocation could improve water conservation capacity of studied watershed in Da Xing’an Mountains.Results obtained not only could provide the criteria reference for evaluating forest management and water conservation function of northeastern forests, but also provide data support and theory service for forestry administrative department to formulate forest management strategy. |
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