亚热带不同树种土壤水源涵养功能

亚热带地区由于大面积的砍伐使天然林被人工林所代替,对森林土壤水源涵养功能造成了很大影响。树种可以通过自身特性来改变土壤物理结构进而影响土壤持水能力,因此合理选择树种对区域水源涵养具有重要意义。然而,立地条件的差异往往会对实验结果产生影响。为减少立地条件的差异,2012年2月在土壤发育和经营历史相同的林地上建立了中亚热带常见树种同质园。2019年8月测定了种植12个树种后不同土层(0—10、10—20、20—30、30—40 cm和40—50 cm)的土壤容重、含水量、总/毛管/非毛管孔隙度、最大/毛管/非毛管持水量和蓄水量。结果表明,种植不同树种7年后,土壤容重、含水量、总/毛管/非毛管孔隙度、最大/毛管/非毛管持水量和蓄水量均在表层(0—20 cm)土壤中差异显著,而在深层(20—50 cm)土壤中差异不显著。土壤孔隙度、持水量和蓄水量均与土壤容重呈显著负相关关系,而与土壤含水量呈显著正相关关系。与其他树种相比,种植鹅掌楸、枫香和全缘叶栾树等落叶阔叶树种可在较短时间内增加土壤孔隙度,提高土壤持水量和蓄水量。因此,在亚热带人工林经营管理中,可在杉木、马尾松纯林中适当引入鹅掌楸、枫香和全缘叶栾树等落叶阔叶树种,提升亚热带森林土壤水源涵养功能。

Soil water conservation functions of different plantations in subtropical forest

Large amounts the subtropical natural forests have been replaced by plantations due to deforestation in the past decades. This conversion may affect the soil water conservation functions. Plantations of local dominant trees may change soil physical structure and further alter soil water holding capacity through their biological properties, so tree selection for plantation is very important for regional water conservation. However, the heterogeneity of the studied sites made the experimental results uncertain with low reliability. To reduce this heterogeneity, a common-garden was established in a subtropical forest by planting twelve trees dominated in this area at a forest stand with the same parent material and forest management at the Sanming Research Station of Forest Ecosystem and Global Change, Fujian Province, China, in February 2012. The soil bulk densities, water contents, porosities (total, capillary and non-capillary), water holding capacities (maximum, capillary and non-capillary), and water storage capacities (maximum, capillary and non-capillary at 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm, and 40-50 cm depth) under the twelve local dominant trees were determined in August 2019. Our results showed that significant differences in bulk densities, gravimetric water contents, porosities (total, capillary and non-capillary) and water holding and storage capacities (maximum, capillary and non-capillary) among the soils planted with different trees were only observed in surface soils (0-20 cm), while there was no significant difference in deep soils (20-50 cm). Soil porosity, water holding capacity and water storage capacity (either in capillary or in non-capillary) were negatively related to soil bulk density but were positively correlated with soil water content. The soil porosities, water holding capacities and water storage capacities were greater in soils planted with Liriodendron chinense, Liquidambar formosana and Koelreuteria bipinnata after seven years of plantation compared with other plantations. These results suggest that these broadleaved trees can be planted together with Cunninghamia lanceolata and Pinus massoniana plantations during forest management for improving the water conservation functions of the humid subtropical forests in Southern China.