Background The stony mountain area is the main forest distribution area in North China, and where is also an important water source area for Beijing and Tianjin City. To some extent, these forests in this area protect the ecological and water resources in North China. Therefore, there is great significance to study the hydro-ecological effects of different forest types in this area.

Methods In order to explore the hydro-ecological effects of the litter and soil of the main forest types in this area, five typical stand types (Larix principis-rupprechtii forest, mixed forest of Pinus tabulaeformis and Quercus mongolica, Q. mongolica forest, mixed forest of Q. mongolica and Betula dahurica, and Lespedeza bicolor shrub) were selected as the research objects, and the indoor immersion method and ring knife method were used to measure the hydrological effects of litter and soil layer respectively.

Results 1) The thicknesses of the litter under different stand types ranged from 21.3 mm to 37.1 mm, and the storage of litter ranged from 15.14 to 32.45 t/hm². The capacity of maximum interception of litter ranged from 23.98 to 84.07 t/hm². Among them, mixed forest of Q. mongolica and B. dahurica had the largest capacity of maximum interception and L. bicolor shrub had the smallest one. The capacity of the modified interception of litter ranged from 18.63 to 68.03 t/hm², decreased by order of mixed forest of Q. mongolica and B. dahurica > Q. mongolica forest > mixed forest of P. tabulaeformis and Q. mongolica > L. principis-rupprechtii forest > L. bicolor shrub. On the whole, the capacity of the modified interception of litter of broad-leaved forest was generally higher than that of coniferous forest, and that of arbor forest was higher than that of shrub forest. 2) There was a logarithmic function relationship between litter water-holding capacity and soaking time (R>0.96), and a power function relationship between litter water holding rate and soaking time (R>0.98). 3) The soil density ranged from 1.06 g/cm³ to 1.19 g/cm³, and the soil saturated water-holding capacity ranged from 374.20 to 588.13 t/hm², and the effective water-holding capacity ranged from 40.40 to 82.83 t/hm², decreased by order of mixed forest of Q. mongolica and B. dahurica > Q. mongolica forest > mixed forest of P. tabulaeformis and Q. Mongolica > L. principis-rupprechtii forest > L. bicolor shrub. There was a power function relationship between the infiltration rate and infiltration rate of soil (R>0.99).

Conculsions In summary, the water conservation functions of litter and soil layers are both the strongest in the mixed forest of Q. mongolica and B. dahurica. The management measures in the pure coniferous forest we suggested is that removing the coniferous tree and planting broadleaf tree to increase the water conservation capacity in the study area. Moreover, people should also strengthen the protection of broad-leaved mixed forests and broad-leaved forest and reduce the human disturbance to the shrub forest for improving the water conservation function in this area.