[Hydro-chemical properties of litter layer in two kinds of plantations in Beijing Xishan Mountain].
The study on the hydro-chemical properties of litter layer in Pinus tabulaeformis and Querous variabilis plantations in Beijing Xishan Mountain showed that after the precipitation passed through the plantations and penetrated into litter layer, the element concentrations in precipitation changed greatly. The concentrations of K+, Na+, Ca2+, Mg2+, NH4+ -N and NO3- -N in litter water had similar changing trends as those in throughfall. The average concentrations of K+, Na+, Ca2+ and Mg2+ in litter water were higher than those in throughfall, but NH4+ -N and NO3- -N were in adverse. Ca2+ increased most, with the increment of 7.54 mg x L(-1) in Q. variabilis plantation and 5.27 mg x L(-1) in P. tabulaeformis plantation. The concentrations of K+, Na+, Ca+, Mg2+ in litter water were higher in Q. variabilis than in P. tabulaeformis plantation, but NH4+ -N and NO3- -N concentrations were lower in Q. variabilis than in P. tabulaeformis. After leaching by precipitation, the nutrients return into woodland was 41.59 kg x hm(-2) in Q. variabilis and 58.12 kg x hm(-2) in P. tabulaeformis, among which, Ca2+ returned more, followed by K+.