Nutrient characteristics of throughfall and stemflow in the natural forest of Pinus densata in the Tibetan plateau

Abstract

Precipitation, throughfall and stemflow were monitoredand collected through the rainy season on a natural forest ecosystemof Pinus densata in the Gongbu Nature Reserve in Tibet. Theconcentrations of N, P, K, Na, Ca, Mg, Si, Mn, Fe, S, Zn and Cuwere analyzed in the precipitation, throughfall and stemflow waters,Thereafter, and according to the amount of water of precipitation,throughfall and stemflow, the net input was calculated for each nutrientin the forest. The results showed that: (1) During the entirerainy season, the average concentration of different nutrients in theprecipitation of the Pinus densata forest was ranked in the followingorder: N>K>Na>Ca>Mg>Si>P>Mn>Fe>S>Zn>Cu. The concentrationof N 29.6145 mg/L, and that of Cu was only 0.1017 mg/L.(2) The average concentration of these nutrients in throughfall followedthe order: N>Na>Ca>K>Mg>Si>P>Mn>Fe>S>Zn>Cu. Thehighest concentration was 11.2843 mg/L for N, and the lowest wasonly 0.0937 mg/L for Cu; the difference between the two was 120.4times. (3) The order of N>K>Ca>Na>Mg>Zn>P>Si>Mn>Fe>Cu>Swas found for the nutrient concentration in stemflow. The concentrationof N (20.5096 mg/L) was 105.2 times higher than that ofthe lowest nutrient (S: 0.1949 mg/L). (4) As a whole, every nutrientwas quite different on average for the stemflow, throughfall andprecipitation. The concentration of Na, Ca, Mg and Zn followed stemflow>throughfall>precipitation. During the entire rainy season, thenet input (kg/hm2) of nutrients in the Pinus densata forest was Na>Si>Ca>Mg>K>Zn>Fe>S>Cu>P>Mn>N, and the net input of N wasnegative.