ISSN:
1573-5036
Keywords:
decomposition
;
dynamic change
;
larch forest
;
minor vegetation
;
nitrogen cycling
;
simulation model
;
uptake
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Nitrogen cycling process and dynamic change over 2 years were studied in 21-year-old planted dahurian larch (Lurix gmelinii (Rupr) Rupr.) in the eastern part of northern China. N concentrations in the plants varied by tissue, age, position in tree and season. In the aboveground components the N concentration was highest in foliage, followed by live branches, bolebark and bolewood. The organic N concentrations in undergrowth and herbs were higher than that in larch tree. The total amount of N accumulated in the larch ecosystem was 13167 kg.ha-1, in which the percentages of N storage in soil, living plants, dead standing and litter were 94.7%, 2.8%, 0.1% and 2.4%, respectively. The uptake of N by vegetation was 56 kg.ha-1.y-1, in which the retention and return were 24 kg.ha-1.y-1 and 32 kg. ha-1 y-1, respectively. Precipitation provided 13 kg.ha-1.y-1 of N, while N loss via runoff was 4 kg.ha-1.y-1 and therefore, the net gain of N by ecosystem was 9 kg.ha-1.y-1. The simulation of N dynamic change showed that an increase in the age of stand was accompanied by a concomitant increase in N storage in the forest floor, whereas N flux from forest floor organic matter into soil would decrease, and consequently, growth rate of larch stands would reduce owing to the inadequacy of available N in the soil. The prediction indicated that the degradation of soil fertility in larch plantation might occur under continuous cropping. The study implied that release rate of N from litter into soil was the key factor in determining and regulating N cycling in larch plantation. The understory minor vegetation in the larch stand plays an important role in speeding up N cycling. The timely thinning is needed to improve growth and development of shrubs and herbs, and to avert the potential soil degradation. The mixed stand of larch with either a certain proportion of broad-leaved or a moderately well developed understory vegetation should be encouraged.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00029352
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