Effect of dry-wet cycles on quantity and characteristic of common tree litter-derived dissolved organic car-bon in subtropical plantations
In subtropical plantations,plant litters often experience repeated dry-wet cycles.To explore the influence of dry-wet cycles on litter-derived dissolved organic carbon(DOC),we conducted a 40-day laboratory incubation experiment with leaf litters from six deciduous broad-leaved tree species,four evergreen broad-leaved tree species,and two evergreen coniferous tree species from typical subtropical plantations of China.There were three treatments:dry(maintaining mass ratio of litter:water below 20∶1),wet(maintaining mass ratio of litter:water at 1∶1),and dry-wet(drying for four days and rewetting for four days,with a total of five cycles).To assess the effects of dry-wet cycles on DOC quantity and characteristics,we investigated the variations of leaf litter-derived DOC amount and spectral characteristics(specific ultraviolet absorbance at 254,284,and 350 nm),and litter mass loss.The results showed that litter mass loss was greater in the wet and dry-wet treatments than in the dry treatment,and that leaf litter mass loss under dry-wet treatment was comparable to that under wet treatment..For both deciduous and evergreen broad-leaved species,litter-derived total DOC production in the dry-wet treatment was higher than that in the dry treatment,but was lower than that in the wet treatment.However,litter of evergreen coniferous trees had lower total DOC production in the dry-wet treatment than in the dry and wet treatments.Litter-derived DOC had higher specific ultraviolet absorbance at 254,284,and 350 nm in the wet and dry-wet treatments than in the dry treatment,indicating a greater aromatic degree of DOC.These findings suggest that repeated dry-wet cycles are an important factor controlling the quantity and quality of litter-derived DOC in subtropical plantations.
万方数据
维普
