Southern Research Station

Title: Belowground carbon dynamics in lohlolly pine (Pinus taeda) immediately following diammonium phosphate fertilization

Author: Gough, Christopher M.; Seiler, John R.

Date: 2004

Source: Tree Physiology 24, 845-851

Description: Forest soils store an immense quantity of labile carbon (C) and a may be large potential sink for atmospheric C. Forest management practices such as fertilization may enhance overall C storage in soils, yet changes in physiological processes following nutrient amendments have not been widely investigated. We intensively monitored below-ground C dynamics for nearly 200 days following diammonium phosphate fertilization of pot-grown loblolly pine (Pinus taeda L.) seedlings in an effort to examine the short-term effects of fertilization on processes involved in soil C sequestration. Soil respiration rates initially increased in fertilized pots relative to controls, followed by a brief reversal in this trend and then a final sustained pattern of elevated rates of soil respiration in the fertilized treatment. Patterns in soil respiration rates overtime reflected changes in autotrophic (root) and heterotrophic (mircobial) components of soil respiration. Root respiration rates were greater in the fertilized treatment 49 days following fertilization and returned to control rates by the end of the study. In contrast, microbial respiration rates and microbial activity per soil C concentration remained depressed over the same time period. Compared with control seedlings, total root biomass was 27% greater in fertilized seedlings harvested at the end of the study indicating that the elevated soil respiration rates ovserved toward the end of the study were a result of increased respiring root biomass. We conclude that fertilization, at least over the short-term, may increase soil C sequestration by increasing belowgound biomass production and reducing microbial driven C turnover.

Keywords: Autotrophic respiration, heterotrophic respiration, microbial respiration, root respiration, soil CO₂ efflux, soil respiration

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Citation

Gough, Christopher M.; Seiler, John R.  2004.  Belowground carbon dynamics in lohlolly pine (Pinus taeda) immediately following diammonium phosphate fertilization .   Tree Physiology 24, 845-851