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In situ carbon flux studies are typically rare over the Himalaya but are important to understand carbon (C) balance. We investigated night-time canopy respiration (R-nc) and soil respiration (R-s) of a deciduous coniferous forest in response to environmental factors. A comprehensive investigation has been carried out on C balance indicators by employing systematic and concurrent measurements over an annual growth cycle of pine (Nov 2010-Dec 2011). The study site consists of uniformly distributed young deciduous Pinus roxburghii plantation having understory as Lantana camara (an invasive shrub). Results underlined that both R-nc and R-s fluxes were highest in the post-monsoon season. Evaporative fraction (EF) and temperature explained maximum variability of fluxes during warm-moist monsoon. Our key finding depicts an inverse significant correlation between day-time canopy photosynthesis (A(c)) and R-nc across the seasons (r=0.83-0.99). This can be explained by the mechanistic physiological phase of optimal anabolism (A(c)) with favorable environmental conditions and minimum level of catabolism (R-nc). The respiration-photosynthesis ratio (R-nc/A(c)) typically ranged from 0.25 +/- 0.11 (peak growing season) to 0.71 +/- 0.16 (winter season) with mean of 0.26 +/- 0.10. The ratio R-s/A(c) was highest during the winter season (2.69 +/- 0.43), while minimum during peak growing season (0.64 +/- 0.29). The R-nc/A(c) ratio and night-time temperature (AT) also revealed that the ratio could increase when AT crossed 24 degrees C. These responses indicate that under climate warming, it may have a significant influence on net plant C uptake. Presence of understory shrub minimizes the R-nc/A(c) ratio, and indicative of a more positive C-balance. Nevertheless, the observations could certainly lend useful insight into C-balance and ecological function in the region. Further, it may be useful in parameterizing and validating C-cycle models.