Abstract
Understanding the change pattern of soil respiration (SR) and its drivers under different bamboo species and land management practices is critical for predicting soil CO2 emission and evaluating the carbon budget of bamboo forest ecosystems. A 24-month field study was performed in subtropical China to monitor SR in experimental plots of local bamboo (Phyllostachys glauca) without fertilization (PG) and commercial bamboo (Phyllostachys praecox) with and without fertilization (PPF and PP, respectively). The SR rate and soil properties were measured on a monthly timescale. Results showed that the SR rate ranged from 0.38 to 8.53 µmol CO2 m−2s−1, peaking in June. The PPF treatment had higher SR rates than the PP and PG treatments for most months; however, there were no significant differences among the treatments. The soil temperature (ST) in the surface layer (0–10 cm) was found to be the predominant factor controlling the temporal change pattern of the monthly SR rate in the PG and PP treatments (i.e., those without fertilization). A bivariate model is used to show that a natural factor—comprised of ST and soil water content (SWC)—explained 44.2% of the variation in the monthly SR rate, whereas biological (i.e., bamboo type) and management (i.e., fertilization) factors had a much smaller impact (less than 0.1% of the variation). The annual mean SR showed a significant positive correlation with soil organic matter (SOM; r = 0.51, P < 0.05), total nitrogen (TN; r = 0.47, P < 0.05), total phosphorus (TP; r = 0.60, P < 0.01), clay content (0.72, P < 0.05) and below-ground biomass (r = 0.60*), which altogether explain 69.0% of the variation in the annual SR. Our results indicate that the fertilization effect was not significant in SR rate for most months among the treatments, but was significant in the annual rate. These results may help to improve policy decisions concerning carbon sequestration and the management of bamboo forests in China.
Highlights
Soil respiration (SR), commonly referred to as the CO2 efflux at the soil surface, is the main channel for carbon transfer from terrestrial ecosystems to the atmosphere [1,2,3]
From November 2012 to November 2013, the monthly SR rates were lowest during winter, gradually increasing from late spring and peaking in summer, with SR rates reaching 2.62, 3.25, and 3.87 μmol CO2 m−2 s−1 in June for the PG, PP, and Phyllostachys praecox with fertilization (PPF) plots, respectively
A significantly positive correlation between the monthly SR rate and the soil temperature (ST) was found for all three treatments at a monthly scale, whereas no significant correlation was observed between the monthly SR rate and the soil water content (SWC) (Table 3)
Summary
Soil respiration (SR), commonly referred to as the CO2 efflux at the soil surface, is the main channel for carbon transfer from terrestrial ecosystems to the atmosphere [1,2,3]. The CO2 efflux from soils to the atmosphere has been estimated as 50–70 Pg C year−1 , accounting for approximately 25% of the total global CO2 emissions; SR plays a critical role in the global carbon cycle [4,5,6]. As an important part of terrestrial ecosystems, forests. Forests 2020, 11, 99 are regarded as one of the most important carbon (C) sinks, and carbon emitted from forest soil may greatly affect the atmospheric CO2 concentration [9,10]. Understanding the carbon cycle in forest ecosystems is important for evaluating the global C budget
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