Stand age‐related effects on soil respiration in rubber plantations (Hevea brasiliensis) in southwest China----中国科学院西双版纳热带植物园

The land use change from tropical forests to rubber plantations has had a great influence on ecosystem‐level carbon (C) exchange and soil C dynamics. This study aimed to assess the variation of soil respiration and its components in rubber plantations of different stand age. A trenching method was used to partition soil respiration (RS) into autotrophic respiration (RA) and heterotrophic respiration (RH) for 3 years in 12, 24, 32, and 49 years‐old rubber plantations. Our results showed that RS changed significantly among rubber plantations, with the highest RS in the old‐growth rubber plantation (49‐y plantation, 147.30 ± 6.91 mg CO2‐C m‐2 hr‐1) followed by the mature (137.16 ± 7.68 and 108.10 ± 4.83 in 24‐y and 32‐y plantation, respectively) and the young (12‐y plantation, 78.43 ± 3.84 mg CO2‐C m‐2 hr‐1) rubber plantations. RS was significantly and exponentially related to soil temperature (P < 0.0001) rather than soil water content which led to higher RS in the rainy season than that in the dry season. The contribution of RA to RS was higher in the mature rubber plantation than that in the young (27%) and the old‐growth (20%) rubber plantations. The sensitivity of RS to increasing temperature (Q10) was higher in 32‐y and 49‐y than in 12‐y and 24‐y rubber plantations. The largest Q10 value of RH and RA was found in the old‐growth (49‐y plantation, 2.95) and the mature (32‐y plantation, 8.01) rubber plantations, respectively. Our results highlight the importance of environmental factors in determining the variation in RS in rubber plantations with different stand age. However, further studies are still required to elucidate the impacting mechanisms of stand age‐related effects on soil respiration such as the differences in photosynthesis in rubber plantations.

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