Soil heterotrophic respiration in response to rising temperature and moisture along an altitudinal gradient in a subtropical forest ecosystem, Southwest China
Science of The Total Environment, 2021
Globally, one-third of the terrestrial carbon (C) is stored in tropical soils. The warming predic... more Globally, one-third of the terrestrial carbon (C) is stored in tropical soils. The warming predicted for this century is expected to increase microbial decomposition in soil and escalate climate change potential by releasing more carbon dioxide (CO2) into the atmosphere. Understanding the response of soils to warming is a key challenge in predicting future climate change trajectories. Here we examined the combined effect of soil temperature (Ts) and soil water content (VWC) on soil heterotrophic respiration (Rsh) and its temperature sensitivity across different altitudes (2400, 1900, and 1450 m ASL) in the Ailaoshan subtropical forest ecosystem, Southwest China. Along the elevation gradient, soil C stocks in the top 50 cm soil layer increased significantly from 10.7 g/ kg at 1480 m ASL to 283.1 g/ kg at 2480 m ASL. Soil cores from various elevations were translocated to the same, and lower elevations and Rsh from those cores were measured every month from February 2010 to January 2014. Temperature sensitivity (Q10) of Rsh for the period was highest at the highest (H) elevation (Q10 = 5.3), decreased significantly towards the middle (M, Q10 = 3.1) and low (L, Q10 = 1.2) elevation. Q10 at M and L elevation did not differ between the place of origin and translocated cores. For the cores within each elevation, Q10 did not vary across the years. Our models suggest that Rsh increased significantly in response to an increase in Ts at each elevation under an intermediate VWC. Hence, the rate of emission was higher in lower elevations due to a higher Ts range. Our findings highlight that the predicted warming over the 21st century will have the greatest impact of Ts on Rsh, especially on the soils at the highest elevations, and will lead towards positive feedback to the climate system.
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Papers by P A Azeez
Wetlands, a major feature of landscape in almost all parts of the world, are among the important ecosystems on Earth. From time immemorial, wetlands and river valleys have played a decisive role in nurturing many cultures and civilizations. However, the history of dealing with wetlands by humankind is fraught with misunderstanding and fear. Wetlands are disappearing at alarming rates across the globe, apparently since they were largely considered synonymous with wastelands to be filled up, drained, occupied and diverted for other human needs, disregarding the vital ecological services these ecosystems offer and the ecological goods we derive from them. A more recent and global issue that concerns both coastal and inland wetlands is the climate change. Limited investigations and experiments, especially in paddy fields, and lack of scientifically robust data have put the wetlands responsible for high methane emissions and ensuing changes in climate. It appears that international pressures from various interest groups have also added to this postulation. Nevertheless, it appears that we are yet to estimate with certainty the role of wetlands as net carbon sources or sinks. In fact, these enigmatic ecosystems need further scientific investigations regarding their role in the Earth system, especially with respect to their structural and functional roles and the ecological services they offer. Wetlands, as a unique ecosystem, have properties that are not adequately covered by terrestrial and aquatic ecology, suggesting that there is a case to be made for wetland science as a distinct discipline, taking input from many fields, including terrestrial and aquatic ecology, environmental chemistry, hydrology and engineering in a typically multidisciplinary perspective. Wetlands are unique in many ways, of which their hydrologic characteristics and roles as ecotones between terrestrial and aquatic systems are notable. Wetland management, as the applied side of wetland science, requires systematic understanding of the various aspects of the system , balanced with legal, institutional and economic realities and expertise from disciplines of biology, ecology and hydrology. The wetland science is not an issue concerning hydrology and water management or confined to be a domain of biologists or ecologists. Wetland science essentially needs to draw upon knowledge base from other disciplines such as sociology, economics, hydrology and engineering as well. Wetlands are closely connected with humankind than any other ecosystems, for their intimate role in human sociocultural development, migration, spread and settlement across the globe. In recent years, wetland science is picking up as interest in wetlands grows; so do professional societies, as well as a number of journals and literature concerned with wetlands.