The response of soil respiration (R s ) to temperature depends largely on the temporal and spatial scales of interest and how other environmental factors interact with this response. They are often represented by empirical exponential equations in many ecosystem analyses because of the difficulties in separating covarying environmental responses and in observing below ground processes. The objective of this study was to quantify a soil temperature-independent component in R s by examining the diel variation of an R s time series measured in a temperate deciduous forest located at Oak Ridge, TN, USA between March and December 2003. By fitting 2 hourly, continuous automatic chamber measurements of CO 2 efflux at the soil surface to a Q 10 function to obtain the temperature-dependent respiration (R t ) and plotting the diel cycles of R t , R s , and their difference (R i ), we found that an obvious temperature-independent component exists in R s during the growing season. The diel cycle of this component has a distinct day/night pattern and agrees well with diel variations in photosynthetically active radiation (PAR) and air temperature. Elevated canopy CO 2 concentration resulted in similar patterns in the diel cycle of the temperature-independent component but with different daily average rates in different stages of growing season. We speculate that photosynthesis of the stand is one of the main contributors to this temperature-independent respiration component although more experiments are needed to draw a firm conclusion. We also found that despite its relatively small magnitude compared with the temperaturedependent component, the diel variation in the temperature-independent component can lead to significantly different estimates of the temperature sensitivity of soil respiration in the study forest. As a result, the common practice of using fitted temperature-dependent function from night-time measurements to extrapolate soil respiration during the daytime may underestimate daytime soil respiration.
This paper studies distributed multi-domain, multilayer provisioning (grooming) in IP/MPLS-DWDM networks. Although many multi-domain studies have emerged over the years, these have primarily considered "homogeneous" network layers. Meanwhile, most grooming studies have assumed idealized settings with "global" link state across all layers. Hence there is a critical need to develop practical distributed grooming schemes for real-world networks consisting of multiple domains and technology layers. Along these lines, a detailed hierarchical framework is proposed to implement inter-layer routing, distributed grooming, and setup signaling. The performance of this solution is analyzed using simulation studies and future directions high-lighted.
Multi-domain traffic engineering is a major focus area for carriers today and crankback signaling offers a very promising and viable alternative here. Although some initial crankback studies have been done, there is still significant latitude for improving multi-domain crankback performance. To address these concerns, this paper studies realistic IP/MPLS multi-domain networks and proposes a novel solution for joint intra/inter-domain signaling crankback. Namely, dynamic intra-domain link-state routing information is coupled with inter-domain path/distance-vector routing state to improve the overall search process. Mechanisms are also introduced to limit setup signaling overheads/delays. The performance of the proposed solution is then analyzed using simulation and compared against other crankback techniques as well as hierarchical inter-domain routing strategies.
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