Effect of tree thinning and skidding trails on hydrological connectivity in two Japanese forest catchments

32 Pags.- 4 Tabls.- 5 Figs. The definitive version is available at: http://www.sciencedirect.com/science/journal/0169555XLand use composition and patterns influence the hydrological response in mountainous and forest catchments. In plantation forest, management operations (FMO) modify the spatial and temporal dynamics of overland flow processes. However, we found a gap in the literature focussed on modelling hydrological connectivity (HC) in plantation forest under different FMO. In this study, we simulated HC in two steep paired forest subcatchments (K2 and K3, 33.2 ha), composed of Japanese cypress (Chamaecyparis obtusa Endl.) and Japanese cedar (Cryptomeria japonica D. Don) plantations (59% of the total area) against a tree thinning intensity of 50% at different time. Additionally, construction of new skidding trails and vegetation recovery was simulated on five thinning-based scenarios that covered a 40-month test period (July 2010 – October 2013). As a future scenario, six check-dams located in the main streams were proposed to reduce sediment and radionuclide delivery. An updated version of Borselli's index of runoff and sediment connectivity was run, using the D-infinity flow accumulation algorithm and exploiting three 0.5-m resolution digital elevation models. On the basis of the pre-FMO scenario, HC increased at catchment scale owing to tree thinning and the new skidding trails. This change was more noticeable within the area affected by the FMO, where HC increased by 11.4% and 10.5% in the cypress and cedar plantations in K2 respectively and by 8.8% in the cedar plantation in K3. At hillslope plot and stream scales, the evolution in the values of HC was less evident, except the increment (by 5.4%) observed in the streams at K2 after the FMO. Progressive vegetation recovery after the FMO triggered a slight reduction of connectivity in all compartments of both subcatchments. Forest roads and especially skidding trails presented the highest values of HC, appearing as the most efficient features connecting the different vegetation patches with the stream network. The spatial and temporal evolution of HC over the five past scenarios correlated well with the observed changes in runoff yield, as well as with the available values of rainfall interception and throughfall before, during, and after the FMO. The simulation of the proposed scenario recommends the construction of check-dams as effective landscape features to somewhat reduce HC and thus to decrease the sediment and radionuclide delivery rates from the two subcatchments.This research was funded by the project ‘Core Research of Evolutionary Science and Technology (CREST): Development of innovative technologies for increasing watershed runoff and improving river environments by management practices of devastated forest plantations’ of the Japan Science and Technology Agency (JST; CREST, 2009, Report #670). Dr. Manuel López-Vicente acknowledges the financial support of his postdoctoral stay at the University of Tsukuba (Prof. Onda Laboratory) in 2015 to the Canon Foundation in Europe (Research Fellowships Program, Fellowship Call 2014).Peer reviewe

Stream Temperature Response to 50% Strip-Thinning in a Temperate Forested Headwater Catchment

Stream temperature is a critical parameter for understanding hydrological and biological processes in stream ecosystems. Although a large body of research has addressed the effects of forest harvesting on stream temperature, less is known about the responses of stream temperature to the practice of strip-thinning, which produces more coherent patches of shade and sunlight areas. In this study, we examined stream temperature response to 50% strip-thinning in a 17 ha headwater catchment. The thinning lines extended through the riparian zone. Paired-catchment analysis was applied to estimate changes in daily maximum, mean, and minimum stream temperatures for the first year following treatment. Significant effects on daily maximum stream temperature were found for April to August, ranging from 0.6 °C to 3.9 °C, similar to the magnitude of effect found in previous studies involving 50% random thinning. We conducted further analysis to identify the thermal response variability in relation to hydrometeorological drivers. Multiple regression analysis revealed that treatment effects for maximum daily stream temperature were positively related to solar radiation and negatively related to discharge. Frequent precipitation during the summer monsoon season produced moderate increases in discharge (from 1 to 5 mm day−1), mitigating stream temperature increases associated with solar radiation. Catchment hydrologic response to rain events can play an important role in controlling stream thermal response to forest management practices.Arts, Faculty ofNon UBCGeography, Department ofReviewedFacultyResearche

Shape control of active surfaces inspired by the movement of euglenids

We examine a novel mechanism for active surface morphing inspired by the cell body deformations of euglenids. Actuation is accomplished through in-plane simple shear along prescribed slip lines decorating the surface. Under general non-uniform actuation, such local deformation produces Gaussian curvature, and therefore leads to shape changes. Geometrically, a deformation that realizes the prescribed local shear is an isometric embedding. We explore the possibilities and limitations of this bio-inspired shape morphing mechanism, by first characterizing isometric embeddings under axisymmetry, understanding the limits of embeddability, and studying in detail the accessibility of surfaces of zero and constant curvature. Modeling mechanically the active surface as a non-Euclidean plate (NEP), we further examine the mechanism beyond the geometric singularities arising from embeddability, where mechanics and buckling play a decisive role. We also propose a non-axisymmetric actuation strategy to accomplish large amplitude bending and twisting motions of elongated cylindrical surfaces. Besides helping understand how euglenids delicately control their shape, our results may provide the background to engineer soft machines

Propagation in the transverse tubular system and voltage dependence of calcium release in normal and mdx mouse muscle fibres

Using a two-microelectrode voltage clamp technique, we investigated possible mechanisms underlying the impaired excitation–contraction coupling in skeletal muscle fibres of the mdx mouse, a model of the human disease Duchenne muscular dystrophy. We evaluated the role of the transverse tubular system (T-system) by using the potentiometric indicator di-8 ANEPPS, and that of the sarcoplasmic reticulum (SR) Ca(2)(+) release by measuring Ca(2)(+) transients with a low affinity indicator in the presence of high EGTA concentrations under voltage clamp conditions. We observed minimal differences in the T-system structure and the T-system electrical propagation was not different between normal and mdx mice. Whereas the maximum Ca(2)(+) release elicited by voltage pulses was reduced by ∼67% in mdx fibres, in agreement with previous results obtained using AP stimulation, the voltage dependence of SR Ca(2)(+) release was identical to that seen in normal fibres. Taken together, our data suggest that the intrinsic ability of the sarcoplasmic reticulum to release Ca(2)(+) may be altered in the mdx mouse