The Experts below are selected from a list of 3228 Experts worldwide ranked by ideXlab platform
Kevin S. Gould - One of the best experts on this subject based on the ideXlab platform.
-
leaf orientation and light interception by juvenile pseudopanax crassifolius cunn c koch in a partially shaded forest environment
Oecologia, 1995Co-Authors: Michael J Clearwater, Kevin S. GouldAbstract:Leaf orientations and light environments were recorded for 40 juvenile Pseudopanax crassifolius trees growing in New Zealand in a partially shaded, secondary forest environment. Efficiencies of interception of diffuse and direct light by the observed leaf arrangments were calculated relative to those of three hypothetical leaf arrangements. Canopy gaps above the study plants were unevenly distributed with respect to azimuth and elevation above the horizon. Our results indicate that photosynthetically active radiation (PAR) received from the sides is more important than that received from directly above. In 33 of the plants leaf orientation was found to be significantly clustered towards one azimuth. The mean azimuth and the mean angle of declination were different for each plant. Leaves were steeply declined, and oriented towards the largest canopy gap at each site. Steep leaf angles reduced interception of direct and diffuse PAR when compared to interception by plant with a hypothetical horizontal leaf arrangement. When compared to a hypothetical arrangement with steep leaf declination and a uniform azimuth distribution, the observed leaf arrangement increased the efficiency of interception of diffuse PAR, but had a variable effect on the interception of direct PAR. Results indicate that the developing leaves of juvenile P. crassifolius orient towards the strongest sources of diffuse light, regardless of their value as a source of direct light. By maximising diffuse light interception while reducing direct light interception, leaf orientation may be a partial determinant of the types of habitats exploited by this species. This study emphasises the importance of considering diffuse light interception for plants growing in partially shaded environments.
-
leaf orientation and light interception by juvenile pseudopanax crassifolius cunn c koch in a partially shaded forest environment
Oecologia, 1995Co-Authors: Michael J Clearwater, Kevin S. GouldAbstract:Leaf orientations and light environments were recorded for 40 juvenile Pseudopanax crassifolius trees growing in New Zealand in a partially shaded, secondary forest environment. Efficiencies of interception of diffuse and direct light by the observed leaf arrangments were calculated relative to those of three hypothetical leaf arrangements. Canopy gaps above the study plants were unevenly distributed with respect to azimuth and elevation above the horizon. Our results indicate that photosynthetically active radiation (PAR) received from the sides is more important than that received from directly above. In 33 of the plants leaf orientation was found to be significantly clustered towards one azimuth. The mean azimuth and the mean angle of declination were different for each plant. Leaves were steeply declined, and oriented towards the largest canopy gap at each site. Steep leaf angles reduced interception of direct and diffuse PAR when compared to interception by plant with a hypothetical horizontal leaf arrangement. When compared to a hypothetical arrangement with steep leaf declination and a uniform azimuth distribution, the observed leaf arrangement increased the efficiency of interception of diffuse PAR, but had a variable effect on the interception of direct PAR. Results indicate that the developing leaves of juvenile P. crassifolius orient towards the strongest sources of diffuse light, regardless of their value as a source of direct light. By maximising diffuse light interception while reducing direct light interception, leaf orientation may be a partial determinant of the types of habitats exploited by this species. This study emphasises the importance of considering diffuse light interception for plants growing in partially shaded environments.
Michael J Clearwater - One of the best experts on this subject based on the ideXlab platform.
-
leaf orientation and light interception by juvenile pseudopanax crassifolius cunn c koch in a partially shaded forest environment
Oecologia, 1995Co-Authors: Michael J Clearwater, Kevin S. GouldAbstract:Leaf orientations and light environments were recorded for 40 juvenile Pseudopanax crassifolius trees growing in New Zealand in a partially shaded, secondary forest environment. Efficiencies of interception of diffuse and direct light by the observed leaf arrangments were calculated relative to those of three hypothetical leaf arrangements. Canopy gaps above the study plants were unevenly distributed with respect to azimuth and elevation above the horizon. Our results indicate that photosynthetically active radiation (PAR) received from the sides is more important than that received from directly above. In 33 of the plants leaf orientation was found to be significantly clustered towards one azimuth. The mean azimuth and the mean angle of declination were different for each plant. Leaves were steeply declined, and oriented towards the largest canopy gap at each site. Steep leaf angles reduced interception of direct and diffuse PAR when compared to interception by plant with a hypothetical horizontal leaf arrangement. When compared to a hypothetical arrangement with steep leaf declination and a uniform azimuth distribution, the observed leaf arrangement increased the efficiency of interception of diffuse PAR, but had a variable effect on the interception of direct PAR. Results indicate that the developing leaves of juvenile P. crassifolius orient towards the strongest sources of diffuse light, regardless of their value as a source of direct light. By maximising diffuse light interception while reducing direct light interception, leaf orientation may be a partial determinant of the types of habitats exploited by this species. This study emphasises the importance of considering diffuse light interception for plants growing in partially shaded environments.
-
leaf orientation and light interception by juvenile pseudopanax crassifolius cunn c koch in a partially shaded forest environment
Oecologia, 1995Co-Authors: Michael J Clearwater, Kevin S. GouldAbstract:Leaf orientations and light environments were recorded for 40 juvenile Pseudopanax crassifolius trees growing in New Zealand in a partially shaded, secondary forest environment. Efficiencies of interception of diffuse and direct light by the observed leaf arrangments were calculated relative to those of three hypothetical leaf arrangements. Canopy gaps above the study plants were unevenly distributed with respect to azimuth and elevation above the horizon. Our results indicate that photosynthetically active radiation (PAR) received from the sides is more important than that received from directly above. In 33 of the plants leaf orientation was found to be significantly clustered towards one azimuth. The mean azimuth and the mean angle of declination were different for each plant. Leaves were steeply declined, and oriented towards the largest canopy gap at each site. Steep leaf angles reduced interception of direct and diffuse PAR when compared to interception by plant with a hypothetical horizontal leaf arrangement. When compared to a hypothetical arrangement with steep leaf declination and a uniform azimuth distribution, the observed leaf arrangement increased the efficiency of interception of diffuse PAR, but had a variable effect on the interception of direct PAR. Results indicate that the developing leaves of juvenile P. crassifolius orient towards the strongest sources of diffuse light, regardless of their value as a source of direct light. By maximising diffuse light interception while reducing direct light interception, leaf orientation may be a partial determinant of the types of habitats exploited by this species. This study emphasises the importance of considering diffuse light interception for plants growing in partially shaded environments.
Yu Liu - One of the best experts on this subject based on the ideXlab platform.
-
rainfall interception recovery in a subtropical forest damaged by the great 2008 ice and snow storm in southern china
Journal of Hydrology, 2020Co-Authors: Lezhang Wei, Zhijun Qiu, Guangyi Zhou, Gulia Zuecco, Yu LiuAbstract:Abstract Canopy interception is an important component of the hydrological cycle of forested catchments, and is influenced by variations in the canopy structure. Extreme meteorological events can have a destructive impact on forest density and structure, and affect the rainfall partitioning by the canopies. Despite extensive investigation of throughfall and stemflow, the response of rainfall interception loss to post-disturbance vegetation recovery is still poorly understood. In this work, we examined the variations in the canopy structure and rainfall interception recovery after a destructive ice and snow storm that occurred in southern China in 2008. Rainfall partitioning into throughfall and stemflow were measured for multiple years at two damaged sites on Nanling Mountain, while the interception loss was modeled using the revised Gash model. The results showed that the vegetation leaf area index (LAI) doubled from 2010 to 2014. This recovery caused the throughfall rate to decrease and the interception rate to increase. The application of the revised Gash model indicates that the vegetation canopy storage capacity (S) and vegetation cover factor (c) increased with the LAI, resulting in an increase in the interception loss and variations in its components. The interception recovery at the study plots provide a biophysical explanation for the threshold behaviors of runoff generation at catchment scale. Comparisons with canopy interception measurements from nearby undamaged secondary forests suggest that interception capacity in the study plots was not fully recovered for the first 5–7 years after the disturbance, indicating that measurements for a longer duration are needed to evaluate the interception recovery from that great disturbance.
Clare J Fowler - One of the best experts on this subject based on the ideXlab platform.
-
visceral sensory neuroscience Interoception
Brain, 2003Co-Authors: Clare J FowlerAbstract:VISCERAL SENSORY NEUROSCIENCE: Interoception By Oliver G. Cameron 2002. Oxford: Oxford University Press Price £39.50. pp. 372. ISBN 0‐19‐513601‐2 Interoception: it is perhaps surprising that this word is not common medical parlance since amongst the other terms introduced by Sherrington, proprioception certainly is. As originally defined Interoception encompassed just visceral sensations but now the term is used to include the physiological condition of the entire body and the ability of visceral afferent information to reach awareness and affect behaviour, either directly or indirectly. The system of Interoception as a whole constitutes “the material me” and relates to how we perceive feelings from our bodies that determine our mood, sense of well‐being and emotions. Clearly this is a field of great relevance to many areas of medicine, to all branches of “internal medicine” as well medical psychology and possibly some branches of psychiatry. The reason why this term is probably missing from our clinical vocabulary so far is that although we have been aware of the underlying concepts of Interoception for decades there have been few methods of systematically studying the underlying principles in humans until the advent of functional imaging. Certainly it has been one of the disappointed aims of clinical neurophysiological research that has been unable to contribute much to our understanding of self‐awareness. This is because all that is accessible to that discipline is the response of large, heavily myelinated fibres, usually to electrical stimuli, whereas the interceptive system afferents are small diameter fibres that can usefully be considered as the afferent limb of the autonomic nervous system. I accepted the offer to …
Jean-matthieu Monnet - One of the best experts on this subject based on the ideXlab platform.
-
Snow processes in mountain forests: interception modeling for coarse-scale applications
Hydrology and Earth System Sciences, 2020Co-Authors: Nora Helbig, David Moeser, Michaela Teich, Laure Vincent, Yves Lejeune, Jean-emmanuel Sicart, Jean-matthieu MonnetAbstract:Snow interception by the forest canopy controls the spatial heterogeneity of subcanopy snow accumulation leading to significant differences between forested and non-forested areas at a variety of scales. Snow intercepted by the forest canopy can also drastically change the surface albedo. As such, accurately modeling snow interception is of importance for various model applications such as hydrological, weather, and climate predictions. Due to difficulties in the direct measurements of snow interception, previous empirical snow interception models were developed at just the point scale. The lack of spatially extensive data sets has hindered the validation of snow interception models in different snow climates, forest types, and at various spatial scales and has reduced the accurate representation of snow interception in coarse-scale models. We present two novel empirical models for the spatial mean and one for the standard deviation of snow interception derived from an extensive snow interception data set collected in an evergreen coniferous forest in the Swiss Alps. Besides open-site snowfall, subgrid model input parameters include the standard deviation of the DSM (digi-tal surface model) and/or the sky view factor, both of which can be easily precomputed. Validation of both models was performed with snow interception data sets acquired in geographically different locations under disparate weather conditions. Snow interception data sets from the Rocky Mountains , US, and the French Alps compared well to the modeled snow interception with a normalized root mean square error (NRMSE) for the spatial mean of ≤ 10 % for both models and NRMSE of the standard deviation of ≤ 13 %. Compared to a previous model for the spatial mean interception of snow water equivalent, the presented models show improved model performances. Our results indicate that the proposed snow interception models can be applied in coarse land surface model grid cells provided that a sufficiently fine-scale DSM is available to derive subgrid forest parameters.
