Tropical rainforests usually have multiple strata that results in a vertical stratification of ecological opportunities foranimals. We investigated if this stratification influences the way bats use the vertical space...Tropical rainforests usually have multiple strata that results in a vertical stratification of ecological opportunities foranimals. We investigated if this stratification influences the way bats use the vertical space in flooded and unflooded forests of theCentral Amazon. Using mist-nets set in the canopy (17 to 35 m high) and in the understorey (0 to 3 m high) we sampled four sitesin upland unflooded forests (terra firme), three in forests seasonally flooded by nutrient-rich water (varzea), and three in forestsseasonally flooded by nutrient-poor water (igapo). Using rarefaction curves we found that species richness in the understorey andcanopy were very similar. An ordination analysis clearly separated the bat assemblages of the canopy from those of the understorey inboth flooded and unflooded habitats. Gleaning carnivores were clearly associated with the understorey, whereas frugivores wereabundant in both strata. Of the frugivores, Carollinae and some Stenodermatinae were understorey specialists, but several Stenodermatinaemostly used the canopy. The first group mainly includes species that, in general, feed on fruits of understorey shrubs,whereas the second group feed on figs and other canopy fruits. We conclude that vertical stratification in bat communities occurseven within forests with lower canopy heights, such as Amazonian seasonally flooded forests, and that the vertical distribution ofbat species is closely related to their diet and foraging behaviour.展开更多
Airborne light detection and ranging (LIDAR) can detect the three-dimensional structure of forest canopies by transmitting laser pulses and receiving returned waveforms which contain backscatter from branches and leav...Airborne light detection and ranging (LIDAR) can detect the three-dimensional structure of forest canopies by transmitting laser pulses and receiving returned waveforms which contain backscatter from branches and leaves at different heights.We established a solid scatterer model to explain the widened durations found in analyzing the relationship between laser pulses and forest canopies,and obtained the corresponding rule between laser pulse duration and scatterer depth.Based on returned waveform characteristics,scatterers were classified into three types:simple,solid and complex.We developed single-peak derivative and multiple-peak derivative analysis methods to retrieve waveform features and discriminate between scatterer types.Solid scatterer simulations showed that the returned waveforms were widened as scatterer depth increased,and as space between sub-scatterers increased the returned waveforms developed two peaks which subsequently developed into two separate sub-waveforms.There were slight differences between the durations of simulated and measured waveforms.LIDAR waveform data are able to describe the backscatter characteristics of forest canopies,and have potential to improve the estimation accuracy of forest parameters.展开更多
Analysis of forest canopy hemisphere images is one of the most important methods for measuring forest canopy structure parameters. In this study, our main focus was on using circular image region segmentation, which i...Analysis of forest canopy hemisphere images is one of the most important methods for measuring forest canopy structure parameters. In this study, our main focus was on using circular image region segmentation, which is the basis of forest canopy hemispherical photography. The boundary of a forest canopy hemisphere image was analyzed via histogram, rectangle, and Fourier descriptors. The image boundary characteristics were defined and obtained based on the following：（1） an edge model that contains three parts, i.e., step, ramp, and roof;（2） boundary points of discontinuity;（3） an edge that has a linear distribution of scattering points. On this basis, we proposed a segmentation method for the circular region in a forest canopy hemisphere image, fitting the circular boundary and computing the center and radius by the least squares method. The method was unrelated to the parameters of the image acquisition device. Hence, this study lays a foundation for automatically adjusting the parameters of high-performance image acquisition devices used in forest canopy hemispherical photography.展开更多
基金supported by Fundaāo para a Ciência e Tecnologia (POCI-PPCDT/BIA-BDE/60710/2004, co-financed by the ERDF, and fellowships SFRH/BD/19620/2004 and SFRH/BDI22829/2005)a Bat Conservation International grant
文摘Tropical rainforests usually have multiple strata that results in a vertical stratification of ecological opportunities foranimals. We investigated if this stratification influences the way bats use the vertical space in flooded and unflooded forests of theCentral Amazon. Using mist-nets set in the canopy (17 to 35 m high) and in the understorey (0 to 3 m high) we sampled four sitesin upland unflooded forests (terra firme), three in forests seasonally flooded by nutrient-rich water (varzea), and three in forestsseasonally flooded by nutrient-poor water (igapo). Using rarefaction curves we found that species richness in the understorey andcanopy were very similar. An ordination analysis clearly separated the bat assemblages of the canopy from those of the understorey inboth flooded and unflooded habitats. Gleaning carnivores were clearly associated with the understorey, whereas frugivores wereabundant in both strata. Of the frugivores, Carollinae and some Stenodermatinae were understorey specialists, but several Stenodermatinaemostly used the canopy. The first group mainly includes species that, in general, feed on fruits of understorey shrubs,whereas the second group feed on figs and other canopy fruits. We conclude that vertical stratification in bat communities occurseven within forests with lower canopy heights, such as Amazonian seasonally flooded forests, and that the vertical distribution ofbat species is closely related to their diet and foraging behaviour.
基金supported by the National Basic Research Program of China(Grant No.2007CB714404)the Central PublicInterest Scientific Institution Basal Research Fund of China(Grant No.IFRIT200803)the National HiTech Research and Development Program of China(Grant No.2009AA12Z1461)
文摘Airborne light detection and ranging (LIDAR) can detect the three-dimensional structure of forest canopies by transmitting laser pulses and receiving returned waveforms which contain backscatter from branches and leaves at different heights.We established a solid scatterer model to explain the widened durations found in analyzing the relationship between laser pulses and forest canopies,and obtained the corresponding rule between laser pulse duration and scatterer depth.Based on returned waveform characteristics,scatterers were classified into three types:simple,solid and complex.We developed single-peak derivative and multiple-peak derivative analysis methods to retrieve waveform features and discriminate between scatterer types.Solid scatterer simulations showed that the returned waveforms were widened as scatterer depth increased,and as space between sub-scatterers increased the returned waveforms developed two peaks which subsequently developed into two separate sub-waveforms.There were slight differences between the durations of simulated and measured waveforms.LIDAR waveform data are able to describe the backscatter characteristics of forest canopies,and have potential to improve the estimation accuracy of forest parameters.
基金Project supported by the Fundamental Research Funds for the Central Universities,China（No.2572014BB04） the National Natural Science Foundation of China（No.31370710） the Specialized Research Fund for the Doctoral Program of Higher Education of China（No.20110062110002）
文摘Analysis of forest canopy hemisphere images is one of the most important methods for measuring forest canopy structure parameters. In this study, our main focus was on using circular image region segmentation, which is the basis of forest canopy hemispherical photography. The boundary of a forest canopy hemisphere image was analyzed via histogram, rectangle, and Fourier descriptors. The image boundary characteristics were defined and obtained based on the following：（1） an edge model that contains three parts, i.e., step, ramp, and roof;（2） boundary points of discontinuity;（3） an edge that has a linear distribution of scattering points. On this basis, we proposed a segmentation method for the circular region in a forest canopy hemisphere image, fitting the circular boundary and computing the center and radius by the least squares method. The method was unrelated to the parameters of the image acquisition device. Hence, this study lays a foundation for automatically adjusting the parameters of high-performance image acquisition devices used in forest canopy hemispherical photography.
