739 research outputs found
Predicting and understanding spatio-temporal dynamics of species recovery : implications for Asian crested ibis Nipponia nippon conservation in China
Acknowledgements This work was supported by the National Natural Science Foundation of China (No. 31372218) and cofunded by the China Scholarship Council (CSC) and the ITC Research Fund, Enschede, the Netherlands. We thank Shaanxi Hanzhong Crested Ibis National Nature Reserve for sharing the data of nest site locations. We are grateful to Brendan Wintle, Justin Travis and two anonymous reviewers for helpful comments on a previous version of the manuscript.Peer reviewedPublisher PD
LiDAR reveals a preference for intermediate visibility by a forest-dwelling ungulate species
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
© 2022 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological SocietyAbstract 1. Visibility (viewshed) plays a significant and diverse role in animals' behaviour and fitness. Understanding how visibility influences animal behaviour requires the measurement of habitat visibility at spatial scales commensurate to individual animal choices. However, measuring habitat visibility at a fine spatial scale over a landscape is a challenge, particularly in highly heterogeneous landscapes (e.g. forests). As a result, our ability to model the influence of fine-scale visibility on animal behaviour has been impeded or limited. 2. In this study, we demonstrate the application of the concept of three-dimensional (3D) cumulative viewshed in the study of animal spatial behaviour at a landscape level. Specifically, we employed a newly described approach that combines ter-restrial and airborne light detection and ranging (LiDAR) to measure fine-scale habitat visibility (3D cumulative viewshed) on a continuous scale in forested landscapes. We applied the LiDAR-derived visibility to investigate how visibility in forests affects the summer habitat selection and the movement of 20 GPS- collared female red deer Cervus elaphus in a temperate forest in Germany. We used integrated step selection analysis to determine whether red deer show any preference for fine-scale habitat visibility and whether visibility is related to the rate of movement of red deer. 3. We found that red deer selected intermediate habitat visibility. Their preferred level of visibility during the day was substantially lower than that of night and twilight, whereas the preference was not significantly different between night and twilight. In addition, red deer moved faster in high-visibility areas, possibly mainly to avoid predation and anthropogenic risk. Furthermore, red deer moved most rapidly between locations in the twilight. 4. For the first time, the preference for intermediate habitat visibility and the adap-tion of movement rate to fine-scale visibility by a forest-dwelling ungulate spe-cies at a landscape scale was revealed. The LiDAR technique used in this study offers fine-scale habitat visibility at the landscape level in forest ecosystems, which would be of broader interest in the fields of animal ecology and behaviour.publishedVersio
LiDAR reveals a preference for intermediate visibility by a forest-dwelling ungulate species
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
© 2022 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological SocietyAbstract 1. Visibility (viewshed) plays a significant and diverse role in animals' behaviour and fitness. Understanding how visibility influences animal behaviour requires the measurement of habitat visibility at spatial scales commensurate to individual animal choices. However, measuring habitat visibility at a fine spatial scale over a landscape is a challenge, particularly in highly heterogeneous landscapes (e.g. forests). As a result, our ability to model the influence of fine-scale visibility on animal behaviour has been impeded or limited. 2. In this study, we demonstrate the application of the concept of three-dimensional (3D) cumulative viewshed in the study of animal spatial behaviour at a landscape level. Specifically, we employed a newly described approach that combines ter-restrial and airborne light detection and ranging (LiDAR) to measure fine-scale habitat visibility (3D cumulative viewshed) on a continuous scale in forested landscapes. We applied the LiDAR-derived visibility to investigate how visibility in forests affects the summer habitat selection and the movement of 20 GPS- collared female red deer Cervus elaphus in a temperate forest in Germany. We used integrated step selection analysis to determine whether red deer show any preference for fine-scale habitat visibility and whether visibility is related to the rate of movement of red deer. 3. We found that red deer selected intermediate habitat visibility. Their preferred level of visibility during the day was substantially lower than that of night and twilight, whereas the preference was not significantly different between night and twilight. In addition, red deer moved faster in high-visibility areas, possibly mainly to avoid predation and anthropogenic risk. Furthermore, red deer moved most rapidly between locations in the twilight. 4. For the first time, the preference for intermediate habitat visibility and the adap-tion of movement rate to fine-scale visibility by a forest-dwelling ungulate spe-cies at a landscape scale was revealed. The LiDAR technique used in this study offers fine-scale habitat visibility at the landscape level in forest ecosystems, which would be of broader interest in the fields of animal ecology and behaviour.publishedVersio
Identifying Birds' Collision Risk with Wind Turbines Using a Multidimensional Utilization Distribution Method
Renewable energy plays a key role in reducing greenhouse gas emissions. However, the expansion of wind farms has raised concerns about risks for bird collisions. We tested different methods used to understand whether birds' flight occurs over wind turbines and found kernel density estimators outperform other methods. Previous studies using kernel utilization distribution (KUD) have considered only the 2 horizontal dimensions (2D). However, if altitude is ignored, an unrealistic depiction of the situation may result because birds move in 3 dimensions (3D). We quantified the 3D space use of the Griffon vulture (Gyps fulvus) in El Estrecho natural park in Tarifa (southern Spain, on the northern shore of the Strait of Gibraltar) during 2012-2013, and, for the first time, their risk of collision with wind turbines in an area in the south of Spain. The 2D KUD showed a substantial overlap of the birds' flight paths with the wind turbines in the study area, whereas the 3D kernel estimate did not show such overlap. Our aim was to develop a new approach using 3D kernel estimation to understand the space use of soaring birds; these are killed by collision with wind turbines more often than any other bird types in southern Spain. We determined the probability of bird collision with an obstacle within its range. Other potential application areas include airfields, plane flight paths, and tall buildings. (c) 2020 The Authors. Wildlife Society Bulletin published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.Peer reviewe
High-throughput Soxhlet extraction method applied for analysis of leaf lignocellulose and non-structural substances
The traditional Soxhlet extraction method is commonly employed to extract soluble components from non-soluble components in a solid matrix, for example, non-structural substances in biomass samples that can be separated from structural lignocellulosic compounds in biomass samples. Conventional laboratory procedures for such extractions typically involve a low sample throughput, with each run being performed individually, resulting in time-consuming and labour-intensive processes, making them impractical for analysing large sample sets. In research fields such as Earth Observation in Forest Ecosystems, extensive fieldwork sampling is required across large study areas, resulting in a substantial number of leaf samples, each with limited mass. In this study, an innovative adaptation of the conventional National Renewable Energy Laboratory (NREL) Soxhlet method is developed to create a high-throughput mini-Soxhlet apparatus that enables the simultaneous extraction of up to nineteen samples, each with a mass of 0.3 g per sample. With this adaptation, we measured the lignocellulose and extractive in 343 leaf samples collected from four temperate forest tree species. This modified approach enhances versatility and can be applied to all solid-liquid extractions and various types of vegetation tissues, such as tree leaves, shrubs, crops, feedstock, and other non-woody samples.âą The solid-liquid extraction method has been implemented in a heating block facilitating 19 small flasks to measure multiple samples simultaneously while requiring only a small sample mass.âą The apparatus set-up was constructed using an alumina heating block mounted on a standard laboratory heating plate. Boiling flask tubes were placed in the heating block and equipped with condenser caps and filters on glass rods on which the solid samples were placed.âą The adjustments made the method suitable for application to diverse vegetation tissues and non-woody sample types. It holds particular appeal for research areas that necessitate a high sample number
Potential of Sentinel-2 spectral configuration to assess rangeland quality
Sentinel-2 is intended to improve vegetation assessment at local to global scales.
Today, estimation of leaf nitrogen (N) as an indicator of rangeland quality is possible using
hyperspectral systems. However, few studies based on commercial imageries have shown a
potential of the red-edge band to accurately predict leaf N at the broad landscape scale. We
intend to investigate the utility of Sentinel-2 for estimating leaf N concentration in the African
savanna. Grass canopy reflectance was measured using the analytical spectral device (ASD) in
concert with leaf sample collections for leaf N chemical analysis. ASD reflectance data were
resampled to the spectral bands of Sentinel-2 using published spectral response functions.
Random forest (RF), partial least square regression (PLSR), and stepwise multiple linear regression
(SMLR) were used to predict leaf N using all 13 bands. Using leave-one-out cross validation,
the RF model explained 90% of leaf N variation, with a root mean square error of 0.04
(6% of the mean), which is higher than that of PLSR and SMLR. Using RF, spectral bands
centered at 705 nm (red edge) and two shortwave infrared bands centered at 2190 and 1610 nm
were found to be the most important bands in predicting leaf N.The Council for Scientific and Industrial Research, Department of
Science and Technology (DST), National Research Foundationâs Thuthuka program, University of Twenteâs Faculty of Geo-information Science and Earth Observation (UTITC),
and Wageningen University.http://www.sherpa.ac.uk/romeo/issn/1931-3195/am2016Geography, Geoinformatics and Meteorolog
Will the Three Gorges Dam affect the underwater light climate of Vallisneria spiralis L. and food habitat of Siberian crane in Poyang Lake?
Almost 95% of the entire population of the Siberian crane (Grus leucogeranus) winter in Poyang Lake, China, where they forage on the tubers of the submerged aquatic macrophyte Vallisneria spiralis. The Three Gorges Dam on the Yangtze River may possibly affect this food source of the Siberian crane by affecting the light intensity reaching the top of the V. spiralis canopy. In this study, the photosynthetically active radiation at the top of the V. spiralis canopy (PARtc) in Lake Dahuchi was modeled from 1998 to 2006, and the potential impacts of changes in water level and turbidity on the underwater light climate of V. spiralis were analyzed. PARtc was calculated from incident irradiance while the losses due to reflection at the water surface, absorption, and scattering within the water column were taken into consideration. The results indicated significant differences in PARtc between years. Six years of water level and Secchi disk depth records revealed a seasonal switching of the lake from a turbid state at low water levels in autumn, winter, and spring to a clear state at high water levels during the monsoon in summer. The highest PARtc occurred at intermediate water levels, which were reached when the Yangtze River forces Lake Dahuchi out of its turbid state in early summer and the water becomes clear. The intended operation of the Three Gorges Dam, which will increase water levels in May and June, may advance the moment when Lake Dahuchi switches from turbid to clear. We suggest that this might increase production of V. spiralis and possibly improve the food habitat conditions for wintering Siberian crane in Poyang Lake
Forest top canopy bacterial communities are influenced by elevation and host tree traits
Background: The phyllosphere microbiome is crucial for plant health and ecosystem functioning. While host species play a determining role in shaping the phyllosphere microbiome, host trees of the same species that are subjected to different environmental conditions can still exhibit large degrees of variation in their microbiome diversity and composition. Whether these intra-specific variations in phyllosphere microbiome diversity and composition can be observed over the broader expanse of forest landscapes remains unclear. In this study, we aim to assess the variation in the top canopy phyllosphere bacterial communities between and within host tree species in the temperate European forests, focusing on Fagus sylvatica (European beech) and Picea abies (Norway spruce).Results: We profiled the bacterial diversity, composition, driving factors, and discriminant taxa in the top canopy phyllosphere of 211 trees in two temperate forests, Veluwe National Parks, the Netherlands and Bavarian Forest National Park, Germany. We found the bacterial communities were primarily shaped by host species, and large variation existed within beech and spruce. While we showed that there was a core microbiome in all tree species examined, community composition varied with elevation, tree diameter at breast height, and leaf-specific traits (e.g., chlorophyll and P content). These driving factors of bacterial community composition also correlated with the relative abundance of specific bacterial families.Conclusions: While our results underscored the importance of host species, we demonstrated a substantial range of variation in phyllosphere bacterial diversity and composition within a host species. Drivers of these variations have implications at both the individual host tree level, where the bacterial communities differed based on tree traits, and at the broader forest landscape level, where drivers like certain highly plastic leaf traits can potentially link forest canopy bacterial community variations to forest ecosystem processes. We eventually showed close associations between forest canopy phyllosphere bacterial communities and host trees exist, and the consistent patterns emerging from these associations are critical for host plant functioning
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