scholarly journals Patch‐scale culls of an overabundant bird defeated by immediate recolonization

2019 ◽  
Vol 29 (3) ◽  
Author(s):  
Richard Beggs ◽  
Ayesha I. T. Tulloch ◽  
Jennifer Pierson ◽  
Wade Blanchard ◽  
Mason Crane ◽  
...  
Keyword(s):  
Patch Scale

scholarly journals Ungulates rely less on visual cues, but more on adapting movement behaviour, when searching for forage

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3178 ◽  
Author(s):  
Jan A. Venter ◽  
Herbert H.T. Prins ◽  
Alla Mashanova ◽  
Rob Slotow
Keyword(s):  
Visual Cues ◽  
A Priori ◽  
Step Length ◽  
Habitat Patch ◽  
Movement Behaviour ◽  
Large Herbivores ◽  
Heterogeneous Landscape ◽  
Equus Burchelli ◽  
Scale Step ◽  
Patch Scale

Finding suitable forage patches in a heterogeneous landscape, where patches change dynamically both spatially and temporally could be challenging to large herbivores, especially if they have noa prioriknowledge of the location of the patches. We tested whether three large grazing herbivores with a variety of different traits improve their efficiency when foraging at a heterogeneous habitat patch scale by using visual cues to gaina prioriknowledge about potential higher value foraging patches. For each species (zebra (Equus burchelli), red hartebeest (Alcelaphus buselaphussubspeciescamaa) and eland (Tragelaphus oryx)), we used step lengths and directionality of movement to infer whether they were using visual cues to find suitable forage patches at a habitat patch scale. Step lengths were significantly longer for all species when moving to non-visible patches than to visible patches, but all movements showed little directionality. Of the three species, zebra movements were the most directional. Red hartebeest had the shortest step lengths and zebra the longest. We conclude that these large grazing herbivores may not exclusively use visual cues when foraging at a habitat patch scale, but would rather adapt their movement behaviour, mainly step length, to the heterogeneity of the specific landscape.

scholarly journals Ungulates rely less on visual cues, but more on adapting movement behaviour, when searching for forage

2017 ◽  
Author(s):  
Jan A Venter ◽  
Herbert H. T. Prins ◽  
Alla Mashanova ◽  
Rob Slotow
Keyword(s):  
Visual Cues ◽  
A Priori ◽  
Step Length ◽  
A Priori Knowledge ◽  
Habitat Patch ◽  
Movement Behaviour ◽  
Large Herbivores ◽  
Scale Step ◽  
Patch Scale ◽  
Priori Knowledge

Finding suitable forage patches in a heterogeneous landscape, where patches change dynamically both spatially and temporally could be challenging to large herbivores, especially if they have no a priori knowledge of the location of the patches. We tested whether three large grazing herbivores with a variety of different traits, improve their efficiency when foraging at a heterogeneous habitat patch scale, by using visual cues to gain a priori knowledge about potential higher value foraging patches. For each species (zebra (Equus burchelli ), red hartebeest (Alcelaphus buselaphus subspecies camaa ) and eland ( Tragelaphus oryx )), we used step lengths and directionality of movement to infer whether they were using visual cues to find suitable forage patches at a habitat patch scale. Step lengths were significantly longer for all species when moving to non-visible patches than to visible patches, but all movements showed little directionality. Of the three species, zebra movements were the most directional. Red hartebeest had the shortest step lengths and zebra the longest. We conclude that these large grazing herbivores may not exclusively use visual cues when foraging at a habitat patch scale, but would rather adapt their movement behaviour, mainly step length, to the heterogeneity of the specific landscape.

scholarly journals Spatial Variation in Canopy Structure across Forest Landscapes

2018 ◽  
Author(s):  
Brady S. Hardiman ◽  
Elizabeth A. LaRue ◽  
Jeff W. Atkins ◽  
Robert T. Fahey ◽  
Franklin W. Wagner ◽  
...  
Keyword(s):  
Temperate Forest ◽  
Forest Canopy ◽  
Spatial Scales ◽  
Canopy Structure ◽  
Ecosystem Functions ◽  
Lidar System ◽  
Stable Point ◽  
Eastern Usa ◽  
Forested Landscapes ◽  
Patch Scale

Forest canopy structure (CS) controls many ecosystem functions and is highly variable across landscapes, but the magnitude and scale of this variation is not well understood. We used a portable canopy lidar system to characterize variation in five categories of CS along N = 3 transects (140–800 m long) at each of six forested landscapes within the eastern USA. The cumulative coefficient of variation was calculated for subsegments of each transect to determine the point of stability for individual CS metrics. We then quantified the scale at which CS is autocorrelated using Moran’s I in an Incremental Autocorrelation analysis. All CS metrics reached stable values within 300 m but varied substantially within and among forested landscapes. A stable point of 300 m for CS metrics corresponds with the spatial extent that many ecosystem functions are measured and modeled. Additionally, CS metrics were spatially autocorrelated at 40 to 88 m, suggesting that patch scale disturbance or environmental factors drive these patterns. Our study shows CS is heterogeneous across temperate forest landscapes at the scale of 10’s of meters, requiring a resolution of this size for upscaling CS with remote sensing to large spatial scales.

Quantification of N2O fluxes and EF values in a pasture using chamber and eddy-covariance technique

2021 ◽  
Author(s):  
Lena Barczyk ◽  
Kate Kuntu-Blankson ◽  
Pierluigi Calanca ◽  
Johan Six ◽  
Christof Ammann
Keyword(s):  
Eddy Covariance ◽  
Linear Interpolation ◽  
Interactive Effects ◽  
Pasture Management ◽  
Grassland Ecosystems ◽  
Nitrogen Inputs ◽  
Seasonal Basis ◽  
Artificial Urine ◽  
Patch Scale ◽  
Relevant Factors

<p>In grassland ecosystems nitrogen (N) inputs are mainly attributed to fertilizer applications for increasing  herbage productivity and to excreta of grazing animals. Cattle, for instance, excrete 75-95 % of the N intake. Accordingly, dung and urine patches of grazing animals form hotspots of nitrate leaching and gaseous N emissions as ammonia (NH<sub>3</sub>) or the important greenhouse gas nitrous oxide (N<sub>2</sub>O). Global default emission factor (EF) values for N<sub>2</sub>O, 2.0 % for grazing based nitrogen inputs (EF3) and 1.0 % for nitrogen inputs via fertilizer applications (EF1) have been suggested by IPCC. However, some countries like New Zealand, Canada or the Netherlands have established country-specific EFs showing considerable regional differences.</p><p>In the present research study, we examine N<sub>2</sub>O emissions of a pasture field in Switzerland in relation to possible drivers. Field scale emissions by eddy covariance are measured in parallel to patch-scale N<sub>2</sub>O fluxes from controlled applications of urine, dung and fertilizer. The patch-scale fluxes are measured by a manually operated chamber ('fast-box') connected to an online gas analyzer. Besides estimating EF values on annual and seasonal basis, relevant factors that might control N<sub>2</sub>O fluxes like environmental conditions (weather parameters, soil moisture, soil temperature), vegetation characteristics (height, composition, nitrogen and carbon content) and pasture management (patch age, grazing, fertilization, cut events, interactive effects) are analyzed. </p><p>We present and discuss results of the first measurement year 2020. Three artificial urine applications during summer and autumn were performed. They show peak N<sub>2</sub>O fluxes of 279-1718 μg m<sup>-2</sup> h<sup>-1</sup> directly after application that decrease to near-background fluxes within 19-43 days. Using a simple linear interpolation of measured N<sub>2</sub>O fluxes, EF values of artificial urine patches vary between 0.57 and 2.44 % indicating a seasonal variability of N<sub>2</sub>O fluxes.</p>

The Influence of Geomorphological Heterogeneity on Biodiversity  I. A Patch-Scale Perspective

2008 ◽  
Vol 12 (2) ◽  
pp. 363-370 ◽  
Author(s):  
Michael R. Burnett ◽  
Peter V. August ◽  
James H. Brown ◽  
Keith T. Killingbeck ◽  
Keyword(s):  
Patch Scale

scholarly journals Analysis of effective resistance calculation methods and their effect on modelling evapotranspiration in two different patches of vegetation in semi-arid SE Spain

2007 ◽  
Vol 11 (5) ◽  
pp. 1529-1542 ◽  
Author(s):  
A. Were ◽  
L. Villagarcía ◽  
F. Domingo ◽  
L. Alados-Arboledas ◽  
J. Puigdefábregas
Keyword(s):  
Aerodynamic Resistance ◽  
Surface Fluxes ◽  
Effective Parameters ◽  
Effective Surface ◽  
Se Spain ◽  
Retama Sphaerocarpa ◽  
In Series ◽  
Eddy Covariance System ◽  
Patch Scale ◽  
Monteith Equation

Abstract. Effective parameters are of major importance in modelling surface fluxes at different scales of spatial heterogeneity. Different ways to obtain these effective parameters for their use in meso-scale and GCM models have been studied. This paper deals with patch-scale heterogeneity, where effective resistances were calculated in two patches with different vegetation (Retama sphaerocarpa (L.) Boiss shrubs, and herbaceous plants) using different methods: aggregating soil and plant resistances in parallel, in series or by an average of both. Effective aerodynamic resistance was also calculated directly from patch fluxes. To assess the validity of the different methods used, the Penman-Monteith equation was used with effective resistances to estimate the total λE for each patch. The λE estimates found for each patch were compared to Eddy Covariance system measurements. Results showed that for effective surface resistances, parallel aggregation of soil and plant resistances led to λE estimates closer to the measured λE in both patches (differences of around 10%). Results for effective aerodynamic resistances differed depending on the patch considered and the method used to calculate them. The use of effective aerodynamic resistances calculated from fluxes provided less accurate estimates of λE compared to the measured values, than the use of effective aerodynamic resistances aggregated from soil and plant resistances. The results reported in this paper show that the best way of aggregating soil and plant resistances depends on the type of resistance, and the type of vegetation in the patch.

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