Lichen cover mapping for caribou ranges in interior Alaska and Yukon

Macander, M. J.; Palm, Eric C.; Frost, G. V.; Herriges, Jim D; Nelson, Peter R.; Roland, Carl A.; Russell, Kelsey L M; Suitor, Mike; Bentzen, Torsten W.; Joly, Kyle; Goetz, Scott J.; Hebblewhite, Mark

doi:10.1088/1748-9326/ab6d38

Cited by 30 publications

(33 citation statements)

References 61 publications

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“…Furthermore, our results demonstrate that snow should be included in future analyses, along with a range of other factors documented as being influential for caribou wintering location, e.g., overgrazing of slow-growing lichen species [ 42 , 136 ]. Macander et al [ 108 ] reported that caribou in interior Alaska prefer lichen habitats in winter until they become overgrazed, and consequently, the herd shifts wintering area within the boreal forest region. The CAH winter range variation may be explained by consistent use of winter ranges south of CD from 2001/02 to 2015/16, interrupted only when the very low fall snow depths allowed caribou to winter north of CD in 2007/08 (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The wandering nature of caribou is undoubtedly influenced by the snow depths they encounter during winter, but the scattered spatial distribution of lichen [ 108 ] may also contribute to their movement behavior. We found that, irrespective of winter range location, caribou selected for areas with higher lichen proportion than otherwise available in the surrounding landscape, indicating the importance of this winter forage resource (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…While the dataset of distributed lichen proportion applied in our movement models does not provide information on lichen biomass, and admittedly represents a coarse measure of winter caribou forage abundance, this study is one of few studies quantifying the combined effects of snow depth and winter forage on caribou movement. New methodologies for mapping and modeling distributions of lichen and other caribou forage species are emerging [ 105 – 108 , 147 ], however, these improved lichen and forage distribution estimates are not available across our entire study area. Future research using such data, e.g., in combination with SnowModel snow depth and caribou location data, could help quantify the effects of snow depth on caribou winter forage accessibility by cratering (e.g., [ 50 , 148 ]).…”

Section: Discussionmentioning

confidence: 99%

“…The patchy distribution of lichen makes mapping of its spatial distribution and biomass challenging. While recent methodologies have been used to successfully map lichen distributions at the landscape scale (~ 30 m; [ 105 – 108 ]), large portions of the CAH winter range are not yet covered by these lichen abundance datasets. Therefore, we mapped caribou winter forage across our study area using the proportion of lichen-rich vegetation based on the 30-m NALCMS land-cover map [ 96 ].…”

Section: Methodsmentioning

confidence: 99%

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Quantifying effects of snow depth on caribou winter range selection and movement in Arctic Alaska

et al. 2021

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Background Caribou and reindeer across the Arctic spend more than two thirds of their lives moving in snow. Yet snow-specific mechanisms driving their winter ecology and potentially influencing herd health and movement patterns are not well known. Integrative research coupling snow and wildlife sciences using observations, models, and wildlife tracking technologies can help fill this knowledge void. Methods Here, we quantified the effects of snow depth on caribou winter range selection and movement. We used location data of Central Arctic Herd (CAH) caribou in Arctic Alaska collected from 2014 to 2020 and spatially distributed and temporally evolving snow depth data produced by SnowModel. These landscape-scale (90 m), daily snow depth data reproduced the observed spatial snow-depth variability across typical areal extents occupied by a wintering caribou during a 24-h period. Results We found that fall snow depths encountered by the herd north of the Brooks Range exerted a strong influence on selection of two distinct winter range locations. In winters with relatively shallow fall snow depth (2016/17, 2018/19, and 2019/20), the majority of the CAH wintered on the tundra north of the Brooks Range mountains. In contrast, during the winters with relatively deep fall snow depth (2014/15, 2015/16, and 2017/18), the majority of the CAH caribou wintered in the mountainous boreal forest south of the Brooks Range. Long-term (19 winters; 2001–2020) monitoring of CAH caribou winter distributions confirmed this relationship. Additionally, snow depth affected movement and selection differently within these two habitats: in the mountainous boreal forest, caribou avoided areas with deeper snow, but when on the tundra, snow depth did not trigger significant deep-snow avoidance. In both wintering habitats, CAH caribou selected areas with higher lichen abundance, and they moved significantly slower when encountering deeper snow. Conclusions In general, our findings indicate that regional-scale selection of winter range is influenced by snow depth at or prior to fall migration. During winter, daily decision-making within the winter range is driven largely by snow depth. This integrative approach of coupling snow and wildlife observations with snow-evolution and caribou-movement modeling to quantify the multi-facetted effects of snow on wildlife ecology is applicable to caribou and reindeer herds throughout the Arctic.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Quantifying effects of snow depth on caribou winter range selection and movement in Arctic Alaska

et al. 2021

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“…Recent studies have indicated that the mapping of caribou lichen is vital for sustainable land management and caribou recovery plans [1][2][3][4][5]. Canadian caribou are threatened by a changing environment due to declining lichen availability, unregulated hunting, habitat disturbances, and herd fragmentation due to human-made infrastructure [2][3][4][5][6]. Lichen is a dominant food source for caribou in the winter, comprising 75% and 25% of their diets in the winter and summer seasons respectively [5].…”

Section: Introductionmentioning

confidence: 99%

Leveraging AI to Estimate Caribou Lichen in UAV Orthomosaics from Ground Photo Datasets

Richardson

Leblanc

Lovitt

et al. 2021

Drones

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Relating ground photographs to UAV orthomosaics is a key linkage required for accurate multi-scaled lichen mapping. Conventional methods of multi-scaled lichen mapping, such as random forest models and convolutional neural networks, heavily rely on pixel DN values for classification. However, the limited spectral range of ground photos requires additional characteristics to differentiate lichen from spectrally similar objects, such as bright logs. By applying a neural network to tiles of a UAV orthomosaics, additional characteristics, such as surface texture and spatial patterns, can be used for inferences. Our methodology used a neural network (UAV LiCNN) trained on ground photo mosaics to predict lichen in UAV orthomosaic tiles. The UAV LiCNN achieved mean user and producer accuracies of 85.84% and 92.93%, respectively, in the high lichen class across eight different orthomosaics. We compared the known lichen percentages found in 77 vegetation microplots with the predicted lichen percentage calculated from the UAV LiCNN, resulting in a R2 relationship of 0.6910. This research shows that AI models trained on ground photographs effectively classify lichen in UAV orthomosaics. Limiting factors include the misclassification of spectrally similar objects to lichen in the RGB bands and dark shadows cast by vegetation.

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Increasing fire frequency and severity will increase habitat loss for a boreal forest indicator species

Palm

Suitor

Joly

et al. 2022

Ecological Applications

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Climate change will lead to more frequent and more severe fires in some areas of boreal forests, affecting the distribution and availability of late‐successional forest communities. These forest communities help to protect globally significant carbon reserves beneath permafrost layers and provide habitat for many animal species, including forest‐dwelling caribou. Many caribou populations are declining, yet the mechanisms by which changing fire regimes could affect caribou declines are poorly understood. We analyzed resource selection of 686 GPS‐collared female caribou from three ecotypes and 15 populations in a ~600,000 km2 region of northwest Canada and eastern Alaska. These populations span a wide gradient of fire frequency but experience low levels of human‐caused habitat disturbance. We used a mixed‐effects modeling framework to characterize caribou resource selection in response to burns at different seasons and spatiotemporal scales, and to test for functional responses in resource selection to burn availability. We also tested mechanisms driving observed selection patterns using burn severity and lichen cover data. Caribou avoided burns more strongly during winter relative to summer and at larger spatiotemporal scales relative to smaller scales. During the winter, caribou consistently avoided burns at both spatiotemporal scales as burn availability increased, indicating little evidence of a functional response. However, they decreased their avoidance of burns during summer as burn availability increased. Burn availability explained more variation in caribou selection for burns than ecotype. Within burns, caribou strongly avoided severely burned areas in winter, and this avoidance lasted nearly 30 years after a fire. Caribou within burns also selected higher cover of terrestrial lichen (an important caribou food source). We found a negative relationship between burn severity and lichen cover, confirming that caribou avoidance of burns was consistent with lower lichen abundance. Consistent winter avoidance of burns and severely burned areas suggests that caribou will experience increasing winter habitat loss as fire frequency and severity increase. Our results highlight the potential for climate‐induced alteration of natural disturbance regimes to affect boreal biodiversity through habitat loss. We suggest that management strategies prioritizing protection of core winter range habitat with lower burn probabilities would provide important climate‐change refugia for caribou.

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Lichen cover mapping for caribou ranges in interior Alaska and Yukon

Cited by 30 publications

References 61 publications

Quantifying effects of snow depth on caribou winter range selection and movement in Arctic Alaska

Quantifying effects of snow depth on caribou winter range selection and movement in Arctic Alaska

Leveraging AI to Estimate Caribou Lichen in UAV Orthomosaics from Ground Photo Datasets

Increasing fire frequency and severity will increase habitat loss for a boreal forest indicator species

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