Cover of tall trees best predicts California spotted owl habitat

North, Malcolm P.; Kane, Jonathan T.; Kane, Van R.; Asner, Gregory P.; Berigan, William J.; Churchill, Derek J.; Conway, Scott; Gutiérrez, R. J.; Jeronimo, Sean M.A.; Keane, John J.; Koltunov, Alexander; Mark, Tina; Moskal, Monika; Munton, Thomas E.; Peery, Zachary; Ramı́rez, C.; Sollmann, Rahel; White, Angela M.; Whitmore, Sheila A.

doi:10.1016/j.foreco.2017.09.019

Cited by 89 publications

(58 citation statements)

References 75 publications

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“…The cover of mature trees accounted for a larger proportion of canopy cover than did young trees across all scales at our spotted owl activity centers. This result is consistent with a recent study that reported the canopy cover of tall (>48 m) trees predicted California spotted owl activity centers (North et al ). Neither of our models containing individual covariates for young or mature forest were competitive for predicting spotted owl activity center selection.…”

Section: Discussionsupporting

confidence: 93%

“…These data have already been used to accurately classify conifer forests into successional stages (Falkowski et al , Kane et al ) and to analyze forest structure and wildlife‐habitat relationships (Vierling et al , Vogeler et al , Hagar et al , Johnston and Moskal , Linnell et al ). For California spotted owls ( S. o. occidentalis ), García‐Feced et al () used lidar data to quantify residual trees in nesting areas and North et al () used lidar data to predict California spotted owl habitat based on cover of tall trees.…”

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confidence: 99%

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Activity center selection by northern spotted owls

et al. 2019

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The federally threatened northern spotted owl (Strix occidentalis caurina) has been intensively studied across its range, and habitat needs for the species have influenced forest management in northwestern North America for decades. Dense forest canopies are often reported in the scientific literature and agency management plans as an important habitat attribute for spotted owls, though the means of measuring forest canopy and interpreting species requirements vary across studies and more importantly, among management plans. We used light detection and ranging (lidar) measurements of canopy cover, canopy surface heterogeneity, and upper canopy surface connectivity, and an index of the presence of a competitive invasive species, the barred owl (S. varia), in multinomial discrete choice models using a Bayesian framework to evaluate selection of forest cover types by spotted owls in Oregon, USA, 2008–2015. We designated yearly activity centers based on the most biologically significant observation during the nesting season (Mar–Aug), generally centered on the nest tree. Spotted owls selected activity centers with more canopy cover and higher heterogeneity of the canopy surface within 100 m than was available within their territories. The average proportion of canopy cover within 100 m of a spotted owl activity center was 0.79 ± 0.12 (SD; range = 0.34–0.99). The presence of barred owls did not explain variability in selection of spotted owl activity centers, but barred owls might not affect third‐order habitat selection within territories, or our index was too spatially coarse to detect these effects on spotted owl resource selection. We demonstrate that lidar provides researchers and managers with a tool that can accurately measure forest canopies over large areas, and assist in mapping spotted owl habitat. © 2019 The Wildlife Society.

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Section: Discussionsupporting

confidence: 93%

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confidence: 99%

Activity center selection by northern spotted owls

et al. 2019

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“…Tall trees may provide cooler, wetter microclimates than shorter trees, and old growth forests with long‐lived tall trees are widely recognized to be among the best lichen habitats (Carey & Johnson, ; McCune, ; Sillett et al, ). Open stands of tall trees were common before Euro‐American settlement in the dry conifer forests in our study area (Safford & Stevens, ), and recent research highlights the importance of tall trees for the spotted owl, a forest associate of conservation concern (North et al, ). Although wildfires are inevitable in many temperate ecosystems, open stands generally burn at lower severity than dense stands.…”

Section: Discussionmentioning

confidence: 81%

Altered fire regimes cause long‐term lichen diversity losses

Miller

Root

Safford

2018

Global Change Biology

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Many global ecosystems have undergone shifts in fire regimes in recent decades, such as changes in fire size, frequency, and/or severity. Recent research shows that increases in fire size, frequency, and severity can lead to long-persisting deforestation, but the consequences of shifting fire regimes for biodiversity of other vegetative organisms (such as understory plants, fungi, and lichens) remain poorly understood. Understanding lichen responses to wildfire is particularly important because lichens play crucial roles in nutrient cycling and supporting wildlife in many ecosystems. Lichen responses to fire have been little studied, and most previous research has been limited to small geographic areas (e.g. studies of a single fire), making it difficult to establish generalizable patterns. To investigate long-term effects of fire severity on lichen communities, we sampled epiphytic lichen communities in 104 study plots across California's greater Sierra Nevada region in areas that burned in five wildfires, ranging from 4 to 16 years prior to sampling. The conifer forest ecosystems we studied have undergone a notable increase in fire severity in recent decades, and we sample across the full gradient of fire severity to infer how shifting fire regimes may influence landscape-level biodiversity. We find that low-severity fire has little to no effect on lichen communities. Areas that burned at moderate and high severities, however, have significantly and progressively lower lichen richness and abundance. Importantly, we observe very little postfire lichen recolonization on burned substrates even more than 15 years after fire. Our multivariate model suggests that the hotter, drier microclimates that occur after fire removes forest canopies may prevent lichen reestablishment, meaning that lichens are not likely to recolonize until mature trees regenerate. These findings suggest that altered fire regimes may cause broad and long-persisting landscape-scale biodiversity losses that could ultimately impact multiple trophic levels.

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“…Analyses of relations between spotted owl population performance indicators and habitat conditions might also include other covariates that were regularly displayed in RSFs, including lower‐slope topographic positions, and certain species of hardwoods. Fine‐scale forest canopy conditions surrounding nest sites, not measured in our studies, may also matter to spotted owl population performance and can be estimated using light detection and ranging technology, or LiDAR (North et al , Gallagher et al , Sovern et al ). Further, quantifications of edge (Comfort et al ) may also improve predictions of spotted owl population performance.…”

Section: Discussionmentioning

confidence: 99%

Barred Owl Effects on Spotted Owl Resource Selection: A Meta‐Analysis

Irwin

Rock

et al. 2019

J Wildl Manag

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We quantified the effects of barred owls (Strix varia) on fine‐scale (~2 ha), spatially explicit selection of putative foraging habitat by 175 radio‐tagged northern spotted owls (Strix occidentalis caurina) from 1998 to 2012 in western Oregon and northern California, USA. We constructed annual nighttime discrete‐choice resource selection functions (RSFs) for northern spotted owls in 8 study areas. We compared RSFs from pooled data from 4 study areas where barred owls were absent or rare (≤14% of spotted owl territories potentially influenced by barred owls) with RSFs from 4 study areas where barred owls were abundant (≥89% of spotted owl territories potentially influenced by barred owls), and we conducted a meta‐analysis of all 8 study areas. Top‐ranked RSFs for individual study areas indicated that the relative probability a forest patch was selected by northern spotted owls for foraging was most strongly associated with basal area of large coniferous trees (≥66 cm diameter at breast height [dbh]) or quadratic mean diameter (QMD, the diameter of trees of average basal area) of all coniferous trees. The influence of such trees was non‐linear, usually quadratic, in 7 study areas, suggesting that an optimal basal area of large‐diameter trees or QMD may be associated with selection of foraging patches. The relative probability of selection of such trees decreased nonlinearly with increasing distance from nest sites in ≥4 study areas. Basal area of all or specific hardwood tree species was linearly associated with increases in the relative probability of a patch being used for foraging in 7 of 8 study areas. The relative probability of selection was also positively associated with densities of large snags (>50 cm dbh), coarse woody debris, and undergrowth shrubs in most study areas where we estimated those covariates. The relative probability that a patch was selected decreased nonlinearly with increasing distance from streams (7 study areas), increasing elevation (5 study areas), and decreasing slope (5 study areas). Barred owls exerted strong effects on habitat selection by spotted owls, which may have attempted to minimize interference competition via spatial segregation. Spotted owls occupying study areas where barred owls were abundant used foraging patches at greater distances from streams, at greater distances from nest sites, and on steeper and warmer slopes than those occupying areas with few or no barred owls. In addition, northern spotted owls in areas where barred owls were abundant exhibited reduced selection for large‐diameter trees close to nest sites but may have compensated by increasing use of large trees in home‐range locations distant from nest sites. Programs that seek to improve the link between spotted owl demographic performance or occupancy rate and habitat conditions should account for the influences of fine‐scale variation in vegetation composition and structure and physiographic conditions. Forest managers may contribute to spotted owl conservation via silvicultural prescriptions ...

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Cover of tall trees best predicts California spotted owl habitat

Cited by 89 publications

References 75 publications

Activity center selection by northern spotted owls

Activity center selection by northern spotted owls

Altered fire regimes cause long‐term lichen diversity losses

Barred Owl Effects on Spotted Owl Resource Selection: A Meta‐Analysis

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