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71.
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Context

Climate and land-use change have led to disturbance regimes in many ecosystems without a historical analog, leading to uncertainty about how species adapted to past conditions will respond to novel post-disturbance landscapes.

Objectives

We examined habitat selection by spotted owls in a post-fire landscape. We tested whether selection or avoidance of severely burned areas could be explained by patch size or configuration, and whether variation in selection among individuals could be explained by differences in habitat availability.

Methods

We applied mixed-effects models to GPS data from 20 spotted owls in the Sierra Nevada, California, USA, with individual owls occupying home ranges spanning a broad range of post-fire conditions after the 2014 King Fire.

Results

Individual spotted owls whose home ranges experienced less severe fire (<?5% of home range severely burned) tended to select severely burned forest, but owls avoided severely burned forest when more of their home range was affected (~ 5–40%). Owls also tended to select severe fire patches that were smaller in size and more complex in shape, and rarely traveled?>?100-m into severe fire patches. Spotted owls avoided areas that had experienced post-fire salvage logging but the interpretation of this effect was nuanced. Owls also avoided areas that were classified as open and/or young forest prior to the fire.

Conclusions

Our results support the hypothesis that spotted owls are adapted to historical fire regimes characterized by small severe fire patches in this region. Shifts in disturbance regimes that produce novel landscape patterns characterized by large, homogeneous patches of high-severity fire may negatively affect this species.

  相似文献   
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Low doses of deltamethrin cause prolonged knockdown of the tsetse fly Glossina morsitans morsitans. Fifty per cent of female flies, treated with the LD15-(48 h) of deltamethrin, failed to regain their capacity for normal flight for 30 h, compared with 6 h for bioresmethrin and 4 h for permethtin at the equivalent dose. Recovery after exposure to tetramethrin occurred within 1 h. The knockdown effect of deltamethrin on males was even more pronounced although, with both sexes, the onset of the effect was delayed for about 3 h. It is suggested that this prolonged knockdown effect of deltamethrin, at extremely low application rates, may make a significant contribution to the effectiveness of the compound against the tsetse fly.  相似文献   
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Context

Reliable information on tree stem diameter variation at local spatial scales and on the factors controlling it could potentially lead to improved biomass estimation over pine plantations.

Aims

This study addressed the relationship between local topography and tree diameter at breast height (DBH) within two even-aged radiata pine plantation sites in New South Wales, Australia.

Methods

A total of 85 plots were established, and 1,302 trees were sampled from the two sites. Airborne light detection and ranging (LiDAR) was used to derive slope and aspect and to link them to each individual tree.

Results

The results showed a significant relationship between DBH and local topography factors. At both sites, trees on slopes below 20° and on southerly aspects displayed significantly larger DBHs than trees on steeper slopes and northerly aspects. Older trees with similar heights also exhibited a significant relationship between DBH and aspect factor, where greater DBHs were found on southerly aspects.

Conclusions

The observed correlation between tree DBH and LiDAR-derived slope and aspect could contribute to the development of improved biomass estimation approaches in pine plantations. These topographical variables are easily attained with airborne LiDAR, and they could potentially improve DBH predictions in resource inventories (e.g. stand volume or biomass) and support field sampling design.  相似文献   
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The mammalian sperm membrane undergoes cholesterol efflux during maturation and fertilization. Although ATP‐binding cassette (ABC) transporters are known to transport cholesterol through cell membranes in other organs, their presence in canine testis, epididymis and sperm has not been proven to date. Hence, the aim of the present study was to localize the ABC transporters ABCA1 and ABCG1 in canine testicular and epididymidal tissue as well as in spermatozoa membranes. To this end, semen samples from 12 dogs as well as testicles and epididymides of four young and healthy dogs were prepared for immunohistochemistry, respectively. Capacitation and acrosome reaction (AR) were induced in aliquots of the semen samples before immunostaining to assess changes in the expression of ABCA1 and ABCG1. Evaluation by confocal microscopy revealed the presence of both ABCA1 and ABCG1 in canine testicles and of ABCA1 in the epididymides. In spermatozoa, only ABCA1 immunoreactivity was detected, mainly in the region of the acrosome and midpiece. After induction of capacitation, ABCA1 signal persisted in the acrosome but disappeared after AR, indicating a loss of ABCA1 with the loss of the acrosome. We conclude that ABCA1 and ABCG1 are expressed in canine testis, whereas only ABCA1 is expressed in epididymis and spermatozoa membrane, both transporters probably contributing to the regulation of membrane cholesterol content.  相似文献   
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