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211.
Fire disturbance is a primary agent of change in the mediterranean-climate chaparral shrublands of southern California, USA. However, fire frequency has been steadily increasing in coastal regions due to ignitions at the growing wildland-urban interface. Although chaparral is resilient to a range of fire frequencies, successively short intervals between fires can threaten the persistence of some species, and the effects may differ according to plant functional type. California shrublands support high levels of biological diversity, including many endangered and endemic species. Therefore, it is important to understand the long-term effects of altered fire regimes on these communities. A spatially explicit simulation model of landscape disturbance and succession (LANDIS) was used to predict the effects of frequent fire on the distribution of dominant plant functional types in a study area administered by the National Park Service. Shrubs dependent on fire-cued seed germination were most sensitive to frequent fire and lost substantial cover to other functional types, including drought-deciduous subshrubs that typify coastal sage scrub and nonnative annual grasses. Shrubs that resprout were favored by higher fire frequencies and gained in extent under these treatments. Due to this potential for vegetation change, caution is advised against the widespread use of prescribed fire in the region. 相似文献
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Anja Gladbach David Joachim Gladbach Martina Koch Alexandra Kuchar Erich Möstl Petra Quillfeldt 《Behavioral ecology and sociobiology》2011,65(7):1491-1498
The measurement of faecal glucocorticoid metabolites is used as a non-invasive technique to study stress in animal populations.
They have been used most widely in mammals, and mammalian studies have also treated issues such as sample stability and storage
methods. In birds, faecal corticosterone metabolite (CM) assays have been validated for a small number of species, and adequate
storage under field conditions has not been addressed explicitly in previous studies. Furthermore, while it is well-established
that baseline plasma corticosterone levels in birds rise with declining body condition, no study so far investigated if this
relationship is also reflected in faecal samples. We here present data of a field study in wild Upland geese Chloephaga picta leucoptera on the Falkland Islands, testing different storage methods and investigating the relationship of faecal CM concentrations
to body condition and reproductive parameters. We found that faecal CM measures are significantly repeatable within individuals,
higher in individuals with lower body condition in both male and female wild Upland geese and higher in later breeding females
with smaller broods. These results suggest that measuring faecal CM values may be a valuable non-invasive tool to monitor
the relative condition or health of individuals and populations, especially in areas where there still is intense hunting
practice. 相似文献
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Gihad E. Chalouhi Anne-Maude Morency Roland De Vlieger José Maria Martinez Thomas Blanc Ryan Hodges Alexandra Gueneuc Greg Ryan Jan Deprest Eduard Gratacos Yves Ville 《黑龙江环境通报》2017,37(10):968-974
We reviewed data from a cohort of fetuses with ureterocele diagnosed and operated prenatally in four fetal therapy centers. Inclusion criteria were (1) ureterocele confirmed on detailed fetal ultrasound examination, (2) absence of additional fetal malformations, and (3) fetal intervention to decompress the ureterocele with local institutional review boards' approval. Data on sonographic follow-up, obstetrical, neonatal outcome, and postnatal evaluation were collected. Ten cases of prenatally treated ureterocele are described. Six cases benefited from a fetoscopy for laser incision and decompression, two cases had an ultrasound guided puncture before resorting to a fetoscopy with laser incision, one case had a balloon catheterization under ultrasound guidance, and one case had an ultrasound-guided opening of the ureterocele with a laser fiber passed through a 20-gauge needle. Mean gestational age at diagnosis was 21.6 GW. Two cases underwent termination of pregnancy. The remaining eight cases recovered normal amniotic fluid volume and delivered a liveborn child at a mean gestational age of 38.6 GW with normal creatinine levels during the first week of life. Prenatal incision provided complete treatment of severely obstructive ureteroceles in 80% of the cases and allowed improvement of urinary electrolytes, renal size and echogenicity, bladder filling in all survivors, and recollection of normal amniotic fluid volume, in case of oligoanhydramnios. © 2017 John Wiley & Sons, Ltd. 相似文献
215.
Alexandra Simon Mercè Bernardo Stanislav Karapetrovic Martí Casadesús 《Journal of Cleaner Production》2011,19(17-18):2057-2065
In the last few years, many organizations have chosen to implement standardized Management Systems (MSs), such as the ones based on ISO 14001 and ISO 9001. However, few studies exist on how firms carry out the process of auditing these MSs.Our goal is to study how companies with more than one standardized MSs conduct the audits and to which extent they integrate the audit elements in order to benefit from the advantages of having a sole, integrated audit system.We provide four case studies and confirm the idea that firms with more than one MS integrate their audits. However, the degree and specific characteristics of this integration vary in the different companies analyzed.This paper contains one of the first qualitative empirical studies regarding the integration of MSs audits. The study provides an original contribution to the understanding of whether and how the four case study organizations have integrated certain aspects of the audit systems, for instance, the human resources, time, and audit inputs and outputs. 相似文献
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Nested vulnerability: exploring cross-scale linkages and vulnerability teleconnections in Mexican and Vietnamese coffee systems 总被引:1,自引:0,他引:1
Analyses of the vulnerability of farm populations and food systems to exogenous change, whether in relation to climatic extremes, market shocks, epidemics or other concerns, have typically been approached through a focus on the place of food production or the specific sub-sector exposed to stress. Relatively little attention has been paid to the ways in which national institutions, history and social expectations transform the same signals of global change into very different outcomes in distinct geographic contexts. The channels that convey signals of change from the global to the local may also work in reverse, connecting the responses and choices of households in one geographic context to outcomes and choices of other households in quite distant places. We draw from recent case studies of farm-level vulnerability and livelihood security in Mexico and Vietnam to demonstrate that coffee smallholders’ independent responses to the risks and opportunities associated with global scale economic and environmental change, are teleconnected and thus can create feedbacks which in turn affect the present and future vulnerabilities of other smallholders around the globe. 相似文献
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