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91.
Assessment of crown condition in eucalypt vegetation by remotely sensed optical indices 总被引:1,自引:0,他引:1
Leaf and crown damage and discoloration characteristics are important variables when defining the health of eucalypt tree species and have been used as key indicators of environmental quality. These indicators can vary significantly over a few hectares, especially in mixed-species forests, making field-based environmental surveillance of crown condition an extremely expensive and logistically impractical task. Reflectance in narrow spectral wavelengths obtained from a field-based spectroradiometer and a Compact Airborne Spectrographic Imager 2 (CASI-2) were collected over eucalypt vegetation of varying condition in southeastern Australia and compared with leaf- and crown-based attributes including percent red foliage discoloration, percent leaf damage, and crown density and crown foliage condition. Of the leaf attributes sampled, percent leaf damage was well correlated with a red-green spectral index (r = 0.68, p < 0.01), and percent red discoloration was well correlated with the slope of the red-edge for selected species (r = 0.89, p < 0.001). Within-tree crown density was well correlated with the slope of the red-edge (r = 0.77, p < 0.001) and a previously published index of plant stress with crown foliage condition (r = 0.88, p < 0.01) for selected species. Despite evidence of strong interspecific variability, a set of narrow spectral wavelengths in the visible and near-infrared regions of the spectrum have been identified that will be useful in the development of forest ecosystem environmental quality indicators. 相似文献
92.
93.
We assessed the relationship between riparian management and stream quality along five southeastern Minnesota streams in 1995
and 1996. Specifically, we examined the effect of rotationally and continuously grazed pastures and different types of riparian
buffer strips on water chemistry, physical habitat, benthic macroinvertebrates, and fish as indicators of stream quality.
We collected data at 17 sites under different combinations of grazing and riparian management, using a longitudinal design
on three streams and a paired watershed design on two others. Continuous and rotational grazing were compared along one longitudinal
study stream and at the paired watershed. Riparian buffer management, fenced trees (wood buffer), fenced grass, and unfenced
rotationally grazed areas were the focus along the two remaining longitudinal streams. Principal components analysis (PCA)
of water chemistry, physical habitat, and biotic data indicated a local management effect. The ordinations separated continuous
grazing from sites with rotational grazing and sites with wood buffers from those with grass buffers or rotationally grazed
areas. Fecal coliform and turbidity were consistently higher at continuously grazed than rotationally grazed sites. Percent
fines in the streambed were significantly higher at sites with wood buffers than grass and rotationally grazed areas, and
canopy cover was similar at sites with wood and grass buffers. Benthic macroinvertebrate metrics were significant but were
not consistent across grazing and riparian buffer management types. Fish density and abundance were related to riparian buffer
type, rather than grazing practices. Our study has potentially important implications for stream restoration programs in the
midwestern United States. Our comparisons suggest further consideration and study of a combination of grass and wood riparian
buffer strips as midwestern stream management options, rather than universally installing wood buffers in every instance.
RID=" ID=" The Unit is jointly sponsored by the US Geological Survey, Biological Resources Division; the Minnesota Department
of Natural Resources; the University of Minnesota; and the Wildlife Management Institute. 相似文献
94.
Phosphorus (P) in rivers in the Mississippi River basin (MRB) contributes to hypoxia in the Gulf of Mexico and impairs local water quality. We analyzed the spatial pattern of P in the MRB to determine the counties with the greatest January to June P riverine yields and the most critical factors related to this P loss. Using a database of P inputs and landscape characteristics from 1997 through 2006 for each county in the MRB, we created regression models relating riverine total P (TP), dissolved reactive P (DRP), and particulate P (PP) yields for watersheds within the MRB to these factors. Riverine yields of P were estimated from the average concentration of each form of P during January to June for the 10-yr period, multiplied by the average daily flow, and then summed for the 6-mo period. The fraction of land planted in crops, human consumption of P, and precipitation were found to best predict TP yields with a spatial error regression model ( = 0.48, = 101). Dissolved reactive P yields were predicted by fertilizer P inputs, human consumption of P, and precipitation in a multiple regression model ( = 0.42, = 73), whereas PP yields were explained by crop fraction, human consumption of P, and soil bulk density in a spatial error regression model ( = 0.49, = 61). Overall, the Upper Midwest's Cornbelt region and lower Mississippi basin had the counties with the greatest P yields. These results help to point out specific areas where agricultural conservation practices that reduce losses to streams and rivers and point source P removal might limit the intensity or spatial occurrence of Gulf of Mexico hypoxia and improve local water quality. 相似文献
95.
Dignity,face, and honor cultures: A study of negotiation strategy and outcomes in three cultures 下载免费PDF全文
Soroush Aslani Jimena Ramirez‐Marin Jeanne Brett Jingjing Yao Zhaleh Semnani‐Azad Zhi‐Xue Zhang Catherine Tinsley Laurie Weingart Wendi Adair 《组织行为杂志》2016,37(8):1178-1201
This study compares negotiation strategy and outcomes in countries illustrating dignity, face, and honor cultures. Hypotheses predict cultural differences in negotiators' aspirations, use of strategy, and outcomes based on the implications of differences in self‐worth and social structures in dignity, face, and honor cultures. Data were from a face‐to‐face negotiation simulation; participants were intra‐cultural samples from the USA (dignity), China (face), and Qatar (honor). The empirical results provide strong evidence for the predictions concerning the reliance on more competitive negotiation strategies in honor and face cultures relative to dignity cultures in this context of negotiating a new business relationship. The study makes two important theoretical contributions. First, it proposes how and why people in a previously understudied part of the world, that is, the Middle East, use negotiation strategy. Second, it addresses a conundrum in the East Asian literature on negotiation: the theory and research that emphasize the norms of harmony and cooperation in social interaction versus empirical evidence that negotiations in East Asia are highly competitive. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
96.
OBJECTIVE: The research literature on drivers' use of cell phones was reviewed to identify trends in drivers' phone use and to determine the state of knowledge about the safety consequences of such use. METHODS: Approximately 125 studies were reviewed with regard to the research questions, type and rigor of the methods, and findings. Reviewed studies included surveys of drivers, experiments, naturalistic studies (continuous recording of everyday driving by drivers in instrumented vehicles), studies of crash risk, and evaluations of laws limiting drivers' phone use. RESULTS: Observational surveys indicate drivers commonly use cell phones and that such use is increasing. Drivers report they usually use hand-held phones. Experimental studies have found that simulated or instrumented driving tasks, or driving while being observed, are compromised by tasks intended to replicate phone conversations, whether using hand-held or hands-free phones, and may be further compromised by the physical distraction of handling phones. Effects of phone use on driving performance when drivers are in their own vehicles are unknown. With representative samples of adequate size, naturalistic studies in the future may provide the means to document the patterns and circumstances of drivers' phone use and their effects on real-world driving. Currently, the best studies of crash risk used cell phone company billing records to verify phone use by crash-involved drivers. Two such studies found a fourfold increase in the risk of a property-damage-only crash and the risk of an injury crash associated with phone use; increased risk was similar for males and females, younger and older drivers, and hands-free and hand-held phones. A number of jurisdictions in the United States and around the world have made it illegal for drivers to use hand-held phones. Studies of these laws show only limited compliance and unclear effects on safety.CONCLUSIONS: Even if total compliance with bans on drivers' hand-held cell phone use can be achieved, crash risk will remain to the extent that drivers continue to use or switch to hands-free phones. Although the enactment of laws limiting drivers' use of all phones is consistent with research findings, it is unclear how such laws could be enforced. At least in the short term, it appears that drivers' phone use will continue to increase, despite the growing evidence of the risk it creates. More effective countermeasures are needed but are not known at this time. 相似文献
97.
Allinson G Mispagel C Kajiwara N Anan Y Hashimoto J Laurenson L Allinson M Tanabe S 《Chemosphere》2006,64(9):1464-1471
In recent times, the apparent population decline of the southern bent-wing bat (Miniopterus schreibersii bassanii) at Bat Cave, Naracoorte has been ascribed to pesticide use in the region, following the finding of organochlorine and orgaonophosphate insecticide residues in bat guano. Adult southern bent-wing bats were collected from Bat Cave and Starlight Cave in 2003. Organochlorine contaminants were detected in all carcass samples: p,p'-DDE was by far the most dominant contaminant with concentrations ranging from 11,000 to 59,000ngg(-1), followed by p,p'-DDT (110-1600ngg(-1)), p,p'-DDD (35-620ngg(-1)), summation operatorPCBs (33-490ngg(-1)), summation operatorchlordane and related compounds (7.9-270ngg(-1)), HCB (1.6-120ngg(-1)), HP epox. (3.1-230ngg(-1)), TCPMOH (3.8-38ngg(-1)), summation operatorHCHs (1.4-9.6ngg(-1)), and TCPMe (0.1-4.2ngg(-1)) (all values on lipid-weight basis). No significant difference in DDE, DDD, DDT, summation operatorDDT, summation operatorPCB, trans-chlordane, heptachlor epoxide, trans-nonachlor, alpha-HCH, beta-HCH, gamma-HCH, TCPMOH or TCPMe concentrations were observed either between sexes within sites, or between sites (p>0.05). However, there were significant differences in HCB and oxychlordane concentrations between sexes and between sites (p<0.05), between site differences in cis-nonachlor concentrations in male bats (p<0.05), and cis-chlordane concentrations between sexes at Starlight Cave, and between males of each site (p<0.05). There were also significant differences in the liver concentrations of some metals between sexes within sites (Ag, Cd, Co, Cu, Pb, Se, Zn), and between sites (Ag, Cd, Co, Cu, Hg, Pb, Se, V, Zn). Clustering or grouping of sites was observed when the OC data was expressed on a lipid-weight basis. These inter-site differences in OC concentrations reflect local exposure over a period of time, and do not unambiguously support any suggestion that we are witnessing incipient speciation. However, for conservation purposes, it may be prudent to assume that there are two sub-populations of M. s. bassani feeding in different locations in this region of southern Australia, rather than the single homogeneous population suggested by genetic studies. 相似文献