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121.
本文在评价用传统方法即赤平极射投影和实体比例投影方法分析节理边坡稳定性的基础上,结合具体工程实例引进了优势结构面的确定、岩体破坏模式的运动学判释、可移动块体的几何判定和关键块体的确定等方法, 使传统方法得到拓宽和完善,从而具有更好的适用性和可操作性。 相似文献
122.
上海PRED的系统分析及调控指标研究 总被引:4,自引:0,他引:4
在对上海PRED研究中,建立PRED系统因子模型,以1978-1995年的数据为基础,计算了上海PRED系统7个因子间的相关系数列出相关矩阵,据此分析了该时期内多因子的演变及其相关性,得出了系统的各因子演变显著的不同步性和单因子演变无规律的跳跃性特征,认为环境与经济是上海PRED系统有效调控关键,经济发展总量的改善和积极管理可以缓解人口等因子的制约作用。 相似文献
123.
《Ecological modelling》2003,170(2-3):453
In this paper, we address three aspects of the brown bear population in Slovenia: its size (and its evolution over time), its spatial expansion out of the core area, and its potential habitat based on natural habitat suitability. Data collected through measurement/observation of the bear population and from the literature are used. A model is developed for each aspect. The results are estimates of population size, a picture of the spatial expansion of the population and maps of its optimal and maximal potential habitat (based on natural suitability). Overall, the brown bear population has been increasing since the establishment of a core protective area and has been expanding outside this area. The habitat suitability maps show that there is room for further expansion. Based on habitat suitability and bear population density, as well as human activity and current damage reports, we recommend that the Alps should be temporarily kept free of the bears, until the necessary mitigation measures regarding human–bear conflicts are carried out. On the other hand it is of crucial importance to adapt human activities and improve bear management in the optimal habitat, with which the goals of successful conservation of the species might be achieved. 相似文献
124.
K. E. Ruckstuhl A. Manica A. D. C. MacColl J. G. Pilkington T. H. Clutton-Brock 《Behavioral ecology and sociobiology》2006,59(5):694-703
We analysed 16 years of census data gathered on the island of Hirta (archipelago of St. Kilda) to investigate the effects
of castration, population density, sex ratio, season and group type on habitat use and social segregation of Soay sheep. From
1978 to 1980, 72 male lambs were castrated. We used this experiment to study how a change in reproductive status could affect
sociality and habitat choice of these males. Males, females and castrates were all segregated outside the rutting season in
autumn. Castrates were the least segregated from females in spring and summer but were most segregated from them during the
pre-rut. The more equal the sex ratios, the higher was the degree of social segregation. The three sex classes used similar
habitat types, namely, Holcus agrostis, Agrostis festuca and Calluna habitats. Holcus agrostis and Agrostis festuca were top- and second-ranked in female and castrate habitat use, while Holcus agrostis and Calluna were the two top habitat types used by rams. It is unclear why males included Calluna heath habitats, but it cannot be excluded that they might have shifted their use depending on forage availability. A lack
in differences in habitat use between castrates and females suggests that body size differences alone cannot be the driving
factor for habitat segregation in male and female Soay sheep and that there are reasons other than body size that could motivate
reproductive males to use additional habitat types, such as Calluna heath. Although habitat use shifted from one habitat type to the next between low- and high-population-density years and
between seasons, there was no clear link between population density and how different groups (male, female or castrate) used
these areas. We discuss effects of reproductive status, population density and sex ratio on social segregation and habitat
use and suggest that these factors need to be taken into account when investigating causes of sexual segregation in ungulates. 相似文献
125.
Population differentiation in female sex pheromone and male preferences in a solitary bee 总被引:2,自引:0,他引:2
Nicolas J. Vereecken Jim Mant Florian P. Schiestl 《Behavioral ecology and sociobiology》2007,61(5):811-821
Population differentiation in female mating signals and associated male preferences can drive reproductive isolation among
segregated populations. We tested this assumption by investigating intraspecific variation in female sex pheromone and associated
male odour preferences among distant populations in the solitary bee Colletes cunicularius (L.) by using quantitative gas chromatography and by performing field bioassays with synthetic blends of key sex pheromone
compounds. We found significant differences in sex pheromone blends among the bee populations, and the divergence in odour
blends correlated positively with geographic distance, suggesting that genetic divergence among distant populations can affect
sex pheromone chemistry. Our behavioural experiments, however, demonstrate that synthetic copies of allopatric female sex
pheromones were cross-attractive to patrolling males from distant populations, making reproductive isolation by non-recognition
of mating signals among populations unlikely. Our data also show that patrolling male bees from different populations preferred
odour types from allopatric populations at the two sites of bioassays. These male preferences are not expected to select for
changes in the female sex pheromone, but may influence the evolution of floral odour in sexually deceptive orchids of the
genus Ophrys that are pollinated by C. cunicularius males. 相似文献
126.
In several ant species, colonies are founded by small groups of queens (pleometrosis), which coexist until the first workers eclose, after which all but one queen is killed. It has been hypothesized that, by producing a larger cohort of workers, cooperating queens may increase colony success during brood raids, a form of competition in which brood and workers from losing nests are absorbed into winning colonies. To test whether this benefit is sufficient to favor pleometrosis, newly mated queens of the fire ant Solenopsis invicta were assembled in groups of one, two, three, or four, reared in the laboratory until the first workers eclosed, then planted in the field in replicated assemblages. The proportion of colonies engaging in brood raids increased with average foundress number per nest and with colony density but was unaffected by variance in foundress number among interacting colonies. Within mixed assemblages of single-queen and multiple-queen colonies, queen number had no effect on the likelihood of engaging in raids or the probability of nest survival through the brood raiding period. However, following nearly 30% of raids, queens moved to new nests and displaced the resident queens. When queen relocation and subsequent mortality were accounted for, it was found that the survival of queens from four-queen groups was substantially higher than that of solitary queens. By contrast, the survival of queens from two-queen colonies was no greater than that of solitary queens. These results show that the competitive advantages of multiple-queen colonies are sufficient to counterbalance the increased mortality of queens within groups only when the number of foundresses is greater than two and when colonies are founded at high density. When colonies lose brood raids, the workers appear to abandon their mothers to join surviving colonies. However, in laboratory experiments, queens attempting to enter foreign nests were significantly more likely to displace the resident queen if their own daughters were present within the invaded nest. Thus, workers may be able to bias the probability that their mother rejoins them and displaces competing queens. 相似文献
127.
Chong Tan Haoran Xu Di Cui Jinlong Zuo Junsheng Li Yubin Ji Shan Qiu Lin Yao Ying Chen Yingjie Liu 《环境科学学报(英文版)》2018,30(5):127-135
The effects of tourmaline on nitrogen removal performance and biofilm structures were comparatively investigated in two identical laboratory-scale sequencing batch biofilm reactors(SBBRs)(denoted SBBR1 and SBBR2) at different nitrogen loading rates(NLRs) varying from(0.24 ± 0.01) to(1.26 ± 0.02) g N/(L·day). SBBR1 was operated in parallel with SBBR2, but SBBR1 was filled with polyurethane foam loaded tourmaline(TPU) carriers and another(SBBR2) filled with polyurethane foam(PU) carriers. Results obtained from this study showed that the excellent and stable performance of SBBR1 was obtained. Ammonia nitrogen removal and total nitrogen removal were higher in SBBR1 than that in SBBR2 with increase of NLR. At an NLR of(0.24 ± 0.01) g N/(L·day), the majority of the spherical and elliptical bacteria were surrounded by the extracellular polymeric substance(EPS) and bacillus or filamentous bacteria in two SBBRs biofilms. When NLR increased to(1.26 ± 0.02) g N/(L·day), the clusters were more obvious in the SBBR1 biofilm than that in the SBBR2 biofilm. Bacteria in SBBR1 were inclined to synthesis more EPS, and the formed EPS could protect the bacteria from free ammonia(FA) under extreme condition NLR(1.26 ± 0.02) g N/(L·day). The results of polymerase chain reaction-denaturing gradient gel electrophoresis analysis showed that the microbial community similarity in SBBR2 decreased more obviously than that in SBBR1 with the increase of NLR, which the microbial community in SBBR1 was relatively stable. 相似文献
128.
本文报导鼎湖山几种赤红壤土壤放线菌的分布与酸度的关系。不同酸度培养基计数结果表明,土壤放线菌数量主要决定于适应在中性环境中生长的类型,适于酸性、强酸性环境生长的类型的数量很少。 相似文献
129.
Jennifer Babin-FenskeMadhur Anand 《Ecological modelling》2011,222(14):2561-2569
The forest tent caterpillar (Malacosoma disstria Hübner) (FTC) has an outbreak cycle of approximately 10 years; however, smaller spatial scale analyses show some regions have longer or more frequent periods of high defoliation. This may be a result of local forest fragmentation, pollution or other sources of stress that may affect FTC directly or indirectly through stress on their hosts or parasitoids. Population dynamics of FTC were examined to investigate how stress may alter the severity and frequency of defoliation. We developed a spatially explicit agent-based model to simulate the host-parasitoid dynamics of FTC. Theoretical and empirically derived parameters were established using past literature and over 50 years of population data of FTC from Ontario, Canada. We find that increasing FTC fecundity, FTC dispersal or parasitoid mortality resulted in more severe outbreaks while a decrease in parasitoid fecundity or searching efficiency resulted in an overall elevation of defoliation. Parasitoid efficiency was the most effective parameter for altering the FTC defoliation. Since plant stress has been shown to alter several of these parameters in nature due to changes in food quality, habitat suitability, and chemical cue interference, our results suggest that forests affected by stressors such as climate change and pollution will have more severe and frequent defoliation from these insects than surrounding unaffected forests. As stressors such as drought and pollution emissions are predicted to increase in frequency or intensity over the next few decades, understanding how they may affect the outbreak cycle of a forest defoliator can aid in planning strategies to reduce the detrimental effects of this insect. 相似文献
130.
For matrix population models, analyses of how sensitive the population growth rate is to changes in vital rates (i.e. perturbations) are important for studies of life history evolution as well as for management and conservation of threatened species. There are two types of sensitivity analyses corresponding to absolute (sensitivity) or relative (elasticity) changes in the vital rates and both types can be applied to both deterministic and stochastic matrix population models. To date, most empirical studies of elasticity and sensitivity of the stochastic growth rate have examined the response to perturbations in the vital rates in a complete set of possible environments. However, it is often of interest to examine the response to perturbations occurring in only a subset of the possible environments. This has been done for periodic time-varying models elsewhere, but here we describe a recently published method for calculating the environment-specific sensitivity and elasticity of the stochastic growth rate and apply this method to data. These environment-specific perturbation analyses provide a logical way of dividing the sensitivity and elasticity among the environments. They give important insight into the selection regime in different environments and can provide valuable information for making management decisions and management evaluations in stochastic environments. 相似文献