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This paper develops a Monte Carlo simulation (MCS)-based reliability analysis approach for slope stability problems and utilizes an advanced MCS method called “subset simulation” for improving efficiency and resolution of the MCS at relatively small probability levels. Reliability analysis is operationally decoupled from deterministic slope stability analysis and implemented using a commonly available spreadsheet software, Microsoft Excel. The reliability analysis spreadsheet package is validated through comparison with other reliability analysis methods and commercial software. The spreadsheet package is then used to explore the effect of spatial variability of the soil properties and critical slip surface. It is found that, when spatial variability of soil properties is ignored by assuming perfect correlation, the variance of the factor of safety (FS) is overestimated, which may result in either over (conservative) or under (unconservative) estimation of the probability of failure (Pf = P(FS < 1)). When the spatial variability of soil properties is considered, the critical slip surface varies spatially and such spatial variability should be properly accounted for. Otherwise, the probability of failure can be significantly underestimated and unconservative.

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Endophytic fungi associated with Chinese oil pine ( Pinus tabulaeformis Carr.) from two distinct climatic sites, Fenghuangshan and Lingyuan in northeast China, were investigated. A total of 2065 fungal isolates were recovered from 4320 tissue segments consisting of needles, bark, and xylem from 30 mature trees for each site. Twenty-one fungal taxa were identified; the remaining 205 isolates (11% of total isolates) did not sporulate and could not be identified. There were higher overall colonization and isolation rates of endophytic fungi from the Fenghuangshan than from the Lingyuan site. At the Fenghuangshan site, the colonization and isolation rates significantly increased with the age of the needles and xylem, but not of the bark. At the Lingyuan site, the colonization and isolation rates significantly increased with the age of the xylem; however, there were no significant differences between 2- and 3-year-old needles and bark, except that they both contained fewer endophytes in 1-year-old by comparison with 2- and 3-year-old needles and bark. Alternaria alternata (Fr.) Keissler, Phoma sp.1, Phomopsis archeri B.C. Sutton, and Leptostroma sp. were the dominant taxa in the bark and needles. There was a high Sorenson’s coefficient (0.89) of endophyte composition similarity between the Fenghuangshan and Lingyuan sites. We conclude that some fungi show a degree of tissue recurrence or specificity and that the composition of endophyte assemblages is not greatly influenced by geographical or climatic factors.