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Mean Minimum Temperature (mean + minimum_temperature)
Selected AbstractsBiogeography of Australian saltmarsh plantsAUSTRAL ECOLOGY, Issue 8 2009NEIL SAINTILAN Abstract The paper seeks to define patterns in the distribution of Australian saltmarsh plants over a continental scale, and test for associations with environmental variables. The distribution of 93 species of Australian saltmarsh plants was documented from the records of the Australian Virtual Herbarium and published reports. The Interim Bioregionalisation of Australia provided a spatial unit for the analysis of patterns of diversity. Saltmarsh diversity was shown to be strongly correlated with latitude and temperature. Multivariate routines including cluster analysis demonstrated consistent geographic patterns in species assemblages. The primary distinction was found to be a north-south divide dissecting the continent at the latitude of 23° south, separating a species-rich southern flora from a species-poor northern flora. Subsequent dissimilarities were defined between coastlines of contrasting orientation. Mean minimum temperature was found to explain nearly 80% of variability in saltmarsh species diversity between bioregions, with diversity inversely related to temperature. [source] Developing an approach to defining the potential distributions of invasive plant species: a case study of Hakea species in South AfricaGLOBAL ECOLOGY, Issue 5 2008David C. Le Maitre ABSTRACT Aim, Models of the potential distributions of invading species have to deal with a number of issues. The key one is the high likelihood that the absence of an invading species in an area is a false absence because it may not have invaded that area yet, or that it may not have been detected. This paper develops an approach for screening pseudo-absences in a way that is logical and defensible. Innovation, The step-wise approach involves: (1) screening environmental variables to identify those most likely to indicate conditions where the species cannot invade; (2) identifying and selecting the most likely limiting variables; (3) using these to define the limits of its invasion potential; and (4) selecting points outside these limits as true absence records for input into species distribution models. This approach was adopted and used for the study of three prominent Hakea species in South Africa. Models with and without the false absence records were compared. Two rainfall variables and the mean minimum temperature of the coldest month were the strongest predictors of potential distributions. Models which excluded false absences predicted that more of the potential distribution would have a high invasion potential than those which included them. Main conclusions, The approach of applying a priori knowledge can be useful in refining the potential distribution of a species by excluding pseudo-absence records which are likely to be due to the species not having invaded an area yet or being undetected. The differences between the potential distributions predicted by the different models convey more information than making a single prediction, albeit a consensus model. The robustness of this approach depends strongly on an adequate knowledge of the ecology, invasion history and current distribution of that species. [source] Variation in the growth and survival of Golden Plover Pluvialis apricaria chicksIBIS, Issue 2 2002J. W. Pearce-Higgins The growth of Golden Plover Pluvialis apricaria chicks is modelled in detail for the first time. The pattern of growth is typical of postnatal development in waders, although the mean fledging time of 37 days is slower than would be expected from adult body weight. Bill length and weight at hatching had significant effects on the rate of weight gain shown by 2-day-old chicks, although this effect was not noticeable at 4 days of age. Chick survival was significantly affected by bill length, as a result of the variation in weight gain. The growth of older chicks was positively correlated with mean minimum temperature. The slow rate of growth exhibited by Golden Plover chicks is discussed in relation to breeding habitat and the effects of weather and hatchling biometrics. [source] Change in mean temperature as a predictor of extreme temperature change in the Asia,Pacific regionINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 10 2005G. M. Griffiths Abstract Trends (1961,2003) in daily maximum and minimum temperatures, extremes and variance were found to be spatially coherent across the Asia,Pacific region. The majority of stations exhibited significant trends: increases in mean maximum and mean minimum temperature, decreases in cold nights and cool days, and increases in warm nights. No station showed a significant increase in cold days or cold nights, but a few sites showed significant decreases in hot days and warm nights. Significant decreases were observed in both maximum and minimum temperature standard deviation in China, Korea and some stations in Japan (probably reflecting urbanization effects), but also for some Thailand and coastal Australian sites. The South Pacific convergence zone (SPCZ) region between Fiji and the Solomon Islands showed a significant increase in maximum temperature variability. Correlations between mean temperature and the frequency of extreme temperatures were strongest in the tropical Pacific Ocean from French Polynesia to Papua New Guinea, Malaysia, the Philippines, Thailand and southern Japan. Correlations were weaker at continental or higher latitude locations, which may partly reflect urbanization. For non-urban stations, the dominant distribution change for both maximum and minimum temperature involved a change in the mean, impacting on one or both extremes, with no change in standard deviation. This occurred from French Polynesia to Papua New Guinea (except for maximum temperature changes near the SPCZ), in Malaysia, the Philippines, and several outlying Japanese islands. For urbanized stations the dominant change was a change in the mean and variance, impacting on one or both extremes. This result was particularly evident for minimum temperature. The results presented here, for non-urban tropical and maritime locations in the Asia,Pacific region, support the hypothesis that changes in mean temperature may be used to predict changes in extreme temperatures. At urbanized or higher latitude locations, changes in variance should be incorporated. Copyright © 2005 Royal Meteorological Society. [source] Problems in evaluating regional and local trends in temperature: an example from eastern Colorado, USAINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 4 2002R. A. Pielke SR Abstract We evaluated long-term trends in average maximum and minimum temperatures, threshold temperatures, and growing season in eastern Colorado, USA, to explore the potential shortcomings of many climate-change studies that either: (1) generalize regional patterns from single stations, single seasons, or a few parameters over short duration from averaging dissimilar stations; or (2) generalize an average regional pattern from coarse-scale general circulation models. Based on 11 weather stations, some trends were weakly regionally consistent with previous studies of night-time temperature warming. Long-term (80 + years) mean minimum temperatures increased significantly (P < 0.2) in about half the stations in winter, spring, and autumn and six stations had significant decreases in the number of days per year with temperatures , , 17.8 °C (,0 °F). However, spatial and temporal variation in the direction of change was enormous for all the other weather parameters tested, and, in the majority of tests, few stations showed significant trends (even at P < 0.2). In summer, four stations had significant increases and three stations had significant decreases in minimum temperatures, producing a strongly mixed regional signal. Trends in maximum temperature varied seasonally and geographically, as did trends in threshold temperature days ,32.2 °C (,90 °F) or days ,37.8 °C (,100 °F). There was evidence of a sub-regional cooling in autumn's maximum temperatures, with five stations showing significant decreasing trends. There were many geographic anomalies where neighbouring weather stations differed greatly in the magnitude of change or where they had significant and opposite trends. We conclude that sub-regional spatial and seasonal variation cannot be ignored when evaluating the direction and magnitude of climate change. It is unlikely that one or a few weather stations are representative of regional climate trends, and equally unlikely that regionally projected climate change from coarse-scale general circulation models will accurately portray trends at sub-regional scales. However, the assessment of a group of stations for consistent more qualitative trends (such as the number of days less than ,17.8 °C, such as we found) provides a reasonably robust procedure to evaluate climate trends and variability. Copyright © 2002 Royal Meteorological Society [source] | ||||||||||