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Summer Precipitation (summer + precipitation)
Selected AbstractsPrecipitation characteristics of the Eurasian Arctic drainage systemINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 11 2003Mark C. Serreze Abstract This study examines characteristics of precipitation over the major watersheds of the Eurasian Arctic drainage system over the period 1960,92. In addition to the Ob, Yenisey and Lena (the three largest drainage systems), we examine the combined Kolyma,Indigirka in eastern Eurasia. Each basin exhibits approximately symmetric mean annual cycles of monthly total precipitation and daily event size, with winter minima and July maxima. These are strikingly similar to the annual cycles of total column water vapour (precipitable water), which fundamentally reflects the control on saturation vapour pressure by temperature. Effective precipitation mechanisms exist in all seasons. However, because of the long distance from strong moisture sources (continentality), precipitation tends to follow the seasonality in column water vapour. An effective contrast is presented for the Iceland sector. Here, the annual cycle of precipitation is tied not to the seasonality in column water vapour, but to the stronger precipitation-generating mechanisms in winter. Hence, the annual cycles of precipitation and column water vapour in this region oppose each other. Mean winter precipitation over the Eurasian watersheds is primarily driven by a modest convergence of water vapour. Whereas precipitation peaks in summer, the mean flux convergence exhibits a general minimum (negative in the Ob). Summer precipitation is hence primarily associated with surface evaporation. A strong role of convection is supported from consideration of static stability, the fairly weak spatial organization of precipitation totals and results from prior studies. On daily time scales, the largest basin-averaged precipitation events, for both summer and winter, are allied with synoptic-scale forcing. This is seen in relationships with cyclone frequency, and patterns of 500 hPa height, vertical motion and the 700 hPa vapour flux. The relative frequency of four 500 hPa synoptic types captures the basic time series structures of precipitation. Copyright © 2003 Royal Meteorological Society [source] Recent decay of a single palsa in relation to weather conditions between 1996 and 2000 in Laivadalen, northern SwedenGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 2 2002Frieda Sjoukje Zuidhoff This study presents the decay of a small palsa complex between 1996 and 2000 in Sweden's southernmost major palsa bog. The outline of the palsa was mapped during three summers in 1996, 1999 and 2000 and an automatic weather station measured air temperature, precipitation, snow depth, wind speed and wind direction between 1997 and 2000. The decay of the palsa was enormous in the dome,shaped part of the palsa complex: the height decreased during the observation period from 2.3 m to 0.5 m. In 2000, the palsa dome had almost totally disappeared: only some peat blocks in a palsa pond were left. The decay of the palsa was complex with a number of degradational processes, of which the main processes were block erosion, thermokarst and wind erosion. Thermal melting has occurred along the edges of the palsa and possibly below the frozen core of the palsa since 1998/99. Wind erosion was observed during summer and the maximum estimated deflation was 80 cm. The decay of the palsa dome was especially large between 1999 and 2000, probably due to a high mean annual temperature, high summer precipitation and the warming influence of the large pond surrounding the palsa. The present climate in the palsa bog with a mean annual temperature of ,0.8°C is not favourable for palsa development and maintenance, despite a strong wind regime which can provide suitable conditions for snowdrift. [source] Estimating annual N2O emissions from agricultural soils in temperate climatesGLOBAL CHANGE BIOLOGY, Issue 10 2005Caroline Roelandt Abstract The Kyoto protocol requires countries to provide national inventories for a list of greenhouse gases including N2O. A standard methodology proposed by the Intergovernmental Panel on Climate Change (IPCC) estimates direct N2O emissions from soils as a constant fraction (1.25%) of the nitrogen input. This approach is insensitive to environmental variability. A more dynamic approach is needed to establish reliable N2O emission inventories and to propose efficient mitigation strategies. The objective of this paper is to develop a model that allows the spatial and temporal variation in environmental conditions to be taken into account in national inventories of direct N2O emissions. Observed annual N2O emission rates are used to establish statistical relationships between N2O emissions, seasonal climate and nitrogen-fertilization rate. Two empirical models, MCROPS and MGRASS, were developed for croplands and grasslands. Validated with an independent data set, MCROPS shows that spring temperature and summer precipitation explain 35% of the variance in annual N2O emissions from croplands. In MGRASS, nitrogen-fertilization rate and winter temperature explain 48% of the variance in annual N2O emissions from grasslands. Using long-term climate observations (1900,2000), the sensitivity of the models with climate variability is estimated by comparing the year-to-year prediction of the model to the precision obtained during the validation process. MCROPS is able to capture interannual variability of N2O emissions from croplands. However, grassland emissions show very small interannual variations, which are too small to be detectable by MGRASS. MCROPS and MGRASS improve the statistical reliability of direct N2O emissions compared with the IPCC default methodology. Furthermore, the models can be used to estimate the effects of interannual variation in climate, climate change on direct N2O emissions from soils at the regional scale. [source] Vegetation responses in Alaskan arctic tundra after 8 years of a summer warming and winter snow manipulation experimentGLOBAL CHANGE BIOLOGY, Issue 4 2005C.-H. A. Wahren Abstract We used snow fences and small (1 m2) open-topped fiberglass chambers (OTCs) to study the effects of changes in winter snow cover and summer air temperatures on arctic tundra. In 1994, two 60 m long, 2.8 m high snow fences, one in moist and the other in dry tundra, were erected at Toolik Lake, Alaska. OTCs paired with unwarmed plots, were placed along each experimental snow gradient and in control areas adjacent to the snowdrifts. After 8 years, the vegetation of the two sites, including that in control plots, had changed significantly. At both sites, the cover of shrubs, live vegetation, and litter, together with canopy height, had all increased, while lichen cover and diversity had decreased. At the moist site, bryophytes decreased in cover, while an increase in graminoids was almost entirely because of the response of the sedge Eriophorum vaginatum. These community changes were consistent with results found in studies of responses to warming and increased nutrient availability in the Arctic. However, during the time period of the experiment, summer temperature did not increase, but summer precipitation increased by 28%. The snow addition treatment affected species abundance, canopy height, and diversity, whereas the summer warming treatment had few measurable effects on vegetation. The interannual temperature fluctuation was considerably larger than the temperature increases within OTCs (<2°C), however. Snow addition also had a greater effect on microclimate by insulating vegetation from winter wind and temperature extremes, modifying winter soil temperatures, and increasing spring run-off. Most increases in shrub cover and canopy height occurred in the medium snow-depth zone (0.5,2 m) of the moist site, and the medium to deep snow-depth zone (2,3 m) of the dry site. At the moist tundra site, deciduous shrubs, particularly Betula nana, increased in cover, while evergreen shrubs decreased. These differential responses were likely because of the larger production to biomass ratio in deciduous shrubs, combined with their more flexible growth response under changing environmental conditions. At the dry site, where deciduous shrubs were a minor part of the vegetation, evergreen shrubs increased in both cover and canopy height. These changes in abundance of functional groups are expected to affect most ecological processes, particularly the rate of litter decomposition, nutrient cycling, and both soil carbon and nitrogen pools. Also, changes in canopy structure, associated with increases in shrub abundance, are expected to alter the summer energy balance by increasing net radiation and evapotranspiration, thus altering soil moisture regimes. [source] Inter-decadal variation of the summer precipitation in East China and its association with decreasing Asian summer monsoon.INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2008Part I: Observed evidences Abstract In recent two decades, North and Northeast China have suffered from severe and persistent droughts while the Yangtze River basin and South China have undergone much more significant heavy rainfall/floods events. This long-term change in the summer precipitation and associated large-scale monsoon circulation features have been examined by using the new dataset of 740 surface stations for recent 54 years (1951,2004) and about 123-yr (1880,2002) records of precipitation in East China. The following new findings have been highlighted: (1) One dominating mode of the inter-decadal variability of the summer precipitation in China is the near-80-yr oscillation. Other modes of 12-yr and 30,40-yr oscillations also play an important role in affecting regional inter-decadal variability. (2) In recent 54 years, the spatial pattern of the inter-decadal variability of summer precipitation in China is mainly structured with two meridional modes: the dipole pattern and the positive-negative-positive ("+ , + " pattern). In this period, a regime transition of meridional precipitation mode from "+ , + " pattern to dipole pattern has been completed. In the process of southward movement of much precipitation zone, two abrupt climate changing points that occurred in 1978 and 1992, respectively, were identified. (3) Accompanying the afore-described precipitation changes, the East Asian summer monsoon have experienced significant weakening, with northward moisture transport and convergence by the East Asian summer monsoon greatly weakened, thus leading to much deficient moisture supply for precipitation in North China. (4) The significant weakening of the component of the tropical upper-level easterly jet (TEJ) has made a dominating contribution to the weakening of the Asian summer monsoon system. The cooling in the high troposphere at mid- and high latitudes and the possible warming at low latitude in the Asian region is likely to be responsible for the inter-decadal weakening of the TEJ. Copyright © 2007 Royal Meteorological Society [source] The precipitation climate of Central Asia,intercomparison of observational and numerical data sources in a remote semiarid regionINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2008Reinhard Schiemann Abstract In this study, we systematically compare a wide range of observational and numerical precipitation datasets for Central Asia. Data considered include two re-analyses, three datasets based on direct observations, and the output of a regional climate model simulation driven by a global re-analysis. These are validated and intercompared with respect to their ability to represent the Central Asian precipitation climate. In each of the datasets, we consider the mean spatial distribution and the seasonal cycle of precipitation, the amplitude of interannual variability, the representation of individual yearly anomalies, the precipitation sensitivity (i.e. the response to wet and dry conditions), and the temporal homogeneity of precipitation. Additionally, we carried out part of these analyses for datasets available in real time. The mutual agreement between the observations is used as an indication of how far these data can be used for validating precipitation data from other sources. In particular, we show that the observations usually agree qualitatively on anomalies in individual years while it is not always possible to use them for the quantitative validation of the amplitude of interannual variability. The regional climate model is capable of improving the spatial distribution of precipitation. At the same time, it strongly underestimates summer precipitation and its variability, while interannual variations are well represented during the other seasons, in particular in the Central Asian mountains during winter and spring. Copyright © 2007 Royal Meteorological Society [source] Covariabilities of spring soil moisture and summertime United States precipitation in a climate simulationINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 4 2007Wanru Wu Abstract This paper explores the space-time connections between springtime soil moisture and summer precipitation over the continental United States by applying a singular value decomposition (SVD) method to a 50-year climate simulation. The first two SVD modes were analyzed. The two leading SVD modes account for 43% of the squared covariance between spring soil moisture and summer precipitation. Their corresponding components explain 14% of the soil moisture variance and 19% of the precipitation variance, respectively, which is larger than that contributed by tropical Pacific sea-surface temperatures (SSTs). The temporal correlations between the two expansion coefficients of each SVD mode are 0.83 and 0.88, respectively, indicating a significant association between spring soil moisture variation and summer precipitation variability. Both positive and negative cross-correlations exist over different regions of the United States in the two modes. Linear regression relates surface relative humidity and surface air temperature to the soil moisture SVD time series. The patterns revealed by the SVD analysis show where the local soil moisture-precipitation coupling contributes to the model's simulation of precipitation. Copyright © 2006 Royal Meteorological Society [source] Trend and variability of China precipitation in spring and summer: linkage to sea-surface temperaturesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2004Fanglin Yang Abstract Observational records in the past 50 years show an upward trend of boreal-summer precipitation over central eastern China and a downward trend over northern China. During boreal spring, the trend is upward over southeastern China and downward over central eastern China. This study explores the forcing mechanism of these trends in association with the global sea-surface temperature (SST) variations on the interannual and interdecadal time scales. Results based on singular value decomposition (SVD) analyses show that the interannual variability of China precipitation in boreal spring and summer can be well defined by two centres of action for each season, which are covarying with two interannual modes of SSTs. The first SVD modes of precipitation in spring and summer, which are centred in southeastern China and northern China respectively, are linked to an El Niño,southern oscillation (ENSO)-like mode of SSTs. The second SVD modes of precipitation in both seasons are confined to central eastern China, and are primarily linked to SST variations over the warm pool and the Indian Ocean. Features of the anomalous 850 hPa winds and 700 hPa geopotential height corresponding to these modes support a physical mechanism that explains the causal links between the modal variations of precipitation and SSTs. On the decadal and longer time scale, similar causal links are found between the same modes of precipitation and SSTs, except for the case of springtime precipitation over central eastern China. For this case, while the interannual mode of precipitation is positively correlated with the interannual variations of SSTs over the warm pool and Indian Ocean, the interdecadal mode is negatively correlated with a different SST mode, i.e. the North Pacific mode. The latter is responsible for the observed downward trend of springtime precipitation over central eastern China. For all other cases, both the interannual and interdecadal variations of precipitation can be explained by the same mode of SSTs. The upward trend of springtime precipitation over southeastern China and downward trend of summertime precipitation over northern China are attributable to the warming trend of the ENSO-like mode. The recent frequent summertime floods over central eastern China are linked to the warming trend of SSTs over the warm pool and Indian Ocean. Copyright © 2004 Royal Meteorological Society [source] Responses of China's summer monsoon climate to snow anomaly over the Tibetan PlateauINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2003Prof. Y. F. Qian Abstract The climatological features of the winter snow depth over the Tibetan Plateau and the summer precipitation in China are diagnosed using datasets obtained from 78 snow observation stations and 160 rainfall stations during 1957 to 1998. The climatic effects of the snow anomaly over the Tibetan Plateau on the regional summer monsoon climate in China are diagnosed and numerically simulated by use of a regional climate model (RegCM2). The singular value decomposition technique is adopted to diagnose the relationships between the previous winter and spring plateau snow depth anomalies and the spring and summer regional precipitation in China. It is found that the snow depth anomaly, especially in winter, is one of the factors influencing precipitation in China; however, it is perhaps not the only one, and even not the most important one. Nevertheless, it is proved that the winter snow anomaly over the Tibetan Plateau is relatively more important than that in spring for the regional precipitation in China. Results of numerical simulations show that the snow anomaly over the plateau has effects that are evident on China's summer monsoon climate. The increase of both snow cover and snow depth can delay the onset and weaken the intensity of the summer monsoon obviously, resulting in a decrease in precipitation in southern China and an increase in the Yangtze and Huaihe River basins. The influence of the winter snow depth is more substantial than that of both the winter snow cover and the spring snow depth. The mechanism of how the plateau snow anomaly influences the regional monsoon climate is briefly analysed. It is found that snow anomalies over the Tibetan Plateau change the soil moisture and the surface temperature through the snowmelt process at first, and subsequently alter heat, moisture and radiation fluxes from the surface to the atmosphere. Abnormal circulation conditions induced by changes of surface fluxes may affect the underlying surface properties in turn. Such a long-term interaction between the wetland and the atmosphere is the key process resulting in later climatic changes. Copyright © 2003 Royal Meteorological Society [source] Pilot study of latewood-width of conifers as an indicator of variability of summer rainfall in the North American monsoon regionINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2001David M. Meko Abstract The variability of the North American Monsoon System (NAMS) is important to the precipitation climatology of Mexico and the southwestern United States. Tree-ring studies have been widely applied to climatic reconstruction in western North America, but as yet, have not addressed the NAMS. One reason is the need for highly resolved seasonal dendroclimatic information. Latewood-width, the portion of the annual tree ring laid down late in the growing season, can potentially yield such information. This paper describes a pilot study of the regional summer precipitation signal in latewood-width from a network of five Pseudotsuga menziesii chronologies developed in the heart of the region of NAMS influence in Arizona, USA. Exploratory data analysis reveals that the summer precipitation signal in latewood is strong, but not equally so over the full range of summer precipitation. Scatter in the relationship increases toward higher levels of precipitation. Adjustment for removal of inter-correlation with earlywood-width appears to strengthen the summer precipitation signal in latewood-width. To demonstrate a possible application to climatic reconstruction, the latewood precipitation signal is modelled using a nonlinear model,a binary recursive classification tree (CT) that attempts to classify summers as dry or not dry from threshold values of latewood-width. The model identifies narrow latewood-width as an effective predictor of a dry summer. Of 14 summers classified dry by latewood-width for the period 1868,1992, 13 are actually dry by the instrumental precipitation record. The results suggest that geographical expansion of coverage by latewood-width chronologies and further development of statistical methods may lead to successful reconstruction of variability of the NAMS on century time scales. Copyright © 2001 Royal Meteorological Society [source] Influence of climate and reproductive timing on demography of little brown myotis Myotis lucifugusJOURNAL OF ANIMAL ECOLOGY, Issue 1 2010Winifred F. Frick Summary 1. Estimating variation in demographic rates, such as survival and fecundity, is important for testing life-history theory and identifying conservation and management goals. 2. We used 16 years (1993,2008) of mark,recapture data to estimate age-specific survival and breeding probabilities of the little brown myotis Myotis lucifugus LeConte in southern New Hampshire, USA. Using Kendall & Nichols' (1995) full-likelihood approach of the robust design to account for temporary emigration, we tested whether survival and breeding propensity is influenced by regional weather patterns and timing of reproduction. 3. Our results demonstrate that adult female survival of M. lucifugus ranged from 0·63 (95% CL = 0·56, 0·68) to 0·90 (95% CL = 0·77, 0·94), and was highest in wet years with high cumulative summer precipitation. First-year survival [range: 0·23 (95% CL = 0·14, 0·35) to 0·46 (95% CL = 0·34, 0·57)] was considerably lower than adult survival and depended on pup date of birth, such that young born earlier in the summer (c. late May) had a significantly higher probability of surviving their first year than young born later in the summer (c. mid-July). Similarly, the probability of young females returning to the maternity colony to breed in the summer following their birth year was higher for individuals born earlier in the summer [range: 0·23 (95% CL = 0·08, 0·50) to 0·53 (95% CL = 0·30, 0·75)]. 4. The positive influence of early parturition on 1st-year survival and breeding propensity demonstrates significant fitness benefits to reproductive timing in this temperate insectivorous bat. 5. Climatic factors can have important consequences for population dynamics of temperate bats, which may be negatively affected by summer drying patterns associated with global climate change. 6. Understanding long-term demographic trends will be important in the face of a novel disease phenomenon (White-Nose Syndrome) that is associated with massive mortalities in hibernating bat species, including M. lucifugus, in the northeastern United States. [source] Tertiary relict trees in a Mediterranean climate: abiotic constraints on the persistence of Prunus lusitanica at the eroding edge of its rangeJOURNAL OF BIOGEOGRAPHY, Issue 8 2008Fernando Pulido Abstract Aim, To investigate the ecophysiological traits allowing persistence of a subtropical relict tree (Prunus lusitanica L.) under a dry Mediterranean climate at the eroding edge of its range. Location, A glasshouse for the study under controlled conditions and two marginal populations located in riparian forests of central Spain and exposed to summer drought, in contrast to subtropical populations that grow in mountain cloud forests. Methods, Two experiments were conducted to assess tolerance to the abiotic conditions found in riparian habitats. In a glasshouse experiment, gas-exchange and light-use parameters were measured to evaluate seedling responses to a factorial combination of irradiance (60%, 10%, 2% and 0.5% full sun) and moisture (well watered control and drought stress). In a parallel field experiment, irradiance and soil moisture were measured as predictors of seedling survival at two sites in which half the seedlings were subjected to a threefold increase in summer precipitation by adding water every 10 days. Results Soil moisture strongly determined survival both in the glasshouse and in the two field sites. In the field, periodic addition of water failed to increase survival. Water-use efficiency (WUE) increased with drought. Seedlings did not tolerate deep shade (2,0.5%) and their performance and survival were better when exposed to moderate (10%) or high (60%) irradiance. The effect of water stress on seedling performance was stronger at moderate irradiance, moderate at high irradiance and negligible at very low light. Seedling size (height and number of leaves) attained after 1 month of experimental treatments had a positive effect on survival at the end of the summer, hence greater survival was not achieved at the expense of vertical growth. Main conclusions, While studies in Macaronesia have shown that P. lusitanica occupies a wide range of moisture conditions along mountain slopes, it behaves as an obligate riparian species in dry peripheral populations. Intolerance to deep shade and tolerance to moderate and high irradiance allow the species to grow in small and moist gaps, or in treeless river sections. Despite the species' low range filling in marginal, drought-prone regions, long-term persistence might have been achieved through shifts to riparian habitats serving as local refuges. [source] Effects of global change on a sub-Arctic heath: effects of enhanced UV-B radiation and increased summer precipitationJOURNAL OF ECOLOGY, Issue 2 2001Gareth K. Phoenix Summary 1The responses of sub-Arctic heathland vegetation to enhanced UV-B radiation and increased summer precipitation over 7 years were investigated in a field experiment in northern Sweden. 2Growth, phenology and reproduction of the dominant dwarf shrubs Vaccinium myrtillus, V. uliginosum, V. vitis-idaea and Empetrum hermaphroditum were studied after 5,7 years of manipulation and retrospective analyses were used to assess growth responses in earlier years. Leaf tissue N and P and 13C natural abundances were determined for V. myrtillus and E. hermaphroditum. Growth responses were also assessed for the moss Hylocomium splendens. 3The deciduous V. myrtillus showed reduced growth, increased leaf thickness and increased flowering and berry production under enhanced UV-B in some years. V. uliginosum, V. vitis-idaea, E. hermaphroditum and H. splendens were, in general, tolerant of UV-B. 4Increased precipitation affected growth only in the evergreen species: stem length and branching were sometimes stimulated in E. hermaphroditum, whereas V. vitis-idaea showed reduced branching. 5Precipitation also increased leaf thickness in V. uliginosum and reduced flowering and berry production in V. myrtillus. 6In the interactions that occurred between enhanced UV-B radiation and increased summer precipitation, combining the two treatments often negated any effect that either may have had separately. The effect of concurrent increases on this ecosystem is therefore likely to be much less than if either occurred singly. 7Enhanced UV-B and increased summer precipitation appeared not to effect dwarf shrub abundances during the first 5 years of the experiment, suggesting that overall this heath may be more tolerant of these environmental changes than previously thought. [source] Climate change scenarios and models yield conflicting predictions about the future risk of an invasive species in North AmericaAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2010Anna M. Mika 1The pea leafminer Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae) is an invasive species in North America and a serious economic pest on a wide variety of crops. We developed a bioclimatic envelope model (BEM) for this species and examined the envelope's potential location in North America under various future climates. 2We compared the future bioclimatic envelopes for L. huidobrensis using either simple scenarios comprising uniform changes in temperature/precipitation or climate projections from general circulation models (GCMs). Our simple scenarios were: (i) an increase of 0.1°C per degree in latitude with a 20% increase in summer precipitation and a 20% decrease in winter precipitation and (ii) an overall increase of 3°C everywhere, also with the same changes in precipitation. For GCM-modelled climate change, we used the Canadian Centre for Climate Modelling and Analysis GCM (CGCM2) and the Hadley Centre climate model (HadCM3), each in combination with two scenarios from the Special Report on Emissions Scenarios (A2 and B2). 3The BEM results using the simple scenarios were more similar to each other than to the results obtained using GCM projections. The results were also qualitatively different (i.e. spatially different and divergent) depending on which GCM-scenario combination was used. 4This modelling exercise illustrates that: (i) results using first approximation simple climate change scenarios can give predictions very different from those that use GCM-modelled climate projections (comprising a result that has worrying implications for empirical impact research) and that (ii) different GCM-models using the same scenario can give very different results (implying strong model dependency in projected biological impacts). [source] PRECIPITATION CHANGES FROM 1956 TO 1996 ON THE WALNUT GULCH EXPERIMENTAL WATERSHED,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2002Mary H. Nichols ABSTRACT: The climate of Southern Arizona is dominated by summer precipitation, which accounts for over 60 percent of the annual total. Summer and non-summer precipitation data from the USDA-ARS Walnut Gulch Experimental Watershed are analyzed to identify trends in precipitation characteristics from 1956 to 1996. During this period, annual precipitation increased. The annual precipitation increase can be attributed to an increase in precipitation during non-summer months, and is paralleled by an increase in the proportion of annual precipitation contributed during non-summer months. This finding is consistent with previously reported increases in non-summer precipitation in the southwestern United States. Detailed event data were analyzed to provide insight into the characteristics of precipitation events during this time period. Precipitation event data were characterized based on the number of events, event precipitation amount, 30-minute event intensity, and event duration. The trend in non-summer precipitation appears to be a result of increased event frequency since the number of events increased during nonsummer months, although the average amount per event, average event intensity, and average event duration did not. During the summer "monsoon" season, the frequency of recorded precipitation events increased but the average precipitation amount per event decreased. Knowledge of precipitation trends and the characteristics of events that make up a precipitation time series is a critical first step in understanding and managing water resources in semiarid ecosystems. [source] Probability distributions, vulnerability and sensitivity in Fagus crenata forests following predicted climate changes in JapanJOURNAL OF VEGETATION SCIENCE, Issue 5 2004Tetsuya Matsui Question: How much is the probability distribution of Fagus crenata forests predicted to change under a climate change scenario by the 2090s, and what are the potential impacts on these forests? What are the main factors inducing such changes? Location: The major islands of Japan. Methods: A predictive distribution model was developed with four climatic factors (summer precipitation, PRS; winter precipitation, PRW; minimum temperature of the coldest month, TMC; and warmth index, WI) and five non-climatic factors (topography, surface geology, soil, slope aspect and inclination). A climate change scenario was applied to the model. Results: Areas with high probability (> 0.5) were predicted to decrease by 91%, retreating from the southwest, shrinking in central regions, and expanding northeastwards beyond their current northern limits. A vulnerability index (the reciprocal of the predicted probability) suggests that Kyushu, Shikoku, the Pacific Ocean side of Honshu and southwest Hokkaido will have high numbers of many vulnerable F. crenata forests. The forests with high negative sensitivity indices (the difference between simulated probabilities of occurrence under current and predicted climates) mainly occur in southwest Hokkaido and the Sea of Japan side of northern Honshu. Conclusion: F. crenata forest distributions may retreat from some islands due to a high WI. The predicted northeastward shift in northern Hokkaido is associated with increased TMC and PRS. High vulnerability and negative sensitivity of the forests in southern Hokkaido are due to increased WI. [source] Rodents, plants, and precipitation: spatial and temporal dynamics of consumers and resourcesOIKOS, Issue 3 2000S. K. Morgan Ernest Resource/consumer dynamics are potentially mediated by both limiting resources and biotic interactions. We examined temporal correlations between precipitation, plant cover, and rodent density, with varying time lags using long-term data from two sites in the Chihuahuan desert of North America: the Sevilleta Long-term Ecological Research site (LTER), New Mexico, USA and a site near Portal, Arizona, USA. We also calculated the spatial correlations in precipitation, plant cover, and rodent dynamics among six sites, five at Sevilleta and one at Portal. At Sevilleta, all three variables were temporally correlated, with plant cover responding to precipitation during the same growing season and rodent populations lagging at least one season behind. At Portal, plant stem count was also correlated with precipitation during the same growing season, but there was no significant correlation between rodents and either precipitation or plant growth. Spatial correlations in plant cover and rodent populations between sites reflected the localized nature of summer rainfall, so that sites with highly correlated summer precipitation exhibited higher correlations in plant cover and rodent populations. In general, our results indicate that limiting resources influence consumer dynamics, but these dynamics also depend crucially on the biotic interactions in the system. [source] Effects of Altered Temperature and Precipitation on Desert Protozoa Associated with Biological Soil CrustsTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2006BRIAN J. DARBY ABSTRACT. Biological soil crusts are diverse assemblages of bacteria, cyanobacteria, algae, fungi, lichens, and mosses that cover much of arid land soils. The objective of this study was to quantify protozoa associated with biological soil crusts and test the response of protozoa to increased temperature and precipitation as is predicted by some global climate models. Protozoa were more abundant when associated with cyanobacteria/lichen crusts than with cyanobacteria crusts alone. Amoebae, flagellates, and ciliates originating from the Colorado Plateau desert (cool desert, primarily winter precipitation) declined 50-, 10-, and 100-fold, respectively, when moved in field mesocosms to the Chihuahuan Desert (hot desert, primarily summer rain). However, this was not observed in protozoa collected from the Chihuahuan Desert and moved to the Sonoran desert (hot desert, also summer rain, but warmer than Chihuahuan Desert). Protozoa in culture began to encyst at 37°C. Cysts survived the upper end of daily temperatures (37,55°C), and could be stimulated to excyst if temperatures were reduced to 15°C or lower. Results from this study suggest that cool desert protozoa are influenced negatively by increased summer precipitation during excessive summer temperatures, and that desert protozoa may be adapted to a specific desert's temperature and precipitation regime. [source] Water Sources of Dominant Species in Three Alpine Ecosystems on the Tibetan Plateau, ChinaJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 3 2008De-Yu Duan Abstract Plant water sources were estimated by two or three compartment linear mixing models using hydrogen and oxygen isotope (,D and ,18O) values of different components such as plant xylem water, precipitation and river water as well as soil water on the Tibetan Plateau in the summer of 2005. Four dominant species (Quercus aquifolioides, Pinus tabulaeformis, Salix rehderiana and Nitraria tangutorum) in three typical ecosystems (forest, shrub and desert) were investigated in this study. Stable isotope ratios of the summer precipitations and the soil water presented variations in spatial and temporal scales. ,18O values of N. tangutorum xylem water were constant in the whole growth season and very similar to those of deep soil water. Water sources for all of the plants came from both precipitations and soil water. Plants switched rapidly among different water sources when environmental water conditions changed. Rainwater had different contributions to the plants, which was influenced by amounts of precipitation. The percentage of plant xylem water derived from rainwater rose with an increase in precipitation. Water sources for broad-leaved and coniferous species were different although they grew in the same environmental conditions. For example, the broad-leaved species Q. aquifolioides used mainly the water from deep soil, while 92.5% of xylem water of the coniferous species P. tabulaeformis was derived from rainwater during the growth season. The study will be helpful for us to fully understand responses of species on the Tibetan Plateau to changes in precipitation patterns, and to assess accurately changes of vegetation distribution in the future. [source] | ||||||||||||||||