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Plant Phenology (plant + phenology)
Selected AbstractsRunoff and soil loss under individual plants of a semi-arid Mediterranean shrubland: influence of plant morphology and rainfall intensityEARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2006E. Bochet Abstract The influence of plant morphology and rainfall intensity on soil loss and runoff was determined at the plant scale for three representative species of a semi-arid patchy shrubland vegetation of east Spain, representing contrasting canopy structures and plant phenologies (Rosmarinus officinalis, Anthyllis cytisoides and Stipa tenacissima). Twenty-seven microplots of less than 1 m2, each containing one single plant, were built to quantify runoff volume and sediment yield under the canopies of the three species. Runoff and rates of soil loss measured in these plots under natural rainfall conditions were compared with control microplots built in the bare inter-plant areas. Precipitation was automatic-ally recorded and rainfall intensity calculated over a two-year period. Results indicated that individual plants played a relevant role in interrill erosion control at the microscale. Compared with a bare soil surface, rates of soil loss and runoff reduction varied strongly depending on the species. Cumulative soil loss was reduced by 94·3, 88·0 and 30·2 per cent, and cumulative runoff volume was reduced by 66·4, 50·8 and 18·4 per cent under the Rosmarinus, Stipa and Anthyllis canopies, respectively, compared with a bare surface. Anthyllis was significantly less efficient than the two other species in reducing runoff volume under its canopy. Differences between species could only be identified above a rainfall intensity threshold of 20 mm h,1. The different plant morphologies and plant compon-ents explained the different erosive responses of the three species. Canopy cover played a major role in runoff and soil loss reduction. The presence of a second layer of protection at the soil surface (litter cover) was fundamental for erosion control during intense rainfall. Rainfall intensity and soil water status prior to rainfall strongly influenced runoff and soil loss rates. The possible use of these species in restoration programmes of degraded areas is discussed. Copyright © 2006 John Wiley & Sons, Ltd. [source] Population genetics analysis of the origin of the Oriental fruit fly, Bactrocera dorsalis Hendel (Diptera: Tephritidae), in northern Yunnan Province, ChinaENTOMOLOGICAL SCIENCE, Issue 1 2007Jianhong LIU Abstract We examined genetic variation in the Oriental fruit fly, Bactrocera dorsalis (Hendel), using six populations in two regions of Yunnan Province, China, to determine the distribution and likely mechanism for the dispersal of this fly. A 501-bp portion of the mitochondrial cytochrome oxidase gene was sequenced from a minimum of eight individuals from each population, and 43 haplotypes were observed in the six Bactrocera dorsalis populations. When comparing the genetic diversity of populations in the northern and southern regions, which differ with respect to elevation, climate and plant phenology, we found a significantly greater haplotype diversity in the southern region (permutation test; P < 0.05), suggesting that the northern populations, those at Kunming and Qujing, probably originated from somewhere in the southern region. FST and number of pairwise differences revealed a high level of differentiation between the Panxi population and the other populations (permutation test; P < 0.05). Although the difference was marginally insignificant, the Shuitang population seemed to have differentiated from both northern populations. The Mantel test did not detect any isolation due to geographic distance. An amova analysis found that 2.56% of the variance was caused by the Panxi population. Haplotype network analysis showed that none of the six populations had a specific genetic lineage. Together, these analyses suggest that long-distance dispersal has occurred for this species, and the species most probably took advantage of both a mountain pass and prevailing air currents. The Panxi population was significantly isolated from the others, probably because of its distinguishing habitat features, host plants or the recent reduction of the population size. [source] Reduced early growing season freezing resistance in alpine treeline plants under elevated atmospheric CO2GLOBAL CHANGE BIOLOGY, Issue 3 2010MELISSA MARTIN Abstract The frequency of freezing events during the early growing season and the vulnerability to freezing of plants in European high-altitude environments could increase under future atmospheric and climate change. We tested early growing season freezing sensitivity in 10 species, from four plant functional types (PFTs) spanning three plant growth forms (PGFs), from a long-term in situ CO2 enrichment (566 vs. 370 ppm) and 2-year soil warming (+4 K) experiment at treeline in the Swiss Alps (Stillberg, Davos). By additionally tracking plant phenology, we distinguished indirect phenology-driven CO2 and warming effects from direct physiology-related effects on freezing sensitivity. The freezing damage threshold (lethal temperature 50) under ambient conditions of the 10 treeline species spanned from ,6.7±0.3 °C (Larix decidua) to ,9.9±0.6 °C (Vaccinium gaultherioides). PFT, but not PGF, explained a significant amount of this interspecific variation. Long-term exposure to elevated CO2 led to greater freezing sensitivity in multiple species but did not influence phenology, implying that physiological changes caused by CO2 enrichment were responsible for the effect. The elevated CO2 effect on freezing resistance was significant in leaves of Larix, Vaccinium myrtillus, and Gentiana punctata and marginally significant in leaves of Homogyne alpina and Avenella flexuosa. No significant CO2 effect was found in new shoots of Empetrum hermaphroditum or in leaves of Pinus uncinata, Leontodon helveticus, Melampyrum pratense, and V. gaultherioides. Soil warming led to advanced leaf expansion and reduced freezing resistance in V. myrtillus only, whereas Avenella showed greater freezing resistance when exposed to warming. No effect of soil warming was found in any of the other species. Effects of elevated CO2 and soil warming on freezing sensitivity were not consistent within PFTs or PGFs, suggesting that any future shifts in plant community composition due to increased damage from freezing events will likely occur at the individual species level. [source] Climate predictability and breeding phenology in red deer: timing and synchrony of rutting and calving in Norway and FranceJOURNAL OF ANIMAL ECOLOGY, Issue 4 2005L. E. LOE Summary 1Timing and synchrony of reproduction are regarded as crucially important factors for fitness in seasonal environments. Natural selection has probably favoured temperate and arctic female herbivores that match reproduction with onset of plant growth in spring. However, breeding synchrony may also be affected by variation in phenotypic quality of females in a population, because females in poor body condition have been found to delay ovulation and subsequent calving. 2We compared breeding phenology, i.e. the timing and synchrony of rutting (roaring, sexual aggregation) and calving of red deer (Cervus elaphus L.) in France (latitude: 49°N) and Norway (latitude: 63°N). We hypothesized (H1) that calving and rutting were later at the site with latest onset of plant growth. 3We further quantified overall environmental predictability as the sum of annual constancy and seasonality and tested three different (not mutually exclusive) hypotheses about breeding synchrony: (H2a) the population experiencing most seasonal plant phenology should show the highest breeding synchrony; (H2b) overall predictability of plant phenology should determine breeding synchrony; and (H2c) breeding should be more synchronized in the population with lowest female body weight variation within age classes because they ovulate more synchronously. 4Calving and rutting, as well as onset of plant phenology, were later in Norway than in France, complying with the first hypothesis. Plant growth in spring was overall more predictable and also more seasonal in Norway than France. Hence we expected higher breeding synchrony in Norway than in France according to H2a and H2b. Variance in female body weight was slightly higher in France than in Norway, which should also cause more synchronized breeding in Norway than in France (H2c). Contrary to all predictions, variance in rutting and calving dates was around two times higher in Norway than in France. 5We suggest two alternative explanations of breeding synchrony. A more variable topography in Norway can make optimal birth date more variable on a local scale than in France, thereby maintaining a higher genetic variance for calving date in Norwegian red deer. Further, population age structure may play a role, as ovulation varies according to female age. Clearly, processes of breeding synchrony are far more complex than previously realized. [source] Predictors of plant phenology in a diverse high-latitude alpine landscape: growth forms and topographyJOURNAL OF VEGETATION SCIENCE, Issue 5 2009Marianne Iversen Abstract Question: Different plant growth forms may have distinctly different functioning in ecosystems. Association of phenological patterns with growth form will therefore help elucidate the role of phenology in an ecosystem. We ask whether growth forms of common vascular plants differ in terms of vegetative and flowering phenology, and if such phenological differences are consistent across environmental gradients caused by landscape-scale topography. Location: A high-latitude alpine landscape in Finnmark County, Norway (70°N). Methods: We assessed vegetative and flowering phenology repeatedly in five growth forms represented by 11 common vascular plant species across an altitudinal gradient and among differing slope aspects. Results: Species phenology clustered well according to growth form, and growth form strongly explained variation in both flowering and vegetative phenology. Altitude and aspect were poor predictors of phenological variation. Vegetative phenology of the growth forms, ranked from slowest to fastest, was in the order evergreen shrubs Effects of plant phenology, nutrients and herbivory on growth and defensive chemistry of plantain, Plantago lanceolataOIKOS, Issue 2 2000C. M. Jarzomski To assess the combined effect of herbivory, nutrient availability and plant phenology on plant mass and defensive chemistry, we conducted a field experiment with plantain (Plantago lanceolata: Plantaginaceae) using three levels of herbivory, three levels of fertilizer and two harvest dates. Shoot mass of the no-herbivory plants showed a nonlinear response to increased fertilizer such that mass with high fertilizer was no greater than that with low fertilizer. In contrast, shoot mass of the low-herbivory plants (12% damage) was not influenced by fertilizer, but for high-herbivory plants (23% damage), there was a positive linear response to increased fertilizer. Increasing nutrient levels caused a decrease in iridoid glycoside concentration. Herbivory did not induce higher iridoid glycoside concentration in leaves of any age. But increasing herbivory resulted in a decrease in the concentration of catalpol in new leaves. Another experiment assessed how leaf age and plant age affected plant defensive chemistry. Total iridoid glycosides increased over 5 weeks, but catalpol only increased in new leaves. Overall, the order of importance in determining variation in iridoid glycoside concentration was plant phenology, nutrient availability and, to a much lesser extent, herbivory. [source] Feeding behavior of lactating brown lemur females (Eulemur fulvus) in Mayotte: influence of infant age and plant phenologyAMERICAN JOURNAL OF PRIMATOLOGY, Issue 10 2006Laurent Tarnaud Abstract Altmann [Baboon Mothers and Infants, University of Chicago Press, 1980] and Dunbar and Dunbar [Animal Behavior 36:970,980, 1988] provided a model that predicts the amount of time spent feeding by lactating baboon females, as related to infant age. Dunbar's model further suggests that food quality affects the amount of time that females devote to feeding activity, and is predictable from rainfall and temperature data. In this study the model was tested with data recorded from births of the Mayotte brown lemur from four maternal dyads (Eulemur fulvus). This study also examines the correlation between female activity budget, quantities of fresh plant matter ingested, and suckling duration using data collected from focal animal samples on the mother,infant dyads. The relationships among rainfall, food supply, and food quality were also tested. It appears that female brown lemurs do not devote more time to feeding during the infant growth period. The data show that female brown lemurs increased their food intake during the early-lactating period when the frequency of suckling is the highest, and before infants begin to eat substantial amounts of solid foods. Thus, the frequency of feeding reflects the cost of lactation better than suckling duration. Furthermore, females did not appear to select foods according to their availability or rainfall levels. I hypothesize that the lack of convergence between lemur data and baboon observations is due to differences between their respective environments and their feeding ecology. These data also indicate that the most significant lactating cost for the brown lemur occurs during the early lactation period. Am. J. Primatol. 68:1,12, 2006. © 2006 Wiley-Liss, Inc. [source] Ecohydrological effects of grazing-induced degradation in the Patagonian Monte, ArgentinaAUSTRAL ECOLOGY, Issue 5 2009ALEJANDRO JORGE BISIGATO Abstract Water-limited ecosystems have undergone rapid change as a consequence of changing land use and climate. The consequences of these changes on soil quality and vegetation dynamics have been documented in different regions of the world. In contrast, their effects on soil water, the most limiting resource in these environments, have received less attention, although in recent years increasing efforts have been made to relate grazing, soil water and vegetation functioning. In this paper, we present the results of field observations of plant phenology and soil water content carried out during two successive years at four sites along a degradation gradient caused by grazing in the Patagonian Monte, Argentina. We also developed a simplified soil water balance model to evaluate how changes in plant cover could affect water balance. Our field observations showed that the soil water content in the soil layer where roots of grasses are abundant (0,25 cm) was higher and the growing cycles were longer in degraded than in preserved sites. Similarly, our modelling approach showed that the deep soil (depth > 10 cm) was wetter in the degraded than in the preserved situation. Simulation also suggested a switch from transpiration to a direct evaporation dominance of water losses with degradation. Although reductions in plant cover related to grazing degradation were associated with a decrease in annual transpiration, the simulated soil water loss by transpiration was higher during summer in the degraded than in the well preserved situation. Thus, our field observations seem to be a consequence of ecohydrological changes causing an accumulation of water in the soil profile during the cold season and its transpiration during summer. In conclusion, our results showed that changes in plant cover caused by grazing disturbance can alter the soil water balance, which in turn can affect vegetation function. [source]
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