An analysis of the outbreaks of the Australian Plague Locust, Chortoicetes terminifera (Walker) during the seasons 1940-41 to 1944-45.

1953 ◽  
Vol 1 (1) ◽  
pp. 70 ◽  
Author(s):  
LR Clark
Keyword(s):  
Soil Moisture ◽  
High Temperatures ◽  
Regional Differences ◽  
Early Summer ◽  
Late Spring ◽  
Seasonal Occurrence ◽  
Severe Winter ◽  
Biotic Factor ◽  
Main Area ◽  
Australian Plague Locust

Outbreaks of the Australian plague locust, Chortoicetes terminifera (Walker), occurred each locus: season from 1940-41 to 1944-45. The largest outbreak, that of 1942-43, was less severe than those recorded in 1937-38, 1938-39, and 1939-40. Consideration of the course of these recent outbreaks in relation to temperature and moisture has again demonstrated the importance of these factors as determinants of the regional and seasonal occurrence of swarms. The curve of limiting conditions for the persistence of swarm populations, obtained by Key (1942), was a useful guide for the interpretation of events in the present analysis. However, a number of discrepancies occurred. These were due probably to a variety of causes, e.g, the kind of infestation concerned, the crudenessof the monthly Meyer ratio as an index of soil moisture and pasture conditions, and regional differences in the upper moisture limits at high temperatures. The results of the present investigation suggest that:(a) The limiting Meyer ratios for the persistence or development of a spring infestation of small, weakly gregarious swarms at temperatures between 60 and 70�F. exceed 4-5; either when the September Meyer ratio is 5 or less, or when the spring is preceded by a severe winter drought.( b ) At temperatures around 75'F., the maximum Meyer ratio at which swarms can exist is approximately 20. (c) At temperatures near the estimated hatching threshold of 57.5'F., swarm hatchings can occur at Meyer ratios as low as 4-5. The collapse of the 1942-43 outbreak in part of the main area infested was due apparently to parasitism by an unidentified fly. Similarly, a biotic factor, possibly the same parasite, was largely responsible for the decline of the 1943-44 outbreak during the late spring and early summer.

scholarly journals Compost and soil moisture effects on seasonal carbon and nitrogen dynamics, greenhouse gas fluxes and global warming potential of semi-arid soils

2019 ◽  
Vol 8 (S1) ◽  
pp. 367-376 ◽  
Author(s):  
Mavis Badu Brempong ◽  
Urszula Norton ◽  
Jay B. Norton
Keyword(s):  
Global Warming ◽  
Soil Moisture ◽  
Global Warming Potential ◽  
Carbon Dioxide Emissions ◽  
Inorganic Nitrogen ◽  
Early Summer ◽  
Late Spring ◽  
Late Winter ◽  
Normal Soil ◽  
Soil Inorganic

Abstract Purpose An 8-week incubation study was conducted to monitor soil inorganic nitrogen (N), dissolved organic carbon (DOC), greenhouse gases (GHG) [CO2, N2O and CH4] and cumulative global warming potential (GWP) in dryland soil. Methods Soil was amended with variable rates of compost (zero, 15, 30 and 45 dry Mg ha−1) and soil moistures [5% (dry), 7% (normal) and 14% (wet) water filled pore space (WFPS)] and experienced biweekly temperature transitions from 5 °C (late winter) to 10 °C (early spring) to 15 °C (late spring) to 25 °C (early summer). Results The addition of 30 and 45 Mg ha−1 compost enhanced N mineralization with 13% more soil inorganic N (7.49 and 7.72 µg Ng−1 day−1, respectively) during early summer compared with lower compost rates. Normal and wet soils had 35% more DOC in the late spring (an average of 34 µg g−1 day−1) compared to the dry WFPS, but transitioning from late spring to early summer, DOC at all soil WFPS levels increased. Highest rates of compost were not significant sources of GHG with normal soil WFPS, compared with lower compost rates. Carbon dioxide emissions increased by 59 and 15%, respectively, as soil WFPS increased from dry to normal and normal to wet. Soils with normal WFPS were the most effective CH4 sink. Conclusion One-time application of high compost rates to dryland soils leads to enhanced N and C mineralization under normal soil moisture and warmer temperature of the summer but will not pose significant global warming dangers to the environment through GHG emissions since soils are rarely wet.

scholarly journals Dikegulac Improves Bougainvillea Flowering during Two Production Seasons

HortScience ◽  
1993 ◽  
Vol 28 (2) ◽  
pp. 119-121 ◽  
Author(s):  
J.G. Norcini ◽  
J.M. McDowell ◽  
J.H. Aldrich
Keyword(s):  
High Temperatures ◽  
Sodium Salt ◽  
Growth Habit ◽  
Foliar Spray ◽  
Early Summer ◽  
Late Spring ◽  
Foliar Sprays ◽  
Early Fall ◽  
Bougainvillea Glabra

The use of dikegulac foliar sprays in production of 4.5-liter hanging baskets (25.4-cm in diameter) of `Barbara Karst' bougainvillea [Bougainvillea ×buttiana (Bougainvillea glabra Choicy X Bougainvillea peruviana Humb. & Bonpl.) `Barbara Karst'] and `Rainbow Gold' bougainvillea (Bougainvillea `Rainbow Gold') was investigated under high temperatures (27.5-32C) and two production seasons (late spring to early summer and midsummer to early fall). During the late production season, liners pruned at transplanting (0 weeks) and treated with 1600 mg dikegulac/liter at 0 and 4 weeks resulted in plants with more flowers than that of controls (pruned only at 0 and 4 weeks), with `Barbara Karst' having a slightly compact, pendulous growth habit similar to that of controls. Dikegulac enhanced flowering compared with controls during midspring to early summer, but it did not result in plants with a slightly compact pendulous growth habit. These results suggest that a foliar spray of 1600 mg dikegulac/liter could substitute for the second pruning during hanging basket production of `Barbara Karst'. Chemical name used: sodium salt of 2,3:4,6-bis-O-(1-methylethylidene)-α-xylo-2-hexulofuranosonic acid (dikegulac-sodium).

Influence of Eurasian spring snowmelt on surface air temperature in late spring and early summer

2021 ◽  
pp. 1-45
Author(s):  
Juan Zhou ◽  
Zhiyan Zuo ◽  
Qiong He
Keyword(s):  
Soil Moisture ◽  
Air Temperature ◽  
Cloud Cover ◽  
Climate Models ◽  
Surface Air Temperature ◽  
Early Summer ◽  
Late Spring ◽  
Shortwave Radiation ◽  
Sensible Heat ◽  
Spring Snowmelt

AbstractThe effect of Eurasian spring snowmelt on surface air temperature (SAT) in late spring (April–May) and early summer (June–July) and the relevant physical mechanisms during 1981–2016 are investigated. Results show that the first mode of the inter-annual Eurasian spring snowmelt represents an east–west dipole anomaly pattern, with an intense center over Siberia and another moderate center around eastern Europe. The European spring snowmelt shows an insignificant relation to the local SAT, whereas the Siberian spring snowmelt has a significant impact on the SAT in late spring and early summer. More Siberian spring snowmelt contributes to higher SAT in late spring and lower SAT in early summer via different mechanisms. In late spring, increased Siberian spring snowmelt corresponds to less local surface albedo and cloud cover, leading to the surface absorbing more shortwave radiation and thereby higher SAT. The sub-surface and deep soil moisture anomalies generated from Siberian spring snowmelt can persist into early summer. Excessive Siberian spring snowmelt corresponds to positive soil moisture anomalies, contributing to decreased sensible heat and increased cloud cover in early summer. Increased cloud cover leads to the surface receiving less shortwave radiation. Thus, lower SAT appears over Siberia in early summer due to reduced sensible heat and shortwave radiation. However, the simulation of Eurasian spring snowmelt variability and its influences on SAT via the snow hydrological effect is still a challenge for the climate models that participated in the Coupled Model Intercomparison Project phase 6.

scholarly journals Climate Differently Impacts the Growth of Coexisting Trees and Shrubs under Semi-Arid Mediterranean Conditions

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 381
Author(s):  
J. Julio Camarero ◽  
Cristina Valeriano ◽  
Antonio Gazol ◽  
Michele Colangelo ◽  
Raúl Sánchez-Salguero
Keyword(s):  
Soil Moisture ◽  
Radial Growth ◽  
Pinus Halepensis ◽  
Growth Dynamics ◽  
Early Summer ◽  
Growth Responses ◽  
Shrub Species ◽  
High Soil Moisture ◽  
Semi Arid ◽  
Mediterranean Conditions

Background and Objectives—Coexisting tree and shrub species will have to withstand more arid conditions as temperatures keep rising in the Mediterranean Basin. However, we still lack reliable assessments on how climate and drought affect the radial growth of tree and shrub species at intra- and interannual time scales under semi-arid Mediterranean conditions. Materials and Methods—We investigated the growth responses to climate of four co-occurring gymnosperms inhabiting semi-arid Mediterranean sites in northeastern Spain: two tree species (Aleppo pine, Pinus halepensis Mill.; Spanish juniper, Juniperus thurifera L.) and two shrubs (Phoenicean juniper, Juniperus phoenicea L.; Ephedra nebrodensis Tineo ex Guss.). First, we quantified the intra-annual radial-growth rates of the four species by periodically sampling wood samples during one growing season. Second, we quantified the climate–growth relationships at an interannual scale at two sites with different soil water availability by using dendrochronology. Third, we simulated growth responses to temperature and soil moisture using the forward, process-based Vaganov‒Shashkin (VS-Lite) growth model to disentangle the main climatic drivers of growth. Results—The growth of all species peaked in spring to early summer (May–June). The pine and junipers grew after the dry summer, i.e., they showed a bimodal growth pattern. Prior wet winter conditions leading to high soil moisture before cambium reactivation in spring enhanced the growth of P. halepensis at dry sites, whereas the growth of both junipers and Ephedra depended more on high spring–summer soil moisture. The VS-Lite model identified these different influences of soil moisture on growth in tree and shrub species. Conclusions—Our approach (i) revealed contrasting growth dynamics of co-existing tree and shrub species under semi-arid Mediterranean conditions and (ii) provided novel insights on different responses as a function of growth habits in similar drought-prone regions.

scholarly journals The temporally varying roles of rainfall, snowmelt and soil moisture for debris flow initiation in a snow-dominated system

2018 ◽  
Vol 22 (6) ◽  
pp. 3493-3513 ◽  
Author(s):  
Karin Mostbauer ◽  
Roland Kaitna ◽  
David Prenner ◽  
Markus Hrachowitz
Keyword(s):  
Soil Moisture ◽  
Debris Flow ◽  
High Intensity ◽  
Debris Flows ◽  
Regional Scale ◽  
Early Summer ◽  
Temporal Separation ◽  
Antecedent Soil Moisture ◽  
Trigger Mechanisms ◽  
Debris Flow Initiation

Abstract. Debris flows represent frequent hazards in mountain regions. Though significant effort has been made to predict such events, the trigger conditions as well as the hydrologic disposition of a watershed at the time of debris flow occurrence are not well understood. Traditional intensity-duration threshold techniques to establish trigger conditions generally do not account for distinct influences of rainfall, snowmelt, and antecedent moisture. To improve our knowledge on the connection between debris flow initiation and the hydrologic system at a regional scale, this study explores the use of a semi-distributed conceptual rainfall–runoff model, linking different system variables such as soil moisture, snowmelt, or runoff with documented debris flow events in the inner Pitztal watershed, Austria. The model was run on a daily basis between 1953 and 2012. Analysing a range of modelled system state and flux variables at days on which debris flows occurred, three distinct dominant trigger mechanisms could be clearly identified. While the results suggest that for 68 % (17 out of 25) of the observed debris flow events during the study period high-intensity rainfall was the dominant trigger, snowmelt was identified as the dominant trigger for 24 % (6 out of 25) of the observed debris flow events. In addition, 8 % (2 out of 25) of the debris flow events could be attributed to the combined effects of low-intensity, long-lasting rainfall and transient storage of this water, causing elevated antecedent soil moisture conditions. The results also suggest a relatively clear temporal separation between the distinct trigger mechanisms, with high-intensity rainfall as a trigger being limited to mid- and late summer. The dominant trigger in late spring/early summer is snowmelt. Based on the discrimination between different modelled system states and fluxes and, more specifically, their temporally varying importance relative to each other, this exploratory study demonstrates that already the use of a relatively simple hydrological model can prove useful to gain some more insight into the importance of distinct debris flow trigger mechanisms. This highlights in particular the relevance of snowmelt contributions and the switch between mechanisms during early to mid-summer in snow-dominated systems.

scholarly journals MANAGEMENT OF LATE SPRING-EARLY SUMMER PASTURE SURPLUSES IN HILL COUNTRY

1984 ◽  
pp. 199-206 ◽  
Author(s):  
G.W. Sheath ◽  
R.W. Webby ◽  
W.J. Pengelly
Keyword(s):  
Early Spring ◽  
Early Summer ◽  
Late Spring ◽  
First Year ◽  
Hill Country ◽  
Continuous Grazing ◽  
Summer Pasture ◽  
Animal Performances ◽  
Grazing Policy ◽  
Made In

Comparisons of controlling late spring to early summer pasture growth on either easy or steep contoured land with either a fast rotation or continuous grazing policy were made in self-contained farmlets for two years. Pasture control was maintained over more land by controlling steep land first and with continuous grazing. Animal performances (ewes, steers) were generally similar for the mid-November to early January treatment period, and subsequently until May shearing. In the first year better animal performances occurred in "steep control" farmlets during winter and early spring, but this was less evident in the second year. Priority control of steep land during late spring-early summer is recommended because of likely longer-term benefits in pasture composition,density and production. Quick rotation grazing through the period provides a better ability to recognise and manage pasture quantities and should be adopted if summer droughts are anticipated. For well fenced properties in summer-wet areas and with integrated stock grazing, continuous grazing during late spring-early summer may be equally suitable. Keywords: hill country, grazing management, pasture control

scholarly journals Impacts of Late-Spring North Eurasian Soil Moisture Variation on Summer Rainfall Anomalies in Northern East Asia

2021 ◽  
Author(s):  
Yinghan Sang ◽  
Hong-Li Ren ◽  
Yi Deng ◽  
Xiaofeng Xu ◽  
Xueli Shi ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Temperature Gradient ◽  
East Asia ◽  
Summer Rainfall ◽  
Low Pressure ◽  
Late Spring ◽  
Boreal Summer ◽  
Pressure Center ◽  
North Eurasia ◽  
The Impact

Abstract This paper reports findings from a diagnostic and modeling analysis that investigates the impact of the late-spring soil moisture anomaly over North Eurasia on the boreal summer rainfall over northern East Asia (NEA). Soil moisture in May in the region from the Kara-Laptev Sea coasts to Central Siberian Plateau is found to be negatively correlated with the summer rainfall from Mongolia to Northeast China. The atmospheric circulation anomalies associated with the anomalously dry soil are characterized by a pressure dipole with the high-pressure center located over North Eurasia and the low-pressure center over NEA, where an anomalous lower-level moisture convergence occurs, favoring rainfall formation. Diagnoses and Modeling experiments demonstrate that the effect of the spring low soil moisture over North Eurasia may persist into the following summer through modulating local surface latent and sensible heat fluxes, increasing low-level air temperature at higher latitudes, and effectively reducing the meridional temperature gradient. The weakened temperature gradient could induce the decreased zonal wind and the generation of a low-pressure center over NEA, associated with a favorable condition of local synoptic activity. The above relationships and mechanisms are vice versa for the prior wetter soil and decreased NEA rainfall. These findings suggest that soil moisture anomalies over North Eurasia may act as a new precursor providing an additional predictability source for better predicting the summer rainfall in NEA.

Development of a nutritional strategy for increasing lamb survival in Merino ewes mated in late spring/early summer

1998 ◽  
Vol 52 (3) ◽  
pp. 213-219 ◽  
Author(s):  
M.B Nottle ◽  
D.O Kleemann ◽  
V.M Hocking ◽  
T.I Grosser ◽  
R.F Seamark
Keyword(s):  
Early Summer ◽  
Late Spring ◽  
Nutritional Strategy ◽  
Lamb Survival
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