Tree-ring evidence of larch sawfly outbreaks in western Labrador, Canada

2010 ◽  
Vol 40 (8) ◽  
pp. 1542-1549 ◽  
Author(s):  
Peter H. Nishimura ◽  
Colin P. Laroque
Keyword(s):  
Black Spruce ◽  
Grid Point ◽  
Regional Scale ◽  
Single Site ◽  
Systematic Sampling ◽  
Larix Laricina ◽  
Regional Trends ◽  
Larch Sawfly ◽  
History Of ◽  
Spatio Temporal

As many insect outbreak reconstructions are typically based on targeted single-site sampling, researchers have often been limited in their ability to draw conclusions about regional trends as opposed to local trends in the data. The results of this paper demonstrate the value of a systematic sampling design when studying spatio-temporal processes that can vary greatly within large continuous areas of forest. Many single-site research programs have been conducted to reconstruct the history of larch sawfly ( Pristiphora erichsonii Htg.) outbreaks in the eastern boreal region of North America. However, no such research has yet been conducted in the region of Labrador. In an attempt to illustrate the strength of a systematic gridded sampling protocol over a single-site study, we sampled a 12-site grid in western Labrador. Dominant and codominant species were sampled at each grid point, resulting in 24 master chronologies. Six eastern larch ( Larix laricina (Du Roi) K. Koch) chronologies (host) and a regional black spruce ( Picea mariana (Mill.) Britton, Sterns, Poggenb.) chronology (nonhost) were used to establish a host–nonhost analysis of past sawfly outbreaks on a regional scale. Both regional and localized larch sawfly outbreaks were identified, but in general, larch sawfly outbreaks in western Labrador appeared to be spatially synchronous and regional in scale.

Régression holocène du couvert coniférien à la limite des forêts (Québec nordique)

1985 ◽  
Vol 63 (7) ◽  
pp. 1213-1225 ◽  
Author(s):  
Réjean Gagnon ◽  
Serge Payette
Keyword(s):  
Picea Mariana ◽  
Black Spruce ◽  
Climatic Conditions ◽  
Larix Laricina ◽  
Charcoal Analysis ◽  
Mosaic Landscape ◽  
The Past ◽  
Modern Period ◽  
History Of ◽  
Forest Limit

The occurrence of tamarack (Larix laricina (Du Roi) K. Koch) and black spruce (Picea mariana (Mill.) B.S.P.) macrofossils or subfossils on the tundroid patches at the forest limit indicates that those patches were colonized by trees in the past. The aim of this study is to reconstruct the fluctuations of the coniferous formations by macrofossil analysis. More than 465 macrofossils and 30 charcoals were collected, 31 and 23 of which, respectively, were 14C dated. The results of charcoal analysis indicated that fires were more frequent in the southern part of the forest limits than in the northern part. During the last millenium three periods of fire (modern, 400, and 900 years) were noted in the southern part, two periods (modern and 600 years) at the forest limit, and none north of the forest limit. The majority of collected macrofossils are from the modern period; their death is related to the action of fire. The mosaic landscape of the forest tundra is related to a deterioration of the climatic conditions coupled with the history of fires.

Dynamics of eastern larch stands and its relationships with larch sawfly outbreaks in the northern Clay Belt of Quebec

2002 ◽  
Vol 32 (2) ◽  
pp. 206-216 ◽  
Author(s):  
Martin-Philippe Girardin ◽  
Jacques Tardif ◽  
Yves Bergeron
Keyword(s):  
Black Spruce ◽  
Critical Factor ◽  
Stand Dynamics ◽  
Larix Laricina ◽  
Gap Dynamics ◽  
Stem Analysis ◽  
Breast Height ◽  
Pristiphora Erichsonii ◽  
Larch Sawfly ◽  
Growth Analyses

Climate change, fires, and insects outbreaks can affect eastern larch (Larix laricina (Du Roi) K. Koch) stand dynamics. To determine which of these factors had the greatest influence on stand dynamics, we sampled four wetlands dominated by larch on the margin of Lake Duparquet in the northern Clay Belt of Quebec. The ages of seedlings, saplings, and trees were determined in twelve 400-m2 plots. Increment cores were taken at breast height to determine past disturbance episodes related, among others, to larch sawfly (Pristiphora erichsonii (Hartig)) activity. Stem analysis was conducted using larch and black spruce (Picea mariana (Mill.) BSP) for identification of post-disturbance releases in height growth. Analyses at the stand and cluster levels showed that larch age structures were characterized by many unsynchronized establishment periods. In addition, a seedlings bank not much older than 10 years characterized many plots. Two larch sawfly outbreak episodes (1895–1912 and 1955–1962) identified by tree-ring and stem analysis were associated with larch establishment. A smaller outbreak in the late 1970s could also have contributed to the initiation of establishment in one stand. Our results suggest that the length (severity) of an outbreak may be a critical factor in explaining the different patterns of establishment observed in these stands. During a severe outbreak, larch establishment may occur mainly from surviving stems (increased seed production), whereas during a mild outbreak, larch establishment may occur from increased survival of pre-established seedlings and saplings. Further studies on the distribution of gaps within larch stands may provide better information on the pattern of mortality (gap dynamics) during an outbreak and may help to better understand larch establishment in these stands.

When the World Laughs

2020 ◽  
Author(s):  
William V. Costanzo
Keyword(s):  
Far East ◽  
Close Attention ◽  
The Far East ◽  
Regional Trends ◽  
Values And Beliefs ◽  
History Of ◽  
National Boundaries ◽  
Lost In Translation ◽  
Cross National ◽  
Film Comedy

This is a book about the intersection of humor, history, and culture. It explores how film comedy, one of the world’s most popular movie genres, reflects the values and beliefs of those who enjoy its many forms, its most enduring characters and stories, its most entertaining routines and funniest jokes. What people laugh at in Europe, Africa, or the Far East reveals important truths about their differences and common bonds. By investigating their traditions of humor, by paying close attention to the kinds of comedy that cross national boundaries and what gets lost in translation, this study leads us to a deeper understanding of each other and ourselves. Section One begins with a survey of the theories and research that best explain how humor works. It clarifies the varieties of comic forms and styles, identifies the world’s most archetypal figures of fun, and traces the history of mirth from earliest times to today. It also examines the techniques and aesthetics of film comedy: how movies use the world’s rich repertoire of amusing stories, gags, and wit to make us laugh and think. Section Two offers a close look at national and regional trends. It applies the concepts set forth earlier to specific films across a broad spectrum of sub-genres, historical eras, and cultural contexts, providing an insightful comparative study of the world’s great traditions of film comedy.

scholarly journals Investigating the Spatio-Temporal Variation of Soil Moisture and Agricultural Drought towards Supporting Water Resources Management in the Red River Basin of Vietnam

2021 ◽  
Vol 13 (9) ◽  
pp. 4926
Author(s):  
Nguyen Duc Luong ◽  
Nguyen Hoang Hiep ◽  
Thi Hieu Bui
Keyword(s):  
Soil Moisture ◽  
River Basin ◽  
Temporal Dynamics ◽  
Regional Scale ◽  
Dry Season ◽  
Red River ◽  
Agricultural Drought ◽  
Severe Drought ◽  
Red River Basin ◽  
Spatio Temporal

The increasing serious droughts recently might have significant impacts on socioeconomic development in the Red River basin (RRB). This study applied the variable infiltration capacity (VIC) model to investigate spatio-temporal dynamics of soil moisture in the northeast, northwest, and Red River Delta (RRD) regions of the RRB part belongs to territory of Vietnam. The soil moisture dataset simulated for 10 years (2005–2014) was utilized to establish the soil moisture anomaly percentage index (SMAPI) for assessing intensity of agricultural drought. Soil moisture appeared to co-vary with precipitation, air temperature, evapotranspiration, and various features of land cover, topography, and soil type in three regions of the RRB. SMAPI analysis revealed that more areas in the northeast experienced severe droughts compared to those in other regions, especially in the dry season and transitional months. Meanwhile, the northwest mainly suffered from mild drought and a slightly wet condition during the dry season. Different from that, the RRD mainly had moderately to very wet conditions throughout the year. The areas of both agricultural and forested lands associated with severe drought in the dry season were larger than those in the wet season. Generally, VIC-based soil moisture approach offered a feasible solution for improving soil moisture and agricultural drought monitoring capabilities at the regional scale.

scholarly journals Simulating Spatio-Temporal Patterns of Bicycle Flows with an Agent-Based Model

2021 ◽  
Vol 10 (2) ◽  
pp. 88
Author(s):  
Dana Kaziyeva ◽  
Martin Loidl ◽  
Gudrun Wallentin
Keyword(s):  
Regional Scale ◽  
Evidence Base ◽  
Wide Field ◽  
Traffic Patterns ◽  
Agent Based Model ◽  
Validation Data ◽  
Agent Based ◽  
Mobility Behavior ◽  
Spatio Temporal ◽  
Models Validation

Transport planning strategies regard cycling promotion as a suitable means for tackling problems connected with motorized traffic such as limited space, congestion, and pollution. However, the evidence base for optimizing cycling promotion is weak in most cases, and information on bicycle patterns at a sufficient resolution is largely lacking. In this paper, we propose agent-based modeling to simulate bicycle traffic flows at a regional scale level for an entire day. The feasibility of the model is demonstrated in a use case in the Salzburg region, Austria. The simulation results in distinct spatio-temporal bicycle traffic patterns at high spatial (road segments) and temporal (minute) resolution. Scenario analysis positively assesses the model’s level of complexity, where the demographically parametrized behavior of cyclists outperforms stochastic null models. Validation with reference data from three sources shows a high correlation between simulated and observed bicycle traffic, where the predictive power is primarily related to the quality of the input and validation data. In conclusion, the implemented agent-based model successfully simulates bicycle patterns of 186,000 inhabitants within a reasonable time. This spatially explicit approach of modeling individual mobility behavior opens new opportunities for evidence-based planning and decision making in the wide field of cycling promotion

scholarly journals Spatio-temporal integration in plant tropisms

2019 ◽  
Vol 16 (154) ◽  
pp. 20190038 ◽  
Author(s):  
Yasmine Meroz ◽  
Renaud Bastien ◽  
L. Mahadevan
Keyword(s):  
Response Function ◽  
Shoot Growth ◽  
Analytic Solution ◽  
Temporal Integration ◽  
Time Varying ◽  
Local Response ◽  
History Of ◽  
Non Local ◽  
Spatio Temporal ◽  
Plant Shoots

Tropisms, growth-driven responses to environmental stimuli, cause plant organs to respond in space and time and reorient themselves. Classical experiments from nearly a century ago reveal that plant shoots respond to the integrated history of light and gravity stimuli rather than just responding instantaneously. We introduce a temporally non-local response function for the dynamics of shoot growth formulated as an integro-differential equation whose solution allows us to qualitatively reproduce experimental observations associated with intermittent and unsteady stimuli. Furthermore, an analytic solution for the case of a pulse stimulus expresses the response function as a function of experimentally tractable variables, which we calculate for the case of the phototropic response of Arabidopsis hypocotyls. All together, our model enables us to predict tropic responses to time-varying stimuli, manifested in temporal integration phenomena, and sets the stage for the incorporation of additional effects such as multiple stimuli, gravitational sagging, etc.

scholarly journals Holocene changes in African vegetation: tradeoff between climate and water availability

2014 ◽  
Vol 10 (2) ◽  
pp. 681-686 ◽  
Author(s):  
C. Hély ◽  
A.-M. Lézine ◽  
APD contributors
Keyword(s):  
West Africa ◽  
Water Availability ◽  
Regional Scale ◽  
Plant Distribution ◽  
Climate Conditions ◽  
Tropical Plants ◽  
Plant Migration ◽  
Spatio Temporal ◽  
The Individual ◽  
Instrumental Records

Abstract. Although past climate change is well documented in West Africa through instrumental records, modeling activities, and paleo-data, little is known about regional-scale ecosystem vulnerability and long-term impacts of climate on plant distribution and biodiversity. Here we use paleohydrological and paleobotanical data to discuss the relation between available surface water, monsoon rainfall and vegetation distribution in West Africa during the Holocene. The individual patterns of plant migration or community shifts in latitude are explained by differences among tolerance limits of species to rainfall amount and seasonality. Using the probability density function methodology, we show here that the widespread development of lakes, wetlands and rivers at the time of the "Green Sahara" played an additional role in forming a network of topographically defined water availability, allowing for tropical plants to migrate north from 15 to 24° N (reached ca. 9 cal ka BP). The analysis of the spatio–temporal changes in biodiversity, through both pollen occurrence and richness, shows that the core of the tropical rainbelt associated with the Intertropical Convergence Zone was centered at 15–20° N during the early Holocene wet period, with comparatively drier/more seasonal climate conditions south of 15° N.

Age, evolution and tectonic history of the Highland Border Complex, Scotland

1984 ◽  
Vol 75 (2) ◽  
pp. 113-133 ◽  
Author(s):  
Gordon B. Curry ◽  
B. J. Bluck ◽  
C. J. Burton ◽  
J. K. Ingham ◽  
David J. Siveter ◽  
...  
Keyword(s):  
Regional Scale ◽  
Plate Boundary ◽  
North American Plate ◽  
Tectonic History ◽  
Lower Ordovician ◽  
Northwestern Margin ◽  
Comprehensive Survey ◽  
History Of ◽  
Early Palaeozoic ◽  
Western Ireland

I. ABSTRACT: Research interest in the Highland Border Complex has been pursued sporadically during the past 150 years. The results and conclusions have emphasised the problems of dealing with a lithologically disparate association which crops out in isolated, fault-bounded slivers along the line of the Highland Boundary fault. For much of the present century, the debate has centred on whether the rocks of the complex have affinities with the Dalradian Supergroup to the N, or are a discrete group. Recent fossil discoveries in a wide variety of Highland Border rocks have confirmed that many are of Ordovician age, and hence cannot have been involved in at least the early Grampian deformational events (now accurately dated as pre-Ordovician) which affect the Dalradian Supergroup. Such palaeontological discoveries form the basis for a viable biostratigraphical synthesis. On a regional scale, it is apparent that the geological history of the Highland Border rocks must be viewed in the context of plate boundary tectonism along the entire northwestern margin of Iapetus during Palaeozoic times.II. ABSTRACT: Silicified articulate brachiopods from the Lower Ordovician (Arenig) Dounans Limestone are extremely rare but the stratigraphically diagnostic generaArchaeorthisSchuchert and Cooper, andOrthidiumHall and Clarke, have been identified. In addition, three specimens with characteristic syntrophiid morphology have been recovered. Inarticulate brachiopods are known from Stonehaven and Bofrishlie Burn near Aberfoyle, and have also been previously recorded from Arran.III. ABSTRACT: Micropalaeontological investigation of the Highland Border Complex has produced a range of microfossils including chitinozoans, coleolids, calcispheres and other more enigmatic objects. The stratigraphical ranges of the species lie almost entirely within the Ordovician and reveal a scatter of ages for different lithologies from the Arenig through to the Caradoc or Ashgill, with a pronounced erosional break between the Llandeilo and the Caradoc.IV. ABSTRACT: A Lower Ordovician (Arenig Series) silicified ostracode fauna from the Highland Border Dounans Limestone at Lime Craig Quarry, Aberfoyle, Central Scotland, represents the earliest record of this group of Crustacea from the British part of the early Palaeozoic ‘North American’ plate.V. ABSTRACT: Palaeontological age determinations for a variety of Highland Border rocks are presented. The data are based on the results of recent prospecting which has demonstrated that macro- and microfossils are present in a much greater range of Highland Border lithologies than previously realised. Data from other studies are also incorporated, as are modern taxonomie re-assessments of older palaeontological discoveries, in a comprehensive survey of Highland Border biostratigraphy. These accumulated data demonstrate that all fossiliferous Highland Border rocks so far discovered are of Ordovician age, with the exception of the Lower Cambrian Leny Limestone.VI. ABSTRACT: The Highland Border Complex consists of at least four rock assemblages: a serpentinite and possibly other ophiolitic rocks of Early or pre-Arenig age; a sequence of limestones and conglomerates of Early Arenig age; a succession of dark shales, cherts, quartz wackes, basic lavas and associated volcanogenic sediments of Llanvirn and ? earlier age; and an assemblage of limestones, breccias, conglomerates and arenites with subordinate shales of Caradoc or Ashgill age. At least three assemblages are divided by unconformities and in theirmost general aspect have similarities with coeval rocks in western Ireland.The Highland Border Complex probably formed N of the Midland Valley arc massif in a marginal sea comparable with the Sunda shelf adjacent to Sumatra–Java. Strike-slip and thrust emplacement of the whole Complex in at least four episodes followed the probable generation of all or part of its rocks by pull-apart mechanisms.

Combining static and dynamic environmental factors at various scales to predict shallow landsliding in South Tyrol, Italy – The Proslide project

2021 ◽  
Author(s):  
Robin Kohrs ◽  
 Lotte de Vugt ◽  
Thomas Zieher ◽  
Alice Crespi ◽  
Mattia Rossi ◽  
...  
Keyword(s):  
Regional Scale ◽  
Remote Sensing Data ◽  
Predisposing Factors ◽  
Physical Models ◽  
Data Driven ◽  
Catchment Scale ◽  
Heterogeneous Model ◽  
South Tyrol ◽  
Daily Precipitation Data ◽  
Spatio Temporal

<p>Shallow landslides in alpine environments can constitute a serious threat to the exposed elements. The spatio-temporal occurrence of such slope movements is controlled by a combination of predisposing factors (e.g. topography), preparatory factors (e.g. wet periods, snow melting) and landslide triggers (e.g. heavy precipitation events).  </p><p>For large study areas, landslide assessments frequently focus either on the static predisposing factors to estimate landslide susceptibility using data-driven procedures, or exclusively on the triggering events to derive empirical rainfall thresholds. For smaller areas, dynamic physical models can reasonably be parameterized to simultaneously account for static and dynamic landslide controls.  </p><p>The recently accepted Proslide project aims to develop and test methods with the potential to improve the predictability of landslides for the Italian province of South Tyrol. It is envisaged to account for a variety of innovative input data at multiple spatio-temporal scales. In this context, we seek to exploit remote sensing data for the spatio-temporal description of landslide controlling factors (e.g. precipitation RADAR; satellite soil moisture) and to develop models that allow an integration of heterogeneous model inputs using both, data-driven approaches (regional scale) and physically-based models (catchment scale). This contribution presents the core ideas and methodical framework behind the Proslide project and its very first results (e.g. relationships between landslide observations and gridded daily precipitation data at regional scale). </p>

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