Thaw circles around tree trunks provide spring ephemeral plants with a big head start on the growing season

Ecology ◽  
2017 ◽  
Vol 98 (12) ◽  
pp. 3224-3226 ◽  
Author(s):  
Mark Vellend ◽  
Amanda B. Young ◽  
Gabriel Letendre ◽  
Sébastien Rivest
Keyword(s):  
Head Start ◽  
Growing Season ◽  
Spring Ephemeral ◽  
Ephemeral Plants

scholarly journals Late canopy closure delays senescence and promotes growth of the spring ephemeral wild leek (Allium tricoccum)

Botany ◽  
2017 ◽  
Vol 95 (5) ◽  
pp. 457-467 ◽  
Author(s):  
Pierre-Paul Dion ◽  
Julie Bussières ◽  
Line Lapointe
Keyword(s):  
Light Availability ◽  
Growing Season ◽  
Tree Canopy ◽  
Strong Impact ◽  
Bud Burst ◽  
Growth And Survival ◽  
Spring Ephemerals ◽  
Spring Ephemeral ◽  
Tree Leaf ◽  
Allium Tricoccum

Spring ephemerals take advantage of the high light conditions in spring to accumulate carbon reserves through photosynthesis before tree leaves unfold. Recent work has reported delayed leaf senescence under constant light availability in some spring ephemerals, such as wild leek (Allium tricoccum). This paper aims to establish whether tree canopy composition and phenology can influence the growth of spring ephemerals through changes in their phenology. Wild leek bulbs were planted in 31 plots in southern Quebec, Canada, under canopies varying in composition and densities. Light availability and tree phenology were measured, along with other environmental conditions, and their effect on the growth of wild leeks was assessed with a redundancy analysis. Higher light availability resulted in better growth of wild leeks. The plants postponed their senescence under trees with late bud-burst, and thus better bulb growth and seed production were achieved. The tree litter and temperature and moisture levels of the soil also influenced the growth and survival of wild leeks. Thus, tree leaf phenology appears to have a strong impact on the growth of spring ephemerals by modulating the length of their growing season and their photosynthetic capacity. This underlines the importance of considering the variation of light availability throughout the growing season in the study of spring ephemerals.

scholarly journals Mapping Spring Ephemeral Plants in Northern Xinjiang, China

2018 ◽  
Vol 10 (3) ◽  
pp. 804 ◽  
Author(s):  
Yuan Qiu ◽  
Tong Liu ◽  
Chi Zhang ◽  
Bin Liu ◽  
Borong Pan ◽  
...  
Keyword(s):  
Northern Xinjiang ◽  
Spring Ephemeral ◽  
Ephemeral Plants

The IBM-PC in electron microscopy

1996 ◽  
Vol 54 ◽  
pp. 612-613
Author(s):  
James F. Mancuso
Keyword(s):  
Head Start ◽  
Image Acquisition ◽  
Cost Effective ◽  
Financial Applications ◽  
Number Of Factors ◽  
Instrument Control ◽  
The Cost ◽  
Training And Support ◽  
Control Image ◽  
Ibm Pc

IBM PC compatible computers are widely used in microscopy for applications ranging from control to image acquisition and analysis. The choice of IBM-PC based systems over competing computer platforms can be based on technical merit alone or on a number of factors relating to economics, availability of peripherals, management dictum, or simple personal preference.IBM-PC got a strong “head start” by first dominating clerical, document processing and financial applications. The use of these computers spilled into the laboratory where the DOS based IBM-PC replaced mini-computers. Compared to minicomputer, the PC provided a more for cost-effective platform for applications in numerical analysis, engineering and design, instrument control, image acquisition and image processing. In addition, the sitewide use of a common PC platform could reduce the cost of training and support services relative to cases where many different computer platforms were used. This could be especially true for the microscopists who must use computers in both the laboratory and the office.

Dynamic Assessment Language Tasks and the Prediction of Performance on Year-End Language Skills in Preschool Dual Language Learners

2020 ◽  
Vol 29 (3) ◽  
pp. 1226-1240
Author(s):  
Janet L. Patterson ◽  
Barbara L. Rodríguez ◽  
Philip S. Dale
Keyword(s):  
Head Start ◽  
Language Learners ◽  
Language Impairment ◽  
Dual Language ◽  
Dynamic Assessment ◽  
Dual Language Learners ◽  
Achievement Testing ◽  
Potential Applications ◽  
Language Screening ◽  
Relationship Of

Purpose Early identification is a key element for accessing appropriate services for preschool children with language impairment. However, there is a high risk of misidentifying typically developing dual language learners as having language impairment if inappropriate tools designed for monolingual children are used. In this study of children with bilingual exposure, we explored performance on brief dynamic assessment (DA) language tasks using graduated prompting because this approach has potential applications for screening. We asked if children's performance on DA language tasks earlier in the year was related to their performance on a year-end language achievement measure. Method Twenty 4-year-old children from Spanish-speaking homes attending Head Start preschools in the southwestern United States completed three DA graduated prompting language tasks 3–6 months prior to the Head Start preschools' year-end achievement testing. The DA tasks, Novel Adjective Learning, Similarities in Function, and Prediction, were administered in Spanish, but correct responses in English or Spanish were accepted. The year-end achievement measure, the Learning Accomplishment Profile–Third Edition (LAP3), was administered by the children's Head Start teachers, who also credited correct responses in either language. Results Children's performance on two of the three DA language tasks was significantly and positively related to year-end LAP3 language scores, and there was a moderate and significant relationship for one of the DA tasks, even when controlling for age and initial LAP3 scores. Conclusions Although the relationship of performance on DA with year-end performance varies across tasks, the findings indicate potential for using a graduated prompting approach to language screening with young dual language learners. Further research is needed to select the best tasks for administration in a graduated prompting framework and determine accuracy of identification of language impairment.

A Heads-Up on Head Start

2007 ◽  
Vol 41 (4) ◽  
pp. 70
Author(s):  
BRYAN R. FINE
Keyword(s):  
Head Start

Head Start: Only the best for America's children.

1994 ◽  
Vol 49 (2) ◽  
pp. 123-126 ◽  
Author(s):  
Nancy Landon Kassebaum
Keyword(s):  
Head Start

Head Start: Criticisms in a constructive context.

1994 ◽  
Vol 49 (2) ◽  
pp. 127-132 ◽  
Author(s):  
Edward Zigler ◽  
Sally J. Styfco
Keyword(s):  
Head Start
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