THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

This Review explains the concept of dissipative solitons and their application to high-energy mode-locked fibre laser cavities. Dynamics and effects such as dissipative soliton ‘explosions’ and ‘rain’ are summarized, and an outlook of the field is also provided.

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Dissipative solitons for mode-locked lasers

A surprise announcement by then prime minister Tony Blair in 1998 led to the creation of a new senior clinical role - the nurse consultant.

Work in progress: The evolving nurse consultant role has all-round benefits and should be embraced, finds Frances Pickersgill

Northern peatlands provide important global and regional ecosystem services (carbon storage, water storage, and biodiversity). However, these ecosystems face increases in the severity, areal extent and frequency of climate-mediated (e.g. wildfire and drought) and land-use change (e.g. drainage, flooding and mining) disturbances that are placing the future security of these critical ecosystem services in doubt. Here, we provide the first detailed synthesis of autogenic hydrological feedbacks that operate within northern peatlands to regulate their response to changes in seasonal water deficit and varying disturbances. We review, synthesize and critique the current process-based understanding and qualitatively assess the relative strengths of these feedbacks for different peatland types within different climate regions. We suggest that understanding the role of hydrological feedbacks in regulating changes in precipitation and temperature are essential for understanding the resistance, resilience and vulnerability of northern peatlands to a changing climate. Finally, we propose that these hydrological feedbacks also represent the foundation of developing an ecohydrological understanding of coupled hydrological, biogeochemical and ecological feedbacks. Copyright © 2014 John Wiley & Sons, Ltd.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/eco.1493

Hydrological feedbacks in northern peatlands

Seedling survival and successful forest restoration involves many silvicultural practices. One important aspect of a successful forest restoration program is planting quality seedlings with high survival capability. Thus the nursery needs to create seedlings with plant attributes that allow for the best chance of success once a seedling is field planted. Since the mid-twentieth century, research foresters have critically examined plant attributes that confer improved seedling survival to field site conditions. This review describes the value of commonly measured seedling quality material (i.e. shoot height, stem diameter, root mass, shoot to root ratio, drought resistance, mineral nutrient status) and performance (i.e. freezing tolerance and root growth) plant attributes defined as important in answering the question of why seedlings survive after planting. Desirable levels of these plant attributes can increase the speed with which seedlings overcome planting stress, become ‘coupled’ to the forest restoration site, thereby ensuring successful seedling establishment. Although planting seedlings with these desirable plant attributes does not guarantee high survival rates; planting seedlings with desirable plant attributes increases chances for survival after field planting.

Why seedlings survive: influence of plant attributes

Structurally different from even-aged and balanced uneven-aged stands, irregular stands are an integral part of forested landscapes in northeastern North America. The maintenance or restoration of irregular stand structure may be desirable, especially in areas under ecosystem-based management. This can be achieved at the stand level through the implementation of irregular shelterwood systems. The objectives of this synthesis are to assemble the existing knowledge about the system, clarify the terminology in use, and discuss its place in silviculture in northeastern North America. Irregular shelterwood is compared with other regeneration methods and we propose a classification based on three variants. This silvicultural system is compatible with ecosystem-based management in forest types driven by partial stand mortality and gap dynamics and provides opportunities for maintaining old-growth forest attributes. However, it presents important challenges, especially with regards to planning, growth and yield prediction, and operational application.

The irregular shelterwood system: Review, classification, and potential application to forests affected by partial disturbances.

Broad-band tunability of erbium-doped silica fiber ring lasers in the 1.48-1.62 /spl mu/m wavelength band is demonstrated through modeling and experiment. Tunability over the erbium-doped fiber amplifier (EDFA) C- and L-bands is achieved with a simple laser design using a single gain medium working in deep saturation. A comprehensive numerical model based on an iterative solution of propagation rate equations and spectrally resolved Giles parameters was used to analyze the impact of various laser variables. The dependence of laser output power on total cavity loss, erbium-doped fiber length, pump power, and lasing wavelength has been investigated. The calculated laser characteristics have been found in good quantitative agreement with the experimentally obtained data. Experimental results concerning wavelength tunability, output power, and lasing wavelength repeatability/stability and spectral purity are also presented.

A broadly tunable erbium-doped fiber ring laser: experimentation and modeling

Vegetation management is crucial to meeting the objectives of forest plantations. Following public hearing processes, chemical herbicides were banned on Crown forest lands in Quebec (Canada) in 2001. Release now mainly relies on mechanical treatments. Our objectives are to review the historical context and the research conducted over the past 15 years that has led to the province’s current vegetation management strategy and to identify the major challenges of vegetation management being faced in Quebec in the context of intensive silviculture and ecosystem-based management. Research has led to an integrated management model without herbicides, adapted to the ecological characteristics of reforestation sites. The Quebec experience illustrates how, on most sites, vegetation management that is based on early reforestation, the use of tall planting stock and intensive mechanical release brings crop trees to the free-to-grow stage without the use of herbicides and without resulting in major effects on vegetation diversity. This vegetation management strategy is an asset in the implementation of ecosystem-based management. However, research demonstrates that mechanical release alone does not promote optimal crop-tree growth, due to rapid resprouting or suckering of competitors and competition from herbaceous species. Therefore, the current strategy poses important challenges in the management of plantations where the objective is to maximise wood production.

Living without herbicides in Québec (Canada): historical context, current strategy, research and challenges in forest vegetation management

Establishment, growth and survival of natural regeneration after clearcutting and drainage on forested wetlands

Une etude a ete etablie en 1993 afin de determiner la performance de quatre dimensions de semis d'epinette noire (Picea mariana) et d'epinette blanche (P. glauca) mis en terre sur deux sites situes au Quebec (Canada), chacun representant un type de competition. A chaque site d'etude, un dispositif en tiroirs subdivises avec 15 et 17 repetitions a ete utilise, avec la presence de competition, la dimension initiale des semis et l'espece, assignees a la parcelle principale, la sous-parcelle et la sous sous-parcelle, respectivement. Les plants de fortes dimensions (PFD) ont recu plus de lumiere et ils affichaient une meilleure croissance que le plant de dimension standard. Les gains de croissance decoulant de la combinaison d'une plantation de PFD avec controle de la competition ont ete multiplicatifs. La vegetation de competition a significativement abaisse le profil saisonnier de la temperature du sol mesuree a 10 cm de profondeur. Cette etude demontre qu'un degagement hâtif est necessaire sur les stations caracterisees par une forte competition de framboisiers et de feuillus intolerants. De plus, sur ces memes stations, un reboisement avec des PFD devrait limiter le besoin de repeter les degagements mecaniques.

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Net effect of competing vegetation on selected environmental conditions and performance of four spruce seedling stock sizes after eight years in Québec (Canada)

Vincent Roy

Papers

The irregular shelterwood system: Review, classification, and potential application to forests affected by partial disturbances.

A broadly tunable erbium-doped fiber ring laser: experimentation and modeling

Living without herbicides in Québec (Canada): historical context, current strategy, research and challenges in forest vegetation management

Establishment, growth and survival of natural regeneration after clearcutting and drainage on forested wetlands

Net effect of competing vegetation on selected environmental conditions and performance of four spruce seedling stock sizes after eight years in Québec (Canada)