926 research outputs found
Phenology and dynamics of an African rain forest at Korup, Cameroon
No full textIn groves of ectomycorrhizal caesalpinaceous legumes in Korup, Cameroon, the most abundant of three co-dominant tree species, Microberlinia bisulcata, has had, and continues to show, very low recruitment. Replacement is likely to favour the two other guild members, Tetraberlinia bifoliolata nod T. morelitma. All three species produce large sufficient seedling banks.
Microberlinia bisulcata attained the greatest tree sizes and had the most pronounced mast fruiting pattern (a 3-year cycle). Masting was associated with peaks in the previous dry-season radiation suggesting a requirement to accumulate carbon reserves before fruiting. More circumstantial evidence points to phosphorus supply as a co-controlling factor.
The dominance of M. bisulcata is most likely due to a recently unique, natural historical event, an epoch of unusually dry years, which allowed its shade-intolerant ectomycorrhizal seedlings to outcompete other species. The putative fungal connections to parents appear to be of no advantage (possibly a disadvantage) to the seedlings under such mature adults.
The composition of Korup is neither constant nor cycling but a fragment of change which might be reset by climatic fluctuations coincident with potential regeneration of a species also adapted to the low-phosphorus soils and strongly seasonal conditions of the site. Understanding the dynamic& of such an African forest requires a stochastic view over several centuries
Englerodendron korupense (Fabaceae, caesalpinioideae), a new tree species from Korup National Park, Cameroon
No full textFIG. 2. — Englerodendron korupense Burgt: A, inflorescense; B, fruits; C, seedlings; D, stem base of the tree from which the type was collected. A, van der Burgt 741; B, van der Burgt 760; C, van der Burgt & Eyakwe 711.Published as part of Van Der Burgt, Xander M., Eyakwe, Moses Bisongi & Newbery, David M., 2007, Englerodendron korupense (Fabaceae, Caesalpinioideae), a new tree species from Korup National Park, Cameroon, pp. 59-65 in Adansonia (3) 29 (1) on page 63, DOI: 10.5281/zenodo.460185
Bragging Rights and the Newbery
No full textIn an article in the Spring 2022 issue of Children and Libraries, celebrating the centennial of the Newbery Medal, author Steven Herb provided an intriguing statistical examination of Newbery Medal and Honor Books and their creators. In addition, the author wished for a “country and state-by-state birth distribution.
Optimal tariffs on exhaustible resources
No full textWe characterize the Markov perfect equilibria of two games in which oligopsonistic importers of an exhaustible resource confront competitive suppliers who have rational expectations. The games differ only in the timing of moves, or the speed with which participants can adjust their plans. The optimal tariff when sellers move first (are less flexible) differs considerably from that in which buyers move first, and sellers retain more control over intertemporal arbitrage opportunities. If the initial stock is small, buyers suffer a disadvantage from being the first-mover; this is reversed if the stock is large
Speech [by David Newbery, Emeritus Professor of Economics, University of Cambridge]
No full textThis contribution was delivered on the occasion of the EUI State of the Union in Florence on 10 May 201
Security of Supply, Capacity Auctions and Interconnectors David Newbery Security of Supply, Capacity Auctions and Interconnectors
No full textAbstract Energy policy aims to deliver security, sustainability and affordability, but politicians treat security of supply as over-riding. Absent market and regulatory failures, liberalized energy-only electricity markets might deliver adequate capacity. Ambitious targets for subsidized renewables and policy uncertainty have undermined the commercial case for the investment needed to handle increased intermittency and raised concerns for capacity adequacy. In response Britain now holds annual capacity auctions. The paper examines the case for, criticisms of, and the outcome of the first auction, criticizing the decision to ignore the contribution that interconnectors make to security of supply. Keywords Introduction Energy policy aims to deliver security, sustainability and affordability, but of these three objectives politicians treat security of supply as over-riding. Given the need to instantly balance supply and demand in the electricity system, ensuring short-term security of supply is normally an obligation placed on system operators, while longer term capacity adequacy is often the subject of regulatory and political concern. EU electricity markets are now liberalized, and generation is, for the most part, not subject to traditional utility regulation, but normal competition policy both domestically and under the scrutiny of DG COMP. If investment decisions could be solely guided by strictly commercial decisions and if markets were not subject to policy interventions or price caps, it is plausible that capacity adequacy could be delivered by profit-motivated generation investment without explicit policy guidance. However, ambitious renewables targets that can only be met at present through support mechanisms, combined with an ineffective climate change instrument in the Emissions Trading System, make predicting future electricity prices subject to substantial political risk, while the large volume of renewables has driven wholesale prices below the long-run marginal cost of supply in many countries, undermining the attractiveness and ability to invest. This paper explains the concept of security of supply for electricity markets, investigates whether energy-only markets could deliver the required standard, identifies market, institutional and political/regulatory failures that undermine confidence that such markets can be relied upon to deliver reliability, and then discusses the way in which the British Government has addressed this problem
The Newbery companion booktalk and related materials for Newbery medal and honor books
No full text"A brief introduction of John Newbery and his publishing record plus a history of the award and a description of how the winners are chosen" precedes a chronological arrangement of the awards from 1922 to 1996, with information on the author, plot summary, themes and subjects, incidents for booktalking, related titles, etc
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Optimal Commodity Stockpiling Rules
No full textStiglitz and Newbery discuss optimal commodity stockpiling rules
Southern Korup Transect Plots Data
No full textText to files on Korup plot data of Gartlan and Thomas
In the southern part of Korup National Park (58o10 N, 8o70 E), 135 plots, each of 80 m x 80m in area, were laid out at 150-m intervals along four E-to-W transect lines (P, Q, R and S; each of 34 plots, excepting Q with 33). Lines were ~5 km in length, and separated S-to-N at ~4 km distance. Shrubs and small trees were very lightly cut to show a way between plots. Each plot was divided into four 40-m x 40-m subplots, although only data at the whole plot level are archived here. Details of the layout and environmental information are found in Gartlan et al. (1986). All trees of ≥ 30 cm gbh (girth at breast height, 1.3 m) were measured and identified. Coordinate locations of trees within subplots were not taken: trees were not tagged. Lianas were also recorded but are not included here. The plots were not marked at their corners in any permanent manner apart from an indication of their location by single tags on trees at the start of each plot on the line. The field work was undertaken in 1975-1977, principally by J. S. Gartlan, D. W. Thomas and F. Namata. Plots were relocatable up to about 1998, after which time many tags had become very difficult to find. Except for transect P, the southernmost line, and which has continued in use for further research up until the present, the other lines have faded.
There are four ASCII-text files. These were the inputs for the abundance tables, classifications and ordinations in Gartlan et al. (1986). (1) ‘korbar.txt’ has the basal areas (ba) per plot (units: m2/0.1-ha) of each tree species, written in the Cornell Condensed Format (CCF) of the programs DECORANA and CANOCO. Each line of the data has a plot number followed by four couplets of ‘species number and ba-value’. (Some lines have trailing zero entries.) Plots numbers are: 1-34, transect P; 35-67, Q; 68-101, R; and 102-135, S. (2) ‘korfre.txt’ has the numbers of trees of each tree species per plot, corresponding to ‘korbar.txt’ and also in the CCF. (3) ‘korlsp.txt’ contains a list of the 444 species’ identifier codes (all transects); and (4) ‘kortax.txt’ is a dictionary of these species’ codes giving their full Latin names and authorities as of 1986, arranged under family names. The taxonomy has not been updated, and the modern user may want to revise it using an international plant names’ index.
These data were also the basis to Newbery & Gartlan (1996) and Newbery et al. (1988, 1997, 1998).
_References
Gartlan, J. S., D. M. Newbery, D. W. Thomas, and P. G. Waterman. 1986. The influence of topography and soil phosphorus on the vegetation of Korup Forest Reserve, Cameroun. Vegetatio 65:131-148.
Newbery, D. M., I. J. Alexander, and J. A. Rother. 1997. Phosphorus dynamics in a lowland African rain forest: The influence of ectomycorrhizal trees. Ecological Monographs 67:367-409.
Newbery, D. M., I. J. Alexander, D. W. Thomas, and J. S. Gartlan. 1988. Ectomycorrhizal Rain-Forest Legumes and Soil-Phosphorus in Korup-National-Park, Cameroon. New Phytologist 109:433-450.
Newbery, D. M. and J. S. Gartlan. 1996. Structural analysis of the rain forest at Korup and Douala Edea, Cameroon. Proceedings of the Royal Society of Edinburgh B 104:177-224.
Newbery, D. M., N. C. Songwe, and G. B. Chuyong. 1998. Phenology and dynamics of an African rain forest at Korup, Cameroon. Pages 267-308 in D. M. Newbery, H. H. T. Prins, and N. D. Brown, editors. Dynamics of tropical communities. Blackwell Science, Oxford
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