A new collection of tree-ring chronologies developed from trees and remnant material located in the western and central Great Plains makes an important contribution to the spatial coverage of the US tree- ring chronology network. Samples from 24 sites were collected from the west-central Great Plains, and to date, ten chronologies have been produced. When correlated with a set of 47 single-station PDSI records, the chronologies display relationships with regional spring and summer drought. The reconstruction of spring PDSI for eastern Colorado generated in this study suggests that the inclusion of Great Plains trees can improve the quality of Great Plains drought reconstructions. The eastern Colorado drought reconstruction explains 62% of the variance in the instrumental record and extends to 1552. This reconstruction provides information about the regional character of major droughts over the past four and a half centuries. Major eastern Colorado droughts include events in the 1580s, 1630s, 1660s, 1730s, and the 1930s. The late 16th century drought, noted as an especially severe drought in the southwestern US, appears in this reconstruction as only slightly more severe than other major droughts in this region.

Within the framework of the linear aggregate model of dendrochronology, the potential role of soil nutrient availability in explaining multi-decadal variation in radial growth at the tree level was studied in the central Spanish Pyrenees. Increment cores were collected from 20 mature Pinus uncinata Ram. and analyzed dendrochronologically. One ion-exchange resin capsule was buried within the root zone of each sampled tree for just over eight months. The resins were chemically extracted and measured for NH₄, NO PO₄, Ca, and K. Statistical relationships between indexed tree growth and soil nutrient availability were determined with regression analysis and bivariate plots. The single most important soil nutrient with respect to decadal-scale dendrochronological tree-growth variables in this study was N in the form NO which explained 22% of variation of trend in growth since 1950. The 20 values of NO₃ availability fell into two subgroups, one of trees with relatively higher NO₃ availability and the other with lower NO₃ availability. When the tree-growth data were grouped based on NO₃ availability, the two resultant index chronologies had different low-frequency features since 1950. Trees with low NO₃ availability have been growing as expected based on past growth, but trees with high NO availability have been growing better than expected. Measuring and analyzing soil nutrient availability at the tree level might enhance environmental applications of dendrochronological research. With soils information at this spatial scale, it is possible to distinguish between subgroups of trees within a tree-ring site and thereby construct subchronologies that differ significantly, especially for variation at the decadal scale. Subsite-chronologies may then lead to different and presumably more informative environmental interpretations relative to those based on a full-site chronology.

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Dendrochronological methods were used to date hail injuries in tree rings of six mountain pines (Pinus mugo var. uncinata) at a site in central Switzerland. Annually dated injuries (1939-1996) were in 89% of the cases attributable to years with severe regional hailstorm occurrence (1957-1996). Days with severe hailstorms were successfully dated in either the earlywood and /or latewood portions of a tree ring in a given year. Tree rings provide an alternative proxy to existing data for reconstructing past severe hailstorm occurrence.

High-resolution paleoclimatic data for West Africa are needed to provide context for contemporary climatic and ecological dynamics. Six hundred trees (22 botanical families, 43 genera and over 70 species) from semi-arid West Africa were evaluated for their suitability for dendrochronological research; specifically ring development. The samples were classified as 'potentially useful', 'problematic', or 'poor' based on the presence and distinctiveness of annual rings, ability to achieve crossdating between radii using skeleton plots on at least some samples, circuit uniformity, ring wedging, and variability of ring widths. Samples were classified as potentially useful if (a) they exhibited distinctive annual rings that could be identified and counted with little uncertainty and be independently verified by a second person with little or no error, (b) crossdating between radii could be successfully achieved, at least on some samples, (c) the rings were generally consistent throughout the stem cross section, (d) ring wedging was minimal (in the relative sense) or absent, and (e) the ring widths were variable, indicating the possibility of climatic sensitivity. Seven species, including five from the Caesalpiniaceae family (Cassia sieberiana, Cordyla pinnata, Daniella oliveri, Isoberlinia doka, Tamarindus indica), and one each from Mimosaceae (Acacia seyal) and Verbenaceae (Gmelina arborea) families, that most closely satisfied these criteria were classified as 'potentially useful'. The 'problematic' category includes those samples that satisfied some of the criteria but for which greater diligence is required to detect rings. Eight species from three families were classified in this category. Finally those samples on which ring detection appears futile given current methods and techniques were classified as 'poor'. Most of the samples classified as 'potentially useful' belong to three botanical families, Caesalpiniaceae, Mimosacae, and Verbenaceae. These results are consistent with the findings of other studies, and therefore support further investigation of the potential of West African trees for tree-ring analysis focusing on these families. Furthermore, inability to crossdate between trees and to explain several ring anatomical features underscores the pressing need for comprehensive field studies of cambial activity during the growing season, and for the identification of dormant seasons. This requirement, and other difficulties discussed suggest a need for increasing the local dendrochronological expertise in West Africa.

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Writing is much like any other activity-the more you read and write, the more proficient you become as a scientist. Here, I provide canons for writing and editing scientific papers that should help novice writers avoid common hazards that could render a manuscript unpublishable. Abstracts should be well-written and concise and contain all the major results and conclusions. The manuscript should be well organized. Sentences in all paragraphs should stick to the central theme of the paragraph. Writers should provide Latin names for species analyzed, and should use SI units in all cases. The use of bulleted lists, active voice, and commas after introductory phrases will improve the clarity of the manuscript. Tables and figures should be clear, well-organized, stand-alone accessories to the text, and usually convey data and results that are numerous or complex. Writers should avoid both plagiarism and self-plagiarism, and should have their manuscript proofread before submitting to a journal. Finally, authors should consult primary references (such as Scientific Style and Format, published by the Council of Biology Editors in 1994) to become familiar with troublesome words and phrases.

Old Douglas-fir (Pseudotsuga menziesii) trees were sampled in the Sierra Madre Oriental of northeastern Mexico and used to develop a 219-year chronology of earlywood width. This chronology is correlated with monthly precipitation totals from January to June recorded at Saltillo some 55 km northwest of the collection site. The chronology was used to reconstruct winter-spring precipitation (January-June total) from 1782-2000. The reconstruction indicates large interannual, decadal, and multidecadal variability in winter-spring precipitation over Saltillo. This variability is vaguely apparent in the short and discontinuous instrumental record from 1950-1998, with January-June totals ranging from 15 to 310 mm, multiyear droughts, and a negative trend in January-June precipitation over the last 50 years. The reconstruction indicates that severe dryness was prevalent over a 24-year period from 1857-1880. This mid-19th century drought exceeds the duration of any droughts witnessed during the 20th century. However, three episodes of winter-spring dryness have prevailed in the Saltillo region after 1950, a much higher frequency of decadal drought than estimated over the past 219 years and aggravating the regional water supply problems associated with this booming manufacturing and ranching center.