Spaces, margins & fonts  
Double-space all material (text, quotations, figure legends, tables, literature cited, etc.) at three lines per inch (12 lines/ 10 cm). Print on only one side of letter (8.5 x 11 inch) or A4 (210 x 297 mm) paper. Leave at least 2.4-cm margins on all sides of each page. Use a 12-point font (proportionally spaced type) or 10 characters/inch (4 characters/cm) if the letter spacing is uniform. Do not hyphenate words at the right margin or justify the right margin. Put the author's name in a header for each page and number all pages, starting with the title page.  Also please number all lines to facilitate reviews. 

Equations, symbols and abbreviations  
Define all symbols, abbreviations and acronyms the first time they are used. Equations to be set separately from the text will be broken into two or more lines if they exceed the width of one column; mark equations for appropriate breaks. Subscripts and superscripts should be clarified by marginal notes. Use leading zeroes with all number <1, including probability values (e.g., p< 0.001). Use boldface roman type to denote matrices and vectors.  

Underlining & italics  
Underlining indicates italicization. (If mathematical expressions are to be set with underbars, this must be indicated clearly on the manuscript, by means of a special note.) Underline or italicize scientific names and the symbols for all variables and constants except Greek letters. Symbols should be italic in the illustrations to match the text. Italics should rarely be used for emphasis.  

Footnotes   
Footnotes to text should be avoided; most footnote material can be incorporated in the text (parenthetically if necessary) to the benefit of readers, editors, and printers.  

Organization of the paper   
Title page  

Running Head. -- A running head of not longer than 40 letters and spaces should be provided at the top of the title page.  
Title. -- Titles should be concise, informative, tell what the paper is about, and contain keywords necessary for digital search and retrieval methods. Titles should be descriptive clauses, not full sentences. The maximum length is 13 words or 100 characters; longer titles will be shortened by the editor. Do not include the authority for taxonomic names in the title or in the abstract. Titles may not include numerical series designations.  
List of Authors. -- For each author, give the relevant address - usually the institutional affiliation of the author during the period when all or most of the research was done. The author’s present address, if different from this, and the author's email address should appear as a footnote at the bottom of the title page.  Individuals listed as authors should have played a significant role in designing or carrying out the research, writing the manuscript, or providing extensive guidance on the execution of the project. Those whose role was limited to providing materials, financial support, or review should be recognized in the Acknowledgments section.

The abstract should explain to the general reader why the research was done and why the results should be viewed as important. It should provide a brief summary of the research, including the purpose, methods, results, and major conclusions. Do not include any literature citations in the Abstract.  

The primary purpose of an abstract is to allow readers to determine quickly and easily the content of a paper. Abstracts should not exceed 200 words.  

Following the Abstract, list up to 12 key words. Words from the title of the article may be included in the key words. Each key word should be useful as an entry point for a literature search. 

If appropriate, organize your article in sections labeled Introduction, Methods, Results, and Discussion. In long articles you may need to add a section for Conclusions. Brief articles usually do not require a label for the Introduction. If the nature of your research requires a different organization, specify the level of each section heading (1st-order head, 2nd-order head, etc.) in the margin.  

A brief Introduction describing the paper's significance should be intelligible to the general reader of the journal. The Introduction should state the reason for doing the research, the nature of the questions or hypotheses under consideration, and essential background.  

The Methods section should provide sufficient information to allow someone to repeat your work. A clear description of your experimental design, sampling procedures, and statistical procedures is especially important.  Do not describe commonplace statistical tests in Methods, but allude to them briefly in Results. If you list a product (e.g., animal food, analytical device), supply the name and location of the manufacturer. Give the model number for equipment specified. Supply complete citations, including author (or editor), title, year, publisher and version number, for computer software mentioned in your article. 

Results generally should be stated concisely and without interpretation, though in complex studies modest interpretation of individual parts can provide context helpful for understanding subsequent parts.  

The Discussion should explain the significance of the results. Distinguish factual results from speculation and interpretation. Avoid excessive review. 

Acknowledgments, including funding information, should appear in a brief statement at the end of the body of the text. 

Avoid excessive citations; cite only essential sources. Before submitting the manuscript, check each citation in the text against the Literature Cited to see that they match exactly. Delete citations if they are not actually cited in the article. The list should conform in sequencing and punctuation to that in recent issues of the journal. All journal titles should be spelled out completely. Provide the publisher’s name and location when you cite conference proceedings or other books.  

The Literature Cited section of a paper may refer only to permanently archived material. If a reasonably diligent scholar 20 years in the future could not be assured of finding a particular source, it would not be acceptable as literature cited. Because Internet sources typically have a short half-life, they may not be included in Literature Cited sections unless there is reasonable evidence of permanency (e.g., ITRDB, NGDC Archives). As a general rule, any publication that has an ISSN or ISBN is acceptable, but should be referenced by name (the URL may be added, but is not essential).  

Do not list abstracts or unpublished material in the Literature Cited. These materials may be listed in the text as personal observations (by an author of the present paper), personal communications (information from others), or public communications (information in published abstracts, or information publicly distributed over the Internet but not permanently archived). The author(s) is expected to verify for all "personal communications" that the authority cited agrees to the use of his or her name. For public communications, the reference should include date printed or accessed, and title of the source, and basic access information such as URL. 

Illustrations  
Each copy of the manuscript should include photocopies of illustrations. Number illustrations in the order in which they are discussed in the text. Group the figure legends in numerical order on one or more pages, separate from the figures. The figure title should be given as the first line of the legend.  

Most illustrations will be reduced to single-column width in the journal; symbols and lettering should be clearly legible after reduction. After reduction, all lettering should be at least as large as the smallest type used in the journal . Uppercase letters are preferred except where SI requires lowercase letters for unit abbreviations. Nomenclature, abbreviations, symbols, and units used in a figure should match those used in the text. Helvetica font is preferable for figures. Use italic lettering only as it is used in the text (e.g., variables, species names). Solid black bars in bar graphs tend to overwhelm the adjacent text; use white, shaded, or hatched bars in preference to black ones.  

To avoid extra expense, do not submit photographic prints unless they are requested. If important details cannot be distinguished on a photocopy, submit a glossy print of that illustration for review purposes. Do not submit prints larger that 22 X 28 cm unless asked to do so. Identify each figure by number with a label at the top of the reverse side. The cost of printing color figures will be billed to the author (currently $550 per figure). If you submit a colored illustration, please specify whether you are willing to pay the costs of reproducing the figure in color. Color figures should be identified with a label on the top of a photocopy; do not attach anything to the back of a color illustration.  

Photographs of organisms and habitats add interest and "reality" to scientific data. Because papers must start at the top of a page, there is often extra space at the end of an article that could be reallocated for an extra photograph. We encourage you to include such a photograph where appropriate. Identify each photograph with a plate number rather than a figure number if it is not essential to the paper. The photo will be published as part of the article if space permits.  

Digital appendices and supplements  
Data used in publications are a vital resource for future research.  For that reason, it is strongly recommended that new data used in the preparation of published articles be made available via online data bases that have some assurance for significant longevity and maintenance into the future.  In the case of tree-ring chronologies and climate reconstructions a recommended online database is the World Data Center for Paleoclimatology (www.ngdc.noaa.gov/paleo/contrib.html). Authors should contribute their data when they complete their final, post-review manuscripts.  For the World Data Center archives, authors will be issued a data contribution number that can be cited in the article.  

Assembly of the manuscript  
Assemble the parts of each copy of the manuscript in this order: title page, abstract, key words, text, acknowledgments, literature cited, print appendices, tables, figure legends, figures, digital appendices and supplements. Number all pages (including appendices, tables, and figures) consecutively.  

Some Conventions  
The words “tree ring” should always be hyphenated when used as an adjective, e.g., “The tree-ring widths were measured.”, and as in “tree-ring research”.  

The single word “crossdate” and its derivatives "crossdated" and "crossdating" should be used rather than the hyphenated version (“cross-dating”) or as two words ("cross date").  

Authorities for scientific names must be provided (preferably when first used), or a reference can be given wherein the authorities can be found. Because usage of scientific names varies between investigators and can be ambiguous when out of context, conformance to a comprehensive nomenclatural standard is highly desirable.  Suggestions for nomenclature standards are available for commonly studied groups.  

Statistical analyses and data presentation  
Authors are free to interpret statistical analyses as they see fit. The author, however, needs to provide the reader with information sufficient for an independent assessment of the analysis. Thus, the assumptions and the model underlying any statistical analysis must be clearly stated, and the presentation of results must be sufficiently detailed. Sampling designs, experimental designs, data-collection protocols, precision of measurements, sampling units, and sample sizes must be succinctly described. Reported statistics usually include the sample size and some measure of their precision (standard error [SE] or specified confidence interval [CI]) except where this would interfere with graphical clarity. The specific statistical procedure must always be stated. Unusual statistical procedures need to be explained in sufficient detail, including references if appropriate, for the reader to reconstruct the analysis. If a software product was used, complete citation should be given, including version number. When reporting results, actual P values are preferred.

Units  
Units of measure should conform to the International System of Units (SI). If measurements were made in other units, include the SI equivalents.

Consult Standard Practice for Use of the International System of Units (ASTM Standard E-380-93) for guidance on unit conversions, style, and usage.  An abbreviated version may be downloaded from the ASTM website. When preparing text and figures, note in particular that SI requires the use of the terms mass or force rather than weight.  When one unit appears in a denominator, use the solidus (e.g., g/m² ); for two or more units in a denominator, use negative exponents (e.g., g m^-2 d^-1 ). Use a capital L as the symbol for liter.