Richard H. Waring | PubMed Health

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Effects of branch length on carbon isotope discrimination in Pinus radiata.

Gas exchange was measured on a pruned Pinus radiata D. Don hedge and on a long-branch P. radiata tree near Hamilton, New Zealand, in spring 1993 when soil water content was close to field capacity. Foliage at the end of long branches (9.0 m) showed a marked drop in net photosynthetic rate and stomatal conductance as the saturation deficit increased, whereas foliage on short branches (0.5 m) showed little change. Mean foliage delta(13)C was -30.1 per thousand for short branches and -26.3 per thousand for long branches. Foliage delta(13)C was correlated with branch length in two genetically improved P. radiata seedlots at four stocking densities. The multinodal seedlot had shorter branches and more (13)C-depleted foliage compared with branches and foliage from the long internode seedlot. There was a strong effect of stocking density on carbon isotope composition in both seedlots. We conclude that branch morphology affects foliage gas exchange properties and foliage carbon isotope composition.

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Lessons learned while extending physiological principles from growth chambers to satellite studies.

Over the last three decades, physiological principles established in laboratory studies have been applied to systems at progressively larger scales and are now firmly merged into the fields of ecology, ecosystem modeling, forest protection, and global change research. To expand the vision of any field requires that scientists from different disciplines build a bridge across the chasm that normally exists between the knowledge bases and perspectives of different fields. Bridges are built most quickly when representatives of different disciplines see the possibility of mutual advantage in collaboration and seek to quickly demonstrate that potential. Usually, however, the process is laborious because approaches and techniques must be modified to address problems at a different level of integration. Successful bridge builders have, almost without exception, established credibility in their own field and have then identified a kindred spirit with similar credentials in another. They usually establish a pilot study that involves apprentices as well as established scientists. If the approach is successful, the younger members of the team often take the lead in further advancements. Managers of large centralized programs should foster interdisciplinary exchange, particularly at times when advancement in one field languishes. To expand collaboration, it is often necessary for scientists to seek common properties that simplify relations across a wide range of biological and physical conditions. This integrative perspective is essential and is fostered by participating in cross-disciplinary workshops and conferences and by reading outside one's field.

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