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Engineering, United States

Lara W.,University of Valladolid | Lara W.,Research Center on Ecosystems and Global Change | Bravo F.,University of Valladolid | Maguire D.A.,Resources and Management
Agricultural and Forest Meteorology

We established a new approach for incorporating dynamic tree biomass variables into dendrochronological studies. A multi-level algorithm was developed for modeling biomass growth from tree-ring chronologies, and for establishing temporal relationships between biomass dynamics and drought. The algorithm, BIOdry, integrates conventional procedures for modeling patterns between tree biomass growth and drought, using dendrochronological data from Mediterranean ecosystems, accounting for multiple sources of variation from sample design, and comparing patterns from contrasting climatic portions of study site during last 50 years. The modeling approach was validated by exploring principal factors affecting annual biomass increments and annual aridity indexes in two Mediterranean pine forests: Pinus pinaster and P. sylvestris. BIOdry corrected several statistical problems related with dendrochronological sampling and modeling of biomass growth. The most important factors affecting relationships between the series were time span of the analysis, regional variations and adaptive strategies of species. Series from trees in the Atlantic region were not sensitive to increasing drought while responses of trees in the Mediterranean regions depended on species. Series from P. pinaster were more sensitive to drought oscillations than series of P. sylvestris. Both species growing in southern Spain have experienced increasing sensitivity to drought during last 50 years. Southern forests are little adapted to decreasing precipitations of autumns and winters. BIOdry can be used for assessing spatial and temporal vulnerabilities of growth attributes derived from tree-ring chronologies to increasing drought. © 2013 Elsevier B.V. Source

Will R.E.,Oklahoma State University | Fox T.,Virginia Polytechnic Institute and State University | Akers M.,University of Georgia | Domec J.-C.,North Carolina State University | And 19 more authors.

The future climate of the southeastern USA is predicted to be warmer, drier and more variable in rainfall, which may increase drought frequency and intensity. Loblolly pine (Pinus taeda) is the most important commercial tree species in the world and is planted on ~11 million ha within its native range in the southeastern USA. A regional study was installed to evaluate effects of decreased rainfall and nutrient additions on loblolly pine plantation productivity and physiology. Four locations were established to capture the range-wide variability of soil and climate. Treatments were initiated in 2012 and consisted of a factorial combination of throughfall reduction (approximate 30% reduction) and fertilization (complete suite of nutrients). Tree and stand growth were measured at each site. Results after two growing seasons indicate a positive but variable response of fertilization on stand volume increment at all four sites and a negative effect of throughfall reduction at two sites. Data will be used to produce robust process model parameterizations useful for simulating loblolly pine growth and function under future, novel climate and management scenarios. The resulting improved models will provide support for developing management strategies to increase pine plantation productivity and carbon sequestration under a changing climate. © 2015 by the authors. Source

Flint M.,University of Queensland | Patterson-Kane J.C.,University of Glasgow | Limpus C.J.,Resources and Management | Mills P.C.,University of Queensland

Causes of disease and mortality in marine turtles are frequently based on opportunistic investigations producing results that may not contribute to knowledge on how to protect their survival rate. Over a 4-year period (2006-2009), the major causes of stranding and morbidity in 100 green turtles (Chelonia mydas) from southern Queensland on the east coast of Australia were determined by comprehensive postmortem examination. Lesions were characterized for analysis using descriptive and probability statistics. Spirorchiid parasitism was found to be the most frequently occurring cause of mortality (41.8%), followed by gastrointestinal impaction (11.8%), microbiological infectious diseases (5.2%), and trauma (5.2%). Spirorchiid parasitism with associated inflammation (75%) was the most frequently occurring disease, followed by gastrointestinal impaction (5.1%). All other diseases were observed at a low prevalence. Assessment of the likelihood of disease being influenced by risk factors (season, maturity, and gender) showed that: (i) there were more observed cases of spirorchiid infection in summer when compared with the other seasons (P = 0.029); (ii) immature turtles had more severe spirorchiid parasite infections than mature turtles (P = 0.032); and (iii) respiratory disorders were more likely (P = 0.01) in summer and autumn than winter or spring. Number of observed cases and severity of spirorchiid lesions were highest in the brain compared with other histologically examined organ systems (all P > 0.1). Further investigation is required to build on these findings, aid management decisions, and determine the significance of these diseases for green turtle survivorship in Queensland. © 2010 International Association for Ecology and Health. Source

Adams D.M.,Resources and Management | Alig R.,U.S. Department of Agriculture | Latta G.,Resources and Management | White E.M.,Oregon State University
Journal of Forestry

Policymakers are examining a wide range of alternatives for climate change mitigation, including carbon offset sales programs, to enhance sequestration in the forest sector. Under an offset sales program, on-the-ground forestry could change as a result of both afforestation and modifications in the management of existing forests. These effects could vary markedly by region in the United States because of differences in areas of agricultural land suitable for afforestation, forest carbon and volume growth characteristics, the structure of landownership, and forest industry concentration. Using a dynamic model of North American markets, our analysis of alternative carbon price levels suggests that the largest carbon increment response would come from changes in forest management: extending rotations, shifting silvicultural regimes, and reforestation to hardwood forest types (in some regions). Carbon payments could also stimulate a substantial afforestation response in eastern regions (North and South). Afforestation is particularly important in the North where timberland area could expand markedly. Much of the area would be planted to hardwoods, stemming the projected decline in hardwood forest types and growing stock volume. Source

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