Dudley J. Raynal

Bio: Dudley J. Raynal is an academic researcher from State University of New York College of Environmental Science and Forestry. The author has contributed to research in topics: Beech & Nutrient. The author has an hindex of 28, co-authored 54 publications receiving 2626 citations. Previous affiliations of Dudley J. Raynal include State University of New York at Purchase & Middle East Technical University.

Use of nitrogen to phosphorus ratios in plant tissue as an indicator of nutrient limitation and nitrogen saturation

Abstract: Summary 1Ratios of nitrogen to phosphorus (N:P) in plant foliage have been used to assess nutrient limitation in wetland ecosystems and to indicate nitrogen saturation. Extension of this application to ecosystems other than wetlands remains to be evaluated. 2We compared published N:P ratios as thresholds of nutrient limitation with published accounts from nutrient-addition experiments and the N:P ratios of understorey vegetation (Acer spp., Dryopteris intermedia, Erythronium americanum, Lycopodium lucidulum, Oxalis acetosella and Viola macloskeyi) from the Catskill Mountains of New York State, USA. We also performed a nutrient-addition experiment to test the response of these understorey plant species to inputs of N and P. 3N:P ratios of Catskill understorey species indicated they were at or near P limitation relative to N:P ratios from other upland ecosystems. Our experiment supported this finding in that none of the species responded to N addition but all increased in P concentration and one increased in biomass with added P. Collectively, these results suggest that the understorey vegetation of the Catskill Mountains is not nitrogen limited, providing further evidence that hardwood forests in this area are nitrogen-saturated. 4Synthesis and applications. This study demonstrates that N:P ratios can be effective predictors of nutrient limitation in upland ecosystems. Therefore N:P ratios can be used for management and monitoring purposes in considering the nutrient status of upland ecosystems with particular relevance to the continued deposition of elevated atmospheric N and to the diagnosis of nitrogen saturation.

Response of tree seedlings to aluminum.

Abstract: This review focuses on the mechanisms underlying aluminum (Al) toxicity in trees. The major topics discussed include the uptake and localization of Al, effects of Al on growth and composition, factors determining the response to Al, proposed mechanisms of Al resistance, and the occurrence of Al phytotoxicity under field conditions.

Long-term trends in the chemistry of precipitation and lake water in the Adirondack Region of New York, USA

Abstract: Long-term changes in the chemistry of precipitation (1978–94) and 16 lakes (1982–94) were investigated in the Adirondack region of New York, USA. Time-series analysis showed that concentrations of SO4 2−, NO3 −, NH4 + and basic cations have decreased in precipitation, resulting in increases in pH. A relatively uniform rate of decline in SO4 2− concentrations in lakes across the region (1.81±0.35 μeq L−1 yr−1) suggests that this change was due to decreases in atmospheric deposition. The decrease in lake SO4 2− was considerably less than the rate of decline anticipated from atmospheric deposition. This discrepancy may be due to release of previously deposited SO4 2− from soil, thereby delaying the recovery of lake water acidity. Despite the marked declines in concentrations of SO4 2− in Adirondack lakes, there has been no systematic increase in pH and ANC. The decline in SO4 2− has corresponded with a near stoichiometric decrease in concentrations of basic cations in low ANC lakes. A pattern of increasing NO3 − concentrations that was evident in lakes across the region during the 1980's has been followed by a period of lower concentrations. Currently there are no significant trends in NO3 − concentrations in Adirondack lakes.

N : P ratios in terrestrial plants: variation and functional significance

Abstract: Contents Summary I Introduction II Variability of N : P ratios in response to nutrient supply III Critical N : P ratios as indicators of nutrient limitation IV Interspecific variation in N : P ratios V Vegetation properties in relation to N : P ratios VI Implications of N : P ratios for human impacts on ecosystems VII Conclusions Acknowledgements References Summary Nitrogen (N) and phosphorus (P) availability limit plant growth in most terrestrial ecosystems. This review examines how variation in the relative availability of N and P, as reflected by N : P ratios of plant biomass, influences vegetation composition and functioning. Plastic responses of plants to N and P supply cause up to 50-fold variation in biomass N : P ratios, associated with differences in root allocation, nutrient uptake, biomass turnover and reproductive output. Optimal N : P ratios – those of plants whose growth is equally limited by N and P – depend on species, growth rate, plant age and plant parts. At vegetation level, N : P ratios 20 often (not always) correspond to N- and P-limited biomass production, as shown by short-term fertilization experiments; however long-term effects of fertilization or effects on individual species can be different. N : P ratios are on average higher in graminoids than in forbs, and in stress-tolerant species compared with ruderals; they correlate negatively with the maximal relative growth rates of species and with their N-indicator values. At vegetation level, N : P ratios often correlate negatively with biomass production; high N : P ratios promote graminoids and stress tolerators relative to other species, whereas relationships with species richness are not consistent. N : P ratios are influenced by global change, increased atmospheric N deposition, and conservation managment.

Assessing the generality of global leaf trait relationships

Abstract: Summary • Global-scale quantification of relationships between plant traits gives insight into the evolution of the world’s vegetation, and is crucial for parameterizing vegetation‐ climate models. • A database was compiled, comprising data for hundreds to thousands of species for the core ‘leaf economics’ traits leaf lifespan, leaf mass per area, photosynthetic capacity, dark respiration, and leaf nitrogen and phosphorus concentrations, as well as leaf potassium, photosynthetic N-use efficiency (PNUE), and leaf N : P ratio. • While mean trait values differed between plant functional types, the range found within groups was often larger than differences among them. Future vegetation‐ climate models could incorporate this knowledge. • The core leaf traits were intercorrelated, both globally and within plant functional types, forming a ‘leaf economics spectrum’. While these relationships are very general, they are not universal, as significant heterogeneity exists between relationships fitted to individual sites. Much, but not all, heterogeneity can be explained by variation in sample size alone. PNUE can also be considered as part of this trait spectrum, whereas leaf K and N : P ratios are only loosely related.

Ecosystem Consequences of Biological Invasions

Abstract: Exotic species affect the biogeochemical pools and fluxes of materials and energy, thereby altering the fundamental structure and function of their ecosystems. Rapidly accumulating evidence from many species of both animal and plant invaders suggests that invasive species often increase pool sizes, particularly of biomass, and promote accelerated flux rates, but many exceptions can be found. Ecosystem dynamics are altered through a variety of interacting, mutually reinforcing mechanistic pathways, including species’ resource acquisition traits; population densities; ability to engineer changes to physical environmental conditions; effects on disturbance, especially fire; regimes; the ability to structure habitat for other species; and their impact on food webs. Local factors of landscape setting, history, and other sources of disturbance constrain ecosystem responses to invasions. New research directions are suggested, including the need for whole-system budgets, the quantification of abundance-impact relationships for particular ecosystem processes, and a better exploration of food web impacts on ecosystem processes.

Invasiveness, invasibility and the role of environmental stress in the spread of non-native plants

Abstract: Invasion ecology, the study of how organisms spread in habitats to which they are not native, asks both about the invasiveness of species and the invasibility of habitats: Which species are most likely to become invasive? Which habitats are most susceptible to invasion? To set the stage for considering these questions with regard to plants, we offer a two-way classification of nativeness and invasiveness that distinguishes natives, non-invasive non-natives and invasive non-natives. We then consider the current state of knowledge about invasiveness and invasibility. Despite much investigation, it has proven difficult to identify traits that consistently predict invasiveness. This may be largely because different traits favour invasiveness in different habitats. It has proven easier to identify types of habitats that are relatively invasible, such as islands and riverbanks. Factors thought to render habitats invasible include low intensities of competition, altered disturbance regimes and low levels of environmental stress, especially high resource availability. These factors probably often interact; the combination of altered disturbance with high resource availability may particularly promote invasibility. When biotic factors control invasibility, non-natives that are unlike native species may prove more invasive; the converse may also be true. We end with a simple conceptual model for cases in which high levels of environmental stress should and should not reduce invasibility. In some cases, it may be possible to manipulate stress to control biological invasions by plants.