Role Of Terrestrial Vegetation Research Articles

Forest cover controls the nitrogen and carbon stable isotopes of rivers

Deforestation affects the ecological integrity of rivers and streams, threatening biodiversity and ecosystem services worldwide. However, few studies have strictly analyzed the effect of the functional responses of tropical streams to changes in forest cover since deforested basins are usually also influenced by confounding anthropogenic inputs. Here we address tropical streams and test whether the stable isotopic ratios of nitrogen (N, δ15N) and carbon (C, δ13C) and the ratio of C:N of ecosystem components vary along a forest cover gradient. We also assess the ecological integrity of streams by in situ measurements using physical features commonly used in stream quality assessments. The results showed that the δ15N of most aquatic components, δ13C of particulate matter and omnivorous fish, and C:N of particulate matter and algae vary significantly with forest cover, indicating the role of terrestrial vegetation in regulating stream biogeochemistry. The dual stable isotope analysis satisfactorily indicated the changes in terrestrial-aquatic connections regarding both N and C cycles, thus showing the role of algae and particulate matter in influencing stream fauna through food web transfers. Our results support the use of stable isotopes to monitor watershed deforestation and highlight the need for reassessment of the effects of anthropogenic inputs on δ15N increase in globally distributed inland waters since the loss of forest is a significant cause in itself.

The role of terrestrial vegetation in atmospheric Hg deposition: Pools and fluxes of spike and ambient Hg from the METAALICUS experiment

[1] As part of the Mercury Experiment to Assess Atmospheric Loading in Canada and the U.S. (METAALICUS), different stable Hg(II) isotope spikes were applied to the upland and wetland areas of a boreal catchment between 2001 and 2006 to examine retention of newly deposited Hg(II). In the present study, a Geographical Information Systems (GIS)-based approach was used to quantify canopy and ground vegetation pools of experimentally applied upland and wetland spike Hg within the METAALICUS watershed over the terrestrial loading phase of the experiment. A chemical kinetic model was also used to describe the changes in spike Hg concentrations of canopy and ground vegetation over time. An examination of the fate of spike Hg initially present on canopy vegetation using a mass balance approach indicated that the largest percentage flux from the canopy over one year post-spray was emission to the atmosphere (upland: 45%; wetland: 71%), followed by litterfall (upland: 14%; wetland: 10%) and throughfall fluxes (upland: 12%; wetland: 9%) and longer term retention of spike in the forest canopy (11% for both upland and wetland). Average half-lives (t1/2) of spike on deciduous (110 ± 30 days) and coniferous (180 ± 40 days) canopy and ground vegetation (890 ± 620 days) indicated that retention of new atmospheric Hg(II) on terrestrial (especially ground) vegetation delays downward transport of new atmospheric Hg(II) into the soil profile and runoff into lakes.

Plant uptake of organic pollutants from soil: Bioconcentration estimates based on models and experiments

The role of terrestrial vegetation in transferring chemicals from soil and air into specific plant tissues (e.g., stems, leaves, and roots) is still not well characterized. We provide here a critical review of plant-to-soil bioconcentration ratio (BCR) estimates based on models and experimental data. This review includes the conceptual and theoretical formulations of the BCR, constructing and calibrating empirical and mathematical algorithms to describe this ratio and the experimental data used to quantify BCRs and calibrate the model performance. We first evaluate the theoretical basis for the BCR concept and BCR models and consider how lack of knowledge and data limit reliability and consistency of BCR estimates. We next consider alternate modeling strategies for BCR. A key focus of this evaluation is the relative contributions to overall uncertainty from model uncertainty versus variability in the experimental data used to develop and test the models. As a case study, we consider a single chemical, hexahydro-1,3,5-trinitro-1,3,5-triazine, and focus on variability of bioconcentration measurements obtained from 81 experiments with different plant species, different plant tissues, different experimental conditions, and different methods for reporting concentrations in the soil and plant tissues. We use these observations to evaluate both the magnitude of experimental variability in plant bioconcentration and compare this to model uncertainty. Among these 81 measurements, the variation of the plant-to-soil BCR has a geometric standard deviation (GSD) of 3.5 and a coefficient of variation (CV; i.e., ratio of the arithmetic standard deviation to the mean) of 1.7. These variations are significant but low relative to model uncertainties, which have an estimated GSD of 10, with a corresponding CV of 14.

Plant Uptake of Organic Pollutants from Soil: Bioconcentration Estimates Based on Models and Experiments-Review

The role of terrestrial vegetation in transferring chemicals from soil and air into specific plant tissues (stems, leaves, roots, etc.) is still not well characterized. We provide here a critical review of plant-to-soil bioconcentration ratio (BCR) estimates based on models and experimental data. This review includes the conceptual and theoretical formulations of the bioconcentration ratio, constructing and calibrating empirical and mathematical algorithms to describe this ratio and the experimental data used to quantify BCRs and calibrate the model performance. We first evaluate the theoretical basis for the BCR concept and BCR models and consider how lack of knowledge and data limits reliability and consistency of BCR estimates. We next consider alternate modeling strategies for BCR. A key focus of this evaluation is the relative contributions to overall uncertainty from model uncertainty versus variability in the experimental data used to develop and test the models. As a case study, we consider a single chemical, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and focus on variability of bioconcentration measurements obtained from 81 experiments with different plant species, different plant tissues, different experimental conditions, and different methods for reporting concentrations in the soil and plant tissues. We use these observations to evaluate both the magnitude of experimental variability in plant bioconcentration and compare this to model uncertainty. Among these 81 measurements, the variation of the plant/soil BCR has a geometric standard deviation (GSD) of 3.5 and a coefficient of variability (CV-ratio of arithmetic standard deviation to mean) of 1.7. These variations are significant but low relative to model uncertainties--which have an estimated GSD of 10 with a corresponding CV of 14.

A review of: “The Role of Terrestrial Vegetation the Global Carbon Cycle: Measurements by Remote Sensing”. By G. M. WOODWELL (Chichester and New York: John Wiley & Sons, 1984.) [Pp. 245.] Price £27·50.

A review of: “<i>The Role of Terrestrial Vegetation the Global Carbon Cycle: Measurements by Remote Sensing</i>”. By G. M. WOODWELL (Chichester and New York: John Wiley &amp; Sons, 1984.) [Pp. 245.] Price £27·50.

The Role of Terrestrial Vegetation in the Global Carbon Cycle: Measurement by Remote Sensing. The Product of a SCOPE Conference Arranged by The Ecosystems Center and Held in Woods Hole, Massachusetts, in May 1979. SCOPE 23.George M. Woodwell

<i>The Role of Terrestrial Vegetation in the Global Carbon Cycle: Measurement by Remote Sensing. The Product of a SCOPE Conference Arranged by The Ecosystems Center and Held in Woods Hole, Massachusetts, in May 1979. SCOPE 23.</i>George M. Woodwell

REVIEWS

Nature's Second Kingdom. By F. Delaporte. Translated by Arthur Goldhammer. Encyclopedia of Plant Physiology, New Series, Volume 10. Hormonal regulation of development II. The functions of hormones from the level of the cell to the whole plant. Edited by T. K. Scott. Cell Culture and Somatic Cell Genetics of Plants, Volume 1. Laboratory procedures and their applications. Edited by I. K. Vasil. Databases in Systematics. Edited by R. Allkin and F. A. Bisby. Plant Chemosystematics. By J. B. Harborne and B. L. Turner. Current Concepts in Plant Taxonomy. Edited by V. H. Heywood and D. M. Moore. Introduction to Principles of Plant Taxonomy. By V. V. Sivarajan. Our Green and Living World: The Wisdom to Save It. By E. S. Ayensu, V. H. Heywood, G.L. Lucas and R. A. Defillips. Lipids in Plants and Microbes. By J. L. Harwood and N. J. Russell. The Role of Terrestrial Vegetation in the Global Carbon Cycle: Measurement by Remote Sensing. Edited by G. M. Woodwell. Chromosomes Today, Volume 8. Edited by M. D. Bennett, A. Gropp and U. Wolf.

The Role of Terrestrial Vegetation in the Global Carbon Cycle: Measurement by Remote Sensing.

The Role of Terrestrial Vegetation in the Global Carbon Cycle: Measurement by Remote Sensing.

Sources and sinks of carbon dioxide in terrestrial ecosystems: Is the land's carbon budget balanced under the influence of man?

This contribution deals with the controversy between certain scientists on the role of terrestrial vegetation and soils in the global carbon cycle. The hypothesis of a significant net release from the vegetation, is rejected by geochemists because of the limited capacity of the ocean to take up this excess carbon dioxide. As for the man-influenced tropics, a comparison of the figures for the potential and the current phytomass, as well as plausible demographic arguments, support the assertion put forward by ecologists that the carbon budget of this zone cannot be balanced. The tropics lose about 1.7-3.9 × 10 15 g/yr of carbon to the atmosphere; however, for several reasons, 0.5-2.8 × 10 15 g/yr may be returned to land ecosystem, mostly in other climatic zones. Thus, a balance is achieved on combining low estimates for the losses with high estimates for the gains. From an ecological perspective, this solution is not a very probable one; nevertheless, it cannot conclusively be eliminated.