Larry L. Tieszen

Bio: Larry L. Tieszen is an academic researcher from United States Geological Survey. The author has contributed to research in topics: Tundra & Normalized Difference Vegetation Index. The author has an hindex of 55, co-authored 133 publications receiving 13853 citations. Previous affiliations of Larry L. Tieszen include University of Alaska Fairbanks & Agricultural Research Service.

Status and distribution of mangrove forests of the world using earth observation satellite data

Abstract: Aim Our scientific understanding of the extent and distribution of mangrove forests of the world is inadequate. The available global mangrove databases, compiled using disparate geospatial data sources and national statistics, need to be improved.Here,we mapped the status and distributions of global mangroves using recently available Global Land Survey (GLS) data and the Landsat archive. Methods We interpreted approximately 1000 Landsat scenes using hybrid supervised and unsupervised digital image classification techniques. Each image was normalized for variation in solar angle and earth‐sun distance by converting the digital number values to the top-of-the-atmosphere reflectance. Ground truth data and existing maps and databases were used to select training samples and also for iterative labelling. Results were validated using existing GIS data and the published literature to map ‘true mangroves’. Results The total area of mangroves in the year 2000 was 137,760 km 2 in 118 countries and territories in the tropical and subtropical regions of the world. Approximately 75% of world’s mangroves are found in just 15 countries, and only 6.9% are protected under the existing protected areas network (IUCN I-IV). Our study confirms earlier findings that the biogeographic distribution of mangroves is generallyconfinedtothetropicalandsubtropicalregionsandthelargestpercentage of mangroves is found between 5° N and 5° S latitude. Main conclusions We report that the remaining area of mangrove forest in the world is less than previously thought. Our estimate is 12.3% smaller than the most recent estimate by the Food and Agriculture Organization (FAO) of the United Nations.We present the most comprehensive, globally consistent and highest resolution (30 m) global mangrove database ever created.We developed and used better mapping techniques and data sources and mapped mangroves with better spatial and thematic details than previous studies.

Fractionation and turnover of stable carbon isotopes in animal tissues: Implications for δ13C analysis of diet

Abstract: The use of stable carbon isotopes as a means of studying energy flow is increasing in ecology and paleo- ecology. However, secondary fractionation and turnover of stable isotopes in animals are poorly understood pro- cesses. This study shows that tissues of the gerbil (Meriones unguienlatus) have different 613C values when equilibrated on corn (C4) or wheat (C~) diets with constant 13c/1ac contents. Lipids were depleted 3.0%o and hair was enriched 1.0%o relative to the C4 diet. Tissue 6t3C values were ranked hair > brain > muscle > liver > fat. After changing the gerbils to a wheat (C3) diet, isotope ratios of the tissues shifted in the direction of the 6a3C value of the new diet. The rate at which carbon derived from the corn diet was replaced by carbon derived from the wheat diet was ade- quately described by a negative exponential decay model for all tissues examined. More metabolically active tissues such as liver and fat had more rapid turnover rates than less metabolically active tissues such as hair. The half-life for carbon ranged from 6.4 days in liver to 47.5 days in hair. The results of this study have important implications for the use of 6~3C values as indicators of animal diet. Both fractionation and turnover of stable carbon isotopes in animal tissues may obscure the relative contributions of isotopically distinct dietary components (such as C3 vs. C,, or marine vs. terrestrial) if an animal's diet varies through time. These complications deserve attention in any study using stable isotope ratios of animal tissue as dietary indicators and might be minimized by analysis of several tissues or products covering a range of turnover times.

Effect of Diet Quality and Composition on the Isotopic Composition of Respiratory CO2, Bone Collagen, Bioapatite, and Soft Tissues

Abstract: The isotopic ratios of common light elements often provide useful information about past geologic, environmental, or biologic history. Bender’s (1968) clear identification of two distinct isotopic values for carbon from C3 and C4 plant organic matter led to the experiments which showed that animal δ13C values were closely related to dietary values (DeNiro and Epstein 1978a; Tieszen et al. 1983). Results from field applications (DeNiro and Epstein 1978b; Vogel 1978; Tieszen et al. 1979; Tieszen and Imbamba 1980) established the usefulness of these tracers and soon led to numerous archaeological studies. C and N, both present in bone collagen, have been most useful to suggest marine versus terrestrial dependence, to establish maize utilization or dependence on legumes, and to identify relative trophic-level positions or carnivory versus herbivory. Recently, attention has been focused on the use of bioapatite CO3 (Lee-Thorp et al. 1989a, 1989b; Lee-Thorp and van der Merwe 1991) as a supplement to collagen, especially in bones older than 10000 years, and as an adjunct to collagen for estimates of carnivory. The 180 signal in bioapatite also has the potential to provide information on the water status of the individual or the environment. Sulfur isotopes δ 34 S), when present in sufficient quantities, as in hair or skin, are also useful and in some cases can distinguish clearly between marine and terrestrial dietary sources (Krouse and Herbert 1988).

Carbon Isotope Discrimination and Photosynthesis

Abstract: We discuss the physical and enzymatic bases of carbone isotope discrimination during photosynthesis, noting how knowledge of discrimination can be used to provide additional insight into photosynthetic metabolism and the environmental influences on that process

Influence of Diet On the Distribtion of Nitrogen Isotopes in Animals

Abstract: The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

Stable isotopes in ecosystem studies

Abstract: The use of stable isotopes to solve biogeochemical problems in ecosystem analysis is increasing rapidly because stable isotope data can contribute both source-sink (tracer) and process information: The elements C, N, S, H, and all have more than one isotope, and isotopic compositions of natural materials can be measured with great precision with a mass spectrometer. Isotopic compositions change in predictable ways as elements cycle through the biosphere. These changes have been exploited by geochemists to understand the global elemental cycles. Ecologists have not until quite recently employed these techniques. The reasons for this are, first, that most ecologists do not have the background in chemistry and geochemistry to be fully aware of the possibilities for exploiting the natural variations in stable isotopic compositions, and second, that stable isotope ratio measurements require equipment not normally available to ecologists. This is unfortunate because some of the more intractable problems in ecology can be profitably addressed using stable isotope measurements. Stable isotopes are ideally suited to increase our understanding of element cycles in ecosystems. This review is written for ecologists who would like to learn more about how stable isotope analyses have been and can be used in ecosystem studies. We begin with an explanation of isotope terminology and fractionation, then summarize isotopic distributions in the C, N, and S biogeochemical cycles, and conclude with five case studies that show how stable isotope measurements can provide crucial information for ecosystem analysis. We restrict this review to studies of natural variations in C, N, and S isotopic abundances, cxcluding from consideration ~5N enrichment studies and hydrogen and oxygen isotope studies. Our focus on C, N, and S derives in part from our

The Mineral Nutrition of Wild Plants

Abstract: Our understanding of plant mineral nutrition comes largely from studies of herbaceous crops that evolved from ruderal species characteristic of nutri­ ent-rich disturbed sites (52). With the development of agriculture, these ancestral species were bred for greater productivity and reproductive output at high nutrient levels where there was little selective advantage in efficient nutrient use. This paper briefly reviews the nature of crop responses to nutrient stress and compares these responses to those of species that have evolved under more natural conditions, particularly in low-nutrient envi­ ronments. I draw primarily upon nutritional studies of nitrogen and phos­ phorus because these elements most commonly limit plant growth and because their role in controlling plant growth and metabolism is most clearly understood (51). Other more specific aspects of nutritional plant ecology not discussed here include ammonium/nitrate nutrition (79), cal­ cicole/calcifuge nutrition (51,88), heavy metal tolerance (4), and serpentine ecology (133).