Late Pleistocene-Recent Atmospheric delta-13C Record in C4 Grasses
Issue Date
1993-01-01Keywords
grassesAjo Mountains
AMS data
Brewster County Texas
C4 plants
Coahuila Mexico
El Paso County Texas
Maravillas Canyon
Otero County New Mexico
Pima County ArizonaPuerto de Ventanillas MexicoWaterman MountainsclimateNew MexicoTexasmiddensArizonaatmosphereisotope ratiosHolocenePleistoceneupper PleistoceneUnited StatesMexicoCenozoicQuaternarycarbondatesisotopescarbon dioxideC 13 C 12stable isotopes
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Toolin, L. J., & Eastoe, C. J. (1993). Late Pleistocene-recent atmospheric delta-13C record in C4 grasses. Radiocarbon, 35(2), 263-269.Journal
RadiocarbonAdditional Links
http://radiocarbon.webhost.uits.arizona.edu/Abstract
Samples of Setaria species from packrat middens, herbarium specimens and modern plants preserve a record of delta-13C of atmospheric CO2 from 12,600 BP to the present. No secular trend is detected between 12,600 and 1800 BP, when the mean value of delta-13C during that period was -6.5 +/- 0.1 per mil (the error is the standard deviation of the mean). Our value agrees with delta-13C averages of pre-industrial CO2 from polar ice cores, and differs significantly from modern regional (-8.2 +/- 0.1 per mil) and global (-7.7 per mil) values, which are higher because of fossil fuel burning.Type
Articletext
Language
enISSN
0033-8222Scopus Count
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The Record of Native People on Gulf of California Islands [No. 201]A century ago it was common knowledge among historians and anthropologists with research interests in northwestern Mexico that Indians had inhabited four large islands in the Gulf of California. Three of these islands—Cerralvo, Espíritu Santo, and San José—are in the far southern Gulf off the coast of Baja California. The fourth island, Isla Tiburón, is located on the mainland side more than 400 km to the northwest, in the constricted region of the Gulf known as the Midriff. At the turn of the twentieth century, Isla Tiburón was well known as the homeland of the Seri Indians and was the only Gulf island still inhabited by native people. Since 1900, ethnohistorical and archaeological research has greatly expanded our knowledge of Indians on both sides of the Gulf. Much of that information, however, pertains to the people living on the peninsula and mainland, and touches on the islands only incidentally. 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Radial Growth Losses in Douglas-Fir and White Fir Caused by Western Spruce Budworm in Northern New Mexico: 1700-1983Regional outbreaks of western spruce budworms (Choristoneura occidentalis Freeman) have recurred at least three times in northern New Mexico since the early 1920's when the U. S. Forest Service first began systematic forest-pest surveys and documentation (Lessard 1975, U. S. Forest Service documents). The current outbreak was first noticed in a small area on the Taos Indian Reservation in 1974, and since then the defoliated areas have increased in New Mexico and Arizona to more than 370,000 acres of Federal, Indian, State and private lands (Linnane 1984). Losses in timber values can generally be ascribed to radial growth loss, height growth loss, topkilling, reduced regeneration, and mortality (Carlson et al. 1983, Fellin et al. 1983). A damage assessment project was initiated in 1978 and was aimed at obtaining measurements of some of these losses in budworm infested stands on the Carson National Forest, New Mexico (Holland and Lessard 1979). A large data base has subsequently been developed, including yearly measurements on topkilling, mortality, defoliation, and insect population changes (Stein 1980, 1981, Stein and McDonnell 1982, Rogers 1984). A growth assessment study was undertaken in 1982 to determine the feasibility of using dendrochronological methods to identify the timing of past outbreaks and to quantify radial growth losses associated with budworm defoliation (Swetnam 1984). Results of this work showed that three major outbreaks during the twentieth century were clearly visible in the tree-ring samples obtained from currently infested trees. The radial growth of host trees was corrected for age, climate and other non-budworm environmental effects, and then growth losses were computed as a percentage of expected growth (Swetnam 1984). Additional collections were obtained in 1984 in order to expand the scope of the radial growth study. The objectives included 1) assessment of a larger number of tree -ring samples, 2) comparison of radial growth losses between the two primary host species - Douglas-fir (Pseudotsuga menziesii) and white fir (Abies concolor), 3) comparison of radial growth losses between age classes, and 4) analysis of the relationship between yearly measurements of defoliation, insect populations and radial growth. This report summarizes the findings of the above analyses. Increment core samples from the 1982 collections are included here, therefore this report supersedes the earlier report (Swetnam 1984). Information is also presented on observations derived from the dated tree-ring series on the timing of occurrence of known and inferred spruce budworm outbreaks for the past 284 years (1700- 1983). This is the longest record of spruce budworm occurrence yet developed for western North America.
