@article {51673, title = {Effects of water, nitrogen and sulfur amendments on cover, density, and size of Chihuahuan Desert ephemerals}, journal = {Journal of Arid Environments}, volume = {16}, year = {1989}, note = {//NMSU//LTER II//Listed in LTER3 proposal as citing LTER2 support//}, month = {1989}, pages = {35-42}, abstract = {

The generality of the water-limited-nitrogen-regulated plant growth hypothesis for desert ecosystems was tested by applying water, nitrogen and sulfur amendments in a complete factorial design to three Chihuahuan Desert ecosystems. Water was added every 2 weeks at a rate to about double the long-term annual precipitation average of 225 mm and nitrogen and sulfur were added once in May 1983 (10 g/m2). Living-canopy area of all herbaceous plants was measured monthly (from April 1983 to December 1984). Since plants can respond to water and nutrients either by establishing more, but smaller, plants or by growing fewer, but larger, plants, density and plant size were measured (once, in me-April 1984). Only C3 winter-ephermerals significantly changed in cover, density or plant size in response to the amendments; no significant responses were observed in C4 summer-ephemerals or perennial grasses and forbs. Species that significantly increased in density did not significantly increase in size and vice versa. Water tended to limit the number (richness) and density of species, whereas nitrogen regulated plant growth (size). Sulfur generally reduced soil pH and species density. This study demonstrated that these general plant responses to increased water and nutrients were highly species and site specific.

}, keywords = {article, articles, ephemeral, also SEE , ephemeral, nutrients, fertilization, also SEE , journal, journals, nitrogen amendment, ephemerals, nutrient amendment, ephemerals, sulfur amendment, ephemerals, water amendment, ephemerals}, doi = {10.1016/S0140-1963(18)31045-0}, url = {files/bibliography/JRN00097.pdf}, author = {J. Ludwig and Walter G. Whitford and Joe M. Cornelius} } @article {51735, title = {Distribution of annual plants in North American deserts}, journal = {Journal of Arid Environments}, volume = {15}, year = {1988}, note = {//NMSU//LTER I, US-IBP//}, month = {1988}, pages = {221-227}, abstract = {

Early researchers concluded that the winter-annual flora was richest in the California deserts and became relatively poorer towards the east, whereas summer-annuals were richest in the deserts of western Texas and their richness progressively declined in to eastern California. US/IBP Desert Biome and subsequent studies support these trends and add much relevant information. Winter-annuals have the C3 photosynthetic pathway, whereas most summer-annuals have the C4 pathway. While the Sonoran and Chihuahuan deserts have a few C3 {\textquoteright}summer{\textquoteright} annuals (actually {\textquoteright}winter{\textquoteright} annuals which can persist into the summer), the Mojave Desert lacks C3 summer-annuals. The Great Basin Desert has only a few prevalent winter or summer-annuals (mostly introduced species). Studies of the micro-distribution of desert-annuals have shown their close association with perennial shrubs. Some shrubs produce substances that are reportedly toxic to some annuals; the role of such toxins in structuring annual plant communities is unclear. The importance of nutrients associated with shrub canopies on the micro-distribution of many desert-annuals is becoming evident through LTER and other studies.

}, keywords = {annual plant, c3 and c4, annual plant, distribution, article, articles, journal, journals, plant, also SEE , plant, annual}, doi = {10.1016/S0140-1963(18)31059-0}, url = {files/bibliography/JRN00074.pdf}, author = {J. Ludwig and Gary L. Cunningham and P. D. Whitson} } @proceedings {51785, title = {A baseline of soil erosion and vegetation monitoring in desert grasslands: Chihuahua, Texas and New Mexico}, volume = {General Technical Report RM-150}, year = {1987}, note = { //NMSU//NONE//ProCite field[6]: In}, month = {October 12-16, 1}, pages = {214-220}, publisher = {USDA Forest Service, Rocky Mountain Forest and Range Experiment Station}, address = {Tucson, Arizona}, abstract = { A long-term monitoring for vegetation and soil changes in desert grasslands of the northern Chihuahuan Desert was started in 1981 as part of the USDA/SEA Antidesertification program. Five study areas were located on the Jornada Experimental Range, Otero Mesa, and Peloncillo Mountains in New Mexico, Big Bend National Park in Texas, and Rancho La Campana in Chihuahua, Mexico. Vegetation was charted in quadrats along 30m permanent transects in these study areas. A high-precision auto-level was used to establish baseline data on the current soil-surface levels along the transects. In the future, recharting vegetation and remeasuring soil-surface level should provide data on rates of change. This data could be used to validate models designed to predict rates of soil erosion and vegetation change.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, desertification, long term monitoring, soil erosion, model, validation data, proceeding, proceedings, soil erosion, transect, soil erosion, transect, vegetation, vegetation transect}, author = {J. Ludwig and Moir, William H.}, editor = {Earl F. Aldon and Gonzales-Vicente, C. E. and Moir, W. H. (eds.)} } @article {51784, title = {Locating discontinuities along ecological gradients}, journal = {Ecology}, volume = {68}, number = {2}, year = {1987}, note = {//NMSU//LTER I//Listed in LTER2 proposal as citing LTER1 support//}, month = {1987}, pages = {448-450}, abstract = {

Cost-efficient ecological and natural surveys need: (1) flexible, logistically simple, and statistically sound sampling methods, and (2) sensitive, computationally simple, and ecologically robust data analysis methods. "Gradsects" (gradient-oriented transects) have recently been shown to be a more efficient sampling method than random sampling using nongradient-oriented transects, especially when surveying large, biologically diverse areas (Gillison and Brewer 1985). If biotic (e.g., vegetation) sampling is oriented along a defined environmental gradient, and the purpose is classification, then simple, efficient analysis techniques are needed. This note briefly reviews appropriate analysis techniques in order to identify ecotones or boundaries along gradsects.

}, keywords = {article, articles, ecological gradients, journal, journals, method, gradient-oriented transects, method, locating ecotones, method, sliding window, resource surveys, transect, ecotones}, doi = {10.2307/1939277 }, url = {files/bibliography/JRN00056.pdf}, author = {J. Ludwig and Joe M. Cornelius} } @article {51783, title = {Primary productivity in arid lands: myths and realities}, journal = {Journal of Arid Environments}, volume = {13}, year = {1987}, note = {//NMSU//US-IBP//}, month = {1987}, pages = {1-7}, abstract = {We tend to view arid environments as harsh and water-limited, due to low amounts of precipitation. In fact, many sites within desert regions receive considerable amounts of water due to run-on; for example, washes (arroyos, wadis). The productivity of these can be high. However, in reality, their extent is small. We often assume productivity of deserts to be only water-limited. Recent research in arid ecosystems indicates, however, that nutrients can be critical to production. We also think of desert precipitation as being unpredictable, in addition to low in quantity. Nevertheless, many of the major arid lands of the world are characterized by highly seasonal patterns of precipitation. Native plant and animal populations have evolved numerous tactics which capitalized on the predictable timing of precipitation. Humans have learned to exploit this predictability by growing crops and raising livestock that can gain from seasonal patters. Humans also manipulate arid environments by removing the limits of productivity through irrigation and fertilization and, while some cases of agricultural production are noteworthy, the reality is that the cost/benefit ratio is not favorable. Furthermore, extensive arid and semi-arid areas are undergoing rapid desertification. Monitoring desertification is essential to our future understanding of arid and semi-arid land productivity.}, keywords = {article, articles, journal, journals, plant, primary production, precipitation, primary production, primary production, nitrogen amendment, primary production, rainfall patterns, rainfall, SEE }, author = {J. Ludwig} } @book {51841, title = {Primary production variability in desert ecosystems}, series = {Pattern and Process in Desert Ecosystems}, year = {1986}, note = {//NMSU//US-IBP//ProCite field[6]: In}, month = {1986}, pages = {5-17}, publisher = {University of New Mexico Press}, organization = {University of New Mexico Press}, address = {Albuquerque, New Mexico}, abstract = {

The primary objective of this paper is to report and discuss variations in AAGNPP of deserts. Specific objectives are related to a number of questions. What ecosystem types within and between deserts have the greatest variations in AAGNPP? Under what environmental conditions are highs and lows observed? Are factors other than water availability limiting ANPP in deserts? What is the probable contribution of belowground production to total annual net primary production (ANPP)? Before discussing these question, I will first attempt to precisely define what I mean by primary production. Then I will present a brief history of primary production studies in deserts, pointing out the recentness of such studies. I will also discuss the methodological difficulties in measuring ANPP in deserts, which largely explains the paucity of primary production studies in deserts.

}, keywords = {book, books, chapter, chapters, primary production, methods, primary production, variability, report, reports}, doi = {10.2307/1308782 }, url = {files/bibliography/86-UNM-Whitford.pdf}, author = {J. Ludwig}, editor = {Walter G. Whitford} } @book {51888, title = {Microcomputer simulation of soil erosion in desert grasslands}, series = {Modelling and Simulation on Microcomputers}, year = {1985}, note = {//USDA//NONE//ProCite field[6]: In}, month = {1985}, pages = {149-152}, publisher = {Society of Computer Simulation}, organization = {Society of Computer Simulation}, address = {La Jolla, California}, abstract = {A long-term ecological monitoring of desertification trends in grasslands of the northern Chihuahuan Desert was established as part of the USDA/SEA Antidesertification program. Five study areas were located on the Jornada Experimental Range, Otero Mesa and the Peloncillo Mountains in New Mexico, Big Bend National Park in Texas, and Rancho La Campana in Mexico. A high precision auto-level was used in 1982 and 1983 to establish baseline data on the current soil-surface level along permanent 30 m transects in these study areas. In the future, remeasurement of these transects should provide data on rates of soil erosion. This data could then be used to validate models used to predict rates of soil erosion. The Universal Soil Loss Equation (USLE) has been used to make such predictions. In this paper a microcomputer version of the USLE model is presented and applied to data from Big Bend National Park.}, keywords = {book, books, chapter, chapters, erosion, SEE (soil), model, soil erosion, report, reports, soil erosion, model}, author = {J. Ludwig}, editor = {Lavery, R. G. (ed.)} } @book {52043, title = {Short-term water and energy flow in arid ecosystems}, series = {Arid Land Ecosystems: Structure, Function and Management}, volume = {Volume 2}, number = {17}, year = {1981}, note = {//NMSU//US-IBP//ProCite field[6]: InProCite field[32]: International Biological Program}, month = {1981}, pages = {271-299}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Great Britain}, abstract = {

The objective of this chapter is to discuss the dynamic behavior of the biotic components of arid ecosystems in relation to water and energy flow between and within seasons. The growth responses of the different plant species occupying adjacent ecosystems in a watershed will be related to water availability and to heat energy levels. Growth and behavioral responses of groups of animals with contrasting adaptations to changing conditions of food and water availability will be discussed. Plant and animal litter redistribution and decomposition patterns will be discussed with respect to patterns of energy flow and climatic variation. Finally, general conclusions about desert ecosystem dynamics with respect to short-term water and energy flow will be stated.

}, keywords = {arid ecosystem, water \& energy flow, arthropod, bird, book, books, chapter, chapters, decomposition,ecosystem dynamics, ecosystem dynamics, abiotic factors, ecosystem dynamics, biotic responses, ecosystem dynamics, energy flow, ecosystem dynamics, water, energy flow, insect, microarthropod, plant, ecosystem dynamics, precipitation,ecosystem dynamics, predator, report, reports, rodent, seed consumer, water}, url = {files/bibliography/81-AridLand-Whitford.pdf}, author = {J. Ludwig and Walter G. Whitford}, editor = {D. W. Goodall and Perry, R. A. and Howes, K. M. W.} } @proceedings {52092, title = {A simulation model of the productivity of spanish bayonet, Yucca baccata Torr.}, year = {1980}, note = {//LOCAL//NONE//ProCite field[6]: In}, month = {1980}, pages = {51-68}, publisher = {Centro de Investigacion en Quimica Aplicada}, abstract = {In a previous study on the amounts of energy accumulated by Yucca baccata low photosynthetic rates were found using laboratory apparatus. Our current studies indicate higher rates using natural levels of irradiance in the field. Our current studies also have characterized a CAM metabolism in Y. baccata and Y. torreyi, but a C3 pathway in Y. elata. An earlier, preliminary simulation model of Y. baccata productivity did not include the mechanism of CAM. Our new simulation model presented here includes the CAM pathway and gives realistic predictions of productivity and carbon allocation in Y. baccata under different environmental conditions.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, model, growth, Yucca, proceeding, proceedings, productivity, Yucca, spanish bayonet, SEE Larrea in the northern Chihuahuan Desert}, year = {1979}, note = {//??//NONE//ProCite field[6]: In}, month = {1979}, pages = {139-150}, publisher = {Centro de Investigacion en Quimica Aplicada}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, Larrea,productivity, proceeding, proceedings, productivity,Larrea, shrub, Larrea}, author = {J. Ludwig and P. Flavill}, editor = {Campos-Lopez, E. and Mabry, T. J. and Fernandez-Tavizon, S. (eds.)} } @proceedings {52188, title = {Distributional adaptations of root systems in desert environments}, volume = {Range Science Dept. No. 26}, year = {1977}, note = {//NMSU//US-IBP//ProCite field[6]: In}, month = {1977}, pages = {85-90}, publisher = {Colorado State University}, edition = {No. 26}, abstract = {Early studies on the distribution patterns of root systems of desert plants are reexamined in view of recent IBP studies. Unpublished studies on root habits of desert plants in North America are used along with studies from other deserts of the world to support conclusions. Desert shrub species with the broadest local and geographical distribution have a generalized type of root system, where a tap root and lateral roots are both capable of extensive horizontal and vertical distribution. This appears to be an adaptation where these species can establish on the highly varied desert soils. However, this distribution adaptation is probably not unique to desert shrubs and thus is not a special adaptive mechanism for drought resistance. Other anatomical, morphological, and physiological adaptations exhibited by desert shrubs are probably of greater importance to their establishment and long-term survival.}, keywords = {abstract, abstracts, conference, conference proceedings, conferences, proceeding, proceedings, root systems, shrub, root system, shrub, root:shoot ratios}, author = {J. Ludwig}, editor = {J. K. Marshall (ed.)} } @article {52241, title = {Size-biomass relations of several Chihuahuan Desert shrubs}, journal = {The American Midland Naturalist}, volume = {94}, number = {2}, year = {1975}, note = {//NMSU//US-IBP//}, month = {1975}, pages = {451-461}, abstract = {Rapid, nondestructive methods are needed to quantify plant biomass dynamics. Methods known as dimension analysis can be used to establish regression relationships between plant biomass and estimate the dry weight of foliage, living and dead stems and roots from canopy area and volume for eight desert shrubs. The results show that volume and canopy area are generally suitable estimators. Regression equations developed for Larrea tridentata compare favorably with equations in similar studies in Arizona and Nevada, suggesting that our results might be applicable in other desert regions, at least for shrubs with well-defined growth forms. Other considerations when using these techniques are discussed.}, keywords = {article, articles, Ephedra, biomass, Flourensia, biomass, journal, journals, Larrea, biomass, method, shrub biomass, Prosopis, biomass, shrub, biomass, shrub, Larrea, Xanthocephalum, biomass, Yucca, biomass, Zinnia, biomass}, author = {J. Ludwig and J. F. Reynolds and P. D. Whitson} } @proceedings {52240, title = {Towards achieving a realistic simulation of a desert ecosystem}, year = {1975}, note = {//NMSU//NONE//ProCite field[6]: In}, month = {1975}, pages = {961-972}, publisher = {AFIPS Press}, keywords = {abstract, abstracts, computer simulation, conference, conference proceedings, conferences, desert ecosystem, model, desert ecosystem, proceeding, proceedings}, author = {J. Ludwig} }