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1. Soil disturbance by animals affects the availability of water, nutrients, sediment and seeds, which are critical for the maintenance of functional ecosystems. We examined long-lived faunal structures across six vegetation communities in the northern Chihuahuan desert of New Mexico, USA, testing the proposition that disturbances in undesertified grassland differ in magnitude and effect from those in desertified grassland. 2. Vertebrate and invertebrate disturbances totalled 18.9 structures ha−1 across 18 sites. The most common were pits and mounds of American badgers (Taxidea taxus, 32%), nests of the ant Aphaenogaster cockerelli (18.8%) and mounds of kangaroo rats (Dipodomys spectabilis, 31%). 3. Desertification...
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Grasslands comprise a small part of the Chihuahuan Desert but are vital to the biological diversity of the ecoregion. Characteristic grasses of the Chihuahuan Desert are tobosa (Pleuraphis mutica) and black grama (Bouteloua eriopoda) but other common species include alakali sacaton (Sporobolus airoides), big alkali sacaton (S. wrightii), mesa dropseed (S. flexuosus), blue grama (B. gracilis), sideoats grama (B. curtipendula ), hairy grama (B. hirsuta), slender grama (B. filiformis), chino grama (B. brevista), spruce top grama (B. chondrosioides), bush muhly (Muhlenbergia porteri), several three awns (Aristida spp.), and fluff grass (Dasyochloa pulchela) (Johnson 1974, Dinerstein et al. 2000). Many of the sites discussed...
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A battery of questions was developed and applied to different stakeholders immersed in knowledge of the condition and the use of grazing of grasslands. One hundred people were surveyed amongst livestock producers (both from private ranches and from communal ejidos), and students and researchers at regional institutions involved in agricultural sciences in different states of Mexico: Coahuila, Durango, San Luis Potosí, and Jalisco. The objective of the survey was to determine aspects of stakeholders’ interpretation of the condition of grasslands in their region under conditions of extensive grazing, such as soil condition, harvest efficiency, vegetation condition, openness to community organizing of grazing, capacity...
Medium-sized kangaroo rats (Dipodomys spp. Gray) function as keystone species in the dynamics of desert bunchgrasses. We tested the hypothesis that kangaroo rat graminivory leads to reduced grass growth and inflorescence production, and that kangaroo rat grass consumption reflects their preferences for open microhabitats. We excluded kangaroo rats from grasses, and measured tiller loss, leaf and tiller growth and inflorescence production. We recorded the extent of tiller loss in grasses varying in tussock size or the extent of surrounding cover. Consumption of tillers by kangaroo rats was extensive, peaking in late summer. Grasses protected from kangaroo rat graminivory showed elevated leaf and tiller growth and...
Geostatistical analyses show that the distribution of soil N, P and K is strongly associated with the presence of shrubs in desert habitats. Shrubs concentrate the biogeochemical cycle of these elements in ?islands of fertility? that are localized beneath their canopies, while adjacent barren, intershrub spaces are comparatively devoid of biotic activity. Both physical and biological processes are involved in the formation of shrub islands. Losses of semiarid grassland in favor of invading shrubs initiate these changes in the distribution of soil nutrients, which may promote the further invasion and persistence of shrubs and cause potential feedbacks between desertification and the Earth's climate system. Published...
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The Sevilleta LTER supports a long-term, integrated, interdisciplinary research program addressing key hypotheses on pattern and process in aridland ecosystems. Sevilleta LTER research includes studies in desert grassland and shrubland communities, and riparian and mountain forests emphasizing pulse driven processes in space and time. Key drivers (e.g., climate, fire, water, resource availability) govern dynamics in each landscape component. Our focus on how biotic and abiotic drivers affect spatial and temporal dynamics of aridland ecosystems allows us to conduct long-term research that addresses important basic theories and yet has significant relevance to regional, national and international priorities. The...
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El cambio climático es un problema con características únicas, ya que es de naturaleza global, sus impactos mayores serán en el largo plazo e involucra interacciones complejas entre procesos naturales (fenómenos ecológicos y climáticos) y procesos sociales, económicos y políticos a escala mundial. Dada la importancia del tema, el Instituto Nacional de Ecología, como parte de su misión de generar y difundir información científica y técnica sobre problemas ambientales prioritarios solicitó a un grupo de especialistas de diversas disciplinas que contribuyeran a este libro aportando y compartiendo sus conocimientos y experiencias sobre los aspectos científicos, sociales, económicos e institucionales del cambio climático....
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Desertification is a global problem, costly to national economies and human societies. Restoration of biological soil crusts (BSCs) may have an important role to play in the reversal of desertification due to their ability to decrease erosion and enhance soil fertility. To determine if there is evidence that lower fertility may hinder BSC recolonization, we investigated the hypothesis that BSC abundance is driven by soil nutrient concentrations. At a regional scale (north and central Colorado Plateau, USA), moss and lichen cover and richness are correlated with a complex water?nutrient availability gradient and have approximately six-fold higher cover and approximately two-fold higher species richness on sandy soils...
The Chihuahuan desert of New Mexico, USA, has changed in historical times from semiarid grassland to desert shrublands dominated by Larrea tridentata and Prosopis glandulosa. Similar displacement of perennial grasslands by shrubs typifies desertification in many regions. Such structural vegetation change could alter average values of net primary productivity, as well as spatial and temporal patterns of production. We investigated patterns of aboveground plant biomass and net primary production in five ecosystem types of the Jornada Basin Long-Term Ecological Research (LTER) site. Comparisons of shrub-dominated desertified systems and remnant grass-dominated systems allowed us to test the prediction that shrublands...
A great many debates have grown up around the notion of desertification as a process of degradation that affects the arid, semi-arid and sub-humid zones of the globe. A fundamental and continuing debate has been over whether desertification actually exists and, if so, how it might be defined, measured and assessed. Rather than simply review the evolution of these debates we examine the contexts in which they take place and how those contexts have contributed to the evolution of our understanding of the intertwined processes that contribute to desertification. The fact that these contexts have changed over time, combined with the fact that some of them are often ignored have both helped to sustain debate. We consider...
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We examined the 10-day response of soil microbial biomass-N to additions of carbon (dextrose) and nitrogen (NH4NO3) to water-amended soils in a factorial experiment in four plant communities of the Chihuahuan desert of New Mexico (U.S.A.). In each site, microbial biomass-N and soil carbohydrates increased and extractable soil N decreased in response to watering alone. Fertilization with N increased microbial biomass-N in grassland soils; whereas, fertilization with C increased microbial biomass-N and decreased extractable N and P in all communities dominated by shrubs, which have invaded large areas of grassland in the Chihuahuan desert during the last 100 years. Our results support the hypothesis that the control...
Understanding the timing of mountain building and desert formation events in western North America is crucial to understanding the evolutionary history of the diverse arid-adapted biota that is found there. While many different, often conflicting descriptions exist regarding geobiotic change in western North America, little work has been done to synthesize these various viewpoints. In this paper we present several case studies that illustrate the differences in the various explanations, based on geological and paleobiological data, detailing mountain uplift and desertification in western North America. The majority of the descriptions detailing mountain building in this area fall into two major periods of uplift,...
We use a spatially explicit landscape model to investigate the potential role of rainfall on shrub?grass transitions in the Jornada Basin of southern New Mexico during the past century. In long-term simulations (1915?1998) along a 2700 m transect running from a dry lake bed to the foothills of a small mountain, we test two hypotheses: (i) that wetter winters and drier summers may have facilitated shrub encroachment in grasslands, and (ii) that increases in large precipitation events may have increased soil water recharge at deeper layers, thus favoring shrub establishment and growth. Our model simulations generally support the hypothesis that wetter winters and drier summers may have played a key role, but we are...
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These data were compiled for monitoring and analyzing the amount of windblown (aeolian) sediment at 100 cm height near Moab, UT. Big Springs Number Eight (BSNE) field aeolian passive sediment traps are summarized by location and time period in shapefiles. Shapefiles also include attributes used to analyze patterns in the aeolian transport. Three different BSNE shapefiles represent 1) a network of BSNEs in a variety of rangelands, 2) BSNEs along downwind edges of unpaved roads where they run perpendicular to the dominant wind direction, and 3) long term BSNE sites used to test imporance of climate trends on aeolian transport. Also included in this data archive are raster files that were created from the BSNE data...
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Fire is critical to maintaining and restoring temperate ecosystems in the South Central U.S. As precipitation patterns and temperatures change in the region, managers require information on how these changes will impact fire frequency, and thus the species and ecosystems within the landscape. To address this need, researchers will use climate model data to predict and map future changes in fire frequency for Texas, Oklahoma, and New Mexico. Researchers will then examine species and ecosystem distribution data to understand the relationship between climate, fire frequency, and species occurrence. This analysis will enable researchers to identify potential future distributions of woody ecosystems and species such...
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Currently in Mexican arid regions, high pressure is applied to natural resources for their utilization, principally in the form of: uncontrolled grazing omnipresent in every corner accessible to cattle, opening high risk lands up for crop production, overexploitation of aquifers, discharge of contaminated waters, riparian areas drying up, exploration and uncontrolled exploitation of natural goods: flora, fauna, oil, gas, etc., without promotion of participatory activities for resource conservation and improvement among users, which results in a poor understanding of the precarious condition of the grassland environment. Se ejerce actualmente en México, una elevada presión de uso de los recursos naturales de estas...
NPS is transforming the way park resource information is managed and delivered to parks, partners, and the public. IRMA (Integrated Resource Management Applications) is the name given to the project that has guided this transformation, and to the web portal that is its end result. View or download the IRMA project brief (.pdf). IRMA is a portfolio of tools and applications, and the beginnings of a "one-stop" for data and information on park-related resources. From IRMA you can search for, view, and download documents, reports, publications, data sets, and park species lists. You can get information on park visitor numbers, park projects, and apply for a park research permit. Park staff can navigate to certain internal...
Categories: Data; Types: ArcGIS REST Map Service, Map Service, OGC WFS Layer, OGC WMS Layer, OGC WMS Service; Tags: Chihuahuan Desert, English, GIS, Madrean, Mojave Desert, All tags...
In this study we present a technique to discriminate between climate or human-induced dryland degradation, based on evaluations of AVHRR NDVI data and rainfall data. Since dryland areas typically have high inter-annual rainfall variations and rainfall has a dominant role in determining vegetation growth, minor biomass trends imposed by human influences are difficult to verify. By performing many linear regression calculations between different periods of accumulated precipitation and the annual NDVImax, we identify the rainfall period that is best related to the NDVImax and by this the proportion of biomass triggered by rainfall. Positive or negative deviations in biomass from this relationship, expressed in the...
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Las colecciones del Observatorio Ambiental se encuentran conformadas por documentos y referencias de publicaciones enfocadas en las problemáticas de medio ambiente sobre el estado de Chihuahua y sus zonas aledañas, tanto dentro del territorio nacional, como con Estados Unidos. El proceso de administración y manejo de las colecciones consiste en la búsqueda, selección, clasificación y catalogación de la información pertinente al estado de Chihuahua.
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The Sevilleta LTER supports a long-term, integrated, interdisciplinary research program addressing key hypotheses on pattern and process in aridland ecosystems. Sevilleta LTER research includes studies in desert grassland and shrubland communities, and riparian and mountain forests emphasizing pulse driven processes in space and time. Key drivers (e.g., climate, fire, water, resource availability) govern dynamics in each landscape component. Our focus on how biotic and abiotic drivers affect spatial and temporal dynamics of aridland ecosystems allows us to conduct long-term research that addresses important basic theories and yet has significant relevance to regional, national and international priorities. The...
    map background search result map search result map Factors Determining Soil Microbial Biomass and Nutrient Immobilization in Desert Soils Evidence for micronutrient limitation of biological soil crusts- Importance to arid-lands restoration Understanding Future Fire Frequency and Impacts on Species Distribution in the South Central U.S. Integrated Resource Management Applications (IRMA) Sevilleta LTER Library Sevilleta LTER Status and Distribution of Chihuahuan Desert Grasslands in the United States and Mexico Cambio climático Bibliotecas del Observatorio Ambiental Value, Condition, and Alternatives for Improvement of Grasslands in Mexico/ Valor, Condición y Alternativas de Mejora de los Pastizales en México Perceptions of the condition of semiarid grasslands under grazing regimes in Mexico/ Percepción de la condición del pastizal bajo pastoreo, en México semiárido Aeolian mass flux, rangeland monitoring site, and unpaved road reach data Sevilleta LTER Library Sevilleta LTER Factors Determining Soil Microbial Biomass and Nutrient Immobilization in Desert Soils Aeolian mass flux, rangeland monitoring site, and unpaved road reach data Evidence for micronutrient limitation of biological soil crusts- Importance to arid-lands restoration Bibliotecas del Observatorio Ambiental Status and Distribution of Chihuahuan Desert Grasslands in the United States and Mexico Understanding Future Fire Frequency and Impacts on Species Distribution in the South Central U.S. Value, Condition, and Alternatives for Improvement of Grasslands in Mexico/ Valor, Condición y Alternativas de Mejora de los Pastizales en México Perceptions of the condition of semiarid grasslands under grazing regimes in Mexico/ Percepción de la condición del pastizal bajo pastoreo, en México semiárido Cambio climático Integrated Resource Management Applications (IRMA)