Patterns of Net Primary Production in Chihuahuan Desert Ecosystems

2006 ◽  
Author(s):  
Laura F. Huenneke ◽  
William H. Schlesinger
Keyword(s):  
Chihuahuan Desert ◽  
Plant Production ◽  
Data Sets ◽  
Desert Ecosystems ◽  
Long Term Ecological Research ◽  
Jornada Basin ◽  
Biological Programme ◽  
Definition Of ◽  
Term Data

The Jornada Basin of southern New Mexico has long been an important location for the study of productivity in desert ecosystems. Researchers have studied the magnitude and sustainability of plant production since the founding of the USDA Jornada Experimental Range (JER) in 1912. The consistent administration and research focus of the JER and of the Chihuahuan Desert Rangeland Research Center (CDRRC) have facilitated a number of long-term studies of vegetation dynamics and productivity. These long-term data sets are especially critical for understanding arid ecosystems, where interannual and decadal scale variation in climate is great and plant performance is strongly constrained by the physical environment. Long-term data, including the net primary productivity (NPP) data that are the focus of this chapter, are also essential for understanding the progression or rather, degradation of ecosystem structure that has been called desertification. Through the years a variety of approaches have been used to evaluate plant production in the Jornada Basin. These approaches span the range from applied or management-oriented techniques, focused primarily on assessing patterns of palatable forage production, to more basic empirical studies based on dimension analysis or similar measurements of plant growth, to estimates based on photosynthetic measurements, to remote sensing and modeling approaches. NPP was a particular focus of the work performed during the International Biological Programme or IBP (1970s) and is still a major emphasis in the Long-Term Ecological Research (LTER) era. Thus, the Jornada provides a unique opportunity to compare the strengths and weaknesses of different approaches applied to a complex system. Ecosystem science has provided a set of general hypotheses about the factors regulating NPP in arid and semiarid ecosystems (reviewed by Noy-Meir 1973; Hadley and Szarek 1981; Ludwig 1986, 1987). These premises include the following: 1. Plant productivity is low relative to that of other ecosystems (Lieth 1975). 2. NPP is regulated primarily by localized water availability and hence should be correlated closely with precipitation (Le Houerou 1984; Le Houerou et al. 1988). This premise is related to Noy-Meir’s (1973) definition of deserts as “water-controlled ecosystems with infrequent, discrete, and largely unpredictable water inputs.”

Tales from a “Lifer” in the Long-Term Ecological Research Program

2016 ◽  
Author(s):  
Debra P. C. Peters
Keyword(s):  
New Mexico ◽  
Principal Investigator ◽  
Ecological Research ◽  
State University ◽  
Ecological Processes ◽  
Principal Investigators ◽  
Long Term Ecological Research ◽  
Jornada Basin ◽  
Term Data

As a long-time member of the Long-Term Ecological Research (LTER) network, first as a graduate student and scientist at the Shortgrass Steppe (SGS) site (1984–1997), then as a scientist at the Sevilleta (SEV) site (1996–present) and now as principal investigator at the Jornada Basin (JRN) site (2003–present), my professional career has been shaped almost entirely by my LTER experiences. My experiences in the LTER program directly contributed to my individual-based approach to ecosystem dynamics combined with the knowledge that the dominant ecological processes can change as the spatial extent increases, and that long-term data are critical to disentangle how these pattern–process relationships change across scales. The LTER program has provided me with international experience and exposure that are valuable to my career. My opportunity to travel overseas has led to bonding experiences and new insights into other ecosystems. My appreciation for the value of K–12 education and the amount of work that is involved in “doing it right” has been shaped by my experiences with the Jornada Schoolyard LTER Program. One of the key challenges that I face in working at an LTER site is the tension between continuing to collect long-term observations with the need and desire to test new ideas that often result from the long-term data but then compete for resources with the collection of those data. Another challenge is in mentoring young scientists to become principal investigators, and in cultivating new relationships with potential co–principal investigators. Currently, I am the principal investigator at the JRN LTER program at New Mexico State University (NMSU) in Las Cruces, New Mexico. I am also a collaborating scientist at the SEV LTER program at the University of New Mexico in Albuquerque, New Mexico. I received my BS in biology at Iowa State University in 1981 and my MS in biology from San Diego State University (SDSU) in 1983. My LTER experiences began as a PhD student at Colorado State University (CSU) through the SGS LTER program in 1984, and these continued while I was a postdoctoral fellow (1988–1989).

A Holistic View of an an Arid Ecosystem: A Synthesis of Research and Its Applications

2006 ◽  
Author(s):  
Brandon T. Bestelmeyer ◽  
Joel R. Brown
Keyword(s):  
Research Program ◽  
Ecosystem Processes ◽  
Primary Objective ◽  
Arid Ecosystems ◽  
Data Sets ◽  
Arid Ecosystem ◽  
Ecological Research ◽  
Long Term Ecological Research ◽  
Jornada Basin

A primary objective of the Jornada Basin research program has been to provide a broad view of arid land ecology. Architects of the program, more recently scientists with the Jornada Basin Long-Term Ecological Research (LTER) program, felt that existing ecological data sets were usually of too short a duration and represented too few ecosystem components to provide a foundation for predicting dynamics in response to disturbances (NSF 1979). This recognition gave rise to the approach of using long-term and multidisciplinary research at particular places to advance a holistic and broad-scale but also mechanistic view of ecological dynamics. Such a view is essential to applying ecological research to natural resources management (Golley 1993; Li 2000). In this synthesis chapter we ask: What has this approach taught us about the structure and function of an arid ecosystem? How should this knowledge change the way we manage arid ecosystems? What gaps in our knowledge still exist and why? The Jornada Basin LTER was established in 1981 with the primary aim of using ecological science to understand the progressive loss of semiarid grasslands and their replacement with shrublands. This motivation echoed that which initiated the Jornada Experimental Range (JER) 69 years earlier. The combined, century-long body of research offers a unique perspective on several core ideas in ecology, including the existence of equilibria in ecosystems, the role of scale, landscape heterogeneity and historic events in ecosystem processes and trajectories, and the linkage between ecosystem processes and biodiversity. From this perspective, we examine key assumptions of this research tradition, including the value of the ecosystem concept and the ability to extrapolate site-based conclusions across a biome. The Jornada Basin research program is also uncommon in its close ties to long-term, management-oriented research. The research questions first asked by the U.S. Forest Service and later by the Agricultural Research Service (ARS), such as how to manage livestock operations, frame much of the Jornada Basin research. This allows us to consider the contributions of this research and synthesis toward answering management questions.

Theoretical Demands for Long-Term Ecological Research and the Management of Long-Term Data Sets

2010 ◽  
pp. 11-25 ◽  
Author(s):  
Felix Müller ◽  
Albrecht Gnauck ◽  
Karl-Otto Wenkel ◽  
Hendrik Schubert ◽  
Michael Bredemeier
Keyword(s):  
Data Sets ◽  
Ecological Research ◽  
Long Term Ecological Research ◽  
Term Data

scholarly journals Indicators of AEI Applied to the Delaware Estuary

2002 ◽  
Vol 2 ◽  
pp. 169-189 ◽  
Author(s):  
Lawrence W. Barnthouse ◽  
Douglas G. Heimbuch ◽  
Vaughn C. Anthony ◽  
Ray W. Hilborn ◽  
Ransom A. Myers
Keyword(s):  
Meta Analysis ◽  
Juvenile Fish ◽  
Fish Populations ◽  
Weight Of Evidence ◽  
Data Sets ◽  
Delaware Estuary ◽  
Fish Stocks ◽  
Trends Analysis ◽  
Definition Of

We evaluated the impacts of entrainment and impingement at the Salem Generating Station on fish populations and communities in the Delaware Estuary. In the absence of an agreed-upon regulatory definition of “adverse environmental impact” (AEI), we developed three independent benchmarks of AEI based on observed or predicted changes that could threaten the sustainability of a population or the integrity of a community.Our benchmarks of AEI included: (1) disruption of the balanced indigenous community of fish in the vicinity of Salem (the “BIC” analysis); (2) a continued downward trend in the abundance of one or more susceptible fish species (the “Trends” analysis); and (3) occurrence of entrainment/impingement mortality sufficient, in combination with fishing mortality, to jeopardize the future sustainability of one or more populations (the “Stock Jeopardy” analysis).The BIC analysis utilized nearly 30 years of species presence/absence data collected in the immediate vicinity of Salem. The Trends analysis examined three independent data sets that document trends in the abundance of juvenile fish throughout the estuary over the past 20 years. The Stock Jeopardy analysis used two different assessment models to quantify potential long-term impacts of entrainment and impingement on susceptible fish populations. For one of these models, the compensatory capacities of the modeled species were quantified through meta-analysis of spawner-recruit data available for several hundred fish stocks.All three analyses indicated that the fish populations and communities of the Delaware Estuary are healthy and show no evidence of an adverse impact due to Salem. Although the specific models and analyses used at Salem are not applicable to every facility, we believe that a weight of evidence approach that evaluates multiple benchmarks of AEI using both retrospective and predictive methods is the best approach for assessing entrainment and impingement impacts at existing facilities.

Trophic Level Relationships in Pelagic Food Webs: Comparisons Derived from Long-Term Data Sets for Oneida Lake, New York (USA), and Lake St. George, Ontario (Canada)

1992 ◽  
Vol 49 (8) ◽  
pp. 1588-1596 ◽  
Author(s):  
Donald J. McQueen ◽  
Edward L. Mills ◽  
John L. Forney ◽  
Mark R. S. Johannes ◽  
John R. Post
Keyword(s):  
New York ◽  
Total Phosphorus ◽  
Trophic Level ◽  
Data Sets ◽  
Phytoplankton Abundance ◽  
Data Set ◽  
Oneida Lake ◽  
Pelagic Food Webs ◽  
Term Data

We used standardized methods to analyze a 14-yr data set from Oneida Lake and a 10-yr data set from Lake St. George. We estimated mean summer concentrations of several trophic level indicators including piscivores, planktivores, zooplankton, phytoplankton, and total phosphorus, and we then investigated the relationships between these variables. Both data sets yielded similar long-term and short-term trends. The long-term mean annual trends were that (1) the relationships between concentrations of planktivores and zooplankton (including daphnids) were always negative, (2) the relationships between concentrations of zooplankton and various measures of phytoplankton abundance were unpredictable and never statistically significant, and (3) the relationships between total phosphorus and various measures of phytoplankton abundance were always positive. Over short periods, the data from both lakes showed periodic, strong top-down relationships between concentrations of zooplankton (especially large Daphnia) and chlorophyll a, but these events were unpredictable and were seldom related to piscivore abundance.

scholarly journals Survivable hypothermia or torpor in a wild-living rat: rare insights broaden our understanding of endothermic physiology

2021 ◽  
Author(s):  
Julia Nowack ◽  
Christopher Turbill
Keyword(s):  
Body Temperature ◽  
Data Sets ◽  
Valuable Insight ◽  
Limited Capacity ◽  
Probability Of Survival ◽  
Reduced Body ◽  
Rattus Fuscipes ◽  
Evolutionary Pathways ◽  
Term Data

AbstractMaintaining a high and stable body temperature as observed in endothermic mammals and birds is energetically costly. Thus, it is not surprising that we discover more and more heterothermic species that can reduce their energetic needs during energetic bottlenecks through the use of torpor. However, not all heterothermic animals use torpor on a regular basis. Torpor may also be important to an individual’s probability of survival, and hence fitness, when used infrequently. We here report the observation of a single, ~ 5.5 h long hypothermic bout with a decrease in body temperature by 12 °C in the native Australian bush rat (Rattus fuscipes). Our data suggest that bush rats are able to rewarm from a body temperature of 24 °C, albeit with a rewarming rate lower than that expected on the basis of their body mass. Heterothermy, i.e. the ability to withstand and overcome periods of reduced body temperature, is assumed to be an evolutionarily ancestral (plesiomorphic) trait. We thus argue that such rare hypothermic events in species that otherwise appear to be strictly homeothermic could be heterothermic rudiments, i.e. a less derived form of torpor with limited capacity for rewarming. Importantly, observations of rare and extreme thermoregulatory responses by wild animals are more likely to be discovered with long-term data sets and may not only provide valuable insight about the physiological capability of a population, but can also help us to understand the constraints and evolutionary pathways of different phenologies.

Changes Over Time

2018 ◽  
pp. 283-305 ◽  
Author(s):  
Peter A. Gell ◽  
Marie-Elodie Perga ◽  
C. Max Finlayson
Keyword(s):  
Data Sets ◽  
Lake Ecosystems ◽  
Wetland Ecosystems ◽  
Sediment Layers ◽  
Time Frames ◽  
Changes Over Time ◽  
The Impact ◽  
Term Monitoring ◽  
Term Data

Freshwater systems are continuously shaped by cyclical and directional forces of change, whether they be natural or anthropogenic. Beyond gradual transitions disturbances can reset their internal dynamics generating an abrupt ecological shift. Long-term data sets of gradual or abrupt change can be accessed by exhuming the physical, chemical, and biological remains archived in the sediment layers within lakes and wetlands. Long-term monitoring programmes offer more detailed evidence, usually over shorter time frames. In combination these records attest to the response of wetlands to climate and the impact of industrialised people. Humans have modified lake ecosystems for millennia and the condition of many wetland ecosystems have changed such that they are now regarded as novel. Long-term records provide targets for wetland restoration and can identify the main drivers of degradation. Identification of the character of modern Ramsar wetlands may be enhanced by reference to records of past state.

Born and Bred in the Long-Term Ecological Research Network: Perspectives on Network Science and Global Collaborations

2016 ◽  
Author(s):  
Melinda D. Smith
Keyword(s):  
Graduate Students ◽  
Positive Impact ◽  
Research Network ◽  
Data Sets ◽  
Ecological Research ◽  
State University ◽  
Multidisciplinary Research ◽  
Long Term Ecological Research ◽  
Kansas State University

I am a plant community and ecosystem ecologist who has conducted research within the context of the Long-Term Ecological Research (LTER) network from the beginning of my scientific career, now almost two decades ago. My research has benefited greatly from site-based research at the Konza Prairie (KNZ) LTER site, as well as from network-level syntheses utilizing data sets and knowledge produced by the collective of LTER sites. My involvement in the KNZ LTER site, in particular, has shown me the strength of conducting site-based research, yet my involvement in synthesis activities within the LTER network and beyond has illuminated the limitations of site-based research for addressing cross-site comparative research. To this end, I have been and continue to be a strong proponent of highly coordinated, multisite experiments, and much of my research is comparative in nature. Being involved in the LTER network from the start of my research career has made me a scientist who is well aware of the benefits and power of collaborative, multidisciplinary research. Because of the benefits and breadth of experiences that I have received from such research endeavors, I encourage my graduate students and postdoctoral fellows to also become involved in such research, and I recognize the positive impact collaborative, multidisciplinary research can have on beginning investigators. I believe that individuals outside of the LTER network (ranging from established principal investigators, to young investigators, to graduate students) are often not fully aware of the benefits of being involved in the LTER network or of the advances in ecological understanding that it has made possible. Thus, there is a need for the LTER network to be more proactive and creative in the ways that it attracts new researchers to get involved in the site-based or network-level research. Ultimately, the LTER network will only benefit from increased involvement by new investigators, who also could serve the role of leading the LTER network in the future. I have been affiliated with the LTER program since beginning as a graduate student at Kansas State University.

Sign in / Sign up

Export Citation Format

Share Document