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PubMed2006

Drought effects on above- and belowground production of a grazed temperate grassland ecosystem.

The effect of climatic variation on terrestrial aboveground productivity (ANPP) has been well studied. However, little is known about how variable climate, including drought, may influence belowground productivity (BNPP), which constitutes most of the annual primary production of grasslands. The objectives of this study were to (1) examine how a 3-year period of declining moisture, which began as climatically wet to average across Yellowstone National Park (YNP) and ended in drought, affected ANPP and BNPP in grasslands of YNP and (2) how herds of grazing ungulates, which were shown previously to stimulate grassland shoot and root growth in YNP, may have interacted with climatic conditions to influence grassland production. ANPP and 0-20 cm BNPP, representing the bulk of the root dynamics, were measured in grazed and ungrazed (fenced) grassland at nine sites ranging widely in elevation, soil conditions and plant production during the 3-year study. Results revealed that 0-20 cm BNPP was strongly influenced by drought (P = 0.0005) and declined from 1999 to 2001 among ungrazed and grazed grasslands by 39 and 49%, respectively. The greater reduction in 0-20 cm BNPP among grazed grasslands was due, in part, to a decline (P = 0.07) in the stimulatory effect of grazing, i.e., the ratio g BNPP stimulated: g shoot consumed. In contrast, ANPP was unaffected by drought in either type of grassland. Thus, the effect of this drought in YNP was a large reduction in BNPP, which was a function of (1) a direct negative influence of increased moisture stress on root growth and (2) a weak interaction between drought and herbivory that led to a decline in the positive feedback from grazers to BNPP. These findings highlight the need to better understand factors that control root growth and to study the effects of climatic variation on grasslands within an ecosystem framework to include potentially important climate-consumer interactions.

Animals↗

PubMed2003

Preliminary assessment of arbuscular mycorrhizal fungal diversity and community structure in an urban ecosystem.

Arbuscular mycorrhizal fungal (AMF) species richness, composition, spore density and diversity indices were evaluated in the Phoenix metropolitan area, Arizona, USA at 20 sampling sites selected to represent the four predominant land-use types found in the greater urban area: urban-residential, urban non-residential, agriculture and desert. AMF spores were extracted and identified from soil samples and from trap cultures established using soil collected at each site. Data were analyzed according to land use, land-use history, soil chemistry and vegetation characteristics at each site. Current agricultural sites were associated with decreased spore densities and historically agricultural sites with decreased species richness. Overall species composition was similar to that previously reported for the Sonoran desert, but composition at each sampling site was influenced by the vegetation from which samples were collected. Sites with the highest degrees of similarity in AMF species composition were also similar to each other in native plants or land use. Conversely, sites with the lowest similarity in AMF composition were those from which the majority of samples were collected from non-mycorrhizal plants, predominately ectomycorrhizal plants or bare soil. Spores of Glomus microggregatum were most abundant in urban sites, while those of G. eburneum were most abundant in desert and agricultural sites. Further studies are needed to determine the functional implications of shifts in AMF communities in urban ecosystems, including effects on plant primary productivity.

Arizona↗

PubMed2004

Geochemical and microbiological evidence for a hydrogen-based, hyperthermophilic subsurface lithoautotrophic microbial ecosystem (HyperSLiME) beneath an active deep-sea hydrothermal field.

Subsurface microbial communities supported by geologically and abiologically derived hydrogen and carbon dioxide from the Earth's interior are of great interest, not only with regard to the nature of primitive life on Earth, but as potential analogs for extraterrestrial life. Here, for the first time, we present geochemical and microbiological evidence pointing to the existence of hyperthermophilic subsurface lithoautotrophic microbial ecosystem (HyperSLiME) dominated by hyperthermophilic methanogens beneath an active deep-sea hydrothermal field in the Central Indian Ridge. Geochemical and isotopic analyses of gaseous components in the hydrothermal fluids revealed heterogeneity of both concentration and carbon isotopic compositions of methane between the main hydrothermal vent (0.08 mM and -13.8 per thousand PDB, respectively) and the adjacent divergent vent site (0.2 mM and -18.5 per thousand PDB, respectively), representing potential subsurface microbial methanogenesis, at least in the divergent vent emitting more 13C-depleted methane. Extremely high abundance of magmatic energy sources such as hydrogen (2.5 mM) in the fluids also encourages a hydrogen-based, lithoautotrophic microbial activity. Both cultivation and cultivation-independent molecular analyses suggested the predominance of Methanococcales members in the superheated hydrothermal emissions and chimney interiors along with the other major microbial components of Thermococcales members. These results imply that a HyperSLiME, consisting of methanogens and fermenters, occurs in this tectonically active subsurface zone, strongly supporting the existence of hydrogen-driven subsurface microbial communities.

Archaea↗

PubMed2004

Determinants of orangutan density in the dryland forests of the Leuser Ecosystem.

Orangutans are the only great ape in Asia. Since orangutan densities vary between habitat types within regions and within similar habitat types among regions, it is important to determine areas with high densities for their protection. In this paper we show that orangutan density in old-growth dryland forests in the Leuser Ecosystem, Sumatra is significantly related to the density of large strangling figs and topsoil pH. In addition, large fig density depends on topsoil pH. Provided that orangutans are present and no hunting or logging occur, topsoil pH seems a promising method for rapid assessment of potential orangutan density over large areas.

Animals↗

PubMed2005

Environmental monitoring and assessment of a Great River ecosystem: the Upper Missouri River pilot.

Most Great River ecosystems (GREs) are extensively modified and are not receiving adequate protection to prevent further habitat degradation and loss of biotic integrity. In the United States, ecological monitoring and assessment of GREs has lagged behind streams and estuaries, and the management of GREs is hampered by the lack of unbiased data at appropriate spatial scales. Properties of GREs that make them challenging to monitor and assess include difficult sample logistics and high habitat diversity. The U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) has developed a comprehensive, regional-scale, survey-based monitoring approach to assessment of streams and estuaries, but has not yet conducted research on applying these tools to GRE monitoring. In this paper we present an overview of an EMAP research project on the Upper Missouri River (UMR). We summarize the assessment objectives for the study, the design for selecting sample locations, the indicators measured at these sites and the tools used to analyze data. We present an example of the type of statements that can be made with EMAP monitoring data. With modification, the set of methodologies developed by EMAP may be well suited for assessment of GREs in general.

Conservation of Natural Resources↗

PubMed2005

Atmospheric deposition on Swiss Long-Term Forest Ecosystem Research (LWF) plots.

Atmospheric deposition of the major elements was estimated from throughfall and bulk deposition measurements on 13 plots of the Swiss Long-Term Forest Ecosystem Research (LWF) between 1995 and 2001. Independent estimates of the wet and dry deposition of nitrogen (N) and sulfur (S) on these same plots were gained from combined simplified models. The highest deposition fluxes were measured at Novaggio (Southern Switzerland), exposed to heavy air pollution originating from the Po Plain, with throughfall fluxes averaging 29 kg ha(-1) a(-1) for N and 15 kg ha(-1) a(-1) for S. Low deposition fluxes were measured on the plots above 1800 m, with throughfall fluxes lower than 4.5 kg ha(-1) a(-1) for N and lower than 3 kg ha(-1) a(-1) for S. The wet deposition of N and S derived from bulk deposition was close to the modeled wet deposition, but the dry deposition derived from throughfall was significantly lower than the modeled dry deposition for both compounds. However, both the throughfall method and the model yielded total deposition estimates of N which exceeded the critical loads calculated on the basis of long-term mass balance considerations. These estimates were within or above the range of empirical critical loads except above 1800 m.

Air Pollutants↗

PubMed2005

The chemistry of soils, rocks and plant bioindicators in three ecosystems of the Holy Cross Mountains, Poland.

In June of 2000, biogeochemical study was carried out in three ecosystems of the Holy Cross Mountains (south-central Poland). This paper presents element concentrations and stable sulfur (and in one site lead) isotope ratios in rocks, detailed soil profiles, and plant bioindicators including epiphytic lichen Hypogymnia physodes (L.) Nyl., mosses (Pleurozium schreberi (Brid.) Mitt., Hypnum cupressiforme Hedw. S. Str., Hylocomium splendens (Hedw.) B.S.G.), Scots pine (Pinus sylvestris L.), common birch (Betula pendula Roth.), aspen (Populus tremula L.) and English oak (Quercus robur L.). Chemical analyses were performed with ICP-AES and AAS methods in the accredited laboratory (Central Chemical Laboratory of the Polish Geological Institute in Warsaw). The principal objective of this study was to compare the chemical composition of rocks, soils and selected plant bioindicators between investigation sites using the same methods of sample collection, preparation and analyses. The results of this study have shown that there is a high variability in concentrations of elements in plant bioindicators from the same sites that can not be explained only by soil properties or anthropogenic influence. This conclusion indicates that for biomonitoring purposes (especially with vascular plants) we cannot neglect individual features of the species examined.

Betula↗

PubMed2006

Climate change, flow regulation and land-use effects on the hydrology of the Peace-Athabasca-Slave System; findings from the Northern Rivers Ecosystem Initiative.

The Northern Rivers Ecosystem Initiative (NREI) was established in the late 1990s to address important science questions resulting from previous studies undertaken by the Northern Rivers Basin Study (NRBS). This manuscript summarizes the results from a number of reports on hydrologic research conducted on the Peace-Athabasca-Slave river and lake systems. Specific concerns expressed by the NRBS and subsequent NREI focused on how these systems were being affected by climate change, flow regulation and land-use changes. Issues addressed in this report include: the fate of aquatic perched basins within the Peace-Athabasca Delta under historical and future climate trends; the sources of major floods that replenish these basins and how the frequency, magnitude and source areas of such events have changed over time; the synoptic weather patterns and atmospheric teleconnections that are responsible for the generation of major snowmelt runoff that drive major floods; the potential effect that climate and land-use changes might have on basin runoff and delta lake levels; the specific hydro-climatic conditions required to produce major ice-jam floods on the Peace River and how these may be altered by climate change; remote-sensing methods to document delta flooding and vegetation change; and the dual effect of climate and flow regulation on the water levels of Great Slave Lake and how these may affect other nearshore processes, particularly wind seiches, that influence flooding of the Slave River Delta. A review of the major findings and recommendations for future research concludes the report.

Canada↗

PubMed2006

The Great Lakes, an ecosystem rehabilitated, but still under threat.

Since 1972, the Parties (United States and Canada, 1987) to the Great Lakes Water Quality Agreement have been working collaboratively to achieve the purpose of the Agreement "to restore and maintain the chemical, physical and biological integrity of the waters of the Great Lakes Basin Ecosystem". Billions of dollars and countless person - hours have been expended towards this end, but have the Parties, and their numerous collaborators at the state, provincial, and municipal levels, along with industry and citizen activists achieved meaningful results? This paper will examine the information provided through various monitoring programs and will assess the success of the Parties' programs, and will also discuss the continuing threats to achieving the purpose of the Agreement.

Animals↗

PubMed2006

Northern Rivers Ecosystem Initiative: context and prevailing legacy.

The Northern River Ecosystem Initiative (NREI), 1997-2004, has provided new scientific knowledge in response to specific recommendations from its predecessor, the Northern River Basins Study (NRBS), 1990-1996. The two initiatives together provide a remarkable body of science which is, and will continue to be, used by resource managers responsible for economic and environmental sustainability in the northern watersheds of Alberta. The NREI focused its investigative efforts on improving our understanding related to ecological considerations of changes in river flow, effect of climate change on flow, ecological responses to pollution and cumulative effects, vulnerability of drinking water quality, and to a lesser degree, wildlife (birds) response to large scale changes within the watersheds. Key findings are briefly presented in this paper and discussed in greater detail in the other NREI papers included in this. Commensurate with the undertakings of NREI, provincial and territorial governments, First Nation and Métis communities, and other administrative organizations such as the Mackenzie River Basin Board, undertook policy, regulatory, and watershed initiatives towards achieving sustainability and providing reliable drinking water quality.

Alberta↗

PubMed2006

Status of the Riparian ecosystem in the upper San Pedro River, Arizona: application of an assessment model.

A portion of Arizona's San Pedro River is managed as a National Riparian Conservation Area but is potentially affected by ground-water withdrawals beyond the conservation area borders. We applied an assessment model to the Conservation Area as a basis for monitoring long-term changes in riparian ecosystem condition resulting from changes in river water availability, and collected multi-year data on a subset of the most sensitive bioindicators. The assessment model is based on nine vegetation bioindicators that are sensitive to changes in surface water or ground water. Site index scores allow for placement into one of three condition classes, each reflecting particular ranges for site hydrology and vegetation structure. We collected the bioindicator data at 26 sites distributed among 14 reaches that had similar stream flow hydrology (spatial flow intermittency) and geomorphology (channel sinuosity, flood-plain width). Overall, 39% of the riparian corridor fell within condition class 3 (the wettest condition), 55% in condition class 2, and 6% in the driest condition class. Condition class 3 reaches have high cover of herbaceous wetland plants (e.g., Juncus and Schoenoplectus spp.) along the perennial stream channel and dense, multi-aged Populus-Salix woodlands in the flood plain, sustained by shallow ground water in the stream alluvium. In condition class 2, intermittent stream flows result in low cover of streamside wetland herbs, but Populus-Salix remain abundant in the flood plain. Perennial wetland plants are absent from condition class 1, reflecting highly intermittent stream flows; the flood plain is vegetated by Tamarixa small tree that tolerates the deep and fluctuating ground water levels that typify this reach type. Abundance of herbaceous wetland plants and growth rate of Salix gooddingii varied between years with different stream flow rates, indicating utility of these measures for tracking short-term responses to hydrologic change. Repeat measurement of all bioindicators will indicate long-term trends in hydro-vegetational condition.

Arizona↗

PubMed2006

Impact of degradation on nitrogen transformation in a forest ecosystem of India.

A study was performed selecting one protected forest and an adjacent degraded forest ecosystem to quantify the impact of forest degradation on soil inorganic nitrogen, fine root production, nitrification, N-mineralization and microbial biomass N. There were marked seasonal variations of all the parameters in the upper 0-10 and lower 10-20 cm depths. The seasonal trend of net nitrification and net N-mineralization was reverse of that for inorganic nitrogen and microbial biomass N. Net nitrification, net N-mineralization and fine root biomass values were highest in both forests during rainy season. On contrary, inorganic nitrogen and microbial biomass N were highest during summer season.There was a marked impact of forest degradation on inorganic nitrogen, fine root production nitrification, N-mineralization and microbial biomass observed. Soil properties also varied with soil depth. Fine root biomass, nitrification, N-mineralization and microbial biomass N decreased significantly in higher soil depth. Degradation causes decline in mean seasonal fine root biomass in upper layer and in lower depth by 37% and 27%, respectively. The mean seasonal net nitrification and N-mineralization in upper depth decreased by 42% and 37%, respectively and in lower depth by 42.21% and 39% respectively. Similarly microbial biomass N also decreased by 31.16% in upper layer 33.19% in lower layer.

Ammonia↗

PubMed2005

Effects of elevated CO2 on foliar quality and herbivore damage in a scrub oak ecosystem.

Atmospheric CO2 concentrations have increased exponentially over the last century and continuing increases are expected to have significant effects on ecosystems. We investigated the interactions among atmospheric CO2, foliar quality, and herbivory within a scrub oak community at the Kennedy Space Center, Florida. Sixteen plots of open-top chambers were followed; eight of which were exposed to ambient levels of CO2 (350 ppm), and eight of which were exposed to elevated levels of CO2 (700 ppm). We focused on three oak species, Quercus geminata, Quercus myrtifolia, Quercus chapmanii, and one nitrogen fixing legume, Galactia elliottii. There were declines in overall nitrogen and increases in C:N ratios under elevated CO2. Total carbon, phenolics (condensed tannins, hydrolyzable tannins, total phenolics) and fiber (cellulose, hemicellulose, lignin) did not change under elevated CO2 across plant species. Plant species differed in their relative foliar chemistries over time, however, the only consistent differences were higher nitrogen concentrations and lower C:N ratios in the nitrogen fixer when compared to the oak species. Under elevated CO2, damage by herbivores decreased for four of the six insect groups investigated. The overall declines in both foliar quality and herbivory under elevated CO2 treatments suggest that damage to plants may decline as atmospheric CO2 levels continue to rise.

Atmosphere↗

PubMed2005

Effects of elevated co2 and herbivore damage on litter quality in a scrub oak ecosystem.

Atmospheric CO(2) concentrations have increased dramatically over the last century and continuing increases are expected to have significant, though currently unpredictable, effects on ecosystems. One important process that may be affected by elevated CO(2) is leaf litter decomposition. We investigated the interactions among atmospheric CO(2), herbivory, and litter quality within a scrub oak community at the Kennedy Space Center, Florida. Leaf litter chemistry in 16 plots of open-top chambers was followed for 3 years; eight were exposed to ambient levels of CO(2), and eight were exposed to elevated levels of CO(2) (ambient + 350 ppmV). We focused on three dominant oak species, Quercus geminata, Quercus myrtifolia, and Quercus chapmanii. Condensed tannin concentrations in oak leaf litter were higher under elevated CO(2). Litter chemistry differed among all plant species except for condensed tannins. Phenolic concentrations were lower, whereas lignin concentrations and lignin/nitrogen ratios were higher in herbivore-damaged litter independent of CO(2) concentration. However, changes in litter chemistry from year to year were far larger than effects of CO(2) or insect damage, suggesting that these may have only minor effects on litter decomposition.

Animals↗

PubMed1987

A large-scale perspective on ecosystems.

Interactions between ecological elements must be better understood in order to construct an ecological life support system in space. An index was devised to describe the complexity of material cyclings within a given ecosystem. It was then applied to the cyclings of bioelements in various systems of material cyclings including the whole Earth and national economies. The results show interesting characteristics of natural and man-made systems.

Animals↗

PubMed2003

Prevention of alveolar echinococcosis--ecosystem and risk management perspectives in Japan.

We focused on the epidemiology of alveolar echinococcosis especially in Japan and discussed control measures to prevent an epidemic. No effective control measures against alveolar echinococcosis have been identified thus far because it is difficult to fully understand the ecology of the parasite and its hosts, i.e. the precise infection route to humans. In Hokkaido, Japan, infection rates among red foxes have recently risen even in low endemic districts. Infection seems to be spreading not only among wild foxes but also among domestic dogs. Despite only sporadic reports of human cases in Japan, we predict that the incidence of alveolar echinococcosis will increase in the near future if no effective preventive measures are put in place. An Echinococcus multilocularis epidemic would have the potential to affect the economy of Hokkaido, due to its impact on the agricultural and tourist industries. Well-designed epidemiological surveys are, therefore, urgently required prior to large outbreaks, based on understanding of the ecosystem around E. multilocularis.

Animals↗

PubMed2004

The paddy, the vector and the caregiver: lessons from an ecosystem approach to irrigation and malaria in Northern Côte d'Ivoire.

Malaria is one of the most serious public health problems in the world. For the last few decades, numerous studies have focused on the potential links between environmental transformations (such as the expansion of irrigation) and malaria occurrence. Most of these studies have been based on relatively simple models outlining the interactions of the host-vector-parasite triad. In this paper, we investigate the links between the intensification of irrigated rice cultivation and malaria. In an attempt to complement biomedical and entomological approaches we propose a model that recognises the influence of human-vector contacts on transmission processes, but stresses the importance of taking into consideration socio-economic and cultural factors in the management of disease episodes, and how these can be affected by transformations of natural resource management strategies. Using a case study in Northern Côte d'Ivoire, we investigated the complex mechanisms by which agriculture-generated changes in ecosystems and socio-economic organisation influence disease risks and produce new scenarios in the management of disease. Our results show that the socio-economic transformation and gender repositioning induced, or facilitated, by the intensification of lowland irrigated rice cultivation influence the health care system for malaria in the study area. They lead to a reduction of the capacity of women to manage malaria episodes among children and influence their vulnerability to the disease. We argue that these elements contribute to higher malaria prevalence in villages involved in double cropping of rice annually.

Adult↗

PubMed2004

Performance of a simple Closed Aquatic Ecosystem (CAES) in space.

A simple Closed Aquatic Ecosystem (CAES) consisting of single-celled green algae (Chlorella pyrenoidosa, producer), a spiral snail (Bulinus australianus, consumer) and a data acquisition and control unit was flown on the Chinese Spacecraft SHENZHOU-II in January 2001 for 7 days. In order to study the effect of microgravity on the operation of CAES, a 1 g centrifuge reference group in space, a ground 1 g reference group and a ground 1 g centrifuge reference group (1.4 g group) were run concurrently. Real-time data about algae biomass (calculated from transmission light intensity), temperature, light and centrifugation of the CAES were logged at minute intervals. It was found that algae biomass of both the microgravity group and the ground 1 g-centrifuge reference group (1.4 g) fluctuated during the experiment, but the algae biomass of the 1 g centrifuge reference group in space and the ground 1 g reference group increased during the experiment. The results may be attributable to influences of microgravity and 1.4 g gravity on the algae and snails metabolisms. Microgravity is the main factor to affect the operation of CAES in space and the contribution of microgravity to the effect was also estimated. These data may be valuable for the establishment of a complex CELSS in the future.

Adaptation, Physiological↗