4,186 research outputs found
Measurement and modeling of the sources and sinks of greenhouse gases from northern wetlands
Northern wetlands contain ≈30% of the world’s terrestrial carbon store, resulting from the incomplete decomposition of plant material inhibited because oxygen diffusion is limited by water saturation of the soil. While this behaviour results in a sink for CO2, anaerobic pathways of decomposition result in wetlands being a large, but variable, source of CH4. Northern wetlands tend to be nitrogen-impoverished, therefore they are not an important source of N2O. However, nitrogen deposition, peat extraction, and other land-use changes have the potential to alter their greenhouse gas (GHG) sink/source function. Until recently, most of the studies on the atmosphere-biosphere exchange of greenhouse gases from northern wetlands were short-term and seasonal. In 1998 the Peatland Carbon Study began continuous measurements of the carbon dynamics of a northern peatland and developed several ecosystem models to be used in simulations of the response of peatlands to climate variability and change. The continuous measurements have established the dominant role of climate variability in determining the magnitude and sign of the fluxes of GHGs. The Peatland Carbon Simulator (PCARS) was developed to use either direct measurements or modeled climate from a land surface process model such as the Canadian Land Surface Scheme (CLASS) which has been modi- fied to incorporate the physical attributes of wetlands as inputs. PCARS illustrates the relative importance of various components of the ecosystem in determining the interannual variability in GHG exchange. Evaluation of PCARS has helped identify significant gaps in our knowledge of peatland systems. A second, more phenomenological model, the Peat Accumulation Model (PAM), demonstrates the overall importance of precipitation in controlling decadal to millennial scale variations in sink/source strength of CO2. The Canadian Global Coupled Climate Carbon Model (CGC3M) Network is attempting to parameterize wetland processes for the inclusion in a global terrestrial ecosystem model for climate simulations, but it is a significant challenge to develop an efficient, yet realistic, wetland simulator for global scale modelling
\u3ci\u3eGOPHERUS POLYPHEMUS\u3c/i\u3e (Gopher Tortoise) COYOTE PREDATION
Gopherus polyphemus is listed as a species of special concern by the state of Florida (Florida Wildlife Code Chap. 39 F.A.C.), and as a threatened species by the Florida Committee on Rare and Endangered Plants and Animals (Moler 1992. Rare and Endangered Biota of Florida: Volume 111, Reptiles and Amphibians. University Press of Florida, Gainesville, Florida. 291 pp.). Coyotes (Canis latrans) are invasive to Florida with ranges that are expanding within the state (Schmitz and Brown 1994. An Assessment of Invasive Non-Indigenous Species in Florida\u27s Public Lands. Florida Dept. Environmental Protection. Tallahassee, Florida. 283 pp.; Wooding and Hardinsky 1990. Florida Field Nat. 18:12-14), including the southeastern coast (Cunningham and Dunford 1970. Quart. J. Florida Acad. Sci. 33:279-280; Brady 1983. Florida Field Nat. 11:40-41; Hill et al. 1987. Wildl. Soc. Bull. 15:521-524; Wooding and Hardinsky, op. cit.). We report here evidence of Coyote predation on Gopher Tortoise hatchlings in southeastern coastal Florida
Uncertainty and the Entanglement of Habitat Loss and Fragmentation Effects in the Management of Northern Bobwhite
There is a need to understand the effects of habitat loss and fragmentation on northern bobwhite (Colinus virginianus) and other grassland bird species and relate this to conservation action and delivery, especially in areas of intensive anthropogenic development. Through our research, we investigated the factors contributing to habitat loss and fragmentation in order to prioritize management within the Gulf Coast Prairie Landscape Conservation Cooperative (GCP LCC) region of Texas, USA. For this geographic region, we completed these objectives: analyzed grassland bird habitat loss and fragmentation resulting from oil and gas development, which has become especially rapid in this region beginning in 2008, projected future habitat loss under possible future economic scenarios, modeled the outcomes of potential management alternatives, and identified drivers of habitat loss and fragmentation to direct management action toward minimizing threats to high-risk habitats. Using a modeling approach, we identified suitable bobwhite habitat and prioritized high-risk areas, particularly focusing on the best candidate areas for successful restoration. Briefly, point count data were related to patch- and landscape-level habitat characteristics using a modeling technique that formally estimated the scale of the landscape effect on bobwhite abundance. Thereafter, we identified possible management alternatives with the guidance of the GCP LCC and other stakeholders and modeled the consequences of these alternatives. Using results from this modeling, we produced an extinction risk map for northern bobwhite in this region. Our research adds to the understanding of the relationship between northern bobwhite populations and the expansion of energy extraction and also uses modeling informed by data to support a decision-making framework that incorporates uncertainty about this system to prioritize the conservation of high-risk and high-value areas of bobwhite habitat
Player migration and opportunity: examining the efficacy of the UEFA home-grown rule in six European football leagues.
The introduction of UEFAs home-grown rule occurred for the start of the 2006–2007 season with the full quota in place
from the 2008–2009 season, which imposed quotas on European clubs. From 2008, clubs are required to have at least 8
players classified as home-grown in the 25-player squad, up from 4 in 2006–2007 and 6 in 2007–2008. This study
examines the efficacy of this rule across the six major European leagues (England, France, Germany, Holland, Italy
and Spain) in relation to playing opportunities (minutes played and appearances) between 1999 and 2015. This was
also examined in relation to age. Since the home-grown rule was introduced for the six nations hosting the major
leagues, the rule had different impacts by nationality. Only Germany saw significant increases in the proportion of
minutes played by their players when comparing the periods before and after the home-grown rules were imposed.
Holland, albeit seeing a slight decrease overall, saw significant increases for playing time for under 21s and 22- to 25-year olds. England and Italy were the two nations where statistically significant decreases in indigenous playing opportunities were recorded since the home-grown rules were introduced
The Geographically Contiguous and Expanding Coastal Range of the Northern Curlytail Lizard (Leiocephalus carinatus armouri) in Florida
KLF9 and JNK3 Interact to Suppress Axon Regeneration in the Adult CNS
Neurons in the adult mammalian CNS decrease in intrinsic axon growth capacity during development in concert with changes in Krüppel-like transcription factors (KLFs). KLFs regulate axon growth in CNS neurons including retinal ganglion cells (RGCs). Here, we found that knock-down of KLF9, an axon growth suppressor that is normally upregulated 250-fold in RGC development, promotes long-distance optic nerve regeneration in adult rats of both sexes. We identified a novel binding partner, MAPK10/JNK3 kinase, and found that JNK3 (c-Jun N-terminal kinase 3) is critical for KLF9\u27s axon-growth-suppressive activity. Interfering with a JNK3-binding domain or mutating two newly discovered serine phosphorylation acceptor sites, Ser106 and Ser110, effectively abolished KLF9\u27s neurite growth suppression in vitro and promoted axon regeneration in vivo. These findings demonstrate a novel, physiologic role for the interaction of KLF9 and JNK3 in regenerative failure in the optic nerve and suggest new therapeutic strategies to promote axon regeneration in the adult CNS
Quantifying integrated proteomic responses to iron stress in the globally important marine diazotroph trichodesmium
Trichodesmium is a biogeochemically important marine cyanobacterium, responsible for a significant proportion of the annual ‘new’ nitrogen introduced into the global ocean. These non-heterocystous filamentous diazotrophs employ a potentially unique strategy of near-concurrent nitrogen fixation and oxygenic photosynthesis, potentially burdening Trichodesmium with a particularly high iron requirement due to the iron-binding proteins involved in these processes. Iron availability may therefore have a significant influence on the biogeography of Trichodesmium. Previous investigations of molecular responses to iron stress in this keystone marine microbe have largely been targeted. Here a holistic approach was taken using a label-free quantitative proteomics technique (MSE) to reveal a sophisticated multi-faceted proteomic response of Trichodesmium erythraeum IMS101 to iron stress. Increased abundances of proteins known to be involved in acclimation to iron stress and proteins known or predicted to be involved in iron uptake were observed, alongside decreases in the abundances of iron-binding proteins involved in photosynthesis and nitrogen fixation. Preferential loss of proteins with a high iron content contributed to overall reductions of 55–60% in estimated proteomic iron requirements. Changes in the abundances of iron-binding proteins also suggested the potential importance of alternate photosynthetic pathways as Trichodesmium reallocates the limiting resource under iron stress. Trichodesmium therefore displays a significant and integrated proteomic response to iron availability that likely contributes to the ecological success of this species in the ocean
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