Amazonian forest-savanna bistability and human impact

AbstractA bimodal distribution of tropical tree cover at intermediate precipitation levels has been presented as evidence of fire-induced bistability. Here we subdivide satellite vegetation data into those from human-unaffected areas and those from regions close to human-cultivated zones. Bimodality is found to be almost absent in the unaffected regions, whereas it is significantly enhanced close to cultivated zones. Assuming higher logging rates closer to cultivated zones and spatial diffusion of fire, our spatiotemporal mathematical model reproduces these patterns. Given a gradient of climatic and edaphic factors, rather than bistability there is a predictable spatial boundary, a Maxwell point, that separates regions where forest and savanna states are naturally selected. While bimodality can hence be explained by anthropogenic edge effects and natural spatial heterogeneity, a narrow range of bimodality remaining in the human-unaffected data indicates that there is still bistability, although on smaller scales than claimed previously.</jats:p

How Agricultural Economists Increase the Value of Agribusiness Research

Historically, there has been declining cooperation between agribusiness firms and agricultural economists. In new product marketing research, firms' tend to conduct their own analyses, partially due to confidentiality, usually consisting of simple univariate or bivariate statistics such as chi-squared tests of independence. The primary objective of this paper is to demonstrate, through a case study, one way in which agricultural economists can add value to agribusiness firms research. Results from the econometric model offer a richer explanation of consumer behavior and may be more useful to agribusiness firms.Teaching/Communication/Extension/Profession,

Effects of Nitrogen, Phosphorus and Potassium on the Propagation and Subsequent Growth of Three Woody Ornamentals

Horticultur

Riparian woodlands in crisis? Disturbance ecology on the Condamine floodplain

The Condamine River, at the headwaters of the Murray-Darling basin, drains one of the most intensively-farmed landscapes in eastern Australia. Riparian woodland remnants on the floodplain sections of the upper Condamine are widely recognised as being in generally poor condition, with evidence of significant dieback and limited recruitment of canopy species, as well as widespread invasion by the introduced perennial herb Phyla canescens (lippia). These communities, in keeping with most remnant ecosystems of agricultural landscapes, are poorly understood in terms of their diversity, function and dynamics (resilience) under altered disturbance regimes. This research investigates the condition (health and function) of Eucalyptus tereticornis/camaldulensis riparian woodland communities of the Condamine floodplain in relation to selected natural and anthropogenic disturbance factors (e.g. climate variability, changes in land- and wateruse, weed invasion) operating at a range of spatial and temporal scales. The study takes a multi-dimensional approach aimed at developing an integrated understanding of key drivers and mechanisms of ecosystem change in these environments. It also investigates the potential of simple conceptual tools (e.g. State-and-Transition and Bayesian Belief Network approaches) to model system dynamics and predict outcomes of future climate and land and water management scenarios, including environmental flow restoration

Tropical Tree Cover in a Heterogeneous Environment: A Reaction-diffusion Model

Observed bimodal tree cover distributions at particular environmental conditions and theoretical models indicate that some areas in the tropics can be in either of the alternative stable vegetation states forest or savanna. However, when including spatial interaction in nonspatial differential equation models of a bistable quantity, only the state with the lowest potential energy remains stable. Our recent reaction-diffusion model of Amazonian tree cover confirmed this and was able to reproduce the observed spatial distribution of forest versus savanna satisfactorily when forced by heterogeneous environmental and anthropogenic variables, even though bistability was underestimated. These conclusions were solely based on simulation results. Here, we perform an analytical and numerical analysis of the model. We derive the Maxwell point (MP) of the homogeneous reaction-diffusion equation without savanna trees as a function of rainfall and human impact and show that the front between forest and nonforest settles at this point as long as savanna tree cover near the front remains sufficiently low. For parameters resulting in higher savanna tree cover near the front, we also find irregular forest-savanna cycles and woodland-savanna bistability, which can both explain the remaining observed bimodality.Comment: 28 pages, 6 figures, 2 tables, supplementary info include

Διερεύνηση της δυνατότητας ανίχνευσης και χαρτογράφησης της καλλιέργειας της φακής Εγκλουβής της νήσου Λευκάδας με αντικειμενοστραφή ανάλυση πολυφασματικών απεικονίσεων

The effects of the hydrological regime on temporal changes to physical characteristics of substratum habitat, sediment texture of surface sediments

Judging the impact of leadership-development activities on school practice

The nature and effectiveness of professional-development activities should be judged in a way that takes account of both the achievement of intended outcomes and the unintended consequences that may result. Our research project set out to create a robust approach that school staff members could use to assess the impact of professional-development programs on leadership and management practice without being constrained in this judgment by the stated aims of the program. In the process, we identified a number of factors and requirements relevant to a wider audience than that concerned with the development of leadership and management in England. Such an assessment has to rest upon a clear understanding of educational leadership,a clearly articulated model of practice, and a clear model of potential forms of impact. Such foundations, suitably adapted to the subject being addressed, are appropriate for assessing all teacher professional development

Admission to hospital following head injury in England: Incidence and socio-economic associations

BACKGROUND: Head injury in England is common. Evidence suggests that socio-economic factors may cause variation in incidence, and this variation may affect planning for services to meet the needs of those who have sustained a head injury. METHODS: Socio-economic data were obtained from the UK Office for National Statistics and merged with Hospital Episodes Statistics obtained from the Department of Health. All patients admitted for head injury with ICD-10 codes S00.0–S09.9 during 2001–2 and 2002–3 were included and collated at the level of the extant Health Authorities (HA) for 2002, and Primary Care Trust (PCT) for 2003. Incidence was determined, and cluster analysis and multiple regression analysis were used to look at patterns and associations. Results: 112,718 patients were admitted during 2001–2 giving a hospitalised incidence rate for England of 229 per 100,000. This rate varied across the English HA's ranging from 91–419 per 100,000. The rate remained unchanged for 2002–3 with a similar magnitude of variation across PCT's. Three clusters of HA's were identified from the 2001–2 data; those typical of London, those of the Shire counties, and those of Other Urban authorities. Socio-economic factors were found to account for a high proportion of the variance in incidence for 2001–2. The same pattern emerged for 2002–3 at the PCT level. The use of public transport for travel to work is associated with a decreased incidence and lifestyle indicators, such as the numbers of young unemployed, increase the incidence. CONCLUSION: Head injury incidence in England varies by a factor of 4.6 across HA's and PCT's. Planning head injury related services at the local level thus needs to be based on local incidence figures rather than regional or national estimates. Socio-economic factors are shown to be associated with admission, including travel to work patterns and lifestyle indicators, which suggests that incidence is amenable to policy initiatives at the macro level as well as preventive programmes targeted at key groups

Development and Implementation of a High Throughput Screen for the Human Sperm-Specific Isoform of Glyceraldehyde 3-Phosphate Dehydrogenase (GAPDHS)

Glycolytic isozymes that are restricted to the male germline are potential targets for the development of reversible, non-hormonal male contraceptives. GAPDHS, the sperm-specific isoform of glyceraldehyde-3-phosphate dehydrogenase, is an essential enzyme for glycolysis making it an attractive target for rational drug design. Toward this goal, we have optimized and validated a high-throughput spectrophotometric assay for GAPDHS in 384-well format. The assay was stable over time and tolerant to DMSO. Whole plate validation experiments yielded Z’ values >0.8 indicating a robust assay for HTS. Two compounds were identified and confirmed from a test screen of the Prestwick collection. This assay was used to screen a diverse chemical library and identified fourteen small molecules that modulated the activity of recombinant purified GAPDHS with confirmed IC50 values ranging from 1.8 to 42 µM. These compounds may provide useful scaffolds as molecular tools to probe the role of GAPDHS in sperm motility and long term to develop potent and selective GAPDHS inhibitors leading to novel contraceptive agents

Urban land planning: The role of a Master Plan in influencing local temperatures

Land use planning (LUP) is central for managing issues related to climatic variation in urban environments. However, Master Plans (MPs) usually do not include climatic aspects, and few studies have addressed climate change at the urban scale, especially in developing countries. This paper proposes a framework with ten categories for assessment of climatic variation in urban LUP. Each category comprises attributes that describe a complex of relationships in influencing local temperature variations. They are analyzed for the case of the Master Plan of Porto Alegre (MPPA), the Southernmost metropolis of Brazil. It is concluded that the MPPA is strongly grounded in climate-related land and zoning coordination, but exhibits weaknesses in building, cartographical and social aspects considered synergistically relevant for tackling problems related to urban climate variation. Furthermore, the MPPA does not contain provisions related to monitoring of local climate and greenhouse gases (GHG) emissions and it is ineffective for improving energy efficiency. Specific MPPA failures stemming from these weaknesses include: an increase of 21.79% in the city's urbanized area from 1986 to 2011 to accommodate a similar increase in population, with significant horizontal sprawl; average temperature rise of 0.392. °C from 1991-2000 to 2001-2010, with statistically significant increases in temperature found since 1931; significant vehicle traffic increases, especially since 2007. From these findings, it is possible to conclude that the MPPA does not offer answers to all the imbalances related to land use, and therefore gives insufficient support to tackle the issue of rising temperatures