“The derived statistics for Bedmap2 show that the volume of ice contained in the Antarctic ice sheet (27 million cubic km) and its potential contribution to sea-level rise (58 m) are similar to those of Bedmap1, but the mean thickness of the ice sheet is 4.6 % greater, the mean depth of the bed beneath the grounded ice sheet is 72 m lower and the area of ice sheet grounded on bed below sea level is increased by 10 %. The Bedmap2 compilation highlights several areas beneath the ice sheet where the bed elevation is substantially lower than the deepest bed indicated by Bedmap1. These products, along with grids of data coverage and uncertainty, provide new opportunities for detailed modelling of the past and future evolution of the Antarctic ice sheets.”
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The Steady-state Mosaic of Disturbance and Succession across an Old-growth Central Amazon Forest Landscape
PNAS, 28 January 2013
Jeffrey Q. Chambers, Robinson I. Negron-Juarez, Daniel Magnabosco Marra, Alan Di Vittorio, Joerg Tews, Dar Roberts, Gabriel H. P. M. Ribeiro, Susan E. Trumbore, and Niro Higuchi
“Old-growth forest ecosystems comprise a mosaic of patches in different successional stages, with the fraction of the landscape in any particular state relatively constant over large temporal and spatial scales. The size distribution and return frequency of disturbance events, and subsequent recovery processes, determine to a large extent the spatial scale over which this old-growth steady state develops. Here, we characterize this mosaic for a Central Amazon forest by integrating field plot data, remote sensing disturbance probability distribution functions, and individual-based simulation modeling. Results demonstrate that a steady state of patches of varying successional age occurs over a relatively large spatial scale, with important implications for detecting temporal trends on plots that sample a small fraction of the landscape. Long highly significant stochastic runs averaging 1.0 Mg biomass⋅ha−1⋅y−1 were often punctuated by episodic disturbance events, resulting in a sawtooth time series of hectare-scale tree biomass. To maximize the detection of temporal trends for this Central Amazon site (e.g., driven by CO2 fertilization), plots larger than 10 ha would provide the greatest sensitivity. A model-based analysis of fractional mortality across all gap sizes demonstrated that 9.1–16.9% of tree mortality was missing from plot-based approaches, underscoring the need to combine plot and remote-sensing methods for estimating net landscape carbon balance. Old-growth tropical forests can exhibit complex large-scale structure driven by disturbance and recovery cycles, with ecosystem and community attributes of hectare-scale plots exhibiting continuous dynamic departures from a steady-state condition.”
International Journal of Remote Sensing, Volume 34, Issue 7, 2013
“We conducted a time series analysis using the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data product over the Alcedo volcano region of Isabela Island in the Galápagos to determine vegetation changes before, during, and after a feral goat invasion and eradication project. Enhanced vegetation index (EVI) values for the Alcedo region of Isabela Island were analysed from 2000 to 2010 with respect to the presence of a large population of goats that was eradicated between 2004 and 2006. This study finds large-scale, seasonal vegetation pattern changes between 2000 and 2005, and 2005 and 2010. Statistically significant EVI decreases prior to and during eradication in zones where goats were present in high numbers and increases following eradication in zones with lower goat density are found. EVI appears to have changed little over the entire study period, though earlier imagery would likely reveal stronger positive post-eradication trends. Because EVI primarily reveals greenness and little about vegetation composition and structure, we find that long-term in situ vegetation monitoring is also needed to obtain a meaningful assessment of the effects of invasion and eradication at the species level.”
Representation of Ecological Systems within the Protected Areas Network of the Continental United States
PLOS ONE, 23 January 2013
Jocelyn L. Aycrigg, Anne Davidson, Leona K. Svancara, Kevin J. Gergely, Alexa McKerrow, and J. Michael Scott
“If conservation of biodiversity is the goal, then the protected areas network of the continental US may be one of our best conservation tools for safeguarding ecological systems (i.e., vegetation communities). We evaluated representation of ecological systems in the current protected areas network and found insufficient representation at three vegetation community levels within lower elevations and moderate to high productivity soils. We used national-level data for ecological systems and a protected areas database to explore alternative ways we might be able to increase representation of ecological systems within the continental US. By following one or more of these alternatives it may be possible to increase the representation of ecological systems in the protected areas network both quantitatively (from 10% up to 39%) and geographically and come closer to meeting the suggested Convention on Biological Diversity target of 17% for terrestrial areas.
“We used the Landscape Conservation Cooperative framework for regional analysis and found that increased conservation on some private and public lands may be important to the conservation of ecological systems in Western US, while increased public-private partnerships may be important in the conservation of ecological systems in Eastern US. We have not assessed the pros and cons of following the national or regional alternatives, but rather present them as possibilities that may be considered and evaluated as decisions are made to increase the representation of ecological systems in the protected areas network across their range of ecological, geographical, and geophysical occurrence in the continental US into the future.”
Atmosphere 2013, 4, 94-112
Alireza Shahabfar and Josef Eitzinger
“Six meteorological drought indices including percent of normal (PN), standardized precipitation index (SPI), China-Z index (CZI), modified CZI (MCZI), Z-Score (Z), the aridity index of E. de Martonne (I) are compared and evaluated for assessing spatio-temporal dynamics of droughts in six climatic regions in Iran.
“Results indicated that by consideration of the advantages and disadvantages of the mentioned drought predictors in Iran, the Z-Score, CZI and MCZI could be used as a good meteorological drought predictor. Depending on the month, the length of drought and climatic conditions of the region, they are an alternative to the SPI that has limitations both because of only a few available long term data series in Iran and its complex structure.”
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URISA invites experienced GIS professionals of all kinds – particularly those with management experience – to review and comment on a draft GIS Capability Maturity Model (GCMM).
The GIS Capability Maturity Model is intended primarily to define the components of an effective GIS operation, as well as to identify the characteristics of a well-managed and mature GIS. The model was originally developed in 2009 and adopted as a URISA initiative in 2010. In 2011 and 2012 it was used to inform development of the Geospatial Management Competency Model by URISA. URISA’s GIS Management Institute conducted an internal review/revision process from October 2012 through March 2013. This process resulted in the version of the model now offered for public review.
Links to the draft GCMM and an online questionnaire for reviewers are available at http://www.urisa.org/GMI_GCMM_PublicReview. The questionnaire will remain open through May 31, 2013. After the public review period, URISA’s GIS Management Institute will review all comments received, make appropriate changes, and publish a fully authorized peer-reviewed version of the model.
[Source: URISA press release]