2,969 research outputs found
Seed Yield Prediction Models of Four Common Moist-Soil Plant Species in Texas
Seed production by moist-soil plant species often varies within and among managed wetlands and on larger landscapes. Quantifying seed production of moist-soil plants can be used to evaluate wetland management strategies and estimate wetland energetic carrying capacity, specifically for waterfowl. In the past, direct estimation techniques were used, but due to excessive personnel and time costs, other indirect methods have been developed. Because indirect seed yield models do not exist for moist-soil plant species in east-central or coastal Texas, we developed direct and indirect methods to model seed production on regional managed wetlands. In September 2004 and 2005, we collected Echinochloa crusgalli (barnyard grass), E. walterii (wild millet), E. colona (jungle rice), and Oryza sativa (cultivated rice) for phytomorphological measurements and seed yield modeling. Initial simple linear and point of origin regression analyses demonstrate strong relationships (P \u3c 0.001) among phytomorphological and dot grid methods in predicting seed production for all four species. These models should help regional wetland managers evaluate moist-soil management success and create models for seed production for other moist-soil plants in this region
Iwi interests and the RMA: An evaluation of the quality of first generation council plans
This working paper analyses the processes adopted by councils for involving hapū
/iwi in plan implementation, including the resource consents process. Three topic issues were investigated to assess plan implementation — urban amenity,
storm water, and issues of importance to iwi. Questions were asked about the capacity of hapū/iwi to engage in the resource consent
process, which resource issues were of concern to them, their relationship with
council and consent applicants, and their perception of the consent process. Most resources listed in the questionnaire were of concern to hapū/iwi, with water
quality, wāhi tapu and heritage the most commonly cited. In conclusion, we found a general dissatisfaction on the part of hapū/iwi with
councils’ performance with respect to both Treaty relationships and consent
processing under the RMA. A further contributing factor to the poor relationships
found between hapū/iwi and councils, was the lack of clarity over the role of hapū and
iwi in resource management. In several districts, diverging responses from hapū/iwi
and councils to questions about level of understanding and commitment suggests there
is a need for more effective communication. These problems are compounded by the
generally low capacity of hapū/iwi to participate in resource consent processes. These findings suggest that there is much to be done to improve relationships and
behaviour of these key stakeholder groups in the plan implementation process if key
provisions in the RMA related to hapū/iwi interests are to be fulfilled. The differences
shown in reciprocal perceptions have serious implications for establishing a sound
working partnership between councils and hapū/iwi in their areas. Making clear these
discrepancies is a first step towards taking the measures needed for building a better
partnership. Further, the capacity of hapū/iwi to participate could be better utilised if
there was greater integration between regional and district councils on issues of
significance and processes for iwi involvement
Evidence of Impulsive Heating in Active Region Core Loops
Using a full spectral scan of an active region from the Extreme-Ultraviolet
Imaging Spectrometer (EIS) we have obtained Emission Measure EM
distributions in two different moss regions within the same active region. We
have compared these with theoretical transition region EMs derived for three
limiting cases, namely \textit{static equilibrium}, \textit{strong
condensation} and \textit{strong evaporation} from \cite{ebtel}. The EM
distributions in both the moss regions are strikingly similar and show a
monotonically increasing trend from . Using
photospheric abundances we obtain a consistent EM distribution for all ions.
Comparing the observed and theoretical EM distributions, we find that the
observed EM distribution is best explained by the \textit{strong condensation}
case (EM), suggesting that a downward enthalpy flux plays an important
and possibly dominant role in powering the transition region moss emission. The
downflows could be due to unresolved coronal plasma that is cooling and
draining after having been impulsively heated. This supports the idea that the
hot loops (with temperatures of 3{-}5 MK) seen in the core of active regions
are heated by nanoflares.Comment: 17 pages, 4 figures, Accepted for publication in The Astrophysical
Journa
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Retroactive skill of multi-tiered forecasts of summer rainfall over southern Africa
Sea‐surface temperature (SST) variations of the oceans surrounding southern Africa are associated with seasonal rainfall variability, especially during austral summer when the tropical atmospheric circulation is dominant over the region. Because of instabilities in the linear association between summer rainfall over southern Africa and SSTs of the tropical Indian Ocean, the skilful prediction of seasonal rainfall may best be achieved using physically based models. A two‐tiered retro‐active forecast procedure for the December–February (DJF) season is employed over a 10‐year period starting from 1987/1988. Rainfall forecasts are produced for a number of homogeneous regions over part of southern Africa. Categorized (below‐normal, near‐normal and above‐normal) statistical DJF rainfall predictions are made for the region to form the baseline skill level that has to be outscored by more elaborate methods involving general circulation models (GCMs). The GCM used here is the Centre for Ocean–Land–Atmosphere Studies (COLA) T30, with predicted global SST fields as boundary forcing and initial conditions derived from the National Centres for Environmental Prediction (NCEP) reanalysis data. Bias‐corrected GCM simulations of circulation and moisture at certain standard pressure levels are downscaled to produce rainfall forecasts at the regional level using the perfect prognosis approach.
In the two‐tiered forecasting system, SST predictions for the global oceans are made first. SST anomalies of the equatorial Pacific (NIÑO3.4) and Indian oceans are predicted skilfully at 1‐ and 3‐month lead‐times using a statistical model. These retro‐active SST forecasts are accurate for pre‐1990 conditions, but predictability seems to have weakened during the 1990s. Skilful multi‐tiered rainfall forecasts are obtained when the amplitudes of large events in the global oceans (such as El Niño and La Niña episodes) are described adequately by the predicted SST fields. GCM simulations using persisted August SST anomalies instead of forecast SSTs produce skill levels similar to those of the baseline for longer lead‐times. Given high‐skill SST forecasts, the scheme has the potential to provide climate forecasts that outscore the baseline skill level substantially
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