158 research outputs found
Assessing impacts of Common Agricultural Policy changes on regional use patterns with a decision support system. An application in Southern Portugal
This paper discusses research aiming at assessing Common Agricultural Policy impacts on agriculture and
forestry. For this purpose an approach is developed that includes a linear programming model to estimate
the Positive Mathematical Programming production cost function coefficients of current agricultural–
forestry activities. It further includes a heuristic — simulated annealing — to generate solutions for each
policy scenario. This model base approach is integrated within a decision support system (DSS) for testing
purposes. The DSS further encompasses a relational database that stores agricultural–forestry technical and
economic data and a geographic information system that stores topological data of regional farm-type land
units. The DSS Graphical User Interface provides tabular and geographical reporting capabilities. Results are
discussed for an application to the Alentejo region in Southern Portugal. Results demonstrate the usefulness
and relevance of the proposed approach to assess the impact of changes in prices and in agricultural policy
on land use patterns and on forestr
Improving management decisions in portuguese forests through fire behaviour modeling: guidelines to support a sustainable landscape
PosterUnderstanding wildfire behavior at the landscape-level is critical to address wildfire
impacts in Portuguese forest management planning.
Thus, fire spread was simulated in three forested landscape to assist forest managers in
identifying high-risk areas for actively integrating stand-level fuel treatments with explicit
landscape-level management planning and develop fire prevention priorities.
Specifically, several modeling applications to detect significant fire-landscape
interactions between stand-level features and fire behavior were fitted to classify
Portuguese forests to fire risk levels and create guidelines to support hazard-reduction
silvicultural practiceN/
A new mixed-integer programming model for harvest scheduling subject to maximum area restrictions
Forest ecosystem management often requires spatially explicit planning because the spatial arrangement of harvests has
become a critical economic and environmental concern. Recent research on exact methods has addressed both the design and
the solution of forest management problems with constraints on the clearcut size, but where simultaneously harvesting two
adjacent stands in the same period does not necessarily exceed the maximum opening size. Two main integer programming
approaches have been proposed for this area restriction model. However, both encompass an exponential number of variables
or constraints. In this work, we present a new integer programming model with a polynomial number of variables and
constraints. Branch and bound is used to solve it. The model was tested with both real and hypothetical forests ranging
from 45 to 1,363 polygons. Results show that the proposed model’s solutions were within or slightly above 1% of the
optimal solution and were obtained in a short computation time
An approach to cork oak forest management planning: a case study in southwestern Portugal
This paper presents results of research aiming
at the development of tools that may enhance cork oak
(Quercus suber L.) forest management planning. Specifically,
it proposes an hierarchical approach that encompasses
the spatial classification of a cork oak forest and the
temporal scheduling of cork harvests. The use of both
geographical information systems and operations research
techniques is addressed. Emphasis is on the achievement of
cork even flow objectives. Results from an application to a
case study in the Charneca Plioce´nica of Ribatejo in
southern Portugal encompassing a cork oak forest extending
over 4.8 thousand ha are discussed. They suggest that
the proposed approach is capable of effective spatial classification
of cork oak management units. They further
suggest that it may be used to select optimal cork even flow
scheduling strategies. Results also show that the proposed
approach may lead to a substantial increase in net present
value when compared to traditional approaches to cork oak
forest management planning
Computer-based tools for supporting forest management. The experience and the expertise world-wide
Report of Cost Action FP 0804 Forest Management Decision Support Systems (FORSYS)Computer-based tools for supporting forest management. The experience and the expertise world-wide answers a call from both the research and the professional communities for a synthesis of current knowledge about the use of computerized tools in forest management planning. According to the aims of the Forest Management Decision Support Systems (FORSYS) (http://fp0804.emu.ee/) this synthesis is a critical success factor to develop a comprehensive quality reference for forest management decision support systems. The emphasis of the book is on identifying and assessing the support provided by computerized tools to enhance forest management planning in real-world contexts. The book thus identifies the management planning problems that prevail world-wide to discuss the architecture and the components of the tools used to address them. Of importance is the report of architecture approaches, models and methods, knowledge management and participatory planning techniques used to address specific management planning problems. We think that this synthesis may provide effective support to research and outreach activities that focus on the development of forest management decision support systems. It may contribute further to support forest managers when defining the requirements for a tool that best meets their needs. The first chapter of the book provides an introduction to the use of decision support systems in the forest sector and lays out the FORSYS framework for reporting the experience and expertise acquired in each country. Emphasis is on the FORSYS ontology to facilitate the sharing of experiences needed to characterize and evaluate the use of computerized tools when addressing forest management planning problems. The twenty six country reports share a structure designed to underline a problem-centric focus. Specifically, they all start with the identification of the management planning problems that are prevalent in the country and they move on to the characterization and assessment of the computerized tools used to address them. The reports were led by researchers with background and expertise in areas that range from ecological modeling to forest modeling, management planning and information and communication technology development. They benefited from the input provided by forest practitioners and by organizations that are responsible for developing and implementing forest management plans. A conclusions chapter highlights the success of bringing together such a wide range of disciplines and perspectives. This book benefited from voluntary contributions by 94 authors and from the involvement of several forest stakeholders from twenty six countries in Europe, North and South America, Africa and Asia over a three-year period. We, the chair of FORSYS and the editorial committee of the publication, acknowledge and thank for the valuable contributions from all authors, editors, stakeholders and FORSYS actors involved in this project
Low-diffusivity scalar transport using a WENO scheme and dual meshing
Interfacial mass transfer of low-diffusive substances in an unsteady flow
environment is marked by a very thin boundary layer at the interface and other
regions with steep concentration gradients. A numerical scheme capable of
resolving accurately most details of this process is presented. In this scheme,
the fourth-order accurate WENO method developed by Liu et al. (1994) was
implemented on a non-uniform staggered mesh to discretize the scalar convection
while for the scalar diffusion a fourth-order accurate central discretization
was employed. The discretization of the scalar convection-diffusion equation
was combined with a fourth-order Navier-Stokes solver which solves the
incompressible flow. A dual meshing strategy was employed, in which the scalar
was solved on a finer mesh than the incompressible flow. The solver was tested
by performing a number of two-dimensional simulations of an unstably stratified
flow with low diffusivity scalar transport. The unstable stratification led to
buoyant convection which was modelled using a Boussinesq approximation with a
linear relationship between flow temperature and density. The order of accuracy
for one-dimensional scalar transport on a stretched and uniform grid was also
tested. The results show that for the method presented above a relatively
coarse mesh is sufficient to accurately describe the fluid flow, while the use
of a refined mesh for the low-diffusive scalars is found to be beneficial in
order to obtain a highly accurate resolution with negligible numerical
diffusion
Evaluacion de la probabilidad de ocurrencia de fuegos en rodales de Pinus pinaster Ait en Portugal
Maritime pine (Pinus pinaster Ait.) is an important conifer from the western Mediterranean Basin extending over 22%
of the forest area in Portugal. In the last three decades nearly 4% of Maritime pine area has been burned by wildfires. Yet
no wildfire occurrence probability models are available and forest and fire management planning activities are thus carried
out mostly independently of each other. This paper presents research to address this gap. Specifically, it presents a model
to assess wildfire occurrence probability in regular and pure Maritime pine stands in Portugal. Emphasis was in developing
a model based on easily available inventory data so that it might be useful to forest managers. For that purpose, data from
the last two Portuguese National Forest Inventories (NFI) and data from wildfire perimeters in the years from 1998 to 2004
and from 2006 to 2007 were used. A binary logistic regression model was build using biometric data from the NFL Biometric
data included indicators that might be changed by operations prescribed in forest planning. Results showed that the probability
of wildfire occurrence in a stand increases in stand located at steeper slopes and with high shrubs load while it decreases
with precipitation and with stand basal area. These results are instrumental for assessing the impact of forest
management options on wildfire probability thus helping forest managers to reduce the risk of wildfire
Assessing impacts of Common Agricultural Policy changes on regional land use
This paper discusses research aiming at assessing Common Agricultural Policy impacts on agriculture and
forestry. For this purpose an approach is developed that includes a linear programming model to estimate
the Positive Mathematical Programming production cost function coefficients of current agricultural–
forestry activities. It further includes a heuristic — simulated annealing — to generate solutions for each
policy scenario. This model base approach is integrated within a decision support system (DSS) for testing
purposes. The DSS further encompasses a relational database that stores agricultural–forestry technical and
economic data and a geographic information system that stores topological data of regional farm-type land
units. The DSS Graphical User Interface provides tabular and geographical reporting capabilities. Results are
discussed for an application to the Alentejo region in Southern Portugal. Results demonstrate the usefulness
and relevance of the proposed approach to assess the impact of changes in prices and in agricultural policy
on land use patterns and on forestry
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