A GIS-based database management application for

Computers and Electronics in Agriculture 27 (2000) 41 – 55 www.elsevier.com/locate/compag

A GIS-based database management application for agroforestry planning and tree selection E.A. Ellis a,*, P.K.R. Nair a, P.E. Linehan a, H.W. Beck b, C.A. Blanche c a

School of Forest Resources and Conser6ation, Uni6ersity of Florida, Gaines6ille, FL 32611 -0410, USA b Department of Agricultural Engineering, Institute of Food and Agricultural Sciences, Uni6ersity of Florida, Gaines6ille, FL 32611 -0410, USA c Dale Bumpers Small Farm Research Center, USDA, ARS, Boone6ille, AR 72927, USA

Abstract Agroforestry (the deliberate growing of trees or shrubs in rural lands) is being promoted in the United States as an alternative resource management system that can bring landowners economic benefits and provide environmental services such as reduced soil erosion, improved water quality and wildlife habitat. Landowners, farmers and extension agents need to be better informed about different agroforestry opportunities and potential tree species. The Florida Agroforestry Decision Support System (FADSS) was designed to aid in the dissemination of such information. FADSS utilizes a geographical information system (GIS) enabling the user to select a location of interest which is linked to spatial data on climate and soils characteristics for the state of Florida. The application also incorporates a database of over 500 trees and 50 tree attributes, forming a relational database. The application structure consists primarily of building database queries using Standard Query Language (SQL). SQL queries are constructed during run-time based on spatial parameters of a selected location, the type of agroforestry system desired, and production and management criteria provided by the user. Experts were interviewed to help develop queries used to select trees and other agroforestry species. Being a prototype, the application is built with a modular and flexible framework in which spatial data of different scales and/or regions as well as plant data may be easily incorporated. Among the major limitations encountered during the development of FADSS with major implications on future agroforestry decision support systems was the current lack of tree information relevant to agroforestry and the lack of research involving

Florida Agricultural Experiment Station Journal Series Number R-017128 * Corresponding author.

0168-1699/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 1 6 9 9 ( 0 0 ) 0 0 0 9 5 - 8

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E.A. Ellis et al. / Computers and Electronics in Agriculture 27 (2000) 41–55

the assessment of suitable trees and their characteristics. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Agroforestry; Decision support system; Geographical information system

1. Introduction Agroforestry, defined as the deliberate growing of trees or shrubs on agricultural lands, is receiving much attention in the United States from academic and government institutions. Agroforestry systems are regarded as an alternative resource management system with potential to mediate some of the problems associated with current agricultural development and practices, for example, soil erosion, environmental contamination, economic deterioration of family farms, and loss of forest resources and wildlife habitat. It is widely argued that agroforestry can contribute towards sustainable agriculture by minimizing inputs and costs, reducing environmental impacts, and providing additional economic benefits to farmers (Pearson, 1995; Schultz et al., 1995; Association for Temperate Agroforestry, 1997). A total of five major types of agroforestry systems have been identified for the region and are described in Table 1: (1) alley-cropping, (2) shelterbelts or windbreaks, (3) silvopastoral, (4) riparian buffers and (5) forest farming (Association for Temperate Agroforestry, 1997; Williams et al., 1997). Current trends in the decrease of family farm land and increases in non-industrial private land, also make it an attractive land use option for private landowners (Plantinga and Buongiorno, 1990). The Southeast is a major supplier of forest products with 70% of the region’s forested land owned by non-industrial private landowners (Zinkhan and Mercer, 1997). The 1996 USDA Farm Bill includes various programs which provide incentives and assistance to landowners and farmers for the establishment of trees on their land (United States Department of Agriculture, 1999). Agroforestry systems apply to programs such as the Environmental Quality Incentives Program, where riparian buffers could be used to improve water quality, or alley cropping systems can be used to reduce soil erosion. The Forestry Incentives Program, which provides up to 65% of tree planting costs, also includes agroforestry systems such as silvopastoral or forest farming. Despite the optimism in the perceived benefits of agroforestry, there are still significant limitations to developing such systems in the United States. For one, there is a lack of basic, applied and multi-disciplinary research on agroforestry in the region. Relatedly, there is little awareness and education among private landowners, land-use professionals and forestry and agricultural extension agents about agroforestry potentials and options (Williams et al., 1997). Moreover, there are multitudes of tree and shrub species which could potentially be incorporated into different systems, but they need to be evaluated for their merits and limitations. This paper describes the development and structure of the application, Florida Agroforestry Decision Support System (FADSS). This prototype application was


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developed with the intention of promoting and informing landowners and extension agents about the potentials of agroforestry and guiding them in selecting appropriate tree or shrub species for agroforestry in specific situations. FADSS integrates a geographical information system (GIS) using spatial data on Florida soils and Table 1 Five major agroforestry systems or practices described for temperate regionsa Alley cropping This practice combines trees, planted in single or grouped rows, with agricultural or horticultural crops which are cultivated in the wide alleys between the tree rows. High-value hardwoods such as oak, walnut, and ash are typically grown in alley cropping combinations. Annual crops (e.g. row crops, forages and vegetables) cultivated between rows of nut or fruit trees (e.g. black walnut) provide extra income before the trees come into bearing and early in the long-term timber rotation. Depending on tree spacing, Christmas tree plantations may be interplanted with annual crops. Alternatively, short rotation woody crops or Christmas trees may be interplanted within plantations of longer-rotation timber trees. Sil6opastoral This practice combines trees with forage (pasture or hay) and livestock production. The overstory tree component provides shade and wind shelter, thereby protecting livestock from temperature stresses. In plantations of softwood or hardwood trees managed for timber or Christmas trees, grazing provides a source of income during the early years of the rotation. Some nut (e.g. black walnut) and fruit orchards may also be grazed to produce income before the trees begin bearing. Silvopasture is different from traditional forest or range management because it is intentionally created and intensively managed. Riparian buffers Riparian buffers consist of strips of perennial vegetation (tree/shrub/grass) planted between cropland or pastures and streams, lakes, wetlands, ponds, or drainage ditches. They are managed to reduce run-off and non-point source pollution from agricultural activities on adjacent lands by trapping sediment, filtering excess nutrients, and degrading pesticides. They can also stabilize streambanks, protect floodplains, enhance aquatic and terrestrial habitat, improve landscape appearance, provide harvestable products, and function as a windbreak in some situations. Windbreaks/shelterbelt Windbreaks are planted and managed as part of a crop or livestock operation to enhance crop production, protect livestock, and control soil erosion. Field windbreaks are used to protect a variety of wind-sensitive row, tree and vine crops, to control wind erosion, and to provide other benefits such as improved bee pollination of crops and wildlife habitat. Feedlot windbreaks help reduce animal mortality, feed and water consumption, and odor. Windbreaks can function as living snow fences to help with water management by dispersing snow more evenly across cropland. A special type of multi-row windbreak (‘timberbelt’) is managed both to protect crops or livestock on a continuous basis, and to produce timber or biomass. Forest farming This practice utilizes a forested area for producing specialty crops which are sold for medicinal, ornamental or culinary uses. Shade tolerant crops such as ginseng, decorative ferns or shiitake mushrooms are intensively cultivated under a forest cover that has been modified to provide the correct level of shade. Suitable understory crops are those that grow naturally under forest conditions, or are adaptable to the edaphic and microclimatic conditions of the site. Forest farming can provide annual/regular income either before, or as an alternative to, harvesting the trees for wood products. a

Source: Association for Temperate Agroforestry.

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climate. In combination with a plant database, FADSS enables users to evaluate potential tree, shrub, grass or crop species for an area of interest under different management options selected such as type of agroforestry system, products or services desired, and/or management practices implemented. Moreover, FADSS was designed to serve as a model that can easily be used for similar applications involving other states in the Southeast.

2. Objectives

The specific objectives of the application were: explore readily available and distributed data for use in the Florida prototype and further applications for the Southeast; promote and inform landowners, farmers and extension agents about the subject of agroforestry and land use potentials; offer a decision support system for agroforestry planning and species selection using criteria such as site characteristics, management objectives and management practices; provide a user-friendly map interface for site selection which is linked to spatial data, eliminating the need for extensive knowledge on regional soils and climate characteristics of an establishment site; provide a user-friendly, comprehensive menu of different management objectives, benefits and practices associated with agroforestry for the appropriate selection of trees; incorporate ecological, economic and management criteria for the selection of agroforestry species, and develop an application which can easily be expanded for other regions in the US by modifying the tree database and incorporating the appropriate soils and climate spatial data.

3. Information sources

3.1. Application database The application incorporates a GIS, utilizing spatial data to find and choose areas of interest and extract climate and soils parameters necessary for agroforestry species selection. Map layers and related data on soils were obtained from the Florida Geographic Data Library, Geoplan, University of Florida. Climate data integrated into the county spatial data was obtained from the Southeast Regional Climate Center. Table 2 summarizes the variety of map or spatial layers and related data tables on climate and soils utilized by FADSS. Another major component of the application involves the plant database consisting of trees, shrubs and grasses adaptable to the state of Florida. This comprehensive database on trees, shrubs and grasses was obtained from the Natural Resource


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Table 2 Spatial layers, data tables and data fields utilized by the FADSS Category

Table description Attributes/fields used by FADSS

Role in FADSS

Spatial data

FL highways FL cities FL soils

None None Map unit ID (MUID) County name

Used for visual geographical reference Used for visual geographical reference Define soils regions within the state of Florida Delimit counties which are linked to climate data for each county

FL county/climate Climate data

FL county/climate

Annual precipitation Minimum temperature Growing season

Links to precipitation tolerances of trees, shrubs and grasses Links to temperature tolerances of trees, shrubs and grasses Links to frost-free day requirements of trees, shrubs and grasses

Soils data

Soil composition

MUID

Links geo-spatial soils regions to their corresponding soils characteristics Links to tree, shrub and grass adaptability to soil textures Links to plant tolerances to drought conditions and their moisture use Links to plants tolerances to anaerobic conditions Links to plants tolerances to anaerobic conditions Links to plants tolerances to saline conditions Links soils regions to appropriate pH conditions Links to plants minimum pH tolerances Links to plants maximum pH tolerances

Soil texture Soil drainage Soil flooding Soil hydric conditions Soil salinity Soil layer

MUID Minimum pH Maximum pH

Crop/forage data Soil yields

MUID Crop/forage name

Links soils regions to suitable crops and forages Suitable crops/forages

Conservation Service (NRCS), National Plant Data Center (Natural Resource Conservation Service, 1998). The database contains over 500 records and over 50 plant attributes. Table 3 lists the principal attributes from the plant database utilized by FADSS. Data tables on climate, soils, crops, trees and grasses form a relational database from which the appropriate agroforestry species can be queried.

3.2. Knowledge acquisition The development of FADSS also involved gathering existing agroforestry information from the literature and obtaining expert advice. Expert ‘knowledge’ was extracted for the purposes of evaluating the variety of management options to be

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considered when planning agroforestry systems and determining the ‘ideal’ tree characteristics for different agroforestry systems and management objectives. Experts on agroforestry systems were asked using questionnaires to evaluate the following sets of criteria: (1) tree characteristics that need to be considered when establishing the agroforestry system, (2) economic and environmental services which the agroforestry land use can provide, and (3) management practices and/or Table 3 Plants database structure and data fields utilized by the FADSS Category

Attributes/fields used by FADSS

Category

General

Common name

Morphological/physiolog Growth rate ical descriptions continued Height at maturity

Scientific name Climatic adaptability

Soils adaptability

Minimum frost free days Maximum precipitation tolerance Minimum precipitation tolerance Maximum temperature tolerance Minimum temperature Production suitability tolerance Anaerobic tolerance Drought tolerance Moisture use Salinity tolerance Soil texture Adaptability Maximum soil pH tolerance Minimum soil pH tolerance

Morphological/physiologi Plant type cal descriptions Allelopathic Carbon/nitrogen ratio Foliage porosity (winter and summer) Foliage texture Growth form Resprout ability Growth habit Shade tolerance

Attributes/fields used by FADSS

Life span Nitrogen fixation Root depth minimum Vegetative spread Berries, nuts or fruits production Fodder suitability Fruit/seed abundance Fuelwood suitability Lumber suitability Palatable to humans Post suitability Pulpwood suitability

Plywood veneer suitability Management suitability Coppice potential Fertility requirement Fire tolerance Palatable to browsing, grazing animals Type of propagation Hedging tolerance Toxicity Planting density (high and low)


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choices that need to be considered for the establishment and maintenance of the agroforestry system. Experts utilized the tree database structure as a guide in selecting the ideal tree characteristics for different management options or criteria elicited by them. The information gathered from the literature and experts was essential in designing the application and composing queries for agroforestry species selection.

4. System development FADSS, designed to run on a typical PC using Windows 95, was developed using Borland Delphi. The use of Delphi was selected for several reasons. For instance, its object-oriented Rapid Application Development system and use of relatively simple Pascal codes, allows the initial application development phase to concentrate on designing an efficient system structure without having to concentrate on tedious programming details. Delphi also allows the integration of MapObjects by the Environmental Systems Research Institute for the incorporation of map components and spatial data. Finally, Delphi contains tools for database access and queries using Standard Query Language (SQL). FADSS is designed to be simple to use, eliminating the need to spend time finding and entering the necessary data. The graphical user interface allows the user to select an area of interest on a map and choose a variety of management options using checkboxes. The use of GIS enables the user to explore geographically without having to know specific climate and soils information. FADSS is structured around a relational database management system which links spatial, soils, climate, and plant data tables. Specific SQL queries for suitable trees, shrubs, forages or crops are built during run-time according to climate and soils characteristics of a selected area and/or management option inputs made by the user. Simple IF-THEN structures are used to evaluate soils, climate and management parameters selected by the user.

5. System structure The application structure consists of four sequential components, informing the user about agroforestry and enabling them to explore the potentials of agroforestry practices in a location of interest. The four components include: (1) introduction and agroforestry information, (2) site selection, (3) agroforestry system selection, and (4) management options and results. Fig. 1 shows a diagram of the different components and their relationships. The application components follow a logical sequence that anyone would consider when evaluating suitable tree, shrub or crop species for agroforestry systems.

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Fig. 1. Diagram of the FADSS application structure and system components indicating different inputs and outputs.

5.1. Introduction and agroforestry information (screen 1) In the introductory screen, the user obtains information on agroforestry through pushbuttons. Also on this screen, the user can enter the agroforestry DSS in the application. Fig. 2 shows screen 1 of FADSS containing this component.

5.2. Site selection (screen 2) Geographical location within the state is an obvious factor related to the adaptability of trees and other species. The first types of variables FADSS considers when deciding on suitable agroforestry species are biophysical, more specifically climate and soils characteristics. In the site selection component of the application, the user is presented with a map of Florida divided into counties. A tool bar above the map allows the user to zoom and pan to find a specific area of interest. When the map is zoomed-in to about the geographical extent of an average county, the user then sees the major roads and different USDA general soils classified in the area. From the toolbar above the map, the user may also select and extract the climate and soils information in an area of interest. These climate and soils parameters are then used for agroforestry species selection. Fig. 3 shows this component in screen 2 of FADSS.


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Fig. 2. Introduction screen (screen 1) of the FADSS used to begin the tree selection decision support system and obtain agroforestry information.

Fig. 3. Site selection screen of the FADSS showing climate and soils parameters of a selected site used for tree selection.

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The first part of an SQL query built during run time is based on climate and soils parameters and conditions associated with a selected location. Climate parameters of annual precipitation, minimum temperature and average growing season are represented and extracted at the county level. Soils information including pH, texture, drainage and flooding conditions are linked to the general soils areas mapped out by the USDA-NRCS State Soil Surveys. After a location has been selected and the user continues using FADSS, the SQL query of the plants database will include statements that select trees adapted (or tolerant) to numerical parameters such as rainfall, temperature and soil pH and descriptive conditions such as drainage type and texture composition. Fig. 4 shows a sample Delphi script which tests for a variety conditions and builds the appropriate SQL queries that incorporate climate and soil variables of the selected location. A very simplified sample format of this script would be as follows: If (annual rainfall=integer parameter) then Add to SQL query (‘Select from trees where minimum precipitation tolerance \:integer parameter’) If (soil texture=sandy) then Add to SQL query (‘and adaptability to coarse textured soil= true’)

5.3. Agroforestry system selection (screen 3) While there are many similar management objectives and options among the major agroforestry practices, they are considered very different types of agro-ecological systems. For this reason, it was decided to treat each one of them on a separate basis. FADSS excludes the forest farming agroforestry system since it involves production of specialty crops in forested land. The Agroforestry System Selection component simply serves as a doorway to evaluate the potentials of each system in terms of possible species which can be incorporated into them. If the user still needs additional information on each agroforestry system, they may obtain their descriptions in this component before proceeding. Fig. 5 shows screen 3 of the Agroforesry System Selection component.

5.4. Management options and results (screens 4 – 7) As mentioned above, each agroforestry system is treated separately. Consequently, this component is actually composed of four sub-components for each agroforestry system considered. In this component the user selects a major management objective, the products or environmental services desired, and/or the management practices implemented or needed. Fig. 6 shows screen 4 representing the sub-component of management options for alley cropping systems. In the case of alley-cropping, the user may select between two types of systems. One emphasizes


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Fig. 4. Sample script used to build queries during run-time based on site climate and soil characteristics.

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silvicultural production and plantations, more akin to temperate alley cropping systems, and another emphasizes continuous crop production, more akin to tropical type alley cropping systems. These selections largely determine what type of tree or

Fig. 5. Agroforesty system selection screen of the FADSS used to select one of the different agroforestry systems considered for tree establishment and retrieve further information on each system.

Fig. 6. Alley cropping system management options screen of the FADSS indicating different options for long-term management, economic or environmental services, and management practices.


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shrub is ideal for that type of alley cropping system in terms of their morphological and physiological characteristics. Additionally, the user may select an economic product (e.g. lumber, pulp or posts) they wish to produce or a specific management practice (e.g. pruning, burning or fertilizing) they plan to implement. Based on the management objective and options criteria selected in this component (or each system sub-component), the required statements are added to a final SQL query of the plants database. Fig. 7 shows a sample script which tests for management options and selects the ideal tree for an alley cropping system. A query button then presents the final results in an output table(s). For example, in the case of silvopastoral systems, the output consists of a list of potential tree or shrub species as well as potential forages that can be incorporated in the selected location. On the other hand, for alley cropping systems, the output consists of potential trees, shrubs and crops suitable to the selected location.

6. Discussion Currently, promotion and adoption of agroforestry alternatives by farmers and landowners in the Southeast is severely handicapped by lack of research and available information as well as the poor awareness of many landowners, extension agents and scientists. FADSS is intended to bridge the information gap and provide a tool for insights in agroforestry planning and species selection. However, an agroforestry decision support system can only bring a modest contribution towards the acceptance, establishment and development of agroforestry in the United States, and its success depends on continued research and on-site extension efforts. For that matter, it was recognized during the development of FADSS that there was an extreme lack of information derived from applied and basic scientific research on agroforestry and potential agroforestry species in the Southeast. This is considered a major shortcoming of FADSS. Conclusive and quantitative data on ideal tree or shrub characteristics for agroforestry systems under different site criteria and management practices are extremely scarce. Moreover, information contained within present tree and shrub databases is somewhat limited, specifically concerning plant attributes of importance to agroforestry tree selection. Nevertheless, we believe that this agroforestry decision support system can guide farmers, landowners, extension agents or scientists in planning agroforestry systems and selecting tree and shrub components based on logical biophysical parameters and rational assumptions on site and management criteria. FADSS is currently being tested by agroforestry and forestry cooperative extension agents at the School of Forest Resources and Conservation, University of Florida. After further refinement, it will be evaluated by county extension agents, landowners and farmers in Florida. Final refinements will then be made during this evaluation phase.

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Fig. 7. Sample script used to query alley cropping agroforestry species according to management options.


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FADSS’s simple design allows a flexible framework from which additional applications for other counties or states in the US or elsewhere could easily be developed. For one, the plant database is suitable or adaptable to any state in the US. The plant database can be readily obtained from the NRCS NPDC and tailored to fit any geographical region. Perhaps more difficult is the accessibility of spatial data for other states. In the case of Florida, the Florida Geographic Data Library provides this data at the county level. With the popularity and increasing use of GIS, other states have developed their own spatial data libraries which will allow their use within the FADSS framework to develop further agroforestry decision support systems for other states in the region.

References Association for Temperate Agroforestry, 1997. The Status, Opportunities and Needs for Agroforestry in United States. University of Missouri, Columbia, MO. Natural Resource Conservation Service, 1998. Natural Resource Conservation Survey. Plants Database Center, PO Box 74490, Baton Rouge, LA 70874-4490. Pearson, H.A., 1995. Agroforestry in the interior highlands. Agrofor. Syst. 29, 181 – 189. Plantinga, A.J., Buongiorno, J., 1990. Determinants of changes in non-industrial private timberland ownership in the United States. J. World Forest Resour. Manag. 5, 29 – 46. Schultz, R.C., Colletti, J.P., Faltonson, R.R., 1995. Agroforestry opportunities for the United States of America. Agrofor. Syst. 31, 117–132. United States Department of Agriculture, 1999. USDA 1996 Farm Bill Conservation Provision. USDA, PO Box 2840, Washington, DC 20013. Williams, P.A., Gordon, A.M.., Garrett, H.E., Buck, L., 1997. Agroforestry in North America and its role in farming systems. In: Gordon, P.A., Newman, S.M. (Eds.), Temperate Agroforestry Systems. CAB International, New York. Zinkhan, F.C., Mercer, D.E., 1997. An assessment of agroforestry systems in the Southern USA. Agrofor. Syst. 35, 303–321.

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A GIS-based database management application for

A GIS-based database management application for

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