2. 1 APPLICATION OF DATA MODELING In natural resources and forest management Yujia Zhang and Bruce E. Borders

3. 2 INTRODUCTION A database is a collection of related data. In forestry, Data are typically stored in electronic files with additional information stored on field tally sheets.

4. 3 During data collection, data formats may be changed, or files may be revised by users individually without informing others, which causes problems in data storage and analysis.

5. 4 The traditional data storage approach results in redundancy in data storage. For example, stand information stored in a tree level file takes large storage space and increases storage cost.

6. 5 Relational database management systems (RDBMS) provide a powerful tool to store and update forest data, review relationships among individual components, and model forest dynamics.

7. 6 Data modeling is a conceptual or logical design of a database. A data model is a set of concepts that refers to types, relations, constraints, and operations of data. DATA MODELING

8. 7 The basic operations of a data model include accessing and updating the database. We use an entity-relation (ER) data model for conceptual analysis and implementation of database.

9. 8 The concepts involved in the ER model are entities, attributes, and relationships. An entity is an object, attributes are descriptions of the properties of the entity, and relationships are interactions among entities.

10. 9 Data are stored in tables. A row in a table is called a tuple, a column header is called an attribute, and a table is called a relation. The data illustrated here are from the Consortium for Accelerated Pine Plantation Studies (CAPPS).

11. 10 The CAPPS plantations were established in 1987. The applied silvicultural treatments are herbicide (H), fertilization (F), herbicide and fertilization (HF), and control (C).

12. 11 A relation schema R of degree n can be denoted as: R (A 1, A 2, …, A n ) where R is the name of the relation and A 1, A 2, …, A n are attributes. RELATION SCHEMA

13. 12 The relation schemas in our data model are: STAND (PlOT_ID, Location, Block, Plot, FirstGrowingSeason, Treatment); TREE (ID, PlantationAge, TreeNumber, DBH, Height, CrownHeight, CronartiumQuartileCode, TipMothCode, DamageCode, Plot_ID);

14. 13 GROUNDCOVER (ID, SubPlot, PlantationAge, PercentAndropogon, HeightAndropogon, PercentGrass, HeightGrass, PercentBroadLeaf, HeightBroadLeaf, Plot_ID) SMALLCOMPETITOR (ID, SubPlot, PlantationAge, Species, TreeHeight, CrownLength, CrownWidth, Plot_ID)

15. 14 LARGECOMPETITOR (ID, Subplot, PlantationAge, Species, TreeHeight, DBH, CrownHeight, BaseHeight, Plot_ID));

16. 15 A relation is a set of tuples. An attribute with distinct value can be used as a primary key to identify a tuple. The value of the primary key must not be null, which is called the entity integrity constraint.

17. 16 A foreign key is needed to maintain the consistency among relations. For example, tree level information and stand level information can be combined together using a foreign key, PLOT_ID.

18. 17 The operations for a relational database include select, project, and join. The notation for operation select is:  ( ) To select trees with DBH larger than 10 cm, we use:  DBH>10 (TREE)

19. 18 Operation project selects certain columns from a table:  ( ) To list tree number, plantation age, and tree height, we use:  TreeNumber, PlantationAge, Height (TREE)

20. 19 Operation join combines two tuples from two relations together: R|  | S To access all trees from location Athens, we use: (TREE)|  | LOCATION=ATH (STAND)

21. 20 The RDBMS installed on the server is Oracle8 Enterprise. Each user can access the database over a network. Data files used by each user can be stored either in the server or PC, or in other external devices.

22. 21 The implementation of a data model includes establishing relations and queries. The following query is used to obtain some stand level information from relations STAND and TREE. DATA MODEL IMPLEMENTATION

23. 22 Assuming a forester wants to know the number of trees per plot, average DBH and average height for each age in stands located in Athens that have accepted herbicide and fertilization, the regarding query is:

24. 23 select s.Location, s.Block, s.Plot, s.FirstGrowingSeason, s.Treatment, t.PlantationAge, count(t.TreeNumber), avg(t.DBH), avg(t.Height) from STAND s, TREE t where s.Plot_ID = t.Plot_ID and s.Location = 'ATH' and s.Treatment = 'HF' group by s.Location, s.Block, s.Plot, t.PlantationAge;

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27. 26 Forest data are characterized with large size of records, complicated relationships, and a diversity of data types. The traditional approach is far from satisfactory for data storage and manipulation. SUMMARY

28. 27 In our database, The relations among data files eliminate redundancy in data storage. All files are stored in a server, which ensures updated data available for each user.

29. 28 For data safety, the redundant hard disks in the server store the mirrored data that can be recovered when the server is down. Also, Oracle8 backup manager can backup the whole database to external storage devices.

30. 29 Users can be granted privileges at different levels by the database administrator (DBA) to view, revise, and transfer files. The database is protected from unauthorized access.

31. 30 Data modeling helps establish a comprehensive database including tree, soil, hydrology, GIS, and wildlife data, which facilitates natural resources and forest management.