Any method for assessment has several positive and negative aspects that make the method suitable or unsuitable under a given set of conditions and resources. These may be the factors such as costs , time, technical manpower availability, and so on. These aspects can be assessed systematically to derive a set of criteria and the corresponding indicators. Criteria are the basis against which a resource is to be assessed. The indicator is the proof of the occurrence or non-occurrence of the resource/methodology and is judged accordingly. Thus, the criteria and indicators (C&I) are the basis on which the utility of a resource or a system can be judged. These C&I, when selected properly and administered judiciously, can provide a better picture of the utility of a system or method. The broad set of C&I for TOF assessment is shown in Table 4.
Table 4. Criteria and indicators for the assessment of trees outside forests
Attributes/criteria for assessment |
Indicators |
Precision |
Standard error |
Time |
Time per district |
Cost |
Cost per district |
Robustness/practicability |
- Training person-days |
Replicability |
Applicability to varying situations (macro-level
applications) |
Table 5. Scoring scheme
Indicator |
Methodologies (scores) |
||||
Ground sampling |
Aerial photography |
Remote sensing |
Remote sensing + ground survey |
Secondary information |
|
1 |
2 |
3 |
4 |
5 |
|
Precision |
8 |
9 |
5 |
8 |
3 |
Time |
4 |
6 |
7 |
7 |
8 |
Cost |
5 |
3 |
4 |
1 |
8 |
Robustness |
3 |
5 |
6 |
9 |
2 |
Replicability |
2 |
2 |
5 |
9 |
2 |
Total score |
22 |
25 |
27 |
34 |
23 |
*The rating scale is a preferential scale, ranging from 1 to 10 in this case.¨ Precision: a high value indicates a higher preference
¨ Time: a higher value indicates greater preference.
¨ Cost: a lower value indicates higher costs and thus lesser preference.
¨ Robustness: a higher value indicates greater robustness.
¨ Replicability: a higher value indicates more replicability (e.g. ground sampling (score 2) indicates that the method is less replicable over a period of time because the time required for ground sampling is lengthy and during that period the vegetation changes substantially.)
Thus, remote sensing and ground survey (column 5) carries 34 points and is the best method considering all 5 criteria namely precision, time, cost, robustness and replicability.
Replacing the numerical values by qualitative information was also suggested. A topographic plot design matrix was designed as shown in Table 6.
Table 6. Topographic plot design matrix
Criteria |
Topography |
Geometry of plots |
|||
Mountain |
Flat |
Block |
Linear |
Scattered |
|
Area |
Small |
Large |
1.0 ha |
0.1 ha |
5 ha |
Shape |
Uneven |
Even |
Square |
Strip |
Round |
Design |
Nested |
Quadrant |
Quadrant |
Transect |
Case-wise |