|Special Public Works Programmes - SPWP - Planting Trees - An Illustrated Technical Guide and Training Manual (ILO - UNDP, 1993, 190 p.)|
|Appendices - Technical sheets|
Replacement planting is an expensive measure. The cost per seedling is double or triple compared with the first planting. Therefore it is necessary to decide carefully if replacement is needed or not. This is done by calculating the survival rate.
Survival is difficult to estimate by simply looking at a plantation site. As looking at each and every seedling planted would be extremely time-consuming, the survival of a portion of the plants is checked. The check should include all sections of the plantation (not only the one closest to the road). The best procedure is to check a number of rows equally distributed across the planting area. In areas of less than 2 hectares, you should sample every 5th row and in areas of above 2 hectares you should sample every 10th row.
For every spot in the row where a tree was planted, mark on a piece of paper whether it is dead/missing or alive. An example of a survival count form is given on the following page. Recording plant survival separately for each line will help you to see in which part of the plantation replacement planting might be needed.
If the plantation consists of more than one species, survival should be checked species-wise. This together with information on how many seedlings were planted of each species (noted on the plantation history form), will make it possible to get a good idea of the survival of the different species. Together with estimates of the average height of the species, it can also provide useful information for planning future plantations.
The survival rate is calculated by dividing the number of surviving plants by the total number of plants and multiplying by 100.
Replacement is needed only if more than two out of ten plants are dead and only where at least two successive seedlings have failed. If the overall rate of failure is less than 20 per cent, replanting is carried out only in places where failures are heavily concentrated.
To make replacement planting easier, bring sticks or ribbons along when counting. Mark any part of the plantation with a high failure rate.
The difference in size between the plants used for replacement and the plants at the site should be kept as small as possible to minimize competition. The survival rate should be checked in time to carry out the replacement planting one year after planting, at the latest, in fast-growing plantations. In slower-growing plantations it should be checked in tune to carry out replacement planting during the second year after planting.
During the survival count, the height growth should be estimated and noted.
Survival count form
Date inspected: ____________
Inspected by: ______________
Planting date: _______
ROUGH SURVIVAL RATE SPECIESWISE
Velvel 0.6 m
Vagai 0.4 m
Usilam 0.2 m