6.1. IN SITU CONSERVATION
6.2. EX SITU CONSERVATION
There are basically two methods used in forest genetic resource conservation, namely the in situ (on site) and the ex situ (off site) conservation methods.
The in situ conservation method is the protection and maintenance of species populations in the ecosystem in which they occur. It is especially adapted to species which cannot be established or regenerated outside their natural habitats. According to Shaffer (1981), there are four main factors which influence the survival of in situ conservation populations: environmental stochasticity, natural catastrophes, demographic stochasticity and genetic stochasticity.
The ex situ conservation method is the protection and maintenance of genetic resources outside their original environment for which the reasons may be:
- to safeguard populations which are in danger of physical destruction, for example, if intensive pressure exists on an important species (or the area where it grows) and the protection in situ is not possible;- to safeguard populations which are in danger of genetic deterioration;
- to ensure a readily available supply of productive material e.g. by creating seed production stands;
- to allow commercial improvement of a species through breeding activities in order to produce genotypes which give higher economic yields.
In an effort to ensure sustainable management and utilization of forest resources in the country, the Government of the Republic of Zambia through the Forestry Department has set aside certain forest areas as protected forests or forest reserves. There are at the moment 432 forest reserves in the country which cover nearly 7.4 million hectares. There are also 6.4 million hectares of forest in national parks which are protected by the National Parks and Wildlife Services. The areas covered by national and local forests designated as protected forests are indicated in tables 5 and 6.
TABLE 5: FOREST AND TREE COVER IN ZAMBIA, 1996
Provinces |
Areas (million ha) |
|||||
Forest reserves |
Forest in open areas |
Game management areas |
National parks |
Trees outside forests |
Total |
|
Central |
0.59 |
1.56 |
2.18 |
1.23 |
1.98 |
7.54 |
Copperbelt |
0.52 |
0.79 |
0.44 |
0.00 |
0.66 |
2.40 |
Eastern |
0.84 |
0.59 |
2.92 |
0.36 |
1.11 |
5.83 |
Luapula |
0.38 |
1.72 |
0.30 |
0.10 |
20.01 |
4.52 |
Lusaka |
0.03 |
0.19 |
0.65 |
0.51 |
0.36 |
1.75 |
Northern |
1.12 |
5.35 |
0.96 |
1.38 |
3.13 |
11.94 |
North-Western |
0.41 |
1.70 |
2.40 |
0.87 |
1.63 |
9.00 |
Southern |
0.67 |
1.45 |
1.52 |
1.02 |
1.97 |
6.64 |
Western |
0.62 |
1.13 |
4.27 |
0.87 |
3.03 |
9.90 |
Total |
7.18 |
14.48 |
15.64 |
6.35 |
15.88 |
59.52 |
Provinces |
Areas (ha) |
||
National forests |
Local forests |
Total |
|
Central |
320326 |
223097 |
543423 |
Copperbelt |
269379 |
231 |
269610 |
Eastern |
678864 |
158963 |
837827 |
Western |
214193 |
276418 |
490611 |
Northern |
799286 |
310969 |
1110255 |
North-Western |
1866560 |
356383 |
2222943 |
Southern |
207690 |
356654 |
564344 |
Total |
4356298 |
1682715 |
6039013 |
TABLE 7: LIST OF BOTANICAL RESERVES BY PROVINCE
Provinces |
Number of districts covered |
Number of botanical reserves |
Copperbelt |
5 |
10 |
Southern |
4 |
6 |
Northern |
6 |
11 |
Eastern |
1 |
3 |
Western |
2 |
6 |
Central |
3 |
5 |
Luapula |
4 |
6 |
North-Western |
4 |
6 |
Total |
29 |
53 |
Very little work has been done on ex situ conservation especially for indigenous tree species. So far, only one species, namely Baikiaea plurijuga, has been tested outside its natural environment on very small trial plots on the Copperbelt. Results have shown very high rates of growth on the Copperbelt, where rainfall is around 1 275 mm per annum, compared to about 726 mm per annum where Baikiaea plurijuga grows naturally. In the plantation trial plots at Masese, which is within the natural habitat for B. plurijuga, a mean height of 6.7 meters was obtained at the age of 33 years, whereas in the trial plot established at Chati on the Copperbelt, a mean height of 17.1 meters was attained at the age of 34 years.
More work on ex situ gene conservation has been conducted on exotic species. Between 1977 and 1979, 70 hectares of gene conservation stands were established in Zambia for testing three provenances of Pinus oocarpa from Central America (Bonete, Mt Pine Ridge and Yucul) and two provenances of Eucalyptus tereticornis from Australia. The gene conservation stands were established at Chati and Siamambo under a FAO (Food and Agriculture Organization of the United Nations) coordinated ex situ Gene Resource Conservation Project. Other countries which participated in this project were Australia, Brazil, Congo, Cuba, India, Ivory Coast, Philippines, Tanzania and Thailand. Kenya joined in 1997. A total of 5 tropical pines and 2 eucalyptus, with a total of 39 provenances and 76 different seedlots, were used in the project. Results from Zambia have been very good except for the illegal cutting of timber especially eucalyptus poles by villagers around Siamambo (Sekeli, 1999).