1. NATURAL RESOURCES IIClassification of NRs Dr. J. Kivelia Department of Geography University of Dar es Salaam

2. Outline • Approaches in classifying NRs • Typology/Classification of NRs • Stock resources • Flow resources • Renewability/non-renewability of NRs

3. Approaches in Classifying NRs • Several approaches in classifying NRs • The common one divides NRs into two broad classes, namely: • Stock resources (non- renewable) • Flow resources (renewable)

4. Typology/Classification of NRs

5. 1. Stock resources • All resources that have taken millions of years to form, e.g. minerals, land, etc. • Viewed as fixed in supply, i.e. non-renewable b’se of time-span of formation (long), • The long time-span of formation makes the resource exhaustible over a short time of use

6. Stock resources (cont’d) • Have different levels of exhaustion • Those consumed by use, affecting future availability, e.g. fossil fuels. • These need optimal management strategies • Those which can be recycled for use over & over again, e.g. copper, tin, iron, etc. i.e. all metals Technology exists to recycle these. Stock remains generally constant overtime

7. Stock resources (cont’d) • Those which are theoretically recoverable, e.g. potash that has been used as fertilizer can be recovered from the soils • Only a small proportion can be recovered • With time, the recoverable proportion can be too dispersed or mixed with impurities, such that meaningful recovery becomes impossible. Will you consider stock resources as completely non-renewable?

8. 2. Flow resources • Those resources naturally renewed within a sufficiently short time-span which is reasonably observable to humankind. • Examples include air, water, soils, animal/plant life, etc. • Under some conditions, some can be non-renewable. • These are known as critical zone resources (CZR)

9. Some are indefinitely renewable if use remains at or below their capacity to regenerate, e.g. solar energy, wind, water, etc. • These are known as non-critical zone resources (NCZR) • Some NCZR can be temporarily depleted b’se of over-use, eg. Over-pumping of rivers, too high levels of effluents/discharge to water-bodies which reduce their capacity regulate wastes • Will you consider flow resources to be always renewable?

10. Renewability of some flow resources, particularly the critical zone resources, depend on human activity – misuse, overuse Viz. optimum uses. • They can be exploited to depletion/exhaustion if RATE of use exceeds RATE of natural replenishment • Remains too small to reproduce, or • highly vulnerable to predation to extinction

11. Examples of exhaustion to depletion • Over-fishing, over-hunting, destruction of habitats, • Activities accelerating processes of salinization, desertification, serious soil erosion to critical levels of renewal, etc

12. Why renewable NRs become non-renewable • Renewable resources may become non-renewable due to: • Use to extinction/exhaustion for resources whose renewal depends on biological reproduction, leading to: • Too small numbers, dispersed populations, etc. thus subjected to predation, extinction. etc. • Over-use or mis-use of renewable resources like soils to situations of severe degradation, salinization & desertification beyond recovery

13. Why renewable NRs become non-renewable • Non-critical NRs may suffer only temporary depletion due to: • Depletion of river water thru over-pumping • Reduced capacity of water-bodies to regulate wastes due to high levels of effluents & sewage discharge • A decline in quality of local air resources due to pollution

14. Conclusion • Man defines and classifies NRs • Essential difference btn stock & flow resources lies in the time-scales over which they develop and come to existence • All NRs are products of natural cycles, therefore they are all renewable but AT VERY DIFFERENT RATES

15. FOOD FOR THOUGHT • Critically analyse the “exhaustive” or “non-renewable” perceptions of stock resources. • ‘All natural resources are products of natural cycles, therefore their classification into renewable and non-renewable resources is essentially meaningless’. Discuss.