A Global Map for Forest Conservation

A Global Map for Forest Conservation

Ryosuke Shibashki, Yoshiaki Honda, Shunji Murai
Institute of Industrial Science, The University of Tokyo
7-22-1, Roppongi, Minato-ku, Tokyo 106, Japan

Abstract
Nowadays deforestation is one of the most serious global problems. It is of urgent importance to moderate deforestation and to promote reforestation to prevent global warming due to the increase of carbon dioxide in the atmosphere. In this study a global map for forest conservation / reforestation is made by evaluating land conditions such as vegetation and soil. The map will be one of basis for policy making to promote carbon dioxide fixation and moderate the discharge.

Introduction
Rapid deforestation, especially in South East Asia and Brazil Amazon, is one of the most serious global problems. Forests play important role as a source of storing carbon in biomass and soil. Furthermore, forests are the major reservoir of biological diversity on land. And they also have functions to prevent natural disasters such as floods.

It is dais that the current area of the Earth’s forest is 4.3 billion hectare and that the decreasing rate is only in the tropical areas 1.1 million hectares per year (IPCC 1990). The main reasons of deforestation are the development of croplands, burn agriculture, stock farming and commercial cut down. These deforestation not only decrease the quantity of carbon fixed by forests, but also releases the carbon to atmosphere which is stores in vegetations and soils by burning live trees for cultivation or fuel timber cut down. The rate of reforestation area is 1.1 million hectare per year in eh tropical areas. It is only 10% of the decreasing area (Kobayashi 1990.) Therefore it is a matter of urgent importance to moderate deforestation and to promote reforestation to prevent global warming due to the increasing of carbon dioxide in the atmosphere. It is reported that the adequate combination of policies to reduce deforestation and to promote reforestation could reduce 24% of the carbon dioxide discharge (World Watch 1988). It is strongly required to make plans of the conservation of forests and reforestation on global scale. However, so far, there have been discussions only on the total area of forest to be conserved and the allowable rate of deforestation from the view point of the global balance of dioxide cycle. It has never been thoroughly investigated which forest- should be conserved or which region has higher possibility of reforestation. With the global evaluation of lands for forest conservation and reforestation the feasibility of an objective value of forest conservation etc. can be examined and action plans can be discussed.

The objectives of this study are;

to evaluate land conditions such as vegetation (current, potential), soil, topography, climate conditions.
to make maps of forest to be conserved and of regions suitable for reforestation. These maps can be a sound basis for policy making to conserve forests and to promote reforestation programs.

Concept of a map for forest conservation and reforestation
by appraising the potential productivity (an ability of carbon dioxide fixation) and the stability of forest ecosystem, the necessity of forest conservation can be estimated from the view point of the reducing carbon dioxide discharge. The forest which forms stable and highly productive ecosystem can be used under adequate management. If the forest ecosystem is largely vulnerable and is lacking in stability it is very likely that the development of cropland in the forest may fail in the long run due tot eh soil or loss degradation after the cut down. The necessity of forest conservation can be approximately evaluated by factors in table 1. On the other hand, the non-forest region where the potential vegetation is forest and the soil and terrain are in good condition (Table 2) would be suitable for reforestation. However, the forest conservation/reforestation map only indicates regions where forest conservation / reforestation is desirable or suitable. The regions where forest must be conserved i.e. forest conservation areas are selected through the comparison with the suitability or desirability for other land uses like cropland or residence. Therefore in addition tot eh suitability for forest conservation/reforestation, the necessity or suitability for other land uses and the impacts of land use changes are also to be discussed to make a land use plan on global scale. The conceptual framework of a global land use plan have to be developed.

Making a map for forest conservation
To make a map for forest conservation, the potential productivity and stability of forest ecosystem have to be evaluated. In this study, natural land conditions as shown in Table 1 are used in the evaluation. The procedure of the evaluation is summarized if Fig. 1. Soil Classification (Table 3)

Soils such as below are suitable for vegetation

soil with rich organism
soil with rich base or silicate which become nourishment
soil which is not stiff.
Soil with good drainage condition.

Table 1 . The conditions to evaluate the necessity of forest conservation

Net Productivity condition	Capability to fix carbon dioxide (primary productivity capability)
Soil condition	Fertility, stability, (Possibility of nonreversible chemical reaction)
Terrain condition	Probability of soil loss and collapse
Climate condition	Severe ness of rain (probability of soil loss) the existence of dry season.
Potential vegetation condition	In a region where potential vegetation is other than forest, it is most difficult to reforest after cutting.

Table 2 . The conditions to estimate the possibility of reforestation

Net Productivity condition	Capability to fix carbon dioxide (primary productivity capability) quantity of bio mass per unit area in reforestation area
Soil condition	Fertility, thickness
Terrain condition	Casiness of reforest work, necessity of defence against soil loss.
Climate condition	Severeness of rain (possibility of soil loss)
Potential vegetation condition	In the region where potential vegetation is forest, conditions are suitable

Table 3 : Soil characteristics and fertility

Fertile	Sterile
Rich organism Rich based and silicateSoft well drainage	Poor organismRich ferric, alminium strongly bleached poorly drainage with hard rock layer

FIG. 1 Flow of making a map for forest conservation.

Table 4 : Fertility ranks of soil class

On the contrary, the following soils ranks lower.

Soil which contains ferrous material or aluminum accumulation

Soil lack of base with poor drainage

FAO-Unesco Soil Map (FAO-Unesco 1971~1981) is used and the soil class are amalgamated into three classes of fertility.

Overlay with the current vegetation map
As a current vegetation map we are Murai, Honda’s vegetation map which is derived from satellite data. We make a map of twenty one categories from three classes of fertility and seven classes of vegetation by map overlay. Figures (Fig. 2~6) are soil fertility map, current vegetation map and soil fertility vs. Current vegetation map.

Discussions

Current vegetation : (Forest) and Soil : (rank 3: the lowest fertility) (a map for forest conservation) These forests areas have soil with no enough organism. Therefore forest conservation effort should be concentrated. Once degraded, it is very difficult to recover as it is. This area is widely spread in the tropics. (fig. 6).
Current vegetation : (Forest) and Soil (rank 1 : the highest fertility) Forest has fertile soil. The utilization of forest including land use changes to cropland, etc. is allowable under proper management.
Current vegetation : (non-forest) and soil : (rank 1: the heighest fertility) These areas are suitable for reforestation.

Conclusions and Future prospects
The land conditions to evaluate the necessity of forest conservation and suitability of reforestation are reviewed. Using these conditions the forest conservation map is made. These map can effectively help to make a forest conservation plan from the view point of reducing carbon dioxide. As for future prospects, it is necessary to improve the forest conservation map using precipitation and terrain data and, by extending the concept of the suitability map to other land use, the conceptual framework of a global land use plan should be formulated.

Reference
(IPPC, 1990) IPCC; Report of the Subgroup on Agriculture, Forestry and Other Human Activities, 1990 .

(FAO-Unesco, 1971~1981) Unesco-Paris; Soil Map of the World 1:5000,000, 1971~1981

(Kobayashi, 1991} Shigeo Kobayasi; Global Warming and Tropical Forest; Forestry technique No. 586, 1991.1

(Murai, Honda, 1990) Shunji Murai, Yoshiaki Honda; Vegetation Mapping Using Global Vegetation Index; V International Congress of Ecology 1990 S2-3-04, 1990.8

(Worldwatch, 1988) Worldwatch Institute; The Flux of Carbon from Terrestrial Exosystems to the Atmosphere in 1980 Due to Changes in Land Use; Geographic Distribution of Global Flux; Worldwatch Paper 83,4. 1988.

Fig. 2 Fertility ranks of soil

Fig. 3 Current vegetation map

Fig.4 Soil (rank1: the heighest fertility) and Curreint Vegetation (non-forest)

Fig.5 Soil(rank2:middle class) and Current Vegetation

Fig.6 Soil (rank3: the lowest fertility) and Current Vegetation (A map for forest conservation)