Ch04

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Based on the current situation and the trends already visible, the expected reference scenario of changes in the region in the next forty years has been specified (Furtado, 1984; GallopÍn, 1986, 1989a; Winograd, 1989a). The scenario implies a partial continuation of the current stagnation followed by a moderate increase in economic growth, but at a level lower than before the current crisis. The pattern of development would be fundamentally unchanged, with an expanding influence of transnational corporations. The regulating role of the state will diminish and market forces will become increasingly dominating. The current social disparities and income concentration would be maintained or increased. Environmental policies will continue to be weak and little enforced, and additional pressures on the ecological base will arise. These will originate in the increasing emphasis on exports for the servicing of external debt, for compensating for the deteriorating terms of trade, and for occupying a niche in the changing world economy. The major dynamic factor in the economy will continue to be industrial production oriented towards the internal market of consumer goods, but with an increasing preponderance of the export sector (raw materials and industrial goods). The new and emerging technologies will enter essentially exoge nously, with the region maintaining its current passive attitude, and generating a number of ecological (as well as social) impacts (GallopÍn 1988). At the international level, closer cooperation between the industrialized countries is expected, leading to a higher coordination of their economic policies. The external debt of the third world would be reformulated, eventually reversing the current net capital flow from the South to the North.

A number of general hypotheses regarding variables directly related to land use have been specified for each scenario, and adjusted for each of the life-zones, by taking into account the current pattern of use, the potential availability of land, the ecological limitations, and the expected pressures for exploitation. The basic reference scenario has been subdivided into a pessimistic and an optimistic subscenario (table 2.5).4 Besides the hypotheses, a gradual decrease in the rate of advance of the agricultural frontier in tropical zones, and a general increase in the intensity of land and inputs use, is assumed for the reference scenario.

The aggregated results from the simulation runs under the reference scenario appear in table 2.6, and the results for each life-zone in table 2.7.

For the whole region, the figures imply the transformation of 4.7 million hectares per year (as an average for the fifty years) of virgin and semi-virgin ecosystems. As much as 80 per cent of the surface will come from the tropical areas, and 20 per cent from the subtropical areas. As much as 45 per cent of this transformed area will become agricultural (30 per cent under shifting agriculture, 15 per cent under permanent agriculture); 30 per cent will be used for grazing and 22 per cent for forest exploitation (timber, charcoal, and fuel-wood).

Two major driving forces account for a large part of the dynamics: ¹ the advance of the agricultural frontier, translating into a decrease of the natural ecosystems and the growth of the agricultural, grazing, and altered areas; and ² the intensification of land use, which in the dry zones increases the wastelands at the expense of the altered ecosystems, and in the humid zones increases the area of altered ecosystems, within which subsistence agricultural activities intensify.

The loss of natural forests will reach from 3.7 to 6.8 million hectares per year, in the optimistic and pessimistic scenarios respectively (table 2.8).

Soil erosion problems originating from deforestation, inappropriate agricultural techniques, overgrazing, and overexploitation will particularly affect the tropical and subtropical mountain rain forests and the subtropical rain forest of Central America, the Andean countries, and Brazil.

Table 2.5 General hypothesis of the simulation scenarios for tropical Latin America

Variable	Pessimistic refer- ence subscenario	Optimistic refer- ence subscenario	Sustainable scenario
Population growth	From 2.2%/yr in 1980 to 1.2% in 2030	From 2.2%/yr in 1980 to 1.2% in 2030	From 2.2%/yr in 1980 to 1.2% in 2030
Average growth of per capita agri- cultural production	Within the range 0 to 0.5%/yr	0.5%/yr	Within the range 0.5 to 1%/yr
Average growth of crop yields	0.5%/yr	1%/yr	Within the range 1.5 to 2%/yr.
Animal carrying capacity (animal units)	From 0.6AU/ha in 1980 to 0.9AU/ ha in 2030	From 0.6AU/ha in 1980 to 1.2AU/ ha in 2030	From 0.6AU/ha in 1980 to l.5AU/ ha in 2030
Annual harvested area	65% of the agri- cultural land in	65% of the agri- cultural land in 1980; 75% in 2030	65% of the agri cultural land 1980; 85% in 2030
Land allocation	Emphasis on ex- port crops	Emphasis on ex- port crops; sec- ondarily, on crop diversification for internal con- sumption and export	Emphasis on crop diversification for internal con gumption and export; secon darily, on export cross

Source: GallopÍn, 1989a; Winograd, 1989a.

Table 2.6 Simulated total changes in fund categories for tropical Latin America 1980-2030, under the reference scenario

	1980	2030	Total change (%)
Natural	46.0	33.5	- 27.1
Altered	20.5	19.2	- 5.6
Agricultural	7.3	11.2	+52.4
Grazing	23.5	30.2	+ 28.2
Plantations	0.3	1.5	+ 459.6
Urban	0.6	1.3	+ 96.5
Wastelands	1.8	3.1	+72.9
Total	100.0	100.0

Table 2.7 Evolution of fund use under the reference scenario (10³ Km²)

	Natural		Agricultural				Grazing
	1980	2000	2030	1980	2000	2030	1980	2000	2030
T&ST F(8,124)	5,795	5,193	4,436	583	744	849	683	745	1,040
T&ST MF(1,251)	158	98	48	178	273	319	473	472	550
T&ST DF(4,747)	1,068	884	678	377	486	576	1,612	1,861	2,183
TS(1,066)	423	367	286	32	46	51	485	543	627
D&M(186)	52	43	34	8	8	8	42	50	53
P&P(922)	173	145	112	23	43	49	422	437	487
T&ST DDS(1,162)	354	309	252	79	92	99	392	366	328
Tropical L. America (17,458)	8,023	7,042	5,845	1,280	1,692	1,951	4,109	4,474	5,268
Latin America (20,417)	8,287	7,286	6,071	1,562	1,995	2,284	5,476	5,806	6,597

Source: Winograd, 1989a.

Key: T&ST F = tropical and subtropical moist forests
T&ST MF = tropical and subtropical montane moist forests
T&ST DF = tropical and subtropical dry forests
TS = tropical savannas
D&M = tropical and subtropical deltas and mangrove forests
P&P = paramo and puna
T&St DDS = tropical and subtropical deserts and dry scrub

Watershed degradation due to deforestation and damming will affect mainly the tropical and subtropical mountain and lowland rain forests in Central America, the Andean countries, parts of South America, Brazil, and Mexico.

Floods due to watershed degradation, deforestation, and natural processes will mainly affect the tropical and subtropical mountain and lowland rain forests in Central America, the Andean countries, and Brazil, and some of the savannas and subtropical forests of the Andean countries and Brazil.

Plantations			Urban			Altered			Wastelands
1980	2000	2030	1980	2000	2030	1980	2000	2030	1980	2000	2030
20	62	122	17	26	39	1,023	1,350	1,634	3	4	4
6	16	31	41	45	53	390	338	235	5	9	15
21	58	110	20	31	47	1,577	1,310	1,001	92	117	152
0	0	0	1	2	3	125	109	99	0	0	0
0	0	0	2	3	4	82	81	84	0	1	3
0	0	0	6	9	12	253	238	202	45	50	60
0	0	0	26	42	64	146	132	119	165	223	302
47	136	263	113	158	222	3,576	3,558	3,374	310	404	536
58	165	316	136	187	264	4,505	4,467	4,217	393	511	688

Desertification associated with overgrazing, excessive extraction of fuelwood, and cyclic droughts will advance mainly in the puna, the dry tropical forests, and the tropical and subtropical desert shrublands in the Andean countries, Brazil, Peru, Mexico, and Central America.

Agricultural pollution will continue in many parts of the cultivated lands in the whole region, and agricultural, industrial, and urban pollution will increase in the deltas and mangrove forests of Central America, the Caribbean, and parts of South America.

The fuelwood deficit will continue to increase in most of the ecosystems. It is anticipated that, by the year 2030, not less than 50 million people will suffer from an acute fuelwood deficit in the western dry areas, the Andean plateau, and in densely populated zones.

The results from the models suggest that agricultural land will become critically scarce by the year 2030 in tropical Latin America, being reduced from 0.46 to 0.27 hectares per person on average. A total of 710 million people (90 per cent of the projected total population of Latin America) will be living in the tropical areas. In order to produce enough food for the population, agricultural inputs will have to increase from the current low to an intermediate level, or to an intermediate to high level (the latter is comparable to the level applied today in the industrialized countries) (Gómez and GallopÍn, 1989a, and table 2.4, above). The situation will be worst in the mountainous areas; the results indicate that agricultural land availability will be reduced to 0.13 hectares per person in the tropical and subtropical mountain forests, and to 0.11 ha/person in the paramo and puna.

Table 2.8 Anticipated losses of natural forests in tropical Latin America according to two reference sub-scenarios (figures in parentheses indicate percentages of total surface of the corresponding life-zone)

	1980	2000		2030
	1980	O	P	O	P
T&ST F
Natural condition(10³ Km²)	5,795 (71)	5,193 (64)	5,035 (62)	4,436 (55)	3,512 (43)
Annual deforesa- tion (Km²/year)	33,650	30,100	38,000	25,550	50,750
Deforestation rate( %/year)	0.58	0.58	0.75	0.58	1.40
T&ST MF
Natural condition(10³ Km²)	158 (13)	98 (8)	80 (6)	48 (4)	0 (0)
Annual deforestation (km³/year)	3,850	3,000	3,900	1,700	0
Deforestation rate(%/year)	2.4	3.0	4.8	3.5	0
T&ST DF
Natural condition(10³ Km²)	1,068 (22)	884 (19)	793 (17)	678 (14)	274 (6)
Annual deforestation (km³/year)	12,950	9,200	13,750	7,000	17,300
Deforestation rate(%/year)	1.2	1.0	1.7	1	6.3

Key: 0 = optimistic reference sub-scenario.
P = pessimistic reference sub-scenario.
T&ST F = tropical and subtropical moist forests
T&ST MF = tropical and subtropical montane moist forests
T&ST DF = tropical and subtropical dry forests

Species extinctions could range from 100,000 to 350,000 species in the next forty to fifty years, considering only those existing in dense tropical forests (Lugo, 1988; Winograd, 1989a).

Table 2.9 Carbon contents of forest biomass in Latin America (tons C/ha)

Life-zone	Natural	Altered
Life-zone	Natural	fallow	exploited
T&ST F	164	63	119
T&ST DF	40	19	-
T&ST MF	133	51	97

Sources: Brown and Lugo, 1982,1984; Fearnside, 1987; Detwiler et al., 1985.

Key: T&ST F = tropical and subtropical moist forests
T&ST MF = tropical and subtropical montane moist forests
T&ST DF = tropical and subtropical dry forests

Table 2.10 Calculated carbon emissions (10⁶ tons of C) due to deforestation in Latin American tropical forests under three alternative scenarios

	1980	2000			2030
	1980	P	O	S	P	O	S
T&ST F	599.3	676.5	536.4	354.0	903.4	455.4	46.0
T&ST MF	31.1	31.5	24.3	9.4	0.0	13.7	5.5
T&ST DF¹	35.2	43.0	30.3	19.2	52.5	24.0	3.6
Total	665.6	751.0	591.0	382.6	955.9	492.7	55.1

Key: P = pessimistic reference scenario; 0 = optimistic reference scenario; S = sustainable scenario
T&ST F = tropical and subtropical moist forests
T&ST MF = tropical and subtropical montane moist forests
T&ST DF = tropical and subtropical dry forests
¹Including tropical savannas.
Note: it is assumed that all the carbon in the biomass is converted into CO₂ during forest hurning.

By using the estimated contents of carbon in forest biomass presented in table 2.9 and the detailed simulated changes in land use, it is possible to anticipate that carbon emissions associated with deforestation could change from 665.6 x 10(6) tons of carbon (1980) to between 493 x 10(6) tons and 956 x 10(6) tons in the year 2030 (table 2.10).

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