Traditional approaches to land use in the light of global environmental changes

pp. 61-65 in Traditional Technology for Environmental Conservation and Sustainable Development in the Asian-Pacific Region

Proceedings of the UNESCO - University of Tsukuba International Seminar on Traditional Technology for Environmental Conservation and Sustainable Development in the Asian-Pacific Region, held in Tsukuba Science City, Japan, 11-14 December, 1995.

Editors: Kozo Ishizuka, D. Sc. , Shigeru Hisajima, D. Sc. , Darryl R.J. Macer, Ph.D.

Copyright 1996 Masters Program in Environmental Sciences, University of Tsukuba. Commercial rights are reserved, but this book may be reproduced for limited educational purposes. Published by the Master's Program in Environmental Science and Master's Program in Biosystem Studies, University of Tsukuba, 1996.

Arkadii A. Tishkov, Dept. of Biogeography , Inst. of Geography, Russian Academy of Sciences, Staromonetny 29, Moscow, 109017, RUSSIA
Victor A. Brovkin, Lab.of Math. Ecology, Inst. of Atmospheric Physics, Russian Academy of Sciences, Pyzhevsky Per. 3, Moscow 109017, RUSSIA, E-mail: victor@pik-potsdam.de
Alexey L. Stepanov, Dept. of Soil Sciences, Moscow State University, Moscow, RUSSIA

Abstract

Key words: landscape optimization, global change, reforestation

Introduction

It is well established now that the so-called "greenhouse effect" -- the certain trace gases (for example, CO2, CH4 , N2O) transmit a larger fraction of solar radiation than that infrared by the Earth surface -- is a critical component of historical changes of global climate. Understanding of this fact led international community to the awareness of current changes in the atmosphere composition and, consequently, to the Framework Convention on Climate Change. The objective of the Convention -- "stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system" -- suggests reduction of the greenhouse gas emission. Aiming, generally, to reduce or stabilize energy consumption, emission reduction programs directly or indirectly affect agriculture, although they normally concern mainly industrial sector of economics.

The agriculture of developed countries consumes more energy than 50-100 years, but produces higher yield per ha. The growing productivity of agricultural lands allows to increase the percentage of forest land. In Russia, for example, the rapid industrialization of agriculture -- transition to technologies based on machinery and chemicals rather than human labor -- began in 1930s. This led to reforestation of Russian North-West. According to Kolchugina and Vinson (1993) reforestation in Russia provided a significant sink (0.517 Gt C /yr) for atmospheric carbon in 1980s. Reforestation is widely recognized option for mitigating the effect of greenhouse gases emission. The current effect of reforestation in Northern Hemisphere is estimated at 0.5 Gt C/yr. Extensive reforestation would require a political decision to commit large areas of agricultural lands to growing trees. According to van Latesteijn (1995), this option for land-use in the European Community would be reasonable from the viewpoint of some political philosophies. For instance, maximization of yield per hectare justifies the cut of 100 millions ha of agricultural land-use in EC (from today ca 120 million ha to ca 20 million ha). This is the same as saying that deforestation is perhaps a result of some political philosophy.

The agricultural production in less developed countries, based mainly on energy embedded in biomass, does not disturb the balance of atmospheric CO2 by burning fossil fuels. However, it results in rapid deforestation when population density is growing. Tropical deforestation was a significant source (1.6 Gt C/yr, according to the IPCC) of atmospheric carbon in 1980s, and it is widely recognized that the rate of deforestation must be decreased. In Europe, stabilization of forest land area was a by-product of the industrialization. This way is unlikely to be suitable now, since it is not consistent with the current policy for reduction of energy consumption. Therefore, other options for the growth of the productivity of agricultural lands in developing countries and, perhaps, in countries with transitional economics should be scanned.

An alternative to industrialized agriculture industrialization is optimization of land-use. This option was realized in Valdai region (Russian North-West) in 19th century. Deforestation in this region achieved its maximum in 18th century. Then, the area of forest lands began to increase, although the population density was rapidly increasing. To understand this switch to reforestation we analyze two pre-industrial strategies of land-use that have replaced shifting slash-and-burn agriculture.

Conflict between the reduction of energy consumption and stabilization of forest area

(THE EQUATIONS ARE NOT ON-LINE)
Industrial agriculture is essentially based on the supply of energy, produced by burning of fossil fuels. In eco-energetics analysis (e.g., Pimentel et al., 1973) an agroecosystem is considered as a transformer of the input flow of 'artificial' energy (Einp ) into the output energy (Eout ) of agricultural production. The ratio


Equation 1

is said to be energetic efficiency of agroecosystem. It normally ranges among 0.3 and 0.9 (Pimentel et al., 1973). Efficiency of crop production is much higher than that of livestock production -- 2.0 vs. 0.13 in case of a farm in Kursk region of Russia in 1985 (Svirezhev et al. 1995). That is, h depends on the structure of agricultural production -- roughly speaking, production of 1 calorie of cereals requires 0.5 calorie of energy, and production 1 calorie of meat requires 7 calories of energy. Expressing the energy in carbon units and estimating the per capita demand for food supply, we come to the following formula for CO2 emission (FI ) caused by food production:


Equation 2
where e is conversion coefficient from energy to carbon dioxide, j is per capita food demands in energy units, and N is population density.
Although pre-industrial technologies of agriculture do not use the energy of fossil fuels, they may cause CO2 emission if the consumption of biomass exceeds the production of biomass. In equilibrium, natural ecosystems produce the same amount of organic matter as it is decomposed. The energy of decomposition is used, in fact, by the pre-industrial agriculture. Therefore, we can describe CO2 emission (FT )caused by traditional agriculture by the following formula.


Equation 3

where r is embedded energy of biomass produced by natural ecosystems. This formula suggests no CO2 emission while N is less than certain critical value Nc:

Equation 4
To avoid the exhaustion of the biotic resources of energy the excess of population density should be compensated by the use of energy coming from fossil fuels. However, eIhI is generally (e.g., Spedding, 1988) bigger than eThT. That is, industrialization of agriculture would produce more CO2 emission than non-sustainable use of biotic resources.

Pre-industrial optimization of agro-landscape: case study of Valdai

The non-sustainable use of biotic resources could last only short time. Then, resources would be exhausted and population should search for mineral resources. In case of Valdai region we could see a different option -- spontaneous optimization of land-use, that maintained and even restored the biotic resources of the region.

Agro-forestry versus deforestation

Shifting cultivation played a certain role in the Valdai region even in the end of the previous century. The ash resulted from burning of trees and shrubs provides fertilization of the podzolic soils that otherwise could not give a good yield of crop. The regular rotation of cleared land began to be practiced from the 15th century, when population density was ca. 4 persons/km2 and ca 15% of the territory was in use. Three-field system came into use from 17th century, and in 18th century deforestation achieved its maximum level. From this time the evolution of agricultural system began to deviate (as far as it is possible to restore from historical evidence) from the evolution of modern mixed farming system as it was described by Grigg (1974). According to Grigg (1974) evolution of mixed farming system has passed the stage of introduction of the three-field system in the early Middle Ages, then the stage of reduction of fallow and the growing of roots and grass as fodder, and then the stage of intensification and shift to livestock products. In case of Valdai region the shift to livestock products occurred before the reduction of fallow. In 1916 the most of agricultural lands (80%) were used for growing cereals, and the percentage of lands used for growing fodder was only 4.6%. The reduction of fallow began simultaneously with the industrialization of agriculture in 30s of this century , and in the end of 1980s the percentage of lands used for growing fodder achieved 50%. It seems that during this period (1850-1930) of deviation from the course of agriculture evolution in Europe and North America an agro-forestry system was used in the region.

Agro-forestry means that woods, crops and animals are grown in some form of spatial arrangement or temporal sequence, "such that the agricultural and forestry components interact beneficially both ecologically and economically" (Spedding, 1988). By the definition such systems maintain forests, as their essential component. Nevertheless, the particular mechanisms that provide beneficial interaction between these two components deserve to be explicitly analyzed.

The energetic efficiency of the agro-forestry system

The development of the agro-forestry system in Valdai region is apparently a result of topography of the region and the bio-geochemical properties of soils (Tishkov, 1994). This is a so-called finite moraine landscape made up of small hills and valleys and covered with soils of varying texture. Some habitats need too much labor to be cultivated, but could provide a good yield of timber or fodder in natural condition. In case of sustainable forestry, gaps cover about the 15% of the forest land. These gaps could provide a good harvest of fodder or could be used as pastures. Moreover, forestry forms a network of roads that makes these sites easy to access. By this means forestry significantly reduces the energetic expenses of livestock feeding (there is really no need to grow roots and grasses for fodder) and, hence, stimulates the increase of the number of animals. The long term use of the field in the landscape of this sort suggested supply of manure. Due to this reason the crop production was determined by the number of animals. The feedback stabilized the system in sense of ratio between the forestry and agricultural land-use (Rf ).

Spatial arrangement of the agro-forestry system

We could see two strategies -- interior and exterior -- of land-use in the Valdai region. They were different in the pattern of Rf growth with the distance from a hamlet (Fig. 1). Interior strategy suggested allocation of agricultural land-use close to the hamlet. This strategy promoted forest integrity and, apparently, the use of various non-timber resources of forest (e.g., game). Exterior strategy suggested quite uniform allocation of agricultural land-use in the vicinity of the hamlet -- that is, promoted the integrity of rural environment. Both of the strategies suggested relatively small average area of fields (3-6 ha) and pastures (0.5-1.5 ha). This prevented eutrophication of adjacent water bodies, although nobody was aware of the environmental pollution at that time.

Prerequisites for the spontaneous land-use optimization

Spontaneous optimization of land-use that took place in Valdai region before the 1930s was very effective in an environmental sense. It is recommended now as a model for development of farms remained within the boundaries of the Valdai national park (158 000 ha) when it was created in 1990. However, the feedback that maintained the stability of the land-use system could not work in any environmental and economic conditions. The prior conditions are landscape heterogeneity, inefficiency of mineral fertilizers and mechanization.

Landscape heterogeneity

The Valdai agro-forestry system has appeared, perhaps, due to pronounced differences in the habitat's suitability for cultivation. It might be that cultivation of some habitats was not more efficient than the use of their forest gaps for fodder supply. The use of forest gaps might give ca 15% of production of the total territory. That is, h of the fodder production by the forestry component (hfor=15/85) is ca 0.18. In case of cultivation some part of production received from the territory had to be spent for feeding horses. Cultivation of fodder needed a certain input of energy as horse labor Ecultivation and, hence, Ecultivation/hlivestock of biomass-derived energy. Therefore, h of the fodder production by the agricultural component should be calculated as hagr=hcultivationhlivestock. In case of chernozem soil and relatively homogenous landscape of Kursk region ,where it might be supposed that hagr=0.26 (hcultivation =2 and hlivestock =0.13), forestry component was not be able to improve the efficiency of agro-systems. But it was apparently able to do this in case of podzolic soils of Valdai -- at least, where the steep slope or heavy soil texture required more large amount of Ecultivation. The pronounced differences in the habitats probably facilitated recognition of the benefit of forestry component.

Inefficiency of mechanization

The Valdai agro-forestry system declined after the 1930s when mechanization of agriculture began. The mechanization was heavily subsidized, that makes it possible to neglect the differences between the habitat's suitability for cultivation. The interior sites (i.e., where interior strategy of land-use was applied) have lost the agricultural component, and exterior -- forestry component. However, the efficiency of mechanization (for cultivation of less suitable sites) without subsidizing is under the question. The growth of prices for fuels becomes a big economic challenge for the agriculture of the region.

Inefficiency of mineral fertilizers

Decline of Valdai agro-forestry system led to increased mineral fertilization. It is common perception that they have low efficiency in this climate, soils and landscape. One explanation is high rate of leaching. Another explanation is denitrification. Denitrification is responsible for gaseous losses of nitrogen that increase with the dose of the nitrogen fertilizers (Fig.2). In a soil under crops they are normally higher than in a fallow soil. As in the case of mechanization, the inefficiency of mineral fertilizers becomes more and more visible with the transition of the economy.

Figure 2: Losses of nitrogen due to denitrification in a sod-podzol soil with growing dose of fertilizer. NB. N20 is also a greenhouse gas: the effect of N20 is 200 times as great as the effect of CO2.

Conclusion

References

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Pimentel, D., Hurd, L. E. & Belloti, A. C., 1973. Food production and energetic crisis. Science , 182: 443-449.
Spedding, C. R. W., 1988. An introduction to agricultural systems. Elsievier Applied Science Publ., Essex, pp. 189
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