LANDSCAPE ECOLOGY in AGROECOSYSTEMS MANAGEMENT - CHAPTER 2 doc

Development of Agriculture and Its Impact on Landscape Functions Lech Ryszkowski and Janusz Jankowiak CONTENTS Introduction Impacts of Agricultural Practices on Landscapes Agricultural L

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Development of Agriculture and Its Impact on Landscape Functions

Lech Ryszkowski and Janusz Jankowiak

CONTENTS

Introduction Impacts of Agricultural Practices on Landscapes Agricultural Landscape Management for Control of Environmental Threats Prospects of Landscape Management in Programs

of Sustainable Development References

INTRODUCTION

It seems obvious that human activities in pursuit of safe food supplies, more comfortable housing, resource exploitation, easier transport of people and goods, and

so on have transformed nature Long ago, when population density was low and people lived in small groups separated by vast ranges of wilderness, visible impact

on environment appeared only locally, and degraded sites eventually regenerated after their use was abandoned Ecologically, primeval people differed from other mammals

by only one very important skill — use of fire — which sometimes had remarkable impact on the local landscape The extinction of the large flightless birds about 50,000 years ago in Australia may be interpreted as the result of habitat destruction by fires ignited by primeval humans (Miller et al 1999) Restricting living activities to a confined area for long periods of time resulted in landscape transformations evi-denced, for example, by changes in animal communities under the pressure of hunting

or gathering Stiner et al (1999) showed that the long-term dependence of paleolithic humans on relatively slow-maturing animals, such as tortoises or edible mollusks,

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caused a decline in their size, a possible sign of overexploitation Ecologically, such impacts are similar to the broad category of animal influences on habitat, such as overgrazing of plant cover by ungulates confined to an island

Improvement of paleolithic technology led to development of tools that increased work efficiency and increased human options to change landscapes To ensure prosperity, people subjugated nature for profits that enabled higher standards of living A crucial event in the subjugation of the countryside was the beginning of agriculture about 10,000 years ago in both the Fertile Crescent and China (rice cultivation) and later in other parts of the world (Pringle 1998) The accumulation

of surplus food enabled large settlements and work division, which led to develop-ment of complex social organization The transformation from the hunter-gatherer lifestyle was a slow process, lasting millennia Inhabitants of southern Egypt used grinding stones as well as mortars and pestles and harvested wild barley and other grass seeds with stone or bone sickles nearly 18,000 years ago (Boyden 1992) In the Fertile Crescent 13,000 years ago, people used sickles for harvesting wild cereals and cultivated some cereals, but at the same time many were still hunters and gatherers (Boyden 1992, Pringle 1998) In large early neolithic settlements excavated

in Anatolia, Turkey — such as Asikli, founded about 10,000 years ago — people lived mostly by hunting and gathering In a large settlement of 2000 families founded about 1000 years later, in Catalhöyük, inhabitants ate both wild and cultivated plants (Balter 1998) About 9000 years ago the main crops, such as einkorn wheat, emmer wheat, barley, lentil, and pea, were domesticated (Lev-Yaduni et al 2000), and the first successful human attempts to subjugate landscape were made

The progress of agriculture was achieved by trial and error with the focus on yield increase The scientific basis for plant cultivation and animal husbandry was developed only about 150 years ago, while the environmental consequences of agriculture were recognized only during the last 30 years Attempts at agricultural landscape management for sustainable development of rural societies are just now being undertaken The consequences of the agricultural revolution, which is the cornerstone for development of civilization, included formation of a complex social organization that relied on class differentiation The important feature of this trans-formation was full-time craft specialization, which in the long run provided positive feedback mechanisms for subjugation of nature, and led to the creation of modern technologies that changed the face of the Earth At the same time, peasants could focus activities only on farming and became more and more dependent on other class services (protection, trade, production of tools) That change enhanced their non-nomadic lifestyle, the activities of which in turn caused accumulated impact on the environment For example, soil erosion started to appear in the Mediterranean hillsides as a result of forest clearing, continuous cultivation of large areas, or

1992)

Maintenance of soil fertility was crucial for intensification of agricultural pro-duction In valleys of major rivers (the Nile, Tigris, Euphrates, and others), recurrent floods brought nutrient supplies each year Soil fertility was sustained by natural

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processes, and cultivation skills and irrigation techniques of peasants ensured con-stant yields Under such conditions, the agriculture provided such surplus food supplies that the great urban states developed in Sumerian Mesopotamia, ancient Egypt, and other river civilizations Their sustainability was endangered by salin-ization or by wars destroying the irrigation systems and exterminating the peasant population

In upland areas, peasants had to face the problem of nutrient replenishment Conversion of forests or grasslands into cultivated fields was accomplished in various ways in the different regions of the world, but one can distinguish a general trend

of agriculture intensification Slash-and-burn agriculture occurred at the stage of development when population density was very low and vast areas of pristine ecosystems were available for conversion The next step, alternating two-field system (crop, fallow), was made possible by the use of farm animal manure, which inten-sified land use for crop production The third step relied on the three-field rotation,

in which on one field an overwintering crop was followed by a spring crop and then left fallow When mineral fertilizers became readily available, the fallow field was eliminated from the crop rotation pattern The cultivation of cereals, row crops, and pulse crops in rotation without intensive application of chemicals is usually referred

to as traditional rotational agriculture In this system, the recycling of nutrients sustaining soil fertility is maintained by rotation of pulse crops (especially legumes) and organic fertilizers produced within the farm, although some inorganic nutrient inputs can constitute a factor of production intensification This method was the most intensive form of cultivation before industrialized agriculture gained momen-tum in the second half of the 20th century, and brought with it intensive use of mineral fertilizers and pesticides, more highly productive cultivars, and total mech-anization of tillage

The driving force for agricultural development has been continuously increasing input of energy, at the beginning by human labor, draft animals, and fire, then by harnessed wind and water energy in mills and application of more efficient tools produced by craftsmen When those craftsmen were replaced by engineers who applied scientific achievements, chemical, electrical, and nuclear energy sources became avail-able for increasing agricultural production and shielding crops from pests, pathogens, harmful climatic conditions, and other obstacles to effective cropping

Boyden (1992) pointed out that the ratio of energy inputs for cropping to energy output (energy value of produced product) in primitive farming societies ranged from 1:15 to 1:20 The same ratio in modern agriculture in the U.K., Holland, or the U.S ranges from 1:0.5 to 1:0.7 Thus, without very substantial input of energy for management modern agriculture cannot provide high yields

Ryszkowski and Karg (1992) estimated that under conditions of moderately intensive agriculture the greatest contribution to energy subsidies provided by farm-ers for cereal cultivation was made by industrial fertilizfarm-ers With input of 60 kg

amounted to 40% of total subsidies Energy subsidies in fuel were almost 28% and machinery amortization (22%) ranked third About 87% of energy subsidies in the

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situation examined were spent on goods produced outside the farm The maintenance

of such a situation was facilitated by the human population harnessing more and more energy fluxes Agriculture became closely tied to activities of other sectors of society Reciprocal and close relationships between agriculture and industry, trade, and other human activities recently attained its full expression in industrialized agriculture Human labor was replaced by work of machines, regeneration of nutri-ents by inorganic fertilizers, biological control of pests and pathogens by use of pesticides, water problems by drainage and irrigation, and so on (Edwards et al 1993) Thus, many obstacles to crop production are under the farmer’s control in modern agriculture, and agroecosystems become to a large extent controlled by humans It is not suprising, therefore, that agriculture has substantial impact on structure and function of the landscape The impacts of agriculture on landscape features are connected with shielding crops against detrimental factors on the one hand, and with the environmental consequences of applied technologies on the other hand

IMPACTS OF AGRICULTURAL PRACTICES ON LANDSCAPES

During the long period of agriculture development, focus was first directed on practical guidelines for keeping stable yields; then, when scientific grounds for production were discerned, the spectacular growth of yield was achieved With the exception of the last two or three decades, agricultural activity was valued as purely beneficial for humanity, and almost nobody thought that farmers’ activities could threaten the environment Conversion of forests or grasslands into cultivated fields changed, of course, the structure of landscape as well as endangered the existence

of some plant and animal species But until industrialized agriculture was developed and global environmental problems were caused by industry and urbanization, the nature conservancy programs assumed that it was possible to shield biological diversity from human influences in national parks, reserves, or other protected habitats When threats to the environment attained global expression (Hannah et al

1994, IUCN 1980, Lubchenco 1998, Pimentel and Edwards 2000, Ryszkowski 2000, Vitousek et al 1997a,b, Watson 1999, and others) the need for reconciliation of human activities with protection of nature was recognized The conviction is slowly growing that it is the way in which natural resources have been used, not the fact that they are exploited, that has resulted in environmental degradation A new paradigm for nature protection is proposed that maintains that nature should not be separated from socioeconomic activities but that instead the two should be reconciled (Ryszkowski 2000) The management of landscape processes can be a useful approach to achieving this goal

While increasing production, farmers subsidize energy to simplify plant cover structure within both cultivated fields (selection of genetically uniform cultivars and weed elimination) and agricultural landscape (elimination of hedges, stretches of meadows and wetlands, small mid-field ponds) Animal communities in cultivated fields are also impoverished Farmers interfere with matter cycling in agroecosystems

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directly by input of fertilizers, pesticides, etc., or indirectly by changing water cycling and decreasing holding capacities of soils for chemical compounds In addition, agricultural activity often leads to decrease of humus contents Increased use of farm machinery enables not only stronger impact on soil but also land surface leveling, modification of water drainage, etc., which causes changes in geomorphological characteristics of terrain These effects of farm activity result in the development of

a less complex network of interrelations among the components of agroecosystems

As a consequence of this simplification, relationships among agroecosystem com-ponents are altered, so that there is less tie-up in local cycles of matter Thus increased leaching, blowing off, volatilization, and escape of various chemical components and materials from agroecosystems should be expected (Ryszkowski 1992, 1994, Ryszkowski et al 1996)

Many environmentally significant effects of agriculture intensification are con-nected with the impoverishment or simplification of the agroecosystem structure However, to obtain high yields, farmers must eliminate weeds, control pests and pathogens, be assured that nutrients are easily accessible only for cultivated plants during their growth, increase mechanization efficiency, etc Therefore, agricultural activity aiming at higher and higher yields leads inevitably to the simplification of agroecosystem structure, which in turn causes further environmental hazards Such ecological analysis leads to a conclusion of major significance for the sustainable development of rural areas: applying intensive means of production, farmers cannot prevent such threats to the countryside as leaching, blowing-off, volatilization of various chemical compounds which causes increased diffuse pollution of ground

wind erosion Biological diversity is also impoverished Clearly, although farmers can moderate the intensity of these processes through careful selection of crops and tillage technologies, they are unable to eliminate them entirely, regardless of the farming system — industrialized, integrated, or organic

These ecological implications can be evidenced by the analysis of the agriculture development in the European Union (EU) within the framework of the Common Agricultural Policy (CAP) The main objective of the CAP was to ensure agricultural self-sufficiency for countries suffering food shortages during World War II To fulfill this goal, the CAP was proposed in the late 1950s and started to operate in the late 1960s Guaranteed high prices were fixed each year for selected products, such as cereals, beef, and milk products Quotas were later imposed and guaranteed prices were lowered Other mechanisms were grants for land improvement, customs pro-tection of agricultural commodities, low-interest loans for investment, and well-organized extension of research services, among others This protectionist policy encouraged intensive agricultural technologies, which resulted in a substantial increase in production For example, the average yield of wheat for all countries of

53% In the same period, the wheat production in the Central and Eastern European Countries (CEEC) increased by 18% (Stanners and Bourdeau 1995), although, as

in the West, great differences between countries were observed The average pro-duction of wheat in Poland was 23% lower than the average for the total EU, but

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the difference is much higher if one compares yield per hectare with the leading EU

(Stanners and Bourdeau 1995)

The success of the CAP led to two constraints: one economical and the second one concerning environmental problems Advances in agricultural technology led to overproduction, and surpluses were stored, which introduced a new burden on the

EU economy The annual rate of increase in agricultural production was 2 to 3% until the mid-1980s, while the rate of increase in consumption was about 0.5% (Laude 1996) Production surpluses accumulated, causing storage problems To address this situation, proposals to increase production were introduced, such as production quotas, set-aside programs, and lower frontier protection

These issues and other economic problems led to reforms of the CAP in 1992 Price-supporting mechanisms were lowered, while emphasis was placed on decou-pling support for farmers from production by tying gains to levels more balanced with market demand Environmental concerns were also taken into account in the new CAP policy The negative environmental effects of the previous CAP policy are now quite well recognized (Stern 1996)

Intensification of agriculture caused environmental threats in the EU The CAP-supported increase in farm sizes was related to more efficient use of labor hours and equipment as well as to lower costs for cultivation of large fields not segmented by shelterbelts, open drainage ditches, etc Lack of permanent plant cover and large open fields exposed to wind and precipitation increased soil erosion processes Presently in Europe, about 115 million ha suffer from water erosion and 43 million ha suffer from wind erosion Water erosion is most severe in the Mediterranean region while wind erosion causes serious damage in the southern Ukraine and regions close

to the northwest coast of the Caspian Sea (European Environment Agency 1998) Agricultural land comprises up to 70% of total territory of the Ukraine, and arable land cover is 55% of the country area (Voloshyn et al 1999) Thus, the majority of the countryside in the Ukraine has been almost totally converted into arable land that is tilled with heavy machinery The water balance is tight, and the central and southern parts of the country suffer water deficits About 43% of the total arable land is threatened by soil erosion (wind and water), and in productive regions of black soils this figure rises to 70% (Voloshyn et al 1999) According to estimates

of Medvedev and Bulygin (1996), about 500 million metric tons of soil is annually lost from cultivated fields Because of erosion processes, the potential fertility of soil is lowered by 1.2 times in weakly eroded soils, by 1.4 times in moderately eroded soils, and by 1.6 times in strongly eroded soils In recent years, because of economic crisis, lower doses of fertilizers and pesticides are used and the intensity

of mechanization has decreased Nevertheless, problems of water, erosion, and soil pollution are still significant

Another serious environmental threat in some European countries (Eastern Ger-many, Poland, Hungary) is water shortage in rural areas The threats caused by water deficits are not as spectacular as air pollution impacts; nevertheless, they constitute

a real menace during warm and especially dry plant growing seasons In Poland,

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mean annual precipitation is 717 mm if corrections for sampling error estimates are considered The uncorrected value of annual precipitation was estimated at 599 mm (Gutry-Korycka 1978) In the central part of Poland, about 80% of precipitation is used for evapotranspiration (Kosturkiewicz and K dziora 1995) The situation indi-cates a very tight water balance, and even a small variation in the ratio of precipitation

to evapotranspiration caused by climatic conditions could have a great ecological and economic impact Low runoff resulting from tight water balance delimits the

total area of Poland In this area, located in the Central Plain, annual water runoff

have not changed over the last centuries, and, therefore, the increasing water shortage can be attributed to the fast removal of precipitated water by developed drainage systems Thus, agricultural production intensification without respect for mainte-nance of water balance, ensuring water storage for the warm season of the year, not only leads to economic problems but also affects the structure of the landscape Many lakes, small ponds, and wetlands disappeared during the 20th century (Kaniecki

Figure 2.1 Change in Polish grasslands area 1970–1989 Over a period of 18 years,

approx-imately 126,000 ha of grasslands were lost (3%) because of drainage and peatbog reclamation (from 4,166 million ha to 4,040 million ha) (Modified after Denisiuk

et al 1992.)

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1991) Changes in vegetation have been observed, and, in particular, many wet

about 126,000 ha of grassland disappeared as a result of drainage and peatbog reclamation (Denisiuk et al 1992) The total grassland area decreased from 4.166 million ha to 4.040 million ha (Denisiuk et al 1992) The change in moisture conditions endangered many plant communities; many plant species common to grasslands recently have become rare Drying grasslands have also endangered many animal species Similar situations have been observed in other European countries Losses of wetlands observed over the last 100 years are continuing despite protection programs launched in many countries At present the least wetland loss is in northern Europe and the greatest wetland loss is in the south (European Environment Agency 1998) In Denmark, from 1954 to 1984, 27% of small water reservoirs were elimi-nated (Bülow-Olsen 1988)

The diffuse pollution of ground water started to appear in the early 1980s in regions of intensive agriculture in all of the EU countries (OECD 1986) In Germany,

in 1985, for example, more than 50% of private water supply systems and 8% of

Organization standards (Kauppi 1990) High concentrations of nitrates exceeding

50 mg per liter of soil solution were detected in Germany, northern France, eastern England, northwestern Spain, northern Italy, and Austria Very high nitrate concen-trations were detected in Denmark, the Netherlands, and Belgium (Stanners and Bourdeau 1995) A recent survey of ground water pollution in Europe showed that 87% of the agricultural area in Europe has nitrate concentrations above the

almost entirely by the use of fertilizers and manure However, local nitrate pollution

is caused by municipal or industrial effluents Thus, in the late 1980s it appeared that modern intensive agricultural practices had brought with them threats to the environment and that the CAP of the EU should be changed by introduction of more environmentally friendly technologies

This situation proved, almost experimentally, that agriculture cannot be consid-ered only in terms of plant and animal production and economy, but that the environmental aspect of these activities should also be taken into account

The other environmental threat brought by agriculture intensification is soil salinization, which appears in the Mediterranean and southeast Europe (Hungary, Romania, the Ukraine, Russia) Salinization appears presently in an area of about

29 million ha (Szabolcs 1991) Irrigation is the main anthropogenic factor influenc-ing salt accumulation under semiarid or arid climatic conditions Other environmen-tal changes caused by agriculture intensification include loss of soil organic matter, acidification, and soil compaction (Van Lynden 1995)

Recognition that environmental threats are increasing forced EU administrators

to change the Fifth Action Programme on the Environment (5EAP) to tackle growing problems of environment deterioration, among which ground-water pollution and depletion as well as impoverishment of biological diversity are quite serious The use of some economic instruments to enhance the control of environmental threats caused by agriculture was proposed by the EU in the new CAP Measures were

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proposed to promote extensive production methods, set aside of parcels, and codes

of good agricultural practice But the integration of environmental concerns into agricultural practice still presents many difficulties

Nevertheless, environmental issues have become a major concern of the CAP, and a strong focus is placed on the need to integrate farming practices with envi-ronment protection “to safeguard the envienvi-ronment and preserve the countryside” (Com 1999) According to the new CAP formulated by the Commission of the European Communities, sustainable agriculture development is founded on five main objectives: competitiveness of production, food safety and quality, fair standards of living for the agricultural community with stabilized incomes, protection of envi-ronment, and job opportunities for farmers and their families (Com 1999) The new approach to agriculture development presented by the CAP is shown by the emphasis

on holistic treatment of all processes driving agriculture The landscape approach is clearly recommended, therefore, because it enables identification and integrated analysis of all processes From this standpoint, “policy choices can be more easily made to express the desired direction for development” (Com 1999) Thus, landscape analysis was recognized by policy makers as a useful tool

AGRICULTURAL LANDSCAPE MANAGEMENT FOR CONTROL

OF ENVIRONMENTAL THREATS

Efficient higher control of environmental threats from agriculture could be achieved by structuring agricultural landscape with various nonproductive compo-nents such as hedges, shelterbelts, stretches of meadows, riparian vegetation, and small ponds Therefore, any activity to maintain or increase landscape diversity is important not only for aesthetics and recreation, but even more so for environment protection and, by the same token, for the protection of living resources in the countryside (Ryszkowski 1994, 1998)

The above considerations lead us to conclude that activities aimed at optimizing farm production and environment as well as protecting biodiversity should be carried out in two different but mutually supportive directions The first component involves actions within the cultivated areas whose objective is to maintain the possibly high level storing capacities of soil and to preserve or improve its physical, chemical, and biological properties Such actions include agrotechnologies, which increase humus resources or counteract soil compaction, and rely on differentiated crop rotations Important effects of humus resources augmentation would be improved water storage capacity, more intensive processes of ion sorption, etc Integrated methods of pest and pathogen control and proper application of mineral fertilizers adapted to crop requirements and to chemical properties of soil help facilitate the same degree nonpoint pollution The effectiveness of such directed activities, which could be called methods of integrated agriculture, depends on good agricultural knowledge That activity will increase farm competitiveness on the market but cannot ensure the elimination of negative side effects of agriculture on the environment

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The second component of the integration program of farm production and envi-ronment protection is the management of landscape diversity It consists of such differentiation of the rural landscape so as to create various kinds of so-called biogeochemical barriers, which restrict dispersion of chemical compounds in the landscape, modify water cycling, improve microclimate conditions, and ensure ref-uge sites for living organisms In landscapes having a mosaic structure, greater amounts of fertilizers can be applied without subsequent water pollution problems (Ryszkowski 1998a) than can be used in a homogenous structure composed of arable fields only This conclusion is very important for the program of sustainable devel-opment of the countryside Implementation of those ecological guidelines into the integrated agriculture policy will help develop new environment-friendly agrotech-nologies that at the same time enable intensive production balanced with the ability

of natural systems to absorb side effects of agriculture without being damaged By saving natural capital of resilience capacities of the landscape, farmers will increase competitiveness of their farms in a manner similar to that described by Jacques Delors, president of the European Commission, in a white paper (1993) that main-tained that improved environmental performance in an industry could increase its competitiveness in the world market

Such a policy requires redefining ideas accepted up to now Emphasis on increased production and its economical protection without much respect for inter-relations of processes and interests should be changed to a more holistic approach that includes landscape issues The heart of the dilemma at the national level is the failure of economies to elaborate efficient ways to incorporate environmental costs into proposals for rural area development

Recent progress in agroecology and especially studies on agroecosystems and rural landscape functions such as energy flows, matter cycling, and biodiversity maintenance have shown that the following threats to environment and protection

of living resources cannot be controlled only at the farm level but must also be curbed by management of the landscape structure diversity:

• Decreased water storage

• Increased pollution from nonpoint sources

• Soil erosion

• Impoverishment of plant and animal communities The protective activities within the farm can only moderate generation of those threats (e.g., by reasonable use of fertilizers, regardless whether organic or indus-trial) Because of interconnectivity of water fluxes in phreatic aquifer of the whole watershed, one can observe widespread ground water migration of chemicals leached from soil of cultivated fields, or, due to large ranges of biota dispersion, the protective activities within the small farm are not sufficient to achieve successful biodiversity protection Thus, protection activities carried out at the landscape level should enhance environmentally friendly technologies applied within the farm

The following activities can be recommended to increase the control of threats

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