Handbook of Ecological and Ecosystem Engineering. Группа авторов
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Figure 1.9 Qualitative assessment of ecosystem services by beaches in the municipality of Ilhéus, state of Bahia, Brazil. Northern shoreline beaches – PS: Pé de Serra; S1: Sargi – trecho 1; S2: Sargi – trecho 2; PR: Ponta do Ramo; L: Luzimares; C: Coqueiros; M1: Mamoã – trecho 1; M2: Mamoã – trecho 2; M3: Mamoã – trecho 3; PT1: Ponta da Tulha – trecho 1; PT2: Ponta da Tulha – trecho 2; V: Verdesmares; B: Barramares; PA: Paraíso do Atlântico; JA1: Jóia do Atlântico – trecho 1; JA2: Jóia do Atlântico – trecho 2; MS: Mar e Sol; J: Japará; FO: Fazenda de Osmar; SD1: São Domingos – trecho 1; SD2: São Domingos – trecho 2; SM: São Miguel.
As the concept of ecosystem service increasingly becomes an operational tool, it is necessary to explain the complexity of the relationships among production, ecosystem service appropriation [22], and impacts on different time and space scales. So far, there has been considerable focus on spatial patterns of ecosystem service provision and appropriation; however, the temporal dynamics have been little explored, as highlighted by Rau et al. [22], who proposed a new way of categorizing ecosystem services based on their temporal dynamics by differentiating linear from nonlinear dynamics in the provision and appropriation of these services.
The authors above have suggested that temporal dynamics can be better integrated into studies about ecosystem services through four stages: (i) defining the appropriate time limits of the system; (ii) identifying the primary types of ecosystem dynamics; (iii) evaluating the spatial scale at which the dynamics develop in the system; and (iv) developing measures to assess such dynamics.
Considering the temporal dynamics of ecosystem services by following the stages suggested by Rau et al. [22] is a way to better plan the management of ecosystem services.
1.3.2 Agriculture and Ecosystem Services
Agriculture is the most widely managed ecosystem globally since it covers approximately one‐third of the earth's surface. Therefore, given its importance, this item addresses agricultural systems, ecosystem services provided by these systems, and their issues, possibilities, and challenges.
Agricultural ecosystems provide food, fibers, fuels, and a range of products essential to human life; thus, they are classified as ecosystem provisioning services. However, agricultural ecosystems depend on many other support and regulation services – such as soil fertility, pollinating agents, and water supplies – to provide these services [16, 39].
There are so‐called ecosystem disservices to agriculture if one considers the most widespread definition of ecosystem services, according to which Nature provides services essential to human survival. All natural ecosystem processes that may reduce productivity or increase production costs – such as herbivory and plants' competition for space, nutrients, and water – are classified as disservices to agriculture [40].
The intensity of the impact that ecosystem services or disservices have on agricultural systems depends on the diversity, composition, and functioning of the landscape surrounding them [41]. Management of ecosystem processes began after humans stopped being hunter‐gatherers and became farmers, based on the degree of service or disservice to agricultural production increase. Management, or manipulation, of processes reached unprecedented levels due to the Green Revolution,5 after which agriculture primarily started to follow a latifundiary monoculture model.
The idea that ecosystem processes must provide products necessary for human survival is dangerous since it makes room for individuals to understand that one can enjoy and interfere in processes that took thousands of years to exist in harmony on our planet. Conservationists and ecologists may see ecosystem management for agricultural purposes as an irreversible interference in natural processes. On the other hand, ecological engineers see changes caused by agriculture in the ecosystem and its services as a means of preserving the natural system and, at the same time, providing provisioning services. Thus, the core question appears to be: can there be a middle ground between the two approaches? In other words, is it possible to manage ecosystems so that all their ecological processes – if well investigated, interpreted, and understood – can be considered ecosystem services (excluding the idea that there are ecological processes acting as disservices to agriculture)?
In light of the current scenario, according to which food production accounts for approximately 69% of greenhouse gas emissions, 70% of freshwater use, and the annual loss of approximately 6 million hectares of agricultural areas due to soil desertification processes [42, 43], it is necessary to manage ecosystem services to provide food of the right amount and quality to the population without generating irreversible environmental burdens. From the moment when a given human activity starts imposing negative “feedbacks” on the population, this activity becomes unstable in the long term and may eventually destroy the population itself [44].
Following the trend of manipulating natural elements to enable increasingly productive agricultural systems, the introduction of genetically modified organisms – so‐called transgenics – is considered the most significant technological revolution in the recent history of agriculture [45]. An organism is considered genetically modified when a given material is subjected to genetic changes that would happen neither naturally nor through crossing or recombination processes [46].
Transgenic organisms have spread worldwide due to an annual increase in their use in agricultural sites, as well as to their import and export in the form of processed foods and animal feed. The trade of these organisms started with promises such as increasing productivity without the need to convert more land into agricultural fields, reducing the use of pesticides, enabling the efficient use of water through drought‐resistant varieties, greater efficiency in fertilizer use, less need to prepare the soil, and, consequently, lower carbon emissions and erosion rates, among others. However, many of these environmental benefits are not observed in all regions and remain scientifically uncertain [47]. Part of the uncertainty results from rapid technology adoption in a world thirsty for profits and higher productivity to guarantee human food, as well as for political reasons and due to the interests of large corporations in accelerating the introduction of these products in the market.
Although the aim of this chapter is not to address how transgenic organisms have been placed in the global market, under what interests or research methodologies, we would like to raise some questions of ecological importance to reason about the difficulties in maintaining ecosystem services in full operation in the face of some techniques used in agriculture. Based on our viewpoint, biotechnology may enable the formation of entirely new ecosystems in the future. But will these ecosystems be efficient and desirable? Will ecosystem services be equally present as they are in natural ecosystems? These questions are certainly far from being accurately answered, but scientists and society must consider them.
One cannot forget that arable lands became part of the ecosystem from the moment human beings started to produce their own food. Thus, when one cultivates genetically modified species, these new organisms are introduced into the ecosystem. Because ecosystems are a complex set of organisms in constant interaction, together they perform a variety of ecological processes; therefore, it is expected that the introduction of a new organism in these ecosystems will change these processes. Thus, it is essential to evaluate the effects of transgenic cultures as a whole, rather than just the results of a single organism in a single environment and in a single period of time. Individual analyses cannot reflect the environmental effects accumulating in ecosystems as a whole.
Below, we list just a few examples of organisms that transgenic plants come into ecological contact with when they are grown [48]:
Other plants belonging to the same, or different, species
Herbivores feeding on plants' shoot or roots
Natural enemies such as plants competing for space, nutrients, water, and light through allelopathy
Pollinating insects visiting transgenic