The work of human beings

According to Yvonne Baskin in “The Work of Nature” Only 3 percent of the global land surface involves parks and protected areas. More than 95 percent is already under direct human influence, whether ploughed, paved, and managed intensively, or occupied by rural or indigenous peoples. Oceans and seas cover seventy percent of the globe, only one quarter of 1 percent are protected from exploitation and degradation.

She says that with population increase, humans are hardly likely to take up less space or exploit fewer resources in the future. She alerts to the fact that we must learn how to use lightly and sustain ably the natural systems that surround us, from swamps, coastal waters, savannas, and tropical forests to hedgerows and woodlands along urban streams. The more we destroy them, the more likely we are to lower the earth’s capacity to support human beings. 

She defends that we need to make choices with greater wisdom. That we must try to better understand how the systems that supply us with food, water energy, and other services will change. By understanding, which biological resources provide necessary ecological services, and how natural systems might remain resilient in the face of global changes, we may eventually come to know which species and ecosystems are more critical in the future.

She believes that until we can understand in both ecological and economic terms just what we can lose when we abandon or degrade what nature provides us with, we are likely to continue destroying the essential elements of our life support systems.

It is believed that degraded lands can be restored to a fully functional and self-sustaining condition, providing hope that much human caused ecological damage can be undone and natural landscapes recreated.  Also most of the terrestrial surface has been directly modified by building, paving, ploughing, grazing, drilling, mining, clearing, logging, draining, pumping, damming; and poisoning.

She states that human intervention has more or less permanently altered the oceans by depleting fish and whale stocks, destroying coral reefs and coastal marshes, and emitting toxic pollutants. The biosphere has been altered by human induced changes in the climate and the chemical composition of the atmosphere.

In her opinion our major concerns up to now regarding biological extinction have been mostly ethical ones involving our responsibility for the earth’s biological heritage, and economic ones concerning the potential loss of economically valuable products as drugs, herbs and foodstuffs.

Ecologists are aware that the impoverishment of species, threatens to erode the basic life support services that make the earth hospitable for humanity.

In their opinion with the human population growing, demanding land, food and resources, millions of species may go extinct before they can be identified and their importance determined.

Yvonne alerts that it is essential to perpetuate the planet’s atmosphere, climate, landscapes, and living services, allowing human civilizations to prosper. Natural systems that are rich, healthy and resilient enough to continue to support human welfare and economic activity for the next decade must be preserved.

According to her the consequences of our behaviour can destroy the habitat for fish and other creatures, modify water currents, and expose coastal sea grass beds and mangroves to the full force of storm waves just by removing a coral reef. 

Land

She says that by cutting down a forest or planting a new type of dominant tree the chemistry of the soil is changed and consequently the way water and nutrients are cycled; the amount of sunlight reaching the ground; the nature of the organisms that exist in the underground; the productivity of forest streams; even local, and sometimes regional, rainfall and temperature.

In her opinion many disease problems worldwide are due to land changes done by humans. Throughout the tropics, artificial water impoundments, such as dams, irrigation works, and continually flooded rice paddies, increase breeding sites for mosquitoes, aquatic snails, and other disease vectors.

Intensification of wetland rice cultivation across Asia, including the introduction of short-cycle rice varieties and the use of heavy pesticides, in her opinion has created conditions that favour snail-borne schistosomiasis and increase encephalitis and malaria mortality worldwide.

Thousands of farmers and field workers contract Japanese encephalitis each season in the flooded rice fields of Asia.

The author defends that the conversion of rangelands to maize fields in Argentina has enabled the formerly rare field mouse to expand. The mouse is both a host and vector for the virus that causes Argentine hemorrhagic fever. 

She reminds us that water logging and salinization of soils are major causes of deterioration in croplands around the world.  One- third of the worlds food is now produced on artificially irrigated lands, and one-half of those fields suffer of salt problems because wasteful amounts of water- far in excess of what the crops can use-are pumped onto poorly drained soils.

She believes that chemical fertilizers have been responsible for the increase in world food production and are now intricately linked to agriculture. One of the major fertilizer ingredients, phosphorus, binds to soil particles and is carried away with surface runoff. Another, nitrate, is highly water soluble and leaches from nitrogen fertilizers, animal wastes, and organic matter, seeping through the soil into streams or groundwater: Nitrates are major plant nutrients in the soil but serious pollutants in drinking water supplies. They have been linked to the increases in lymphatic cancer, and, at high levels in drinking water, nitrates can cause a type of anaemia in infants.

Soil

According to Yvonne the soil is a complex and richly diverse ecosystem, but mostly treated as dirt - poisoned, ploughed, scraped and still having to support any plant sown into it. She says that creating a few centimetres of new top soil from disintegrating bedrock and organic decay can take several hundred or thousand of years, meaning that lost soil is not a renewable resource on an any time scale. It is the interactions between the soil and plant and animal communities that create and maintain the characteristic soils of a region.

She believes that changes in biodiversity aboveground can alter not only the subterranean environment but also the resources flowing into it. The conversion of large swaths of the landscape to intensive agriculture can completely decouple plant productivity from the process of decomposition and nutrient cycling. She alerts that the harvesting of crops often eliminates organic inputs to the soil, and fertilizer applications substitute the natural process of nutrient release by soil organisms.

In her opinion any activity that alters what grows in the soil risks changing the way the soil community functions: who does the work, how quickly, and what products these organisms release.          

She says that many farmers sterilize their soils with toxic fumigants before planting, intended to kill fungal pathogens. Key soil workers are certain fungi that form intimate and mutually beneficial relationships with the roots of most plant, improving the structure of the soil.

For her the more common problem caused by intensive livestock and agricultural operations are the creation of harsh working conditions to fungi populations that are greatly reduced or eliminated. Clearing, burning, tilling, compacting the soil with heavy machinery, applying pesticides and herbicides, and reducing plant diversity in crop fields all destroy the underground community.

She concludes that our activity is having a profound impact on natural nutrient cycles and the interdependence between plants and the soil community. Every time people drive cars, fire up power plants and factories, or burn forests, gases and particulates are released having impact on the functioning of ecosystems worldwide.

She points out that humans now fix and make available to the living world more atmospheric nitrogen than all natural processes together. She also says that we have changed the synchrony between plants and the soil, disrupting the work of the underground community making it unable to support the vital aboveground processes.

Productivity

 According to the author productivity represents the growth that supports all animal consumers, their predators, and ultimately the myriad creatures of decay. In all human-managed systems, from crop fields to plantation forests, people have reduced the number of plant species very drastically.

She says that the amount we use directly as food, fibber, timber, or fuel represents 3 percent of the earth’s output of organic matter. If we add the productivity of croplands, gardens, golf curses, lawns, perks and other areas devoted entirely to human activities, plus the biomass fed to livestock or burned to clear land, the total rises to 19 percent.

Expansion in her opinion has been a major driving force changing the landscape and eliminating habitat and resources for other species. Today nearly one-third of the earth’s land surface is devoted to agricultural uses.

She states that more than 90 percent of the world’s food is supplied by fifteen plant species, and nearly two-thirds of that total comes from just three grains: rice, corn, and wheat. This simplification has more to do with economic considerations, than with biological principles.

For her trees, wildflowers, grasses, and shrubs cannot survive and produce for long without the services of the birds, bees and bats that pollinate them; the mammals and birds that disperse their seeds; insect predators that control plant pests; grazers that help shape the plant community; and finally, the decomposers. Each or these organisms, in turn, depend on relationships with other plants and animals.”

 The power to shape the land.

In her opinion humans have played the most important role in reshaping the earth by felling forests, ploughing grasslands, filling wetlands, and transforming other natural landscapes to agricultural and urban uses. She says that we and our earth moving machines now are more able to shift the very rock and soil of the planet into new configurations compared with glaciers, winds, tectonic up lift, or any other geological force.

She tells us that forty billion tons of earth each year is moved worldwide - during mining operations, construction and indirectly eroding it away by ploughing croplands and clear cutting forests. Only rivers, surging and meandering through their floodplains, constantly remodelling their channels and banks, rival with humans. 

She alerts that humans sculpt the earth more dramatically; our specialty is simplifying the landscape, turning diverse forests or meadows into tree farms, uniform rows of grain, or monotonous expanses of concrete and lawn.

In her opinion influential organisms disappear as a side effect of land clearing or other direct human alteration of the landscape.

Changes in biodiversity that alter the distribution or flow of resources can affect the landscape’s workings, especially its productivity and the conservation of water, soil, and nutrients.

Climate and atmosphere.

According to Yvonne the type of vegetation that covers a landscape influences the continuous exchanges of heat and moisture between the earth’s surface and the atmosphere, these exchanges determine the climatic character of a region-its temperature, rainfall, and wind patterns. Incoming solar energy powers the system, and vegetation plays a leading role in determining the fate of the sunlight that reaches the earth.

She says that the major greenhouse gases are water vapour, CO2, methane, nitrous oxide, and manmade molecules known has chlorofluorocarbons.

In her opinion as modern industrial societies developed, CO2 levels have risen and are continuing to rise at about half of one percent per year, due to increased burning of coal, oil, and other carbon-rich fossil fuels, as well as the cutting and burning of forests.

She points out that about one-fourth of the human contribution to rising trace gas levels comes from deforestation, and most of that gas is Co2 released into the air from soils and vegetation when the trees are cut and burned.

She says that land clearing also releases significant amounts of methane and nitrous oxide, especially when felled trees are burned. Ploughing the cleared land for crops over time can release 25 percent of the carbon stored in soil organic matter. Nitrogen fertilizers applied to these fields lead to further emissions of nitrous oxide. Putting cattle on the land or flooding it for rice paddies increases the emission of methane. The higher the doses of fertilizer a field has received, the greater its methane emissions to the atmosphere.

She alerts that nitrous oxide is a very long-lived greenhouse gas whose production has nearly doubled in the past century. Automobile exhausts generate some of this rising tide of nitrous oxide, the burning of other nitrogen-loaded fossil fuels such as coal, and in agricultural areas where high rates of nitrogen fertilizer are applied to the soils.

She concludes, “The biological feedback mechanism that has the best chance of keeping the planet in an amenable state is our own species seldom exercised power of self-control.”