|Natural forests affect soil formation and may act as biotic pumps, affecting rainfall and climate. English photo.|
By Céline Caron
Two recent areas of research may have turned our knowledge of the forest upside down. They are pedogenesis (soil formation) applied to agriculture – i.e., the idea that much of our quality soil fertility derives from the deciduous forest; and the biotic pump theory – i.e., the idea that natural forests may be indispensable for rainfall, and, thus, for agriculture.
I have written about pedogenesis applied to agriculture, including the use of ramial chipped wood (RCW) – wood chips from deciduous tree branches that are less than 3 inches in diameter – for The MOF&G (See www.mofga.net/MOFGApedia/RamialChippedWood/tabid/232/Default.aspx).
The biotic pump theory is newer and may add to the idea that forests are the primary keepers of the biosphere, as their tall, wide, three-dimensional canopy captures sunlight and condenses humidity. Forests can build natural capital and benefit our livelihood tremendously and in complex ways that human technology and ingenuity cannot equal.
Soil: The Interface with the Sun
Soil is earth’s interface with the sun, and the sun is the source of all life on earth. We are the earth through the soil that nourishes all life; soil integrates life with the mineral world. In fact, French soil scientist Claude Bourguignon, in Jean Druon’s 2007 film Alerte à Babylone, says that 80 percent of earth’s living mass is in the soil.
Our world economy does not value soil, except when it erodes or does not respond to our high yield expectations – particularly for market agriculture, the basis of most economies worldwide. Farmers are used to planning for the coming year or for the next few years, but they should also consider the next 100 years – or better, the seventh generation, as North American Indians do – embracing nature’s methods to ensure soil health and farming sustainability.
With long-term effects in mind, note that compost and manure have their greatest effects in the first couple of years after they are added to soils, while major effects of additions of RCW last from three to five years.
Soils in the Making
Agricultural soils took millions of years to develop – a difficult concept for humans to absorb, as three generations is a long time for us. About 300 million years ago, coniferous trees dominated forests, with deciduous trees dominating about 65 million years ago. Arable agricultural land in temperate climates came mostly from those deciduous forests, which were rich in organic matter, well aerated and alive with flora and fauna. The prairies don’t have the same soil structure that evolved in deciduous forests, where small branches, leaves and rootlets accumulated on the ground and over centuries supported a diversity of plants, animals and fungi that do not exist elsewhere and that actively participate in creating fertile soil.
The decline of forests, particularly of deciduous forests, has been accompanied by the decline of civilizations. Half the forests that existed at the dawn of agriculture have been destroyed. To preserve soil and biodiversity on earth, we should preserve the remaining forests.
In addition to preserving forests and their soils, we can mimic fertile forest soils by incorporating RCW in agricultural soils. The lignin of angiosperms – especially of oak, king of the forest and of soil fertility – is central to humification and biological controls of fertility. Hardwoods contain both guaiacyl and syringyl lignin in varying ratios among species, while softwoods contain primarily guaiacyl lignin. (1) The lignin of hardwoods deeply impacts most mesic soils (soils with a balanced supply of moisture) through the multilevel life that these soils support.
The basic mechanisms of this complex process are regulated by Basiomycetes, “white rot” fungi that use enzymes to produce fulvic and humic acids from lignin. These acids, the basis of soil aggregate formation (2), are produced best by deciduous trees due to the chemical structure of their lignin. Evergreens perform poorly, as their lignin is broken down by “brown rots,” which produce polyphenols and aliphatic compounds.
Native peoples often went to great lengths to nourish their soil. Native Americans built mounds of organic matter to grow some of their food that did not come directly from the forest. Swiss and Chinese peasants collected eroded soil by hand, after heavy rains, and returned it to pastures and fields. Swiss foods were several times higher in minerals and fat-soluble vitamins than equivalent products from most European and American sources. (3) In Nepal, soil is so rare that lowlands are reserved for growing food and settlements are higher in the mountains.
Unfortunately the opposite has been happening in industrial agriculture since the early 1950s, when intensive agriculture – the Green Revolution – began, with its heavy machinery, deep plowing, and synthetic chemical fertilizers and pesticides, all of which have been destroying soil biodiversity. Soil is fragile – biologically, chemically and physically. Synthetic chemical additives mineralize soil organic matter, so soil becomes compacted and less able to nourish plants, and so farmers add more synthetic chemical fertilizers and use stronger pesticides until the soil is dead. Now with the addition of genetically engineered crops and their accompanying pesticides (especially herbicides) to the mix, desertification is well underway. When the soil dies, life dies.
Those dead soils from industrial farms blow away or wash into rivers and streams. It is not the rain or wind that causes erosion, it is agricultural systems, as less soil remains for roots to penetrate.
The Forest as Rain Maker
Just as erosion is not caused, per se, by flooding, desertification is not caused by climate change but by eradication of the forest and by modern ways of working the soil. Because of eradication of natural forests combined with intensive agriculture, we now have floods in dry periods!
Russian researchers Victor Gorshkov and Anastassia Makarieva theorize that natural forests are biotic pumps and must be maintained for water availability. Monocultures or tree plantations are not as effective biotic pumps as natural forests, they say.
As with all life processes, the biotic pump and the soil are highly organized, complex processes. Quoting Gorshkov and Makarieva, “The biotic pump is a mechanism in which natural forests create and control ocean-to-land winds, bringing moisture to all terrestrial life.” (4) These researchers believe that condensation from forests, not temperature differences, drives the winds that create precipitation over land.
If forests are rain and soil makers, the natural capital and services they provide drive our economy. Forests benefit life in many ways:
• Forests absorb more solar energy (92 to 98 percent) than agricultural fields (2 to 8 percent). Orchard trees combined with multi-storey plants also absorb 92 to 98 percent of solar energy, which they convert through photosynthesis into matter and into the water cycle. (5) Trees pump this solar energy into the soil in summer and release it through root systems in winter.
• Forests condense more humidity and produce more food, in the form of seeds, nuts, fruits, mushrooms and more, than agriculture.
• Trees maintain and restore underground water reservoirs, a critical resource for the biosphere and for humankind.
• Tree roots penetrate soil deeply and pump water, minerals, nutrient-containing bacteria and other small organisms to surface soils. Water is constantly pumped, recirculated and evenly distributed through mulches made from branches and leaves.
• Rain and melting snow slowly percolate through the forest floor, keeping water levels stable in ponds, rivers and lakes and avoiding floods.
• Trees and other plants not only capture but also emit moisture when needed into the environment for plant and animal food production, keeping the land dry and the water flowing.
• Forested riverbanks help lighten heavy clay soils and strengthen sandy soils from erosion by wind and runoff. They reduce silting and the need for cleaning while protecting wildlife habitats and functions. Trees absorb surplus water, keeping insect breeding habitat and populations low.
• Forests purify air, water and soil by absorbing CO2. They also remineralize and humify mined soils.
• Small animals, fish, amphibians and insects, which thrive in forests, convert biomass for wildlife and human benefit.
According to Gorshkov and Makarieva, complex natural forest communities, with their plants, animals, bacteria, fungi and other organisms, are stable ecosystems that not only create soil and, likely, an ocean-to-land moist air flow, but also prevent extremes in this air flow, such as hurricanes, tornadoes, severe droughts and floods. Natural forests take decades or even centuries to develop to the point where they can act as biotic pumps. Destroying forests leads to the opposite effects, including greenhouse effects, say Gorshkov and Makarieva.
This scientific message has important economic implications. “First of all,” say Gorshkov and Makarieva, “people and governments worldwide should realize that economic growth cannot occur at the expense of cutting forests either in one’s own country or elsewhere. It is undermining the very pillars of our civilization’s existence.” Natural forests are needed to “run the hydrological cycle on land and for agricultural soil fertility.” Cutting 50-year-old trees at the rate at which they regrow is not sustainable, say the researchers. They believe that governments should support research that finds alternatives to paper and other products from trees so that existing forests can be preserved.
Living with Nature
Humanity must heal its deadly estrangement from nature and work with it rather than against it – before major collapses of ecosystems. Life in its myriad manifestations and the ever-enchanting wonders of nature are too sacred and precious to be wasted and blindly destroyed, as we are collectively doing now. We should consider ways to conserve soil in particular.
Our modern culture presents itself as something normal in its evolution, as if there is no other choice but to continue to live alienated from earth’s ecosystems. We continue to use natural resources as if they were infinite, but soil has biological limits, and ignorance of these limits explains soil degradation and desertification.
Food production and harvesting are the foundation of the human relationship with the earth, so we constantly interact with earth’s soil and water to support and renew our physical body. The planet supports 7 billion people with two limited resources: water and soil. Their sustainable management is critical, because we cannot augment their quantity. When we take care of the forest, humanity thrives.
Woodlands still make nearly one-third of earth’s land area, and humans and forests are intertwined. The forest can continue to provide a livelihood if we alter our mindset. Half of our medications come from trees. The underground biomass in forests may equal that growing above ground. Trees create networks and exchange electrical and chemical signals and enter into cooperative arrangements. There is so much to discover about plant intelligence.
Water and forests are inseparable. Forest filter, store or digest pollutants. Forests are like sponges, absorbing water during floods and giving it back during droughts. Rainfall is born in the forest. Through transpiration, water absorbed by tree roots is released as water vapor. Trees also produce substances that seed clouds, and the vapor condensing from those clouds becomes life-giving water. Plant life cycles water, air, earth and sunlight – the whole living ecology on which we all depend.
Forests are the guardians of climate. They store more carbon than is contained in the earth’s entire atmosphere.
Worldwide, 300 million people live in forests and 1.6 billion – nearly one in four – directly depend on forests for their daily livelihood.
Take a close look at the forest. We and the forest are one. We have always needed them. Today they need us.
How to Restore a Rainforest, by Willie Smits, TED Talk, 2009. www.ted.com/talks/willie_smits_restores_a_rainforest.html. In order to save orangutans, Willie Smits pieced together a complex ecological puzzle to find a way to regrow clearcut rainforest in Borneo. In the process, he created a blueprint for restoring fragile ecosystems and supporting indigenous cultures.
Hope in a Changing Climate, 2011, by Plant for the Planet, created by John D. Liu, director of Environmental Education Media Project. https://vimeo.com/19661805. Demonstrates restoring ecosystem functions in large-scale damaged ecosystems, improving the lives of people who have been trapped in poverty for generations, and sequestering carbon.
1 Ioana Stănculescu et al., 2008. Raman Spectra of Decayed Wood Samples, Analele Universitătii din Bucureşti. https://gw-chimie.math.unibuc.ro/anunivch/2008-2/AUBCh2008XVII24145.pdf
2 Leisola, M. and Garcia, S., 1989. The mechanism of lignin degradation. In Coughlan M., ed. Enzyme Systems for Lignocellulose Degradation. Elsevier Science Publishers
3 Nutrition and Physical Degeneration: A Comparison of Primitive and Modern Diets and Their Effects, by Paul B. Hoeber, Harper & Bros., 1939
4 “New meteorological theory argues that the world’s forests are rainmakers,” by Jeremy Hance, Feb. 1, 2012; https://news.mongabay.com/2012/0201-hance_interview_bioticpump.html#)
5 Welcoming Orchard Food Production Efficiencies – Guidelines for operating a Forested Earth, by Douglas F. Jack, 2009. https://docs.google.com/document/preview?hgd=1&id=1OAgYJ19P9oA9dWkKfKl_IodTsR17vZMjkQqZ98_5TCc&pli=1
About the author: Céline Caron, an evolutionary ecologist and earth doctor, is a long-time practitioner of organic agriculture in Quebec, a friend of rivers, wetlands, forests, soil, biodiversity and simple living. She writes in both French and English.