Environmental Restoration

Science And Strategies For Restoring The Earth

John Berger

• Publisher: Island Press
• Year: 2012
• Print ISBN: 9780933280939, 9780933280946
• eBook ISBN: 9781597268783
• Subtopic: Ecology

Environmental Restoration is the product of a ground-breaking conference on ecological restoration, held in January 1988 at the University of California, Berkeley. It offers an overview from the nation's leading experts of the most current techniques of restoration, including examples of the complex and subtle biological interactions we must understand to ensure success.

Chapters cover restoration of agricultural lands, barrens, coastal ecosystems, prairies, and range lands. Additional sections address temperate forests and watersheds, mined lands, soil bioengineering, urban issues including waste treatment and solid, toxic, and radioactive waste management. The book also covers restoration of aquatic systems, includes chapters on strategic planning and land acquisition, and provides examples of successful projects.

PART I

RESTORATION OF LAND

AGRICULTURAL LANDS BARRENS, COASTAL ECOSYSTEMS, PRAIRIES, AND RANGELANDS

THE RESTORATION OF AGRICULTURAL LANDS AND DRYLANDS

DAVID A. BAINBRIDGE

ABSTRACT: Throughout the world, drylands used for agriculture and grazing are deteriorating. In the United States, drylands are also experiencing moderate-to-severe desertification and declining productivity. Lands once productive and profitably are being abandoned as a result of declining fertility, increased sensitivity to drought, high water tables, salinization, and groundwater overdrafts. Farmland productivity in humid and subhumid areas of the world is also declining as a result of unsustainable management practices. These lands can be restored by reversing the social and ecological factors that led to their deterioration and by establishing new incentives for restoration.

KEY WORDS: drylands, farmland, rangeland, restoration, reforestation, revegetation.

INTRODUCTION

THE WORLD’S AGRICULTURAL lands and drylands are deteriorating as a result of mismanagement. Fertility of agricultural lands is declining, erosion is widespread, and production increases are not matching population gains in many areas.

The drylands are in the worst condition, as a result of inappropriate agricultural practices, overgrazing, and tree cutting for fuel. Recent estimates place the worldwide area of land affected by moderate-to-severe desertification at 22.5 million km² (Dregne 1986), an area two and one half times the size of the United States. More than a fourth of the drylands of the United States are more than moderately desertified.

The deterioration of these lands can be measured by the reduced productivity of desirable plants, alterations in biomass and diversity of the micro-and macrofauna, accelerated soil erosion, and increased risk for human occupants. The causes for this decline in drylands productivity include overgrazing, inappropriate dryland cultivation, overpumping of groundwater, deforestation, and poor drainage of irrigated lands (Sheridan 1986).

The problems of farmland deterioration in the United States first received national attention during the Dust Bowl years of the 1930s. After the Second World War new forces emerged that encouraged further land degradation. Foremost among these were the massive irrigation schemes of the West; the development of farm chemicals which offered the illusion of fertility maintenance; and the short-term control of pests and diseases needed to grow extensive monocultures of the same crop year after year. These problems were compounded by government research and regulatory programs which subsidized chemicals, energy, water, and commodities without concern for environmental or social impact.

The area of agricultural land that has been abandoned in the United States is not known, but Pimentel et al. (1976) suggested that an estimated 80 million ha have been either totally ruined for crop production or so heavily damaged as to be only marginally productive.

Range deterioration in the United States was most catastrophic in the late 1800s as a result of serious overstocking. Within this period the carrying capacity of the California range was reduced by half (Burcham 1957).

Land deterioration results from complex interactions of cultural and ecological factors. Finding solutions that will both prevent further decline and restore degraded lands will require an approach that combines ecological, technical, and cultural understanding of these problems. Developing restoration programs that work in the United States will provide a sound base for addressing similar problems elsewhere in the world.

RESTORING AGRICULTURAL LANDS

Most of the land suited for continued agricultural production is already in production but much is in very poor condition. The elements of a restoration program for farmland will depend on the soil, climate, cropping system, market, and the farmer’s experience and skill. In general, a restoration program will include a decreased emphasis on chemical inputs, an increased diversity of crops, and an attempt to mimic the structure and function of natural ecosystems. In many cases, trees and animals are included in the farm system to provide better utilization of the farm resources.

A restoration program will often include: subsoiling or deep chiseling to break up compacted soil and facilitate root growth (Sykes 1946); use of manure, mulch, compost, or green manures to restore soil organic matter and biological activity, and improve soil structure and tilth (Pieters 1927; Turner 1951); primary reliance on biological nitrogen fixation rather than commercial fertilizers (Subba Rao 1982); conversion from moldboard plowing to conservation tillage (Sprague and Triplett 1986); establishment of a rotation program; intercropping and/or multiple cropping (Francis 1986); development of integrated pest management programs that maximize use of biological controls and minimize use of chemical controls (Huffaker and Messenger 1976); and establishment of windbreaks, hedgerows, and drain channel vegetation to control erosion (Bennett 1939). In addition the farm program should include a monitoring program to track conditions in each field and to ensure that both macro- and micronutrients removed in harvested crops are replaced.

Many excellent farm restorations have been achieved by improved management (Howard 1943; Berry 1981). Agricultural land restoration will be aided by the development of perennial grains and tree crops which can be grown with limited inputs and beneficial environmental impacts in areas where production of conventional annual crops can be very destructive (Jackson 1980; Bainbridge 1986; Wagoner 1986).

Restoring abandoned agricultural land can be relatively easy and economical because conventional farm equipment can be used for cultivation and seeding. Thousands of hectares of abandoned agricultural land have been restored to productive use as rangeland in the western United States. In southeastern Oregon, for example, range managers estimate that the livestock carrying capacity was doubled by restoration efforts (Heady and Bartolome 1976).

The low value and limited economic potential of much of this abandoned land makes low-cost restoration essential. Although long-term fallow periods will lead to revegetation in some cases, the native seed stock is commonly exhausted, and the soil structure and fertility have deteriorated sufficiently to limit or prevent revegetation. Where funding is limited, treatment may have to be limited to pitting or imprinting to increase surface roughness and infiltration. If more money is available, direct seeding with mixes of forbs, grasses, shrubs, and trees can be added.

Restoration of agricultural land in subhumid and humid areas is much easier than in arid areas; extensive areas of the United States that were in poor condition have been reforested by natural processes. In New England, for example, where the boom years for farming in the mid-1800s led to extensive conversion of forest to agricultural use, most of the marginal land has now reverted to forest. In the southeastern United States, direct seeding of oaks has proved effective for reforesting abandoned farmland (Krinard and Francis 1983), and trees should be an integral element in most restoration schemes (Smith 1988).

Every year more than a million hectares of agricultural land is developed for housing, highways, and other uses. Much of this land could be kept in production if development were more wisely managed. Village Homes, a 200-unit residential development in Davis, California, kept more than 17% of the land area in agricultural use (Bainbridge et al. 1978).

RESTORING DRYLANDS

Some of the little known yet important factors that are involved in restoration of drylands are the living soil crust, soil structure, chemistry, microbiology, microsite differences, and fire.

Soil crusts include lichens, ferns, algae, and other cryptogams. Cryptogamic crusts have been ignored by range managers until recently, despite early suggestions that they might be important for plant establishment (Booth 1941). More recent studies have shown that grazing can degrade the cryptogamic crust (Anderson et al. 1982) and reduce infiltration (Loope and Gifford 1972).

Other recent work on the effects of grazing on soil properties and plant succession has demonstrated the importance of microsite changes and the role these play in determining which species increase and which decrease (Eckert et al. 1987). They found that moderate trampling encouraged the establishment of desirable plants on range in excellent condition, but led to further deterioration of land in poor condition.

Fire was used extensively by indigenous people to manage vegetation. Fires of natural origin also strongly influence the course of plant succession. Fire suppression may have many unintended and unwanted effects and should be more carefully considered in land management (Minnich 1987). Fire is an important tool for grassland management and restoration (Berger 1985).

Dryland restoration is made difficult by the limited potential for immediate return on investment. Sheridan (1986) estimated that the cost of dryland restoration ranges from $60-3,000/ha. Presentations at the Second Native Plant Revegetation Conference held in San Diego (Rieger and Steele 1987) made it clear that even larger expenditures can lead to poor results if ecological and soil factors are not considered. Attempts to reestablish native vegetation without restoring native soil conditions failed completely in many cases. Yet plant establishment and restoration have been successful when ecological considerations are properly addressed (Virginia and Bainbridge 1987; Khoshoo 1987).

PRINCIPLES OF SUCCESSFUL RESTORATION

The foundation of an economical and successful restoration program is a clear understanding of the environment and the plants, animals, and people involved. A restoration program should begin with a study of the history of the land, its native vegetation (and human influences), the soil characteristics of comparable undisturbed native soils, and as much information as possible on the interactions between plants, animals, and humans. When this information is available, a draft plan for restoration can be developed.

The second step should be a series of test plots to evaluate the strategies for restoration that app...

Table of contents

• ABOUT ISLAND PRESS
• Title Page
• Copyright Page
• Table of Contents
• PREFACE
• INTRODUCTION
• PART I - RESTORATION OF LAND
• PART II - RESTORATION OF AQUATIC SYSTEMS
• PART III - STRATEGIC PLANNING AND LAND ACQUISITION FOR RESTORATION
• SELECTED BIBLIOGRAPHY
• RESTORING THE EARTH: THE ORGANIZATION
• CONFERENCE PAPERS AND TAPES
• ABOUT THE EDITOR
• INDEX
• ALSO AVAILABLE FROM ISLAND PRESS
• ISLAND PRESS BOARD OF DIRECTORS