Reforestation of Degraded Lands

Home , Forest degradation, List of forests in India, Rainforest, Reforestation, Tree planting, Wood production

Sustaining Tropical Forest Resources: Reforestation of Degraded Lands

May 1983 I SU~;rAIINII\JG TROPICAL RESOURCES NTIS order #PB84-104041

'#l' -.---- \ ~ :::. -- Library of Congress Catalog Card Number 83-600533

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 Deforestation has claimed half of the world’s original tropical forest lands. The result has been a decline in the land’s inherent productivity, with serious repercus- sions on human welfare. One solution to this vast problem is reforestation. More specifically, tree planting on degraded lands can help restore land productivity as well as provide wood for building materials, fuel for cooking, and fodder for livestock. This background paper is designed to provide the U.S. Congress with an overview of some reforestation technologies and their possible beneficial and adverse impacts. It also discusses the constraints and opportunities for the introduction of these technologies in such activities as timber and fuel production, watershed protection, and agroforestry. This paper is part of OTA’s forthcoming assessment Technologies To Sustain Tropical Forest Resources, A concurrent background paper, Sustaining Tropical Forest Resources: U.S. and International Institutions, will focus on the role of various institutions in developing and implementing technologies to sustain tropical forest resources. These analyses form the main part of OTA’s response to the general request of the House Committee on Foreign Affairs and the Senate Committee on Energy and Natural Resources, and supported by the Subcommittee on Insular Af- fairs of the House Committee on Interior and Insular Affairs and the Subcommit- tee on Environmental Pollution of the Senate Committee on Environment and Pub- lic Works. This paper was authored by OTA analysts Susan Shen and Alison Hess. OTA also wishes to acknowledge the tropical forest resources advisory panel and ex- ecutive agency liaisons who reviewed this document and contributed technical information to the OTA staff.

. . Ill Leonard Berry, Panel Chairman Center for Technology, Environment, and Development Clark University

Eddie Albert Chuck Lankester Conservationist U. N. Development Program me Hugh Bollinger Director Robert Owen Plant Resources Institute Chief Conservationist (retired) Trust Territory of the Pacific Islands Robert Cassagnol Technical Committee CONAELE Christine Padoch Institute of Environmental Studies Robert Cramer University of Wisconsin Former President Virgin Islands Corp. Don Plucknett Gary Eilerts CGIAR Appropriate Technology International World Bank John Ewel Department of Botany Allen Putney University of FZorida ECNAMP West Indies Lab Robert Hart Winrock International Jeff Romm Susanna Hecht Department of Forestry Department of Geography University of California University of California Marilyn Hoskins Richard E. Schultes Department of Sociology Harvard Botanical Museum Virginia Polytechnic Institute Harvard University John Hunter* Michigan State University John Terborgh Department of Biology Norman Johnson Princeton University Vice President, North Carolina Region Weyerhaeuser Co. Henry Tschinkel Jan Laarman Regional Offi”ce for Central American Programs Department of Forestry Agency for International Development North Carolina State University U.S. Department of State

“ Resigned in ]u1}I 1982.

iv OTA Tropical Forestry Staff

H. David Banta, Assistant Director, 07A Health and Life Sciences Division

Walter E. Parham, Program Manager Food and Renewable Resources Program

Susan Shen Alison Hess Chris Elfring Bruce Ross-Sheriff

Administrative Staff Phyllis Balan, Administrative Assistant Nellie Hammond Carolyn Swarm

OTA Publishing Staff

John C. Holmes, Publishing (lfficer John Bergling Kathie S. Boss Debra M, Datcher Joe Henson Doreen Foster Linda Leahy Donna Young Contents

Chapter Page 1. Introduction and Background ...... 3

Z. Reforestation Technologies ...... 13 3. Constraints and Opportunist es ...... 41 Appendix A: Commissioned Papers and Authors . . . . . ~` ...... 47 Appendix B: Acronyms ...... 48 References ...... 51

vii Approximately 2 billion hectares (5 billion acres) of tropical lands are in various stages of degradation and have, in theory, potential for reforestation. Most manmade reforestation is done with imported species. Many native trees, more familiar to local people, have untapped potential for reforestation. Tree plantations using only one species are widespread, Little effort is being made to develop technologies for multiple-species reforestation, Selection and breeding of superior trees in temperate zones have gradually produced varieties adapted to specific site conditions that give as much as 50 percent yield gains. However, such work is just beginning in the tropics. New cloning techniques can produce millions of “supertrees,” but they increase the risk of failure because of reduced genetic diversity. Organized programs of seed collection, processing, certification, storage, and distribution are needed to develop the seed quality and quantity necessary for large-scale reforestation, Bacterial and fungal inoculants can increase tree survival and growth, especially on degraded lands. Many of the needed inoculants are not yet commercially produced, Reforestation is most likely to be successful when programs are designed to provide what local people want. In many cases, this means the creation of various kinds of incentives for local participation. New technologies have the potential to reduce the costs of reforesting degraded lands; however, better methods are needed to measure important but indirect benefits in order to justify the reforestation investment.

. . . Vlll Chapter I Introduction and Background Contents

Page Introduction ...... 3 Background ...... 5 Definition of Degraded Lands ...... 5 Tropical Soils and Climates ...... 5 Scope and Causes of Land Degradation ...... 7 Reclamation Using Trees...... 8

Table Table No. Page I. Tropical Lands Recently Undergoing Severe Desertification ...... 7

List of Figures FijweNo. Page l._Tropical Forests and Woodlands, for the purpose of the Report, are Located at Latitudes South of 23.5° N and North of 23.5° S, and at Other Frost-Free Localities ...... 4 2. The Role of Forests ...... 10 Introduction and Background

INTRODUCTION

Eleven million hectares (ha) of the world’s other uses. Trees protect soil from the effects remaining tropical forests are converted to of tropical heat, rain, and wind. Soil tem- other land uses or to wasteland each year (33). peratures are lower under tree canopies, per- About half of the Earth’s original tropical forest mitting reaccumulation of organic matter that land has thus been altered. Deforestation can restores soil structure and microbiota and en- be beneficial where cleared tropical land can hances moisture- and nutrient-holding abilities. sustain agriculture. Under available farming Bacteria on the roots of some trees produce ni- technologies, however, many remaining tropi- trogen fertilizer, while fungi on tree roots can cal lands cannot sustain agriculture and are convert soil minerals to useful forms. In dry soon abandoned or converted to less produc- areas, trees can help to prevent the rise of tive uses. Often, forests cannot regrow natural- saline ground water (92). Where surface soils ly on these degraded lands. are dry or infertile, deep tree roots can tap un- derground reservoirs of nutrients and water Tropical nations* (fig. 1) have about 650 mil- and bring them to the surface. lion ha of cropland and nearly 2 billion ha of land in various stages of degradation (33,114). In recent years, reforestation efforts have in- Those regions with rapidly growing popula- creased. Of the approximately 11.5 million ha tions—Asia, Central America, North Africa, of planted forest in 1980 in the tropical nations, and the heavily populated parts of East and some 40 percent have been planted since 1976 West Africa—need productive land most des- (33). About 60 percent of this was planted for perately, yet have the most rapid deforestation industrial purposes (lumber, veneer, pulpwood, and extensive areas of degraded land. In many etc.). The other 40 percent was nonindustrial of these places, firewood has become so scarce (fuelwood, watershed protection, etc.). While that certain foods requiring cooking have been it is not known how much of this planting oc- eliminated from the diet. People must use crop curred on degraded land and how much oc- residues and dried dung for fuel, which robs curred on recently cleared primary forests, it the soil of organic matter and nutrients and ac- is probable that a 1arge and increasing propor- celerates erosion. Soil eroded from degraded tion of the reforestation, especially nonindus- lands fills riverbeds and reservoirs, increasing trial planting, is occurring on degraded sites the severity of floods and causing water scar- (37). cities. This background paper discusses techniques The best solution for stopping this trend of to reforest tropical lands and gives special em- land degradation is to prevent inappropriate phasis to degraded lands and community-ori- land-use practices on forested lands. Where ented forestry. It does not address methods to this is not possible, reforestation is one way to manage existing forests, nor does it focus on improve the productivity of many degraded public policies or institutional mechanisms to lands and provide useful products for the peo- sustain tropical forests. Those issues are cov- ple. Trees provide wood, fuel, food, fodder, and ered in a forthcoming OTA report, Technol- ogies To Sustain Tropical Forest Resources, *In this b,~(.k~round paper, tropical lands include all lands lo- and in another background paper, U.S. and in- (:ated at Iatltudes south of 23.5 N and north of 23.5 s. ternational Institutions.

3 4 ● Background Paper #1: Reforestation of Degraded Lands -;I at Located Localities Are Report, Frost·Free the of Other at and Purpose S, 0 the for 23.5 of North Woodlands, and N and 0 Ocean 23.5 AUanlic of North Forests South Tropical 1.- Latitudes Figure _P8clliCOcean Cepflcom cancer---lo.,.p..." of of Tropic Tropic __ -- Ch. l—introduction and Background ● 5

BACKGROUND

To understand the constraints on existing re- report, * a simple but useful breakdown of trop- forestation techniques and the potentials of ical areas divides it into three types: 1) hot, wet new ones, it is first necessary to define land lands, 2) arid/semiarid lands, and 3) mountain- degradation, briefly describe tropical soils and ous lands. climates, and discuss the causes of land deg- Most tropical soils on hot, wet lands have sig- radation and benefits of reforestation. nificant fertility problems. Year-long high temperatures and high rainfall combine to accel- Definition of Degraded Lands erate the removal of nutrients needed by plants Degradation of tropical land is a physical, from rock materials and soil mineral particles. chemical, and biological process set in motion The residual minerals tend to be composed by activities that reduce the land’s inherent pro- mostly of aluminum, silicon, iron, oxygen, and ductivity. This process includes accelerated water—a chemical composition so restricted erosion and leaching, decreased soil fertility, that many food or tree crops will have stunted diminished natural plant regeneration, dis- growth or will not survive. An estimated 2 per- rupted hydrological cycle, and possible salini- cent of the soils of hot, wet lands, if cleared zation, waterlogging, flooding, or increased of vegetation, will irreversibly harden on dry- (119), drought risk, as well as the establishment of ing severely limiting reestablishment of weedy plants that displace more desirable plant any vegetation (67). species, Evidence that the degradation process In arid/semiarid lands, soil nutrients needed is advancing includes, for example, a reduc- by many plants become available to plants with tion in the water-holding ability of the soil, a sufficient water (16). However, if most of the decrease in the amount of soil nutrients avail- water evaporates from the soil surface rather able to plants, a reduction of the soil’s ability than percolating down, dissolved solids or salts to hold nutrients, or soil compaction or surface can accumulate at or near the land surface in hardening. concentrations that many plants will not toler- This definition implies a strong interrelation- ate (43). ship between inappropriate land-use practices Mountainous lands** are cooler than the and land degradation. In some places degrada- other two categories and exist in both wet and tion is manifest (e. g., erosion and desertifica- dry climates. Because they have steep slopes, tion), whereas in others it is inferred (e.g., their soils are easily eroded. Much of the rain- declining crop yields). fall in the wetter regions runs off the land surface rather than percolating into the ground. Tropical Soils and Climates Consequently, soils in mountainous lands are likely to be rocky and thin, except perhaps on Although the chemical, physical, and bio- the lower slopes (16), logical processes that occur in the tropics are the same as those elsewhere in the world, the rates often are accelerated. Tropical air, soil, and water temperatures are higher; rainfall is more intense and erratic; and the growing sea- *See Van Wambeke (1 19) and Fripiat and Herbillon (36) for son is longer than in temperate parts of the more detailed information. These are good references on soils world. These factors affect tropical forests and of the hot wet tropics. They not only contain the commonly cited their soils. Further, they can place severe con- information on agriculture, soil names, etc., but also provide discussions of mineralogical and chemical processes. straints on certain land uses. Although detailed * *Elevated areas throughout the tropics typically from 750 soil descriptions are beyond the scope of this meters and abet’e. 6 ● Background Paper #1: Reforestation of Degraded Lands

Photo credit. B C Stone for the National Academy of Sciences

Severely degraded lands on Guam which were once covered by tropical forests Erosion has uncovered large expanses of infertile soil

Photo credit OTA staff Barren landscapes on islands along the south coast of China reflect deforestation that occurred hundreds of years ago Ch. l—/ntroduction and Background ● 7

Scope and Causes of productivity is greatly decreased. After 1 to 5 Land Degradation years, the land typically is abandoned by farmers who move on to other areas. The land then In much of the open woodlands of arid and reverts to secondary forest, vines, brush, or semiarid areas, overgrazing and repeated fires grasses of low nutritive value. Land abandon- have converted the vegetation to a degraded ment is caused by decreasing crop yields and fire climax stage. Consequently, soils become increasing weed control problems (57). Nor- dry and little woody regeneration occurs. Fire- mally, these farmers (shifting cultivators) allow tolerant vegetation—often unpalatable to ani- fallow periods of 10 to 15 years, thus giving mals—persists, leading to a desert-like state. To- enough time for soils to recuperate some pro- day, there are few undisturbed woodlands or ductivity, However, in a growing number of savannas in these regions. An estimated 20.5 places, increased population pressures lead to million hectares (ha) of tropical arid lands, an shortening of these periods. Food production area about the size of South Dakota, become is then greatly decreased, leading to even decertified every year. To date, an estimated stronger pressures to clear more forest. Such 1.56 billion ha of tropical land have undergone effects of acute population pressure are evident desertification (table I). in Haiti, El Salvador, and parts of the Philip- pines and Indonesia (131). Detailed descrip- Desertification occurs in the savanna region tions of tropical agriculture and its effect on of North Africa as well as in the savannas of soils include: Laudelout (71); Nye and Green- southern tropical Africa and northeast Brazil. land (88); Jurien and Henry (60); Watters (123); In the Sudan and elsewhere in North Africa, Sanchez (104); Lal and Greenland (69]. the populations of grazing animals—including goats, sheep, cattle, and camels—number in the Population growth rates in tropical countries millions and their grazing intensity has severe- are the world’s highest. Growing numbers and ly impaired natural regeneration of forests and rising aspirations lead to more than propor- forage (28), Consequently, people have had to tional increases in the demand for food, fuel, range farther in search of fodder for their fodder, and building materials (15). Population animals and wood for cooking and heating growth also requires increased land for ur- (131). banization and village expansion, energy pro- Forest degradation and loss under the rainy duction, and transportation (14). and seasonal environments may not be so se- With few exceptions, such as the river valleys vere as under the arid and semiarid environ- of West Africa where river blindness is being ments, but the effects on people are similar. eradicated, most of those lands that can sus- There are approximately 156 million ha of tain stable agriculture probably have been tropical moist forest, 181 million ha of forest cultivated. Remaining unused lands are those fallow, and 84 million ha of deforested water- already degraded, or those too infertile for con- sheds available for reforestation (131 ). When tinuous farming without constant infusion of areas cleared by agriculturalists are exposed high-cost inputs such as commercial fertilizer. to abundant rainfall, erosion, and leaching, soil Without these inputs, the land becomes susceptible to degradation, thus reducing the standard of living (49,108). Table 1 .—Tropical Lands Recently Undergoing Severe Desertification (million hectares) In recent years, some developing countries Region Total decertified area have been planning and encouraging move- Latin America. . . . 701,8 ment of people, usually into sparsely occupied Africa, ...... 685.0 Virgin tropical forests, Two examples are India and Pakistan . 170.0 Brazil’s planned colonization of the Amazon 1,556.8 Total ...... Basin via the Transamazon highway and Indo- SOURCE United NatIons, UN Conference on Desertification: Round-Up, Plan of Action and Resolutions (New York United Nat Ions, 1978) nesia’s colonization of its outer islands (49,108). In both cases, people are moved between re- some may be impossible to reclaim. In addi- gions that are geographically and geologically tion, reforestation of degraded lands may not different and thus they are ill-equipped to cope be so profitable, in financial terms, as reforesta- with the new environment. Consequently, in- tion of rich, fertile lands. However, in many appropriate land use practices have led to de- countries, fertile sites are reserved for agricul- creased crop yields. Forest clearing exposed tural activities. Given the dwindling amount the lands to heavy erosion and depleted the of good lands and the increasing demands for soil’s nutrient supply, leading to land degrada- forest products, it is necessary to consider all tion and to indebtedness and landlessness for alternatives. Reforestation is an alternative that the people. has the potential to rehabilitate the degraded soils and provide many goods and services for The expansion of lands under cultivation will industrial and local needs. continue, given the rising pressures. More lands will become degraded and subsequently abandoned. To break this cycle, some of these Reclamation Using Trees degraded lands can be reclaimed via reforestation. Tree planting of degraded lands is not a For degraded sites it is often advantageous panacea to deforestation or inappropriate land to plant trees because of their ability to use uses. Some degraded lands will be difficult and water and nutrients inaccessible to plants with Ch. 1— Introduction and Background ● 9 — shallow roots and because they supply a mul- Soils under forest cover often have high or- titude of products: wood, fuel, fodder, and ganic matter content. Land-use practices that others. Moreover, a tree canopy acts as a buf- jeopardize the soil’s organic content therefore fer against the direct impact of raindrops on can have adverse effects on successful}’ refor- the soil. The litter and humus layers underlying esting degraded lands. the forest absorb moisture, allowing water to The living network of roots near the surface infiltrate the ground and recharge the ground of forest soils provides mechanical support for water supply (92). Trees, by shading the soil, steep slopes; this root network is the main con- reduce soil temperatures and thus promote ac- tribution to slope strength and prevention of cumulation of organic matter and retard possi- landslides (100). Consequently, trees are par- ble soil hardening, ticularly valuable for watershed protection and The presence or absence of organic matter for arresting desertification in areas of mov- in any soil is an important factor in the soil’s ing soils (e. g., sand dunes). Some trees act as productivity. Soil organic matter is important soil improvers as well as soil protectors. to soil productivity because it: Leguminous trees and forbs have the capacity to enrich soil with nitrogen. Legume trees have ● contributes to the development of soil ag- nutrient-rich leaves which can be used as fod- gregates, which enhance root development der or mulch (80,81). and reduce the energy needed to work the soil; There are many reasons for planting trees. • increases the air- and water-holding ca- Provision of goods for household and industrial pacity of the soil, which is necessary for use (see fig. 2) is equally as important as reha- plant growth and helps to reduce erosion; bilitative factors. For local needs, a tree species ● releases essential plant nutrients as it with several attributes or a mixture of tree spe- decays; cies can be planted to obtain multiple benefits • holds nutrients from fertilizer in storage —e. g., ability to enrich soil fertility, wood suit- until the plants need them; and able for fuel and poles, and nutritious leaves ● enhances the abundance and distribution for fodder. of vital soil biota (90). 10 . Background paper #1: Reforestation of Degraded Lands

Figure 2.— The Role of Forests

< . Controlled runoff, water Catchment r I supplies, trrlgatlon, soil Y protection 4 fertllily, oxygen

* < Recreation, tourism, Ecology and wild national parks, protection Ecological effects — - I life conservation of endangered species of flora and fauna

Windbreaks, shelter belts, dune fixation, reclamation of eroded lands

— Fuelwood and a Cooking, heating, and charcoal household uses

Shifting cultivation, forest — Agricultural uses r 1 grazing, nitrogen fixation, mulches, fruits and nuts L

Housing, buildings, - Building poles L construction, fencing, furniture

Plt saw!ng and Jolnery, furniture, con- Indigenous consumption sawmilling struction, farm buildings I i

Ropes and string, - Weaving materials baskets, furniture,

4 furnishings 4 Serlculture, aplcul - Silk honey, wax Iac ture, erlculture

Carving, Incense, chemicals glassmaking I L 8 {t J

Naval stores tannin, . Gums, resins. turpentine, distillates and OIIS resin, essential oils &

Reduction agent for steel- 9 Charcoal r 1 making, chemicals, poly vinyl chloride [PVC) dry cells 6

Transmission poles I pitprops 1 I 1 T Lumber joinery, furniture 1 I Industrial uses l— Sawlogs packing. ‘shlpbuilding * dt h mining, construction sleepers I Plywood, veneer, furniture, Veneer logs 4 containers. construction I H 1 1 I J

Newsprint. paperboard. prlntlng and writing paper - Pulpwood . containers, packaging

● dissolving pulp, distillates textiles and clothing

Particle board fiberboard Residues A wastepaper I

SOURCE World Bank 1978 Chapter 2 Reforestation Technologies Contents

Page What To Plant ...... 13 Native. Exotic Species ...... 13 Monoculture. Polycuhure ...... 14 Single-Purpose v. Multipurpose Trees ...... 15 Genetic Improvement...... 15 Planting Materials ...... ~.t...... 17 Seed...... 17 Nursery Planting Stock ...... 18 Direct Sowing ...... t ...... 24 Transplanting Wildlings and Stumps ...... 25 Land Preparation ...... 26 Manual v.Mechanical Clearing ...... 26 Soil Improvement ...... 27 Tree Planting ...... 28 Repairing Eroding Watersheds ...... 28 Reforesting Unproductive Grasslands ...... 29 Arid and Semiarid Lands ...... 31 Saline/Alkaline Lands . . 0 ...... 33 protection and Maintenance of Trees ...... 36 Protection From Livestock Damage ...... 36 Weed Control...... 36 Local Participation ...... 36 Reforestation Using Combinations of Trees With Agricultural Crops ...... 38

List of Tables Table No. Page 2. Suitability of Various Types of Nursery in the Tropics ...... ,.,...... 18 3. Comparison Between Container and Bare-Rooted Methods of Raising Seedlings 20 4. Vegetative Propagation Techniques Used With Tree Species ...... 21 5. Possible Candidates for Aerial Seedings in Developing Countries ...... 26 6. A Selection of Tree Species Tolerant of Saline and Alkaline Conditions ...... 35

Figure Figure No. Page 3. Production of Nursery Stock in the Tropics ...... 17 Chapter 2 Reforestation Technologies

Reforestation, for the purposes of this paper, man manipulation, it is a technology worthy refers to the planting of seeds, plants, or parts of further investigation and research. Silvicul- of plants to establish trees. This definition in- tural treatments of naturally regenerated for- cludes afforestation. * This section of the paper ests to encourage and enhance natural repro- discusses various preplanning considerations, duction have great potential for preservation the application of various technologies on dif- of genetic resources and may be less costly ferent types of degraded lands, and alternative than plantations (122). Preliminary studies indi- technologies to maintain the newly restored cate that productivity of naturally regenerated site. Both new and promising technologies, as forest plots can be equal to or greater than the well as conventional techniques, are described, productivity of plantations after 40 years (59), The results suggest that plantations may not Although a discussion of natural regenera- have an advantage over natural regeneration tion” * of forests is outside the scope of this in the long term. However, few techniques background paper because it requires little hu- have been developed to manage native tropical forests, and those few attempts have concen- trated mainly on the tropical rain forests and moist deciduous forests (111).

PLANT

Before a reforestation effort is initiated, a to produce products—e.g., food, fuel, fodder, decision must be made as to what to plant. The or commercial timber—to meet the needs of the choice of tree species depends on the site to people. be reforested. In this case, “site” includes not only the physical environment but also socio- Native v. Exotic Species economic factors—especially the needs of land Most large-scale tropical plantations to pro- users. Trees selected to reforest degraded lands duce industrial timber use exotic species. * The must be able to thrive on open lands, compete most commonly used genera are 1% us, Euca- with aggressive weeds, and withstand stress lyptus, Gmelina, Tectona, Terminalia, Cupres- (e.g., drought, fire, low fertility). It is especial- sus, Cunninghamia, and Araucaria. Some ly beneficial if the species can add nitrogen to lesser known genera such as Cedrela, Triplo- the soil and provide products that serve the chiton, Anthocephalus, Aucoumea, Albizia, needs of local communities. and Agathis also are gaining popularity. Most The debate whether to use native or exotic of these genera, though indigenous to the trop- tree species, to plant in monoculture or ics, are planted as exotics (37). polyculture, and to select single-purpose or Despite objections that exotic species are multipurpose trees continues. Meanwhile, sev- susceptible to increased disease risk, they have eral factors may influence the selection. been used exclusively in plantings in the Among them are the objectives of reforestation, tropics. This may be because there is much ex- availability of seeds, and the level of costs perience, information, and research on exotics, (labor, cash, and risk) associated with reforesta- especially on Pin us, Eucalyptus, and Tectona. tion alternatives, The primary reason for the There are arguments for and against the wide- kinds of reforestation addressed in this background paper is to restore degraded lands and *Trees that are not nat i~rc to a locale.

13 14 ● Background Paper #l: Reforestation of Degraded Lands

spread use of exotic species. Proponents cite forest, yield a greater variety of products, and their initial reduced susceptibility to native in- are less susceptible to pests than are monocul- sects and diseases as an advantage, However, ture. Interplanting legume (nitrogen-fixing) exotic species may be more susceptible to seri- tree species with other commercial tree species ous damage if native pathogens and pests adapt may reduce the amount of fertilizer required to the new hosts, since the exotics are unlike- after successive rotations. In experimental ly to have evolved resistance to these orga- plantations, Indonesians are interplanting Cal- nisms. liandra with Pin us merkusii and with Eucalyp- tus deglupta to yield firewood for local use, The use of native species—ones that grow Calliandra also shades trees such as Agathis naturally in the local region—in plantations has loranthifolia, which require shade initially for been largely ignored. The reasons for this vary better growth (83). from lack of familiarity with many tropical tree species to lack of seed supplies, and the some- Yet little actual experience has been gained times slower growth rates of native species, dealing with polyculture plantations either at The latter is a common argument for using ex- the industrial scale or in village forests (131). otics over native species (37,131,135). However, Only recently have projects been established while this difference may occur where rainfall where mixtures of species have been planted is above 1,5oO millimeters (mm), growth of ex- for a variety of end uses (e.g., GTZ, IDRC, and otics and native species usually are similar in USAID projects in the Sahel). Areas of mixed the arid and semiarid parts of Africa (126). plantations are beginning to be established in the social forestry projects of Asia, especially Arguments supporting reforestation using India and Nepal, Even in those projects, infor- native species are varied. First, native species mation is lacking on the optimum species mix- are adapted to the local environment and thus ture and spacing. The management of mixtures may be less susceptible to stress, serious dis- of tree species for production is biologically ease, and pest damage. Local people are more complex, especially for more than two species. familiar with their native plants and have more It becomes even more difficult where multiple uses for them (54), Similarly, the timber of products are extracted from multiple species native species is likely to be known to local under multiple harvesting regimes. However, wood-using industries. Further, use of native perceived benefits of polyculture planting, trees contributes to the conservation of native flora and fauna (29).

Monoculture v. Polycuhre

The use of a single species in forest plantations is known as monoculture. Monoculture plantations may be more susceptible to disease and pest outbreaks. Some diversity can be achieved by alternating species in blocks of land being planted or by alternating different genetic varieties of the same species, This method should prevent pests that develop and multiply in one plantation block from spreading rapidly to other blocks of trees having the Photo credlf. COMALCO for NAS same genetic makeup (135), Polyculture: African mahogany (Khaya species) planted between Leucaena leucocephala trees on highly aluminous Multiple species (polyculture) plantations soil in Weipa, North Queensland, Australia. Leucaena is are, in theory, better able to mimic the natural being tested as a nurse crop for mahogany Ch. 2— Reforestation Technologies • 15 ———— especially in the context of social forestry, tioned above, is a legume. Its kin, Acacia man- make them worthy of further investigation. gium, outperforms other species on degraded lands in Malaysia. Wood of this species has Single-Purpose v. Multipurpose Trees potential for sawtimber, veneer, furniture, firewood, pulp, and particle boa rd. Its leaves can Forest plantations in the past served in- be used as forage for livestock (85). The foliage dust rial purposes and thus grew only one prod- of species such as Calliandra is readily eaten uct, such as sawtimber or pulpwood. Now, by cattle and goats; its flower provides rich nec- with an increasing demand for food, fuel, and tar to produce Calliandra honey (84). Man} fodder, plantations are needed to serve a varie- other tropical legumes exist whose potentials ty of objectives, Thus, the use of multipurpose are unknown. trees is becoming increasingly important, especially on degraded lands where population Little is known of the variability in growth pressure is often high. Acacia albida, a and performance of multipurpose tree species. multipurpose tree, bears leaves at the begin- Variation is related to habitat so that each ning of the dry season, thus providing shade planting site should be tested with genetically when most other trees are bare. It also yields different varieties of the same species. Such ef- edible seed pods at a time when little other fod- forts are under way. The National Academy der is available. The tree enhances soil fertili- of Sciences (NAS) is designing and implement- ty because it fixes nitrogen and provides leaf ing international trials of tree species for the mulch, and it can be used as firewood (82). A. Sahel and of multipurpose tropical tree species albida is just one of more than 1,000 species for many grantee institutions. Both the Inter- r of the genus Acacia (84]. Other multipurpose national Council for Research in Agroforestr} trees exist that perform equally well and hold (ICRAF) and the Commonwealth Forestry“ In- great promise for reforestation. Various lists stitute are cooperating with NAS in preparing of these promising species are available (44,79, manuals for evaluation of multipurpose spe- r 80,83,84,85,118,1 25). cies. But even when correct species and pro~ - enances are known, there is still a major gap The family Leguminosae deserves special at- in the knowledge of silvicultural techniques for tention in the process of selecting trees for re- multipurpose tree plantings. Here, little infor- forestation. Legumes are among the first to col- mation is available, and no research guide ex- onize newly cleared land. Acacia albida, men- ists, Despite these obstacles, multipurpose trees merit special consideration because of their ‘ \ \ , * - ; ‘ “ ! :>+,f multiplicity of likely benefits. ,, . . . t~,. ‘ ~ ji. . _-, , I,. , ‘ :’;, \ ‘ ‘ ,>, :;,.;;:::” ; ~ Genetic Improvement ! i, r . , ,’\’ ~!.-~ ,:,; ;, ; ~ ,,,, ,;’~:;’ ;;:(+.;;, : :j ),,~ { .,1}> : l\ J ::k ~ Plant breeding has been responsible for about ~\ ‘i ~ii ,+ j ; ‘ f ‘ ~ ! , f, ‘~ j ; , ~ ,; ‘?’, ~ ~, { ~ ; : 1, \ “ };’[ f half of the spectacular gains in agricultural crop yields accomplished in the past three ;;j~; ;;,’;{g;~~~$jg decades. The application of genetic science to :~ (i forestry lags many decades behind agriculture, partly because it takes a longer time to breed % trees than agricultural crops. However, tree > - breeding programs in industrialized nations ~ ‘ [ ! “ ~ ~ : ‘ ~ .~.. ~.;. \ -- ‘“ : ~ ~r,;i-:, : have already achieved important productivity i’ :, i,. . :&&1 ,,. ~:, .p~f& ~’, ~~&z gains–l0 to 20 percent in first generation and Photo credit A S Bhat for NAS 35 to 45 percent in second generation seed Multi purpose trees such as Sesbania grandiflora can orchard progeny-for industrial timber plan- provide firewood, fodder, food, and green manure and hold promise for reforesting eroded wastelands tations (87). First genetic selections have throughout the tropics yielded gains of as much as 50 percent in some 16 ● Background Paper #1: Reforestation of Degraded Lands energy plantations (97). Tree breeding pro- ing trees from early plantings that did grow grams could greatly accelerate genetic im- well on such sites to establish a seed orchard, provement of trees, especially tropical trees, an adapted race for the degraded sites has been and forestry yields from degraded land sites produced (135), could increase. Conventional provenance testing is a major Most reforestation projects in the tropics use undertaking. For proper statistical analysis, seeds without testing them to see whether they hundreds of trees from each seed source are are genetically appropriate for the project’s site planted in replicated blocks and grown to conditions. Since most tree species used in maturity. The process generally takes so long reforestation are found over broad geographic that the original seed source may be unavail- ranges, different races within the same species able by the time results are available. When that have adapted to different environments. Thus, happens, the test plots must be developed as a species’ suitability to a particular site can seed orchards, further prolonging the process. vary depending on the race used. A well-estab- This usually takes too long to accommodate an lished technique matching races with sites is individual reforestation program, Many prove- called provenance* testing. Seeds of the de- nance tests do not yield results because of sired species are collected from various sites premature termination of the projector depar- (provenances) and tested at the site to be ture of the investigator. Therefore, provenance reforested or at a site with a similar environ- testing must be carried out by established insti- ment. tutions that can maintain long-term programs. Once the best provenance has been identi- The potential to shorten the time needed for fied, several options are available to obtain tree improvement is increasing as new tech- planting materials, Seeds from the desired niques are being tested. Tissue culture (dis- provenance sometimes can be purchased. Al- cussed in the following section) can rapidly ternatively, individual trees from the prov- mass-produce clones of chosen individuals enance test can be selected as parent material. from a provenance test. The clones can then Once the best individuals have been identified, be tested for particular microsites or outplanted they can be used to establish seed orchards or at the reforestation site. The establishment of to produce rooted cuttings for planting mate- international networks of cooperating scien- rials. This ensures that only seeds and seed- tists to collect seeds or planting material and lings from superior trees are used in the refor- to record environmental data for each parent estation program. Another technique is to use tree can reduce the number of provenances to superior trees from an environment similar to be evaluated for each test. Another new tech- the reforestation site to establish a seed orchard nique, where many provenances are planted without the provenance testing. If the desired in one stand (single tree randomized plots), al- species already grows on the reforestation site lows the testing of many more provenances and if superior trees have not been eliminated, without a corresponding increase in budget or then it is possible to obtain planting materials personnel. And the propagation of clones en- adapted to the site from those trees. Where this sures that the provenance with the exact genet- is feasible, it is probably the fastest and least ic materials is used, thus allowing more types expensive approach. to be tested, The U.S. Forest Service, in experi- ments with Eucalyptus in Florida, used single These tree improvement and selection tech- tree randomized plots and cloning to shorten niques have been successful for reforestation the time for screening of appropriate prove- on degraded tropical lands. For example, Euca- nances (38). These techniques have not been lyptus grandis generally does not grow well on used in reforestation of degraded tropical the steep, eroding, and phosphorus-deficient lands. Before that can be done, pilot-scale im- soils of Andean slopes in Columbia. By select- plementation projects, ones having at least a *Testing populations of the same species to study their per- 10-year timespan for sufficient results to ap- formance under a range of site and climatic conditions. pear, need to be initiated. Ch. 2—Reforestation Technologies ● 17

PLANTING MATERIALS

Various techniques are used to propagate Seed trees, Some propagation techniques have been known for centuries (e.g., direct seeding) and To reforest degraded lands, seeds of various are available for implementation; others (e. g., species must be available in great quantities. tissue culture) are at various stages of develop- Today, supply falls short of need, The seed ment or are undergoing refinement. (See fig. supply for species most commonly used in 3 for schematic chart of production of nursery tropical, industrial plantations (pines, eucalyp- stock and table 2 matching nursery planting tus, Gmelina, teak) is adequate, although some stock with land classifications. ) valuable provenances are in short supply and

Figure 3.— Production of Nursery Stock in the Tropics

Vegetative I Seed 1 I 1 Product Ion of propagulesa Graft/ Tissue Seed bed Container 1< I bud culture

v Raising of Transplant Containerized propagules beds plants I I

(Root pruning) Soft container Container and Met hod Rigid filler with medium identical container medium (plastic, pulp, etc.)

Type of Planting stock planting stock

Piants incomplete Plants complete. [ I 1 \ Tall plants, leaves Root & shoot With root bare Clay balls stripped (Striplings) cut back (stumps) bail root (boulette) ● a . aA structure (e g cutt (ng seed) that propagates a plant SOURCE Evans 1982 18 ● Background Paper #l: Reforestation of Degraded Lands

Table 2.—Suitability of Various Types of Nursery Planting Stock for Reforestation in the Tropics — Climatic—. conditions Type)yypepe, of planting Lowland rain Montane Rain Dry/semidecidu- Areas of unreli- Arid areas site forest Forest ous forest able rainfall Dense forest Tall, whole plants Tall, whole plants Potted stock or Potted stock, or strippings stumps stumps, strippings Open exploited Tall, whole plants Tall, whole plants Potted stock or Potted stock or forest/line or strippings stumps stumps planting — Agricultural land/ Large, bare-rooted Small, bare-rooted Potted stock. Potted stock. Robust-potted eroded land/ plants. Potted or mini potted Root-pruned, Root pruned, stock (sowing) taungya systems stock. Direct stock. Direct bare-rooted bare-rooted sowing sowing stock, stumps. stock, stumps. Direct sowina Direct sowing Clean weeded Small, bare-rooted ‘Small, bare-rooted, Potted or root- Potted or root- Robust-potted land or minipotted or mini potted pruned, bare- pruned, bare- stock (sowing) stock. Direct stock. Direct footed stock. rooted stock. sowing sowing Direct sowing Direct sowing Areas with risk of Large strippings Large strippings Large-potted Large-potted Robust-potted bird damage or stock or stumps stock or stumps stock animal browsing SOURCE J Evans (29) their natural origins are threatened with dealers generally sell seeds without adequate genetic impoverishment or extinction. The information regarding the place where the par- seed supply for multipurpose, agroforestry ent trees were grown. The use of poorly iden- species, on the other hand, is small. Organized tified seed often has made it impossible to trace programs of seed collection, extraction, stor- the origin of seed which produced a promis- age, and distribution are needed to develop the ing stand meriting further trial or one of bad quantity necessary for large-scale reforestation. form to be avoided, Full records of all forest seedlots should be made and copies should ac- Seed storage of tropical tree species is a prob- company all seed distributions, Most impor- lem. Tropical species show great variation in tantly, every shipment of seed should show their capacity to retain viability under natural how the species was identified, where and conditions. Many large-seeded species have when the seed was collected, and specific site Swietenia short periods of viability; seed is and stand information about the seed source viable for only 6 weeks. Other species retain (see ref. 29 for a sample certificate of seed their viability only under certain conditions. origin). Thus, the recipient will know the quali- Araucaria hunsteinii Seed of will die if allowed ty and origin of a seedlot if problems develop to dry out. Legume tree seeds must be kept dry later. International attention was drawn to this and free from insect or rodent damage to re- problem at a meeting sponsored by the Nitro- tain their viability (29). Seed storage is therefore gen-Fixing Tree Association held at Bellagio, an important part of reforestation efforts. Italy, in September 1982. It will also be the Many factors influence the longevity of seed focus of a meeting proposed by ICRAF to be in storage. Recently, some progress has been held in 1983 (74), made in this area. Seeds of some tropical plant species can now be stored in liquid nitrogen (3). Another problem exists regarding the trans- Nursery Planting Stock fer of seeds within a nation and international- Seedlings ly because the records of seed source and genetic history are sometimes poor (17,58), Plans Growing seedlings in a forest nursery is the to control planting material (e.g., ref. 89) do not customary way of raising planting stock in the yet apply to tropical countries, and tree seed tropics. (See ref. 91 for sample technical man- Ch 2— Reforestation Technologies • 19 ual on nursery practices. ] The two most common methods of raising tree seedlings are: 1) in open beds for bare-root planting, and 2) in containers for seedlings to be planted with nursery soil around the roots. Seedlings, in the past, were raised in open beds and planted in the field bare-rooted. Those -, . . - ‘ seedlings, however, were susceptible to desic- v -“ ,-- $ “ ‘ . ..-:- .- : .:-- .’ -. cation and survival was poor. Survival im- ‘ . , .. . - *-=

-.. - , ‘ *.. + proved when seedlings were taken in individ- /- *- - . . - - . ual containers from the nursery to planting sites with soil still around the roots. Container- AAi ized seedling techniques have evolved from the —. , ---Y “Tf :-. method of cutting into the nursery bed between Photo credit OTA sfaff each seedling so that a cube of soil remained Tree seedling containers in Hawaiian nursery, Roots grow attached to the roots (Swaziland bed system) out of a hole i n the base of each container, a technique to starting seedlings in the containers. The called “air pruning” types, sizes, and durability of containers vary greatly. Choice of container usually depends for more details on growing seedlings in con- on cost and convenience, but containers often tainers. are bulky to transport because of the soil. The various types of containers can be clas- Vegetative Propagation sified according to their porosity: Another technique is vegetative propagation, ● impervious containers—metal, plastic, or the reproduction of planting stock without the other materials; use of seed. Vegetative propagation has the ad- ● semipervious or pervious containers— vantage of hastening production of genetically mostly paper based, not removed at plant- superior plants and massive reproduction of ing; and clones, assuring that the plants will all be of ● pre-filled containers—individual units of the desired genetic type. It has the disadvan- growing medium (29). tage of higher risks because of lack of genetic diversity, It also requires greater technical ex- The most commonly used container is the im- pertise. Vegetative propagation is widely used pervious type. Although most are plastic bags for reproducing crop trees such as rubber, co- or metal tubes, local materials can be used. conut, tea, coffee, cocoa, and oil palm. More Bamboo, wood veneer, and banana or palm detailed trial work is needed to develop effi- leaves have been used widely in different parts cient operational systems for many tropical for- of the world (32). For example, Paper Industry est species. Corp. of the Philippines uses waste veneers from peeling operations. The use of closed-bot- Methods of vegetative propagation include tom containers, however, can result in root cuttings, air layering, budding, grafting, and coiling if the seedling is left in the tube too long. tissue culture (see table 4 for a brief assessment This can be avoided with more modern con- of each of the techniques). Rooted cuttings re- tainers that have an open bottom and are sus- main the most popular method. Each year, sev- pended above the ground. The roots self-prune eral million Eucalyptus trees are propagated when they come to the air below the contain- from rooted cuttings in Pointe Noire, Congo, ers. See table 3 for a comparison of container and Aracruz, Brazil (131). Casuarina junghuh- and bare-rooted methods. Also, see Tinus and niana is propagated by cuttings in Thailand McDonaId (112), Venator (120), andTinus(113) and India (83). Once the technique is devel- 20 ● Background Paper #1: Reforestation of Degraded Lands

Table 3.—Comparison Between Container and Bare-Rooted Methods of Raising Seedlings

Container system Bare-rooted system Materials Need as many containers as seedlings. Supply of Nursery site with easily worked soil suitable for bed good soil for potting mix cultivation Equipment Container filling tools, soil sieving screen. Several implements for plowing, leveling, bed forma- Tubing shed tion, seed sowing, undercutting, lifting, etc. Labor Labor intensive, not easily mechanized. Much labor Well suited to mechanization. Most labor intensive needed for container filling, seed sowing, weeding, components are lifting and packaging, but even and container removal at planting. Typically 10 to these may become mechanized in the future. At 20 workers per million seedlings produced Beerburrum, Queensland, 2 to 3 people raised 1.4 million seedlings per year Transport Bulky and heavy to transport, costly over long Plants easy to transport over long distances distances Silviculture Excellent survival at planting, except that overgrown Good survival depends on careful timing of lifting plants become pot-bound and suffer serious root and planting, to coincide with wet weather, and deformation and later instability adequate conditioning of plants. Gives poorer results where climate is unreliable Supervision Easier to grow satisfactorily, timing of operations Requires a high degree of supervision to ensure not too critical, but may suffer more from casual proper timing and regularity of operations neglect of watering, shading, etc. Protection Fresh soil in every container reduces chance of Reuse of same soil may lead to buildup of patho- buildup of pathogens or soil pests. Diseased seed- gens or soil pests. Pests and diseases more likely Iings easily isolated and discarded. Weed control to affect all seedlings in a bed tedious cost High labor intensity tends to produce more costly P. caribaea in Queensland U.S. $20 per 1,000 (1978) seedlings. Costs per seedling including overheads E. camaldulensis in Niger U.S. $60 per 1,000 (25) are: A. cunninghamii in Queensland, using metal tubes U.S. $70 per 1,000 (1978) Pinus caribaea in Fiji (small tubes) U.S. $30 per 1,000 (1978) E. camaldulensis in Niger U.S. $140 per 1,000 (25) Albizia falcataria in the Philippines (short nursery life) U.S. $10 per 1,000 (1978) Suitability All smaller nurseries and especially: 1) for good sur- 1) Large production nurseries raising only a few vival in arid conditions, 2) when many different species for planting and where climate is depend- species are raised, 3) where plants are distributed able, 2) raising “stump” plants and as a cheap to the public and post-planting care is likely to be method for hardy species poor—e.g., extension nurseries SOURCE J Evans (29) oped, the cost of production is low. For exam- good form, product utility, or adaptation to ple, at Aracruz, Brazil, 230 laborers produce problem sites (i.e., high acidity, saline soils, 10 million rooted cuttings annually at a total etc.), and the use of tissue culture can shorten cost of as little as U.S. $0.10 per plant. For most the time necessary to reproduce a large stock hardwood species, a team of two to three pro- of planting material with the necessary charac- fessionals with a budget of $200,000 should be teristics. A large number of provenances can able to develop a system in 2 to 3 years (131). be tested in a confined space within a limited time period for many of the particular desired Another vegetative propagation method that characteristics. (See refs. 13 and 98 for more holds great promise is tissue culture (also called information on tissue culture.) micropropagation). This technique can rapidly produce thousands or even millions of prop- The technology is well established in tropical agules from a single parent; thus, it has great agriculture and tropical horticulture (e. g., oil potential for genetic improvement programs. palm), but it is still in the developmental stage Reforestation requires planting materials with for most tree species. The cost of plantlets and desirable characteristics such as rapid growth, the sophistication of the technologies make Ch, 2—Reforestation Technologies ● 21

Table 4.—Vegetative Propagation Techniques Used With Tree Species — Technique Description Advantages Disadvantages Grafting and budding The union of a shoot or branch Propagation of elite selections Many trees are graft. onto the rootstock of another which do not root readily incompatible plant Maturity/juvenility of the tree is preserved. Mature tissue continues to produce seed Cuttings The induction of root forma- Preservation of maturity or Cuttings may not survive the tion on sections of stems, juvenility of mother tissue. time period to root branches, or suckers (the for- Mature plant cuttings con- Very difficult with many tree mation of sucker shoots on tinue to flower and produce species sections of roots from some seed May require up to 1 year for species) Resulting plants can be some trees screened for resistance to soil pests Least labor intense means of vegetative propagation Air layering The induction of root forma- Maturity/juvenility of plants is tion on shoots that are still maintained: shoots from attached to the mother tree mature tissue plants will continue to produce seed Shoots are nourished by the mother plant Tissue culture The sterile culture-of small Very high volumes of plants Useful when other methods pieces of the mother tree can be produced in short are not feasible (such as buds, leaf tissues, periods of time from a small Most labor intense method etc.). Also known as “micro- amount of mother plant Mature tissues become juve- propagation” nile so no seed can be produced rapidly Requires use of special facilities Some potential for genetic variation SOURCE Plant Research Institute, OTA background paper, 1981 ‘- tissue culture unlikely to replace the use of cut- Trials have shown that seedlings inoculated tings for large-scale reforestation in tropical with fungi show improved growth and survival areas. Its nearer term use is likely to be in es- over uninoculated controls (18,21,56,70,77). tablishment of “super tree” orchards to pro- Some scientists suspect that certain fungi produce seeds or cuttings. vide plants with resistance to low pH, heavy metal toxicants, high temperatures, and other Mycorrhizae and Rhizobium stresses common to degraded sites. Seedling survival and growth rates in the Methods for reinoculating damaged soils nursery and at the planting site can sometimes with mycorrhizal fungi include: be improved by using special kinds of fungi ● inoculating containerized plants or bare- and bacteria. Associations between tree roots root nursery stock prior to outplanting, and mycorrhizal fungi are essential for healthy ● pelletizing seed with mycorrhizal in- growth of most tropical trees. The fungi are ac- oculum prior to sowing, and tive in the transport of nutrients and water to ● inoculating soil at the planting site with plant roots and, in some cases, are important laboratory produced cultures. for the release of nutrient elements from mineral and organic soil particles (76). Populations These techniques are being developed, but of mycorrhizae are found naturally in soils, but characteristics of the most widely used tech- these can be depressed after long-term clear- nique for inoculum production—pot culture— ing and/or topsoil removal, making reestablish- pose a major constraint to commercial applica- ment of vegetation on degraded lands difficult. tion. The fungus is grown in association with 22 ● Background Paper #1: Reforestation of Degraded Lands

“i#i’

4“ . . . .

. ‘ ,- - , - , r,, . &,.$*\. Photo credit: T Wood a. k-, “J;~=-

, .7 “.,- ;, , 3 Ectomycorrhizal fungi on roots of Douglas-fir . , . ?+ ‘ “, Trees of the legume family can grow well on degraded land with low nitrogen content because their roots can be a symbiotic host for Rhizobium bacteria which fix nitrogen. Rhizobium bacteria, within tree root nodules, produce an enzyme that causes conversion of nitrogen gas (available in the soil but unavailable to the plant as a nutrient) to ammonia. The ammonia, a common fertilizer, is converted to compounds such as amino acids and transported throughout the tree for use in synthesiz- ing plant protein. Thus, some legume leaves, pods, and seeds are highly nutritious as food or fodder, and the leaves are an excellent fertilizer and soil conditioner. Maximum production of ammonia requires infection of the legume’s roots with the right type of Rhizobium. Most soils contain Rhizobium, but degraded soils probably con- Photo credit” Weyerhaeuser Co tain fewer types and lesser amounts of the bac- Tissue cultured Ioblolly pine plantlet ready to be teria. Thus, the appropriate type of Rhizobium transferred from Weyerhaeuser Co. ’s may not be present at the site of a reforesta- laboratory to the soil tion effort, or present in enough quantity to in- fect the tree roots. An association with an in- roots of living plants in pots of soil or sand in appropriate type of Rhizobium may occur, in a greenhouse. The soils, infected roots, or which case little fertilizer may be produced. fungal spores are then harvested and used as inoculum. Unfortunately, this technique is An old inoculation technique is to collect bulky, clumsy, slow, and susceptible to con- root nodules from a vigorous legume tree, grind tamination by pathogens (94). them up, and use the product to inoculate other Ch. 2—Reforestation Technologies ● 23

slurry to the tree seed just before planting in the nursery or field. An adhesive such as gum arabic can be used to ensure that inoculum ad- heres to each seed. Fertilizers such as lime, rock phosphate, and molybdenum can be added to the seed coating to protect the seed and to feed the emerging seedling (48). The inoculant also can be drilled into the soil with the seed at planting. It is possible to inoculate growing trees, but inoculation at the time of planting seems the most efficient method. Inoculation of legumes with Rhizobium has been practiced in agriculture in industrialized nations for many years. Use of this technique in tropical agriculture is not yet well established, but it is being promoted by several institutions. Unfortunately, the application of this technique in forestry is not well accepted. In- oculants are living organisms that must be transported and stored carefully and used cor- rectly to retain their viability. These requirements can be difficult to achieve, especially at remote tropical sites needing reforestation. Most importantly, inoculants for tropical legume trees commonly are not available be- Photo credit: T. Wood cause of a lack of production. Nitrogen-fixing nodules formed on the roots of Acacia pennatula, a fast-growing tropical woody legume, by These constraints are being overcome slow- Rhizobiurn species ly. Inoculants for some tropical legume trees, such as Leucaena and Calliandra, are now trees of the same species. Because of differing available commercially. Research centers, such responses to various soil conditions, however, as Centro International de Agricultural Trop- the collected nodules may not contain the ap- ical in Colombia and the Nitrogen Fixation by propriate type of Rhizobium. Development of Tropical Agricultural Legumes project at the other techniques has greatly enhanced the like- University of Hawaii produce inoculants on a lihood of the correct association. For example, pilot scale as a service for researchers and, oc- different types of Rhizobium collected from casionally, legume growers. While most of the nodules from natural sites are isolated, cul- biological nitrogen fixation work at these insti- tured, and stored. Then various combinations tutions is on nonwoody agricultural legumes, of tree provenances and soil types are tested inoculants for legume trees are gradually being against the various types of Rhizobium to find developed and efforts are under way to educate the most productive combinations. Then, the tropical forestry specialists about this technol- appropriate Rhizobium for a particular refores- ogy. tation project can be reproduced in culture and The roots of some nonlegume trees also can sent to the nursery. be infected by micro-organisms that produce Inoculants from cultures are relatively sim- nitrogen fertilizer for the tree. Casuarina, ple to use and cheap, costing only a small frac- planted on tropical degraded lands, is an ex- tion of a cent per tree, The inoculant is in ample of this group of trees. Techniques to powder form and can be applied as a dust or culture the micro-organisms that associate with 24 ● Background Paper #1: Reforestation of Degraded Lands

when applied to tree seedlings, and it may have application in tropical forestry, especially in areas where rainfall is limited and sporadic, and where plant desiccation is a problem. Super-slurper can increase aeration and improve drainage through its expansion capabil- ity. It can be used in a variety of ways: mixed into soil or greenhouse media, applied as seed coating, distributed in the hole prior to transplanting, and broadcast over an area to be seeded. The latter, however, is prohibitively expensive because of the amount required and the biodegradable nature of the copolymer. The most promising, economically sound use of super-slurper is its application into the slurry bucket during bare-root planting. This is an effective means of preventing bare root desiccation.

Direct Sowing

Direct sowing means that seed is planted directly at the site. This technique is feasible where seed is plentiful and where mortality of seed and germinating plants is low (101). Thus far, only a few species have been planted this Photo credit Wood way in the tropics: Acacia arabica, A. mearn- Nitrogen-fixing nodules formed on the roots of red alder sii, Gmelina arborea (Senegal/Gambia), Leu- (Alnus rubra) by an actinomycete in the genus Frankia caena Zeucocephala (Philippines), Azadirachta indica (Nigeria), Cassia siamea (Tanzania), and these nonlegume trees are not yet available. Pinus caribaea and P. oocarpa (Honduras) However, the use of ground nodules from al- (65,78). ready established trees is possible and practical for areas where these trees are native. The advantage of direct sowing is that no nursery is required and planting costs are low. Soil Conditioners On the other hand, seedling survival may be low (23) because of weed competition, lack of Soil conditioners, used to increase soil pro- tending, poor weather, or animal damage, Ger- ductivity, are materials other than commercial mination success can be increased by pretreat- fertilizers or organic matter that change the ing seed with fungicide, insecticide, and bird properties of soil physically, chemically, or and rodent repellents. biologically (4). Chemical substances such as Agrosoke and Erosel (plastics) or “super- Direct sowing can be done either by hand or slurper” (water-holding starch copolymers) are machine (e. g., tractor or plane). Although the examples. The super-slurper was developed by use of aircraft to sow seeds largely is still un- the U.S. Department of Agriculture to increase proven in the tropics, it shows promise in ac- seedling survival and growth rates through an celerating reforestation programs through its ability to absorb, store, and release water to the ability to seed large and remote areas quickly. plant on demand (5). Although it is better It is not, however, a replacement for other known in agriculture, it has shown promise planting techniques. It is simply another tool Ch. 2—Reforestation Technologies ● 25

Aerial seeding for the tropics is at a developmental stage. Only a few sites and species have been tested. (See table 5 for a list of possible candidates for aerial seeding.) The technique entails many logistical problems. Lack of aircraft and logistic, administrative, and communications support are major constraints. The lack of large seed quantities is another constraint. Poor control exists over tree spacings. The seeds used are usually wild or unimproved strains because seeds from genetically selected strains are yet too scarce and expensive to use. On the other hand, the mere fact that there are no capital costs for nurseries nor for the out- 1945 planting of seedlings makes aerial seeding attractive.

Transplanting Wildlings and Stumps

Other sources of planting materials exist for reforestation. Natural forest seedlings (wildlings) and root suckers are sometimes trans- planted, usually from moist tropical forests, with variable results. Stumps, a nursery stock that has been subjected to drastic pruning of both roots and shoot, can be planted directly into the ground. Stump planting is especially suited for species that have a dominant taproot (32). Examples of species that have been planted 1976 as stumps are Acacia cyanophylla, Azadiracta indica, Cassia siamea, Chlolophora excelsa, Photo credit U S Army and James Black, Jr for NAS Cordia alliodra, Dalbergia sissoo, Gmelina ar- Corregidor Island at the entrance of Manila Bay, bomb borea, Tectona grandis, and Pterocarpus spp. pocked and denuded in WWII, was air sown with (29). During transit, stumps are normally cov- Leucaena. It has become the dominant vegetation ered with wet sacks or layers of large leaves to prevent desiccation. to be considered when reforesting remote, rugged sites not easily reached by people or land vehicles. 26 ● Background Paper #l: Reforestation of Degraded Lands

Table 5.—Possible Candidates for Aerial Seedings in Developing Countries

Humid tropics Semiarid areas Tropical highlands Acacia auricu/liformis Acacia albida Acacia mearnsii Other Acacia spp. Acacia nilotica Alnus acuminata Albizia falcataria Acacia saligna Alnus nepalensis Albizia lebbek Acacia senegal Alnus rubra Other Albizia spp. Anacardium occidental Callitris spp. Anthocephalus chinensis Azadirachta indica Eucalyptus globulus Avicennia spp. and some Colophospermum mopane Grevillea robusta other mangroves Eucalyptus citriodora Inga spp. Calliandra calothyrsus Eucalyptus tereticornis Mimosa scabrella Cassia siamea Haloxylon aphyllum Pinus oocarpa Other Cassia spp. Haloxylon persicum Robinia pseudoacacia Casuarina spp. Pinus halepensis Cecropia spp. Prosopis spp. Croton spp. Zizyphus mauritiana Derris indica (Pongamia glabra) Zizyphus spina-christi Eucalyptus deglupta Other Eucalyptus spp. Ficus spp. Flindersia brayleyana Gliricidia sepium Gmelina arborea Leucaena Ieucocephala Macaranga spp. Maesopsis eminii Melaleuca spp. Melia azedarach Melochia indicia Muntingia calabura Musanga spp. Neoboutnoia spp. Pinus caribaea Pinus kesiya Sesbania grandiflora Spathodea campanulata Syzygium cumini Terminalia catappa Trema spp. SOURCE Nat/onal Academy of Sc/ences (78) –

LAND PREPARATION

Nutrient deficiency, soil compaction, lack of completely weed-free sites for rapid early water-holding capacity, and surface hardness growth, whereas direct seeding of Calliandra are characteristics of degraded lands that influ- on unprepared sites has been successful (29). ence the success or failure of plant establishment. Because of these problems, many sites Manual v. Mechanical Clearing need some type of preplanning preparation such as fertilization, clearance of competing Land preparation can be either done by hand weedy vegetation, or loosening of the soil. The or by machine. On degraded lands with grass degree and type of land preparation depend or weeds, the land is usually disked. Burning on several factors: capital and labor available, is an efficient method under certain conditions, site and soil conditions, vegetative cover, and On gentle slopes or flat degraded lands, the use species to be planted. For example, lmperata of tractors is popular. In areas with residual grassland may require burning and disking be- scrubby trees, large tractors with heavy chains fore planting Eucalyptus, a tree that requires between them are used to pull down undesir- -— Ch. 2—Reforestation Technologies ● 27 able trees. Some of the vegetation might be be necessary to add nutrients during land used to make charcoal or be burned. Land preparation. Several techniques exist to in- clearing methods involving hand or chain saw crease soil nutrients, including mulching with cutting followed by burning may be better than organic or inorganic matter, the use of green clearing by heavy equipment. The reasons are: manure (especially herbaceous legumes), the 1) ash has fertilizer value, 2) heavy machinery use of nitrogen-fixing trees, and commercial can cause soil compaction, and 3) bulldozers fertilizers, can displace topsoil (106). On fragile, steep slopes with highly erodible soils, the only Mulching—placing vegetative matter around suitable method is to manually cut, pile, and/or the base of the tree—suppresses weeds, im- burn the scrub vegetation (135). proves soil moisture conditions, and augments soil organic matter (95). Legume or nonlegume Further advantages of manual methods are nitrogen-fixing trees can improve soil with that they are less constrained by the rainy their ability to produce nitrogen fertilizer [see season, they require few skills, and the capital sec. on “Nursery Planting Stock”). Foliage cost is relatively low. In addition, manual land dropped by legumes is nitrogen-rich and will preparation provides temporary employment augment soil fertility as it decays. to laborers and causes minimal damage to soil. A disadvantage of manual clearing is the need Historically, tropical foresters have relied to recruit, manage, and provide logistics in re- more on seed provenances and thinning prac- mote areas for a substantial number of labor- tices than on commercial fertilizers to increase ers, Mechanical clearing, on the other hand, productivity (92). Use of commercial fertilizers requires high capital inputs for equipment for forestry purposes is not likely to become maintenance; supplies of fuel, oil, and spare widespread in the tropics given their high cost parts; and operator training and supervision. and the priority given to their use in food pro- yet in general, mechanical clearance is cheap- duction. In most tropical countries, much of er than manual clearance (29), The choice be- the commercial fertilizer must be imported. tween manual and mechanical land prepara- The cost in foreign exchange combined with tion must be made on a case-by-case basis, de- uncertainty of plant response limit their ap- termined by all these considerations. plication. However, Carton de Colombia has experimented with the application of about 50 grams (g) of fertilizer in planting holes on ex- Sell Improvement tremely nutrient poor soils. The results after On degraded sites, land preparation is espe- 3 years have been promising (68). If small cially important for soil improvement. Plow- amounts of fertilizer can produce significant ing suppresses weeds and breaks up soil sur- results, further evaluation is needed to deter- face compaction, and ripping breaks up deep- mine the best formulations and amount of nu- er, hardened layers. Contour plowing or using trients needed per seedling. Research is needed contour barriers of dead vegetation also can on other deficiencies that limit growing trees. reduce soil erosion in areas where vegetation Some highly weathered tropical soils offer is cleared. Both plowing and ripping are lim- problems when fertilized with essential plant ited to gentle topography. Catch dams, bench nutrients such as phosphorus and potassium. terraces, and contour trenches all function to Phosphorus can become so tightly held by soil arrest soil movement, thereby improving soil minerals that plants can extract little for their stability and productivity. Ridging in various benefit, whereas potassium is not held by the forms–tie ridging, stepped ridges, small catch- soil and is leached away (37,64). The use of the ments—serve to improve drainage and soil wrong fertilizer, or incorrect amounts of fer- aeration and to retain water on the site (40,128). tilizer, can reduce yields. For instance, applica- The soils of degraded lands commonly are tion of 100 g of potassium chloride (KC1) per poor in available nutrients; therefore, it may Pin us caribaea tree depressed growth and in- 28 ● Background Paper #1: Reforestation of Degraded Lands

creased mortality on Nigerian savanna sites show a dilute mineral content nearly equiva- (61). lent to that of distilled water (107,117). The disease is absent probably because the waters Moreover, the use of fertilizer may cause contain so little calcium that the snails cannot water-associated environmental problems such build shells. The introduction of lime, even in as increased eutrophication that hampers nav- small quantities, into such waters might pro- igation (52) and may trigger the onset of new duce significant environmental changes, in- health problems. For instance, a large part of cluding spreading schistosomiasis. Fertilizers the Amazon River Basin has the required en- can be both beneficial and detrimental, so the vironmental conditions for the presence of impacts of various fertilizer application need schistosomiasis, a serious parasitic disease to be thoroughly examined before widespread transmitted by freshwater snails. Chemical use. analyses of waters draining large areas here

TREE PLANTING

Reforestation of degraded lands is similar to Repairing Eroding Watersheds reforestation in general. The main differences are the intensity of site preparation, the selec- Deforestation of montane regions is one of tion of tree species, and intensity of mainte- the most acute and serious ecological problems nance and protection. Well-established technol- today (27). Some 10 percent of the world’s ogies for propagating, planting, and tending population live in mountainous areas, while certain tropical trees and tree crops have been another 40 percent live in the adjacent low- applied in developing countries. These technol- lands. Thus, half of mankind is affected by the ogies, however, need refinement and adapta- tree cover, or lack of it, on mountain water- tion for local site conditions. The management sheds (72). Yet no precise estimates exist of the of soils, particularly where continuous tree pro- scale of the problem. Data from FAO and other duction is the goal, is of great importance (75, agencies indicate that some 87 million ha of 104), If reforestation of degraded lands is to be montane watershed land need reforestation profitable and, at the same time, restorative of (131), land quality, more work is needed in selecting Maintaining or replacing tree cover on moun- high-yielding, fast-growing, soil-enriching, and tain slopes is very important for soil protection stress-tolerant species and provenances that (see ch, 1). Trees intercept raindrops, slowing produce products desired by the local people their speed and transforming them into a or landowners. steady, gentle flow of water down trunks and Substantial experience and information have from leaf tips. The roots foster infiltration of been accumulated. Foresters from developing water into the ground to replenish ground wa- and developed countries alike have had experi- ter, Removing the protective tree canopy can ence with plantations, mostly growing exotic greatly alter the water regime. This results in species—some in the tropics, some on degraded floods after heavy downpours as high intensity lands, Recent references on plantation technol- raindrops compact the soil surface promoting ogies include Evans (29), ILO (55), FAO (32), runoff, landslides, and erosion (93). Ghosh (40), Wattle Research Institute (124), and Efforts to establish tree cover on montane Champion and Seth (19). slopes must overcome the erosion and land- The following section draws on previous dis- sliding that may be common to those defor- cussions to assess tree planting on specific ested sites. In areas where erosion is not severe, degraded lands: eroded watersheds, semiarid natural regeneration of vegetation can occur and arid lands, unproductive grasslands, and and restricting use of the site may be the most saline/alkaline lands. effective and least expensive method to reestab- Ch. 2—Reforestation Technologies ● 29

inaccessible locations aerial seeding may be more appropriate and should be investigated.

To ensure that watershed protection continues, reforestation programs must integrate the people’s needs for food, fodder, and fuel with the need for watershed protection. Spe- cies selection should be based on productive as well as restorative characteristics. Fast- growing legume trees and other multipurpose trees can help to meet these criteria, as can agroforestry, where trees are used to support and enhance agriculture. Project planning must also take into account the people living in the lower reaches of the watershed and in other nearby areas. Their demands on the watershed for wood and other products must be either met or supplied from elsewhere for Photo credit: US Forest Servfce a reforestation program to be assured success. A catch dam, constructed from local materials, is used i n the gully to halt further soil erosion Reforesting Unproductive Grasslands lish tree cover. However, when erosion is acute, primitive dams made of rock, soil, and, if avail- Conversion of tropical rainforest into farm able, tree stems and branches can be con- or grazing land commonly results in rapid structed in gullies to halt soil movement down- depletion of soil plant nutrients and ac- slope until trees can be established. Such bar- celerated soil erosion. In some places, the riers S1OW water movement and trap soil. Chan- degradation process leads to takeover by per- nels and walls can be constructed to divert sistent, aggressive weed species of low nu- water flow from vulnerable areas. Water-spread- tritive value (9). Often the combined problems ing techniques can be used to spread runoff of low soil fertility and weed infestation water over relatively flat areas, reducing its become so great that the land is abandoned. erosive potential. Control of sheet erosion Such lands are subject to frequent uncontrolled down a slope can be accomplished by terrac- fires. Whenever the vegetation is burned, ero- ing, contour hedges and furrows, and low re- sion becomes very severe, and productivity is taining walls. reduced further. These lands can contribute to degradation of other sites by causing increased Planting sites in montane environments must siltation of waterways, floods, and periodic be prepared by hand to avoid soil damage. water shortages. Where trees are to be established on degraded watersheds, it is necessary to have tall, well- lmperata is the main invader grass species established seedlings by the end of the first year in Southeast Asia and parts of Africa, Known to avoid being shaded by the ground cover also as cogon and alang-alang, this sharp-edged plants, Seedlings raised in containers have bet- grass grows a dense network of roots and unter survival and initial growth rates than bare- derground stems, crowding out other species root seedlings. They can be prepared for site and depriving them of moisture during the dry conditions (hardened) in the nursery by re- seasons, Because Imperata is an aggressive, peated root pruning and by regulating water- rhizomatous grass, burning may induce rapid ing and amount of direct sunlight (39]. How- regeneration, Plowing Imperata rhizomes into ever, use of bare-root seedlings often allows pieces only encourages it to regenerate into larger areas to be planted (96). In remote and several plants (105]. 30 • Background Paper #l: Reforestation of Degraded Lands

Imperata occupies some 16 million once- Acacia auriculiformis, Calliandra calothyrus, forested ha (one-twelfth of the total land area) Gliricidea maculata, and Leucaena leuco- in Indonesia (31,62,116). The Indonesian grass- cephala are species that have been used exten- lands are expanding by 150,000 ha annually sively in Southeast Asia, Acacia auricu]iformis (109) and could eventually cover an area com- will grow on the poorest sites, is deep rooting, parable to existing cropland. In the Philippines, and has a dense crown (102). Direct seeding Imperata covers one-fifth of total land area (41). of A. auriculiformis on Imperata grasslands in It has been identified as a problem in Thailand, Malaysia yielded poor results, but large seed- Malaysia (31), and Papua New Guinea (99). If lings of this tree can withstand competition the percent coverage of Southeast Asia is simi- from the grass (86). The use of 20 centimeter lar to that of Indonesia, there maybe 40 million (cm) tall seedlings raised in nurseries in plastic ha of Imperata grasslands in the region. tubes gave good results (8). Best tree growth results if the grass is cut and burned prior to In Central and South America, the invasion planting (129). A. auriculiformis is susceptible of toxic weeds into cattle ranches cleared from to fire, but this has not been recorded as a cause virgin forest is a growing problem. Soil nutrient for failure of reforestation projects (131). It also depletion and weed invasion can cause live- is a drought-resistant, soil-improving species. stock production to drop to such an extent that ranches have to be abandoned. Comprehensive Calliandra calothyrus is a fast-growing, deep- statistics are lacking, but estimates indicate that rooted tree with a dense crown. It improves some 8 million ha of forest have been cleared poor soil by nitrogen fixation and high litter for 350 large ranches in the Brazilian Amazon production, and it is fire resistant (102). In a Basin and an unreported area for another trial of direct seeding of Imperata grassland 20,000 smaller ranches (115). Yet 85 percent of that had been burned and plowed, the survival the ranches in one major area around Para- rates after 7 years were: gominas has been abandoned (50). C’. calothyrus 10.4 percent Special treatment is needed for those areas L. leucocephala 8.3 percent infested with Imperata and for the many aban- A. auriculiformis 2.6 percent doned cattle ranches in the Amazon Basin and Success was not obtained where the site was elsewhere in Latin America. Although the tech- not first prepared (47). Indonesians use Callian- niques discussed here were developed for lands dra to reforest land infested with Imperata covered by Imperata, the basic principles can cylindrica, Eupatorium species, and Sac- be applied to other derived grasslands. charum species (83). Gliricidia maculata grows faster than C. calothyrus and can tolerate very poor soils that Techniques for Reforesting would be unsuitable for the latter species. It Imperatu Grasslands improves soil through nitrogen fixation and lit- Tree species selected for reforestation of 1m- ter production. It has the disadvantage, how- perata grasslands should possess the following ever, of an open crown that allows some characteristics to counter those factors that growth of weeds such as Imperata due to allow grass to dominate: penetration of sunlight (102). G. maculata has been used to control the growth of Imperata easy establishment, in young rubber plantations (110) and is easily rapid early growth in poor soil conditions, established from cuttings. The establishment deep rooting, of L. leucocephala seems difficult by compari- dense crown to shade out Imperata, son (30), nitrogen-fixing and soil-improving characteristics, and On upland grass-covered sites, Leucaena Zeu- fire resistance (131). cocephala has not grown so rapidly as the trees Ch. 2— Reforestation Technologies •. 31 — listed above. The varieties of Leucaena avail- a thicket of Leucaena exists, and the pernicious able for reforestation are better suited to mar- grass is gone (81). ginal lowland conditions (sea level to 500 meters (m)) (11). Some varieties grow rapidly to Arid and Semiarid Lands become trees, while others have a shrub form. Leucaena canopy is fairly open in the early Desertification can occur not only in arid and years after planting; thus, careful tending is semiarid lands but in certain humid environ- necessary to reduce competition from weeds ments as well, In either case, removal of the (11). Given early attention, L. leucocepha]a can vegetative cover alters the water regime and establish itself firmly. Some of the shrub vari- reduces the moisture content of the soil, lead- eties have rapid and copious seed production, ing eventually to desertlike conditions, An es- enabling the shrubs to spread down slopes and timated 1.56 billion ha of tropical lands are produce dense cover. Leucaena, planted with undergoing severe desertification (I 14]. The no other vegetation, may not suffice for ero- problem is particularly acute in Africa and sion control on steep slopes because the leaves Latin America, Reforestation of these degraded tend to fold up at night and when under stress, lands is intended to: thus reducing the amount of canopy cover to • stabilize soils, including sand dunes, shield the ground from heavy rain. It is a soil • reduce wind and water erosion, improver with good litter production, nitrogen • improve microclimates, and fixation, and very deep rooting. The latter, to- • produce fuel, fodder, and other products. gether with very rapid resprouting after cutting, indicates potential resistance to grass For detailed descriptions of reforestation tech- fires. In addition, dense stands may shade out nologies appropriate for decertified land, see undergrowth, leaving little grass on the ground Kaul (63), Goor and Barney (42], Weber (127), to burn, making it usefuI as a firebreak (81). Adams et al. (l), Delwaulle (25), and Evans (29). Since water is the main constraint in semiarid In the Philippines, planting has been done and arid lands, reforestation techniques gener- simply by burning the grass, opening a furrow ally entail improving water conditions, which with a plow pulled by a water buffalo, and also include choice of tree species, water man- dropping in Leucaena seeds, In about 3 years, agement, soil stabilization, and protection of trees. Drought Resistant Species: Many trees and shrubs native to arid and semiarid areas are drought resistant. These drought resistant species can be improved through genetic programs designed to identify, breed, and propagate the most productive of the drought tolerant provenances. Most of the drought resistant species can be reproduced by vegetative propagation (131) and this can be very impor- ##\ t. i tant for species susceptible to seed-eating in-

‘ - *;? “ seedlings are normally used instead of seeds : t x,ai,,% H “, <*, ..- because seeds may be sought after by small “? ~•ÿÿÿø ., mammals or insects. Good nursery practices Photo credit: Btsson are essential, Great care is needed to produce Planting bare-root Leucaena seedlings on Imperata- a hardened plant with a well balanced, straight infested grassland i n the Philippines root system, Sometimes, direct sowing of 32 Ž Background Paper #l: Reforestation of Degraded Lands drought resistant species is preferred, especially for the species that have long and fast- growing taproots that may be damaged in a nursery or in transfer to the field. Other Species: In arid or semiarid regions, the major limiting plant nutrient is likely to be nitrogen. Hence, the use of nitrogen-fixing trees can be extremely valuable. Lists of numer- ous tree species adapted to these areas and that have proven successful are found in Goor and Barney (42), Weber (127), Adams et al. (l), NAS (79), and Webb et al. (125). Water Management: Successful reforestation in areas with low rainfall depends on collection and retention of water at the planting site. Water must be directed to the rooting zone of trees and retained there as long as possible. Methods include plowing and ripping the soil surface to increase infiltration, ripping parallel to the slope to retain water, construction of bench terraces on steeper slopes, and funneling moisture onto a smaller area (water harvesting). The latter requires construction of minicatchments that concentrate water into the rooting SOURCE’ F, R Weber for VITA zones of individual trees. The treatment of soil with mulches of dust, organic matter, plastic, Microcatchments are used in reforesting arid lands. Small depressions are constructed around the base of or light-colored stones can reduce evapotran- seedling or small tree with the general slope of the spiration and thus conserve water. Except for surrounding soil surface shaped to move mulching and construction of minicatchments, rainfall towards the tree most water-management techniques require the use of tractors and other machinery. Soil and Sand Stabilization: The destruction of vegetation in arid and semiarid areas makes soil susceptible to wind erosion. Drifting sand encroaches on agricultural land and engulfs settlements (32). However, where the sands can be stabilized, they can often be successfully af- forested and become productive. The principle of dune stabilization is to im- mobilize the sand long enough for vegetation to become established. The usual practice is either to erect artificial barriers of brushwood or other materials in a grid pattern or to plant sand-binding grasses and trees in a similar pattern. Planting large nursery stock in deep pits may obviate the need for other dune treatments. The use of a mulch or a heavy liquid Photo credit: U.S. Agency for Irrternational Development derived from petroleum or latex as a ground Planting sand-binding grasses to stabilize shifting sand Ch. 2—Reforestation Technologies ● 33

cover has had some success, but is less reliable Mine Spoils: A Special Case than traditional methods and has only been Mine spoils occupy little total area in the used on a pilot scale (90,131). tropics, but they can be an important local The goal of reforestation on shifting sand rehabilitation problem where land is scarce, dunes is to establish firm rooting by the plant. The treatment of mine spoils is analogous to Only those plants that thrive on fluctuating that of decertified lands, although the presence moisture and nutrient supply and germinate of toxic chemicals may provide an additional with little water seem to succeed. A planting problem. Reforestation of such wastelands is method consists of mixing together seeds of usually difficult, but techniques are available several species and sowing them at three dif- to prepare the sites successful for tree growth. ferent depths in a trench—near the surface, In general, it may be necessary to: slightly deeper, and at about 8 cm from the bot- reshape the site to minimize erosion; tom. During a good rainfall season, the seed- cover it with soil; lings on the bottom maybe killed by waterlog- neutralize strongly acidic sites with lime; ging while the top ones survive, but during a buffer it with peat, humus, or other mate- light rainfall season, the top two lines may die rials to reduce toxicity; because of desiccation while the bottom ones loosen the soil for better aeration; and/or survive (39). fertilize the site (32). Complete Protection: The exclusion of Site condition will have great influence on browsing animals in many regions—even in the choice of species and the likely social or areas with shifting sand—will result in recov- economic results of the reforestation effort. ery of the natural herbaceous and woody plant Costs of reforesting mine spoils are usually cover. Sometimes natural regeneration can oc- high, but as part of a mining operation they are cur despite centuries of land degradation. affordable. One such project, Baobab Farms in Since local people in arid and semiarid lands Kenya, has converted an entire devastated usually depend heavily on livestock, a solution limestone quarry into an economically produc- is to provide an alternative source of fodder by tive agroforestry plantation (12), planting fast-growing hedges that provide nutritious foliage and have the ability to resprout, The list of trees suitable for planting at mine The problem is often to convince the herders spoils is limited, as not many trees can tolerate to pen the cattle and cut and carry fodder from the extreme soil conditions. Species that can the hedges. rapidly add humus and nitrogen to the soil are highly desirable. For example, Casuarina trees The primary causes of desertification are have been used to reclaim mined spoils in Thai- simple to list, but they are linked together in land, Papua New Guinea, and the Dominican a complex web that makes the effects of the Republic (84), whole greater than the sum of the individual parts. Thus, the success of any reforestation program, particularly in the semiarid and arid Saline/Alkaline Lands lands, will depend on more than mere technical development. The cooperation of local Saline soils contain sufficient soluble salts people is needed to ensure protection, proper (e.g., NaCl] to harm plant growth by prevent- care, and thus survival of the trees, To get this ing uptake of soil moisture. Water within the cooperation, the needs of the people as they plant actually moves outward to the saline soil perceive them must be paramount when de- to dilute the salt solution. Therefore, even signing the reforestation project. where the saline soil is wet the plant will ex- 34 ● Background Paper #1: Reforestation of Degraded Lands

perience drought stress. Alkaline soils may or upward movement of ground water and

may not contain soluble salts (e.g., Na2CO3). deposition of salts in upper soil layers; The major drawback to use of alkaline soils is the penetration of roots opens up the soil, that soil minerals retain so much sodium on improving permeability and facilitating their surfaces that plant growth and soil struc- leaching of deposited salts; ture are adversely affected. The kind of salt also soil structure and microbiology are further affects the platy soil clay minerals. Where soil improved by incorporation of organic mat- structure is good, the platy clay minerals are ter deposited on the surface as litter; and arranged in random fashion. Sodium, however, increased transpiration from vegetative tends to reduce the random orientation of clay cover can reduce waterlogging by lower- minerals, in some cases allowing them to rear- ing the water table in areas where it is too range in parallel layers as in a deck of cards. high. This orientation reduces pore spaces and thus Successful reforestation of salt-affected lands soil permeability. Tillage problems in soils hav- depends on the following: ing this clay mineral arrangement are common; such soils do not break up easily. 1. Careful analysis of soil chemistry and structure. Soluble salt concentration and Overall, approximately 121 million ha of sa- pH should be among the first measure- line/alkaline desert soils exist in the tropics: 36 ments to be made. (In practice, selection million ha in India and Pakistan; 31 million ha of planting material often proceeds within Africa; and 54 million ha in South America out even this fundamental information, ) (35). Each year approximately 500,000 more 2. Correct choice of planting and soil enrich- hectares of excessively irrigated lands become ment techniques to match soil character- saline or alkaline as a result of inadequate istics: drainage or use of irrigation water that is too ● In many cases, trees must be planted in salty. Capillary action draws moisture to the deep pits to get maximum survival rates. irrigated soil surface where it evaporates, leav- ● Planting on bund ridges (dikes) has been ing salts in or on the topsoil. In some cases, successful in some cases as such micro- salts can be leached from upland soils and bed- sites are better drained, which promotes rock, raising runoff salinity from deforested leaching of toxic salts, slopes and adversely affecting agricultural soil ● Establishment of trees in alkaline soils in lowland areas of the watersheds by causing often requires addition of soil amend- temporary or lasting waterlogging and conse- ments and fertilizers, such as 5 kilo- quent salinization (10). Even the continuous ad- grams (kg) of gypsum per pit to replace ditions to the soil of salt from sea breezes can exchangeable soil sodium with calcium, have negative effects (16). Other factors that and application of nitrogen and phos- contribute to formation of saline and alkaline phorus fertilizers and/or green manure. soils include the presence of impervious sub- ● In saline soils with pH less than 8.5, it soil layers, a dry climate, saucer-shaped topog- is possible to secure good tree establish- raphy, and use of brackish irrigation water (39). ment without replacing the soil, and even the gypsum may not be required. Techniques for Afforesting Saline and ● Trees should be planted in alkaline soils Alkaline Lands immediately after the start of the rainy season, For saline soils, planting should Reforestation of saline and alkaline lands can follow two or three heavy showers that have a number of beneficial effects on the phys- leach out salts (22). ical, chemical, and biological soil properties: ● For most tree species irrigation should ● soil surface shading by trees reduces sur- use freshwater only, Weeding also is face evaporation and, consequently, the necessary in the first 3 years (22). Ch. 2—Reforestation Technologies ● 35

● Seedlings should be of a proper size for cannot be guaranteed in such extreme con- maximum survival—e,g., over 1 meter ditions. In the State of Haryana, India, (m) for Eucalyptus hybrids, and over Prosopis juliflora and Acacia nilotica are 0.45 m for Acacia nilotica and Prosopis grown together on severely deteriorated juliflora. sites having sporadic tree/shrub cover. P. 3. Selection of species suitable for particular juliflora is grown on barren regions, and site characteristics. Table 6 lists species A. nilotica can produce high yields of that grow well in saline and/or alkaline fuelwood and fodder. Proper seed selec- conditions. The table also shows some im- tion and plantation management can re- portant economic uses for some species. sult in trees with good form rather than Yields and quality of produce, of course, low, spreading shrubs,

Table 6.—A Selection of Tree Species Tolerant of Saline and Alkaline Conditions+ —.— — — Species Saline tolerance Alkaline tolerance Uses Country Acacia niloticaa up to 0.3 ”/0 ssc “ – Up to pH 9 Fw/fd/Ta/G – India A. saligna Saline soils Alkaline soils Fw/SC/SB/Fd/G — A. tortilis — Alkaline soils Fw/T/Fd/SC — Albizia lebbek Saline soils (moderate soils) — Fw/T/Sh/Fd/SC India Azadirachta indica Sites free of salt intop 60 cm. Up to Up to pH 9.8 Fw/T/O/SB/Sh/ India 0.45% SSC subsoil SC/Ta/PC Butea rnonosperma As A. indica As A. indica — India Casuarina equisetifoliaa Coastal sites, sandy areas — Fw/T/SC/Sh/ China/ PW/SB/Ta India Dalbergia sissoo A A. indica As A. indica — India Eucalyptus hybrida up to 0.3 ”/0 ssc Up to pH 9 — India E. camaldulensisa EC 12 to 17 mmhos/cm in top 30 cm pH 7 to 8.2 Fw/T/SB/B/PW Israel E. gomphocephala Saline soils — Fw/T/SC/Sh/SB Kuwait E. microtheca Saline soils Alkaline soils Fw/T/SB Sudan E obtusa Saline soils — — Kuwait E. occidentalis Saline soils — Fw/T/Sh — E. tereticornis Saline soils — — Sudan Gleditsia triacanthos Saline soils — Fw/Fd — Haloxylon ammodendron Saline soils — — — Leucaena leucocephala Saline soils — Fw/Fd/SC India (K8 and Fiji varieties) Pongamia pinnata As A. indica As A. indica India a Prosopis juliflora 0.54 ”/0 ssc (up to 1% ssc) pH 9.5 (UP to pH 10) Fw/Fd/SC India Prosopis pallida Coastal sites — Fw/Fd/B Hawaii Prosopis tamarugoa Highly saline tolerant — Fw/Fd/SC Chile Tamarix aphyllaa Saline soils — Fw/T/SC/SB U.S.S.R. T. manifera Saline soils — — U.S.S.R. T. ramosissima Saline soils — — U.S.S.R. T. tetranda Saline soils — — U.S.S.R, Terminalia arjuna As A. indica As A. indica — India

NOTE Salln!tv tolerance IS eXDreSSed elthe;-rn terms of Dercent soluble salt content (SSC) or electrolytic conductivity (EC) In un!ts of mmhos/cm The countrv hstl na denote’s the country In which the relevant trials were made It IS not an exclus{ve listing ‘Denotes species of particular Importance for reclamation of sallne/alkaline lands Key to Economic Uses B —bee forage, Fd—fodder, Fw—fuelwood; G —gum, O—oIl, PC—pest control, PW—pulpwood, SB—shelterbelts, SC— soil conserva tlon, T—timber of whatever qual!ty, and Ta—tannin

+ Mangr eves are not Included SOURCE Yadav (134) Goor and Barney (42) and NAS (79) 36 ● Background Paper #1: Reforestation of Degraded Lands

PROTECTION AND MAINTENANCE OF TREES

Reforestation does not stop after the trees Another alternative includes subsidizing have been planted. To be successful, reforesta- farmers with livestock feed or with cash to pur- tion efforts require protection of young trees chase feed during the period when trees are for years. Proper care and maintenance of the most susceptible to animal damage. Once the planted site are essential to ensure survival of trees are firmly established, controlled access trees to maturity. Once grown, there is the to the planted area is allowed for controlled problem of monitoring timber harvests and of tree pruning for fodder. Grazing underneath systematic replanting, To pay workers to plant the tree canopy can be beneficial as a means trees is not difficult, but to provide incentives of weeding, However, livestock grazing on for people to keep them alive is. Primary causes recently reforested watersheds can be harm- of reforestation failure, other than inappropri- ful because animals compact the thin topsoil, ate technologies, are uncontrolled grazing and thus leading to poor tree growth and increased fires, competition from weeds, and uncon- runoff, The use of game repellent, tested in the trolled cutting for fuel, fodder, and lumber. United States against deer, has promise. Simi- lar tests must be conducted for goats and Protection From Livestock Damage sheep.

Livestock grazing is a common cause of re- Weed Control forestation failure, especially in the semiarid and arid tropics. Direct protection through Weeding is an important aspect of plantation fencing or guards tends to be very expensive. establishment. Weeds compete directly with Other, less costly, methods include planting un- seedlings for light, soil nutrients, and water. palatable trees (e.g., Cassia samea) or thorny They can smother and eventually kill young trees (e.g., Parkinsonia) as barriers around the trees by shading and growth habits, They also plantation. The use of living fences is becom- increase fire hazards and shelter harmful ing a more widespread practice because they animals (29). provide a number of auxiliary benefits in- There are three main methods of weeding— cluding shade, fodder, windbreak effect, fuel, manual, mechanical, and chemical, The man- and wildlife habitat. ual method is the most common and straightforward and requires little skill or capital. It can be done on all sites, in almost all weather conditions, and with all species. Mechanical weeding methods may be used in large plantation projects, but generally they are not considered profitable in the tropics. In many tropical countries, chemical weed control techniques have been tested and found successful, but because of safety and cost problems they seldom become the main means of weed control (2),

Local Participation

Where the shortage of firewood for cooking Photo credit G Budowski for NAS and heating is acute, wood theft probably will Diphyse robinioides used as living fence posts in Costa Rica, The fence provides protection and shade for occur, No straightforward solution exists for animals. Its foliage can be continuously harvested for theft when hunger and cold are the driving forage, firewood, or green manure forces. This reflects a prevailing social prob- Ch. 2— Reforestation Technologies ● 37

lem that must be dealt with in any reforestation will quickly recognize that this method pro- scheme. The problem is particularly acute in duces much more fodder than when animals Africa where women and children must travel were allowed to graze freely. for many hours to gather wood for cooking (26). Another incentive is to guarantee provision Whatever the type and location of tree plant- of inputs, credit, and technical assistance when ing, cooperation of local people is essential for required. Where land tenure is a problem, establishment and sustained use of newly measures could be formulated to offset the risk planted trees (7). Tree planting programs are to participants caused by the lack of secure most successful when local communities are ownership of the trees—e. g., giving title to the involved and when the people perceive clearly land, short-term licenses, or improved finan- that success is in their self-interest. Because cial incentives. most trees do not yield much benefit for several years, the technical options offered must dem- Trees that can provide locally valued prod- onstrate explicit benefits to the people. Long- ucts are highly valued (54). Poor people do not term financial benefit/cost analyses are not perceive and rarely receive benefits from in- meaningful to poor people, while social bene- dustrial plantations. Apart from temporary em- fits are not easily understood or valued by proj- ployment and some stimulation of local econ- ect managers. On the other hand, people cer- omies, most benefits of commercial reforesta- tainly understand the concepts of scarcity and tion programs go to the central government risk and may respond to incentives. In local and the private companies involved, Even communities, support can be generated through though forestry may offer a worker higher pay demonstration plantings, commercial plantings than agriculture, work may be temporary, and by entrepreneurs with larger land holdings, labor frequently is not available when needed. education of community leaders, extension and During the critical planting and weeding sea- training programs working directly with farm- son, for example, many laborers wish to work ers or laborers, and direct financial assistance their own lands. Again, forestry competes with or provision of substitutes (131). agriculture. When given the choice, farmers will usualIy opt for the latter. Therefore, an im- Village woodlots provide an alternative to portant incentive to get individual landowners cutting in larger areas reforested for other pur- to plant trees is the possibility of growing poses. Subsidizing charcoal or kerosene is also enough food, fuel, and fodder to meet individ- an option until reforested areas can be har- ual requirements with some left over for sale. vested on a sustainable basis for fuel. In any case, incentives must be created to encourage If reforestation is done only to reestablish people to care and maintain the reforested area trees on a degraded site, in the long run the until the benefits can be reaped. For example, same forces that initially led to deforestation a village woodlot project in the State of Gujarat, and degradation will continue. Experience has India, which involved planting trees on de- shown that local participation in tree planting graded communal grazing lands, was able to can have positive and long lasting effects on meet the need of the people by allowing grass the land and the people. Agroforestry, com- for fodder to be cut and carried to livestock munity forestry, and social forestry systems are during the second year of tree growth. This ap- alternatives that seem to ensure the long-term proach enabled the people to continue feeding sustainability of the restored land by design- their livestock and simultaneously care for and ing reforestation efforts so that the people who maintain the reforested area (6). Often people live on the site are principal beneficiaries. 38 ● Background Paper #1: Reforestation of Degraded Lands

REFORESTATION USING COMBINATIONS OF TREES WITH AGRICULTURAL CROPS

Tree planting, by itself, addresses the bio- ● opportunity for self-sufficiency in agricul- physical processes of land degradation but not ture and wood products for the individual the socioeconomic causes of degradation. In- small-plot landholder. creasing demands for basic human needs and Agroforestry as a science is only in its infan- inappropriate systems for producing them are cy. Much more information is needed on the the root causes of most land degradation. interaction of trees and agricultural crops. Ac- Therefore, the most sustainable resource use tive studies are being conducted at ICRAF, systems will be those that produce a combina- CATIE, and the Forest Research Institute in tion of food, fuel, fodder, and construction Dehra Dun, India, materials. The use of multipurpose trees is one method of achieving this kind of productivity; Many agroforestry systems exist in which the combination of such trees with annual trees, livestock, and agricultural crops are used crops or animals is another, The latter method in combination, theoretically in perpetuity. For is now widely referred to as agroforestry. It en- detailed discussions of various agroforestry compasses all practices that combine forestry, systems, see FAO (34), Vergara (121), Grainger agriculture, and livestock raising, The inter- (44), de las Salas (24), King (66), Chandler and planting of annual crops with trees in reforesta- Spurgeon (20), and Wilkin (130). Discussion in tion technology systems may yield the follow- this paper is limited to just one of these agro- ing results: forestry systems called “taungya.” Its principal objective is to plant crops with trees used for • stabilization of shifting cultivators by pro- wood production. Taungya entails leasing for- viding alternative activities; est land to peasant farmers who clear the land, • early returns from the use or sale of val- plant crops among the trees, and after an uable agricultural crops to offset the costs agreed period move on to clear new lands. Al- of removing unwanted vegetation and re- though this method has been criticized as a planting with desired species; way for colonialists to acquire labor, it does • benefits to farmers from increased soil pro- have applicability in some modern reforesta- tection and reduced weeding; and tion schemes. Taungya is a well-established agroforestry practice. It can be used to achieve several ob- I jectives: to prepare land for tree planting, plant agricultural crops among trees, facilitate weeding, and ensure that suitable soil protection measures are taken. Taungya can, with small changes in rotation length of food and fiber crop and spacing regimes, accommodate a con- siderably increased food production and population (73). The full potential of agroforestry systems such as taungya has not yet been tapped. How-

Photo credit G Budowski for NAS ever, the greatest promise of agroforestry is the potential of addressing some key ecological Agroforestry: Three stratum coffee plantation. Coffee is planted in the shade of Erythrina poeppigiana (leguminous problems of the land and socioeconomic prob- tree) with Cordia alliodora (timber tree) towering above lems confronting the people. Chapter 3 Content.

Page Technological Constraints ...... 41 Technological Opportunities ...... 42 Other Considerations...... 43 Chapter 3 Constraints and Opportunities

TECHNOLOGICAL CONSTRAINTS

Currently available technologies can be di- Even though more seeds are needed, care rectly applied to reforestation of degraded should be taken in their collection. No mecha- lands. For almost any type of land, someone, nism exists today to control the quality of tree somewhere, has grown trees. However, impor- seeds traded. Most tree seed dealers do not tant technical constraints exist that must be supply adequate information on the origin of overcome to expedite reforestation. Some of the seed and this results in the use of genetic these constraints are: types that are poorly matched to site conditions. Planting the wrong seeds may cause a ● shortage of planting stock; reforestation project to fail. Similarly, it may ● inadequate attention to collecting, testing, be difficult to trace the origin of those seeds and distributing high quality seeds and that do produce well to get more planting ma- clones; terial. Seed certification procedures have been ● lack of information and research; and established for agricultural seeds and to a much ● lack of trained staff. lesser extent for tree seeds in Europe (89), In addition, because it is economically infeasi- Canada, and the United States. These are val- ble to reforest the broad expanse of degraded uable aids for controlling genetic history and tropical land using conventional technologies, seed quality, but they are extremely difficult the technologies need to be redesigned to re- to negotiate and control, particularly interna- quire less organization, less infrastructure, and tionally, less capital investment, Only then can there be rapid and widespread reforestation. Another constraint on reforestation is the lack of relevant and timely information and One major technical constraint to reforesta- research. Without accurate data, it is impossi- tion is the shortage of planting stock. The seed ble to understand how and why land became supply is generally adequate for species com- degraded or to plan the proper scale and ac- monly used in tropical industrial plantations tion needed. Although the data base is improv- (pines, eucalyptus, Gmelina, teak), although ing because of the Global Environment Moni- some valuable provenances are in short sup- toring System (GEMS] sponsored by FAO and ply and their natural origins are threatened UNEP, it will require continuous refining and with genetic impoverishment or extinction. On updating, Information is unavailable on silvi- the other hand, seeds for most of the multipur- culture of various tropical tree species (es- pose and nitrogen-fixing tree species are avail- pecially species with many uses), on species able only in small quantities and are often of and provenances suited for specific sites, on poor quality. The seed supply problem can be management of mixed-species plantations, and alleviated through the use of vegetative prop- on the best follow-on maintenance and protec- agation such as rooted cuttings or tissue tion. culture, These techniques have great potential to accelerate the process of matching prov- Even when information on appropriate spe- enances to specific site conditions and to cies and technologies is available, it often is not reproduce those provenances on a massive disseminated effectively to scientists, techni- scale. Caution is advised because these tech- cians, and decisionmakers. This is partly be- niques greatly reduce the genetic base and thus cause of a dearth of published material and can increase the forest’s susceptibility to out- insufficient information transfer within coun- breaks of pests and disease. tries. Another constraint on information flow

41 42 ● Background Paper #1: Reforestation of Degraded Lands

is the lack of an institution with a mandate to forestry jobs are in the government sector, coordinate reforestation research, develop- which is poorly rewarded in comparison ment, and implementation on degraded trop- with the private sector; ical lands. Thus, foresters are often unaware competition among ministries, between of what is being done elsewhere in their own ministries and industry, and among na- country, in other projects or administrative dis- tional and international agencies, and the tricts, or by various research agencies, Further- emphasis on post-graduate qualifications more, they are often unaware of previous work for promotion have led to a “brain drain” in their own region. Duplication, redundancy, from the local government agencies. and waste of precious time occur. Yet even when staff numbers and training are Finally, in most tropical countries there is a adequate, their efficiency can be impaired by lack of sufficient numbers of trained staff at poor project management and poor logistical professional and technical levels for direct and technical support (126). Further: operational forestry research or for extension ● government officials generally are unwill- work. The reasons are many: ing to serve in rural areas where the need • forestry ranks low in public recognition; is greatest; presumably this will continue • financial rewards are poor in comparison until the market is saturated with trained with other professions, since most tropical personnel.

TECHNOL0GICAL OPPORTUNITIES

Opportunities exist to overcome these tech- tionally. Support for tree improvement ac- nological constraints, including: tivities will encourage self-sufficiency in seed production and allow genetic improvement to developing international systems for seed serve local needs, source identification, collection, production, and distribution; Genetic improvement can give gains of 10 to supporting programs on tree improve- 30 percent in yield in the first few generations ment, propagation of Rhizobia and mycor- (131), and generations can be as short as 2 to rhizae, mixed species plantations, and 3 years for some tropical trees. Clonal propaga- other related subjects; tion has great potential, particularly where supporting efforts to disseminate research seed is in short supply and where certain site- information globally, regionally, and in- specific genetic characteristics are desired. country; Techniques for mass production of cuttings including research and dissemination of can be developed locally by private nurseries, information as components of reforesta- universities, or research institutions (including tion programs; and forest departments). Additional research may creating incentives for developing country be required, particularly for fast growing trop- people to enter forestry, such as changing ical species with short rotations. Financial sup- the reward systems in forestry institutions. port for techniques such as tissue culture may prove beneficial in the long run because its Lack of sufficient and appropriate planting greatest value may be in gene conservation. materials can be alleviated by developing in- Given the potential to increase survivorship ternational systems to identify seed origin, cer- and yield with inoculation of seedlings with tify quality, and collect seeds in commercial Rhizobium or mycorrhizae (as described in ch. quantities; protect natural stands to conserve 2), additional support could be given to collect, germ plasm; and establish seed orchards from identify, culture, test, and mass propagate pro- which seeds can be made available interna- ductive strains of those bacteria and fungi. Ch. 3— Constraints and Opportunities ● 43

Research on interactions between agricultur- Improvements in information dissemination al crops and trees has begun in many parts of can be linked to a well-coordinated research the world, However, very little research is effort based on some systematic, scientific ap- being conducted on mixing species of trees, It proach eliminating unnecessary duplication is a practice that is seldom used and poorly and waste. In some cases assistance may be understood. Support could be given to initiate needed from established research institutions more research in this area. The research should to design research programs and to help train aim at both the biological interactions of tree research staff to interpret and implement re- mixtures and at management systems to follow sults. Donor institutions can help, for example, when one species begins to dominate another. by providing appropriate equipment, Twinning of research institutions in developed and devel- Inadequate information gathering and dis- oping nations is one vehicle to provide this semination lead to inefficient expenditure of kind of support. (See ref. 132 for more informa- funds. The publication of information on local tion. ) However, other methods to coordinate reforestation and research in internationally funding for research need to be formulated. available journals could help to prevent con- Providing additional staff, like reforesting ad- stantly “reinventing the wheel, ” Providing pub- ditional hectares, requires increased govern- lished literature to operational and research ment expenditures, and, where necessary, fi- personnel, especially at the field level, could nancial or technical support from donor insti- enhance the likelihood of the most appropriate, tutions. Staff recruitment and maintenance de- up-to-date, and low-cost reforestation techno- pend on a rewarding career structure with suf- logies being applied to the degraded land. Re- ficient financial inducement. In many coun- sults of local research and management experi- tries provision of additional staff could be pro- ence can be published locally at low cost in the vided at little extra cost by restructuring forest form of departmental technical notes and bulle- agencies to reduce unnecessary duplication tins. Efforts should be made to ensure that staff and complex hierarchies (131). members receive relevant materials, read them, and, where appropriate, use them. Distributing Forestry extension is becoming increasing} information internationally is more compli- important as planners recognize that project cated and expensive. The Commonwealth For- success depends largely on active participation estry Bureau (CFB) maintains al] of its forestry of local people. Incentives must be developed research information in Lockheed Dialog, a to entice more foresters to live and work in the computer-based information retrieval system field to provide necessary support to local peo- in California, but too few institutions in tropi- ple. Unfortunately, most existing forest serv- cal countries have access to necessary comput- ices are not structured to provide forestry ex- er terminals or money to use this service. Mail tension services, nor is staff trained in exten- service and reprints are also expensive, Donor sion and communication skills (6]. Therefore, institutions might help by financing an inter- major changes are in order for forestry ad- national information service to provide micro- ministration, staffing, and training—changes fiches containing each month’s CFB abstracts also designed to acknowledge that forestry ex- to developing countries, Thus, field staff could tension needs to work with local women who, be kept up to date on current literature and the in many countries, perform the tasks of plant- latest advances in reforestation, ing and caring for crops including trees (53).

OTHER CONSIDERATIONS

Forestry is low in priority in many tropical economic returns are often spread over a long countries, Forest plantations have not com- time and short-term profits are low compared peted well against other land uses because the to those of alternative investments. This is 44 ● Background Paper #1: Reforestation of Degraded Lands often in conflict with government priorities for degraded lands. Yet methods are not developed projects with quick returns (for which leaders to measure the important but indirect benefits receive more political credit) and with bankers to justify investment in reforestation. who use conventional discounting methods and have little interest in moderate returns in Many nonmarket costs and benefits must be 30 years. In addition, the lack of comprehen- included in economic analysis, especially for sive forestry or land use policies has prevented reforestation projects where the indirect forestry investment and development. But firm benefits may be more significant than direct policy guidelines from the governments can benefits. But benefits such as improved en- produce significant results. For example, fiscal vironmental quality are often the most difficult tax incentives for private reforestation estab- variables to quantify. Economists are grappling lished by the Brazilian Government have led with this problem. International development to an increase in the rate of reforestation in banks tend to treat many nonmarket considera- Brazil (103). By giving tax breaks to landowners tions in a qualitative fashion rather than try- who reforest their lands, the Brazilian Govern- ing to develop artificial values for them (45). ment has given recognition to the importance However, unless treated carefully, simply list- of reforestation. ing nonquantified variables may serve to re- move them from consideration. Therefore, Reforestation projects may not receive ade- given the large uncertainties in selecting the quate funding and support because benefit/cost best method for reforestation of a degraded analysis can show unfavorable results when it site, it may be advisable to try out in practice fails to include both direct and indirect costs several approaches until the uncertainties have and benefits. Adequate analysis also requires been sufficiently reduced (51). comprehensive data on costs, benefits, and man- or machine-times and productivities, yet Most experts find that major constraints to much of this information is unknown at the reforestation of degraded tropical lands are project planning stage. Price estimates often economic, institutional, and social rather than are unreliable and do not account for inflation. technical, A technical package, once accepted Information on labor requirements is usually by funding institutions and the host-country missing as well, Moreover, in forestry, yields government, may solve certain problems, but are difficult to predict because of the long-term many obstacles to its acceptance remain. Ex- nature of the enterprise, climate and manage- perts must remember that “forestry is not, in ment uncertainty, and, more importantly, a essence, about trees. It is about people. It is lack of accurate information on site/species in- only about trees so far as they serve the needs teractions. New technologies, such as tissue of the people” (46), Successful reforestation re- culture to accelerate vegetative propagation quires sufficient funds, strong political will, and bacterial inoculation to increase seedling massive popular support, and cooperation survival, are reducing the costs of reforesting among all involved parties. Appendixes Appendix A Commissioned Papers and Authors

Technologies and Technology Systems for Refor- Afforestation and Management of Tropical estation of Degraded Tropical Lands Wastelands in India P. J. Wood, J. Burley, and A. Grainger R. C. Ghosh Commonwealth Forestry Institute, Calcutta, India oxford, England Technologies for Reforestation of Degraded Lands in the Tropics C. M. Gallegos, C. B. Davey, R. L. Kellison, P. A. Sanchez, and B. J. Zobel Universities for International Forestry (UNIFOR) Syracuse, New York

47 Appendix B Acronyms

AID — Agency for International ICRAF – International Council for Research Development in Agroforestry CATIE — Centro Agronomico Tropical de IDRC – International Development Investigacion y Ensenanza Research Center CEQ — Council on Environmental Quality ILO – International Labor Organization CFI — Commonwealth Forestry Institute NAS – National Academy of Sciences CIAT — Centro International de NFTA – Nitrogen Fixing Tree Association Agricultural Tropical NifTAL — Nitrogen Fixation by Tropical FAO — Food and Agriculture Organization Agricultural Legumes Project of the United Nations NRC – National Research Council GEMS — Global Environment Monitoring PICOP – Paper Industry Corporation of the System Philippines GTZ — German Agency for Technical UNEP — U.N. Environment Program Cooperation (Deutsche Gesellschaft UNESCO — U.N. Educational, Scientific, and fuer Technische Zusammenarbeit) Cultural Organization

48 References References

1. Adams, R., et al,, Dry Lands: Man and Plants al Publishing and Documentation, 1968), 118 (London: Architectural Press, 1978), 152 pp., PP. as cited in Wood, et al., 1982. 17. Burley, J., “Choice of Tree Species and Possi- 2. AlIan, T. G., “Plantation Planting and Weeding bility of Genetic Improvement for Smallholder in Savanna, ” Savanna Afforestation in Africa and Community Forests, ” Commonwealth (Rome: Food and Agriculture Organization, Forestry Review 59(3] :311-326, 1980, as cited 1977), pp. 139-148. in Wood, et al., 1982. 3. Anonymous, “Seeds From Nine Tropical Plant 18. Call, C. A,, “Effects of Endomycorrhizae on Species Previously Thought Unsuited to Stor- the Establishment and Growth of Native age in Liquid Nitrogen Proved Successful in Shrubs on Paraho Processed Oil Shale and Dis- Tests, ” Diversity 1(3):2, 1982. turbed Native Soil, ” Ph. D. thesis, Utah State 4. Anonymous, “Plastic Irrigation, ” Discover University, Logan, Utah, 1981, 132 pp. 3(11):73, 1982. 19 Champion, H. G., and Seth, S. K., General Sil- 5. Anonymous, “Super Slurper, ” Agricultural vicuZture for India (Delhi, India: Controller of Research, ARSIUSDA, 1975. Publications, 1968), 511 pp., as cited in Wood, 6. Arnold, J, E. M., “Community Participation in et al., 1982. Forestry Projects, ” prepared for Conference 20 Chandler, T,, and Spurgeon, D. (eds.), Inter- on Forestry and Development in Asia, held in national Cooperation in Agroforestry, Pro- Bangalore, India, Apr. 19-23, 1982, 12 pp. ceedings of DSE/ICRAF Conference, Nairobi 7, Arnold, J. E. M., Forestry for Community Kenya, July 16-21, 1979, 469 pp. Development (Rome: Food and Agriculture 21. Daft, M. J., and HacskayIo, E,, “Growth of En- organization, 1981), 16 pp. domycorrhizal Red Maple Seedlings in Sand 8. Barnard, R, C., “The Control of Lalang (Im- and Anthracite Spoil, ” Forest Science 23:207- perata arundinacea var. major) by Fire and 216, 1977. Planting, ” Malaysian Forester 17:152-156, 22. Dalal, S. S., “Afforestation of Salt-Affected 1954, as cited in Wood, et al., 1982. Soils in Haryana,” Proceedings of Second All- 9. Batchelder, R. B., and Hirt, H. F., “Fire in India Forestry Conference, Dehra Dun, India, Tropical Forests and Grasslands,” U.S. Materi- 1980, as cited in Wood, et al., 1982. al Command, U.S. Army Natick Laboratory, 23. Dalmacio, M, V., and Banragen, F., “Direct Technical Report 67-41-ES, 1966, 380 pp. Seeding of Pin us kesiya as Affected by Time 10. Bettenay, E., “Trees for Managing Land for of Seeding, Site Preparation and Seed Coat- Water Yield and Quality,” Integrating Agricul- ing, ” Silvatrop. Philipp. For. Res. Journal ture and Forestry, K. N. W. Howes and R. A, 1:215-222, 1976, as cited in Evans, 1982. Rummery (eds.) (Melbourne, Australia: CSIRO, 24, de las Salas, O. (cd,), Agroforestry Systems in 1978), pp. 33-38, as cited in Wood, et al., 1982. Latin America, proceedings of a workshop at 11. Blom, P. S., “Leucaena, a Promising Versatile CATIE, Turrialba, Costa Rica, March 1979, Leguminous Tree for the Tropics, ” Interna- UNU/CATIE, 226 pp. tional Tree Crops journal 1:221-236, 1981, as 25. Delwaulle, J. C., “Forest Plantations in Dry cited in Wood, et al., 1982, Tropical Africa, ” Bois For;ts Tropicale 3-I 7 12, Bollinger, H., forest ecologist, personal com- (78) and 3-17 (79), 1977, as cited in Wood, et munication, 1983. al., 1982. 13. Bonga, J, M., and Durzan, D. J. (eds.], Tissue 26. Eckholm, E., and Brown L., Spreading Deserts Culture in Forestry (The Hague, The Nether- —the Hand of Man, Worldwatch Paper No. lands: Martinus Nijhoff/Junk Publishing, 13 (Washington, D, C.: Worldwatch Institute, 1982), 426 pp. 1977), 40 pp. 14. Brown, L., The Worldwide Loss of Cropland, 27. Eckholm, E,, Losing Ground (New York: W. World Watch Institute, Paper 24, October W, Norton & Co, 1976), 223 pp. 1978. 28, El Dafei, A. R, A., “Forests and the Rural 15. Brown, L., In the Human Interest (New York: Sudanese Community,” Woodpower: New W. W. Norton & Co., 1974). Perspectives on Forest Usage, J. J. Talbot and 16. Buringh, P., Introduction to the Study of Soils W. Swanson (eds.) (New York: Pergamon in Tropical and Subtropical Regions (Wagen- Press, 1981), pp. 89-102, as cited in Gallegos, ingen, The Netherlands: Centre for Agricultur- et al,, 1982.

51 52 ● Background Paper #l: Reforestation of Degraded Lands

29, Evans, J., Plantation Forestry in the Tropics Press, 1976], 2d cd., 504 pp., as cited in Wood, (Oxford, England: Clarendon Press, 1982), 472 et al., 1982, PP. 43. Goudie, A,, Duricrusts in Tropical and Sub 30. Falvey, J. L., “Gliricidia maculata—A Review, ” tropical Landscapes (London: Oxford Univer- International Journal of Tree Crops 2, in press, sity Press, 1973), 174 pp. 1982, as cited in Wood, et al,, 1982. 44 Grainger, A., “The Development of Tree Crops 31. Fontaine, R. G,, et al., “Secondary Succes- and Agroforestry Systems, ” The International sions, ” Tropical Forest Ecosystezns-A State Tree Crops JournaZ 1(1):3-14, 1980, as cited in of KnowZedge Report, A. Sasson and B. Hop- Wood, et al., 1982. kins (eds.) (Paris: UNESCO/UNEP/FAO, 1978), 45. Gregersen, H., “Valuing Goods and Services pp. 216-232, as cited in Wood, et al,, 1982. From Tropical Forests and Woodlands, ” OTA 32. Food and Agriculture Organization, Establish- commissioned paper, unpublished, 1982, 58 pp. ment Techniques for Forest Plantations, G, W. 46. Gribbin, J., “The Other Face of Development,” Chapman and T, G. Allan, Food and Agricul- New Scientist 96(1334):489-495, 1982. ture Organization Forestry Paper No. 8, Rome, 47, Hadipoernomo, “Critical Land Rehabilitation 1978, 183 pp. With Air Seeding, ” Duta Rimba 5(31):9-12, 33. Food and Agriculture Organization, Tropical Jakarta, Indonesia, 1979, as cited in Wood, et Forest Resources Assessment Project [GEMS): al., 1982. Tropical Africa, Tropical Asia, Tropical Amer- 48, Halliday, J., “Agrotechnologies Based on Sym- ica (4 vols,] (Rome: Food and Agriculture Orga- biotic Systems That Fix Nitrogen,” Background nization/UNEP, 1981), Papers for Innovative Biological Technologies 34. Food and Agriculture Organization, Agrofor- for Lesser Developed Countries, paper No. 5, esterie Africaine (Rome: Food and Agriculture Washington, D. C., 1981, pp. 243-270. Organization, 1981), 44 pp. 49. Harrison, P,, “Can Indonesia Farm the 35, Food and Agriculture Organization/UNESCO, Swamps?” New Scientist, Dec. 22-29, 1977, pp. Desertification Map of the World, prepared for 804-805. the U.N, Conference on Desertification, 1977, 50. Hecht, S. B., “Some Environmental Conse- UNEP, Nairobi, Kenya, 1977. quences of Conversion of Forest to Pastures 36. Fripiat, J., and Herbillon, A. J., “Formation and in Eastern Amazonia, ” Ph. D. thesis, Depart- Transformation of Clay Minerals in Tropical ment of Geography, University of California, Soils, ” Soils and Tropical Weathering, Proc. Berkeley, 1980. of Bandung Symposium, Natural Resources 51. Hirschman, A. O., Development Projects Ob Research XI, UNESCO, Paris, 1971, pp. 15-22. served (Washington, D. C.: The Brookings In- 37. Gallegos, C. M., Davey, C. B., Kellison, R. L., stitution, 1967], 197 pp. Sanchez, P. A., and Zobel, B. J., “Technologies 52. Helm, L, G., Weldon, L. W,, and Blackburn, for Reforestation of Degraded Lands in the R. D., “Aquatic Weeds, ” Man Impact on the Tropics, ” OTA commissioned paper, unpub- Environment, T, R. Detwyler (cd.) (New York: lished, 1982, 134 pp. McGraw-Hill Book Co,, 1969), pp. 246-265, 38. Geary, T., Asia Coordinator of Forestry Sup- 53. Hoskins, M., “Community Forestry Depends port Program, USFS/AID, Washington; D. C., on Women,” Unasyzva 32(130):27-32, 1980. personal communication, 1982, 54. Hoskins, M,, “Community Participation in 39. Ghosh, R. C,, “Afforestation and Management African Fuelwood Production, Transforma- of Tropical Wastelands in India, ” OTA com- tion, and Utilization, ” paper prepared for missioned paper, unpublished, 1982, 80 pp. workshop on Fuelwood and Other Renewable 40. Ghosh, R. C., Handbook of Afforestation Tech- Fuels in Africa (Paris: 1979), 62 pp. niques (Delhi, India: Controller of Publica- 55 International Labor Organization, “Appropri- tions, 1977), 411 pp., as cited in Ghosh, 1982. ate Technology for the Establishment and 41 Gibson, T, A., and van Diepen, D,, “Land Use Maintenance of Forest Plantations” (Manila: in Northern Thailand Highlands, ” U.N. Pro- ILO, 1979), as cited in Wood, et al,, 1982. gramme for Drug Abuse Control (Chiang Mai), 56< Janos, D, P., “Mycorrhizae Influence Tropical unpublished report, 1977, as cited in Wood, et Succession, ” Biotropica 12 (supplement):56- al., 1982. 64, 1980, 42 Goor, A. Y., and Barney, C. W,, Forest Tree 57, Janzen, D. H., “Tropical Agroecosystems, ” Planting in Arid Zones (New York: Ronald Science 182:1212-1219, 1973, References . 53

58. Jones, N., and Burley, J., “Provenance Nomen- 73. Lundgren, B., “The Use of Agroforestry to Im- clature, Genetic History and Seed Certifica- prove the Productivity of Converted Land, ” tion, ” Sihrae Genetica 22(3):53-58, 1973, as OTA commissioned paper, unpublished, 1982, cited in Wood, et al., 1982. 82 pp. 59. Jordan, C. F., and Farnsworth, E. G., “Natural 74. Lundgren, B., Director, ICRAF, personal com- vs. Plantation Forests: A Case Study of Land munication, 1982. Reclamation Strategies for the Humid Trop- 75. Lundgren, B., “Plantation Forestry in Tropical ics, ” Environment] Management 60(6):485-492, Countries—Physical and Biological Potentials 1982. and Risks, ” Reports in Forest Ecology and 60. Jurien, F., and Henry, J., “Can Primitive Farm- Forest Soils No. 31, Swedish University of ing be Modernized?, ” IN,EAC Ser. Hors 1969, Agrisciences, 1980, as cited in Wood, et aI., Institut National pour L’Etude d’Agronomique 1982. De Congo, Brussels, 1969, 445 pp., as cited in 76. Menge, J., “Mycorrhiza Agriculture Technol- Gallegos, 1982. ogies, ” Background Papers for Innovative Bio- 61. Kadeba, O., “Nutritional Aspects of Afforesta- logical Technologies for Lesser Developed tion With Exotic Tree Species in the Savanna Countries, Office of Technology Assessment Region of Nigeria, ” Commonwealth Forestry Workshop, Nov. 24-25, 1980, committee print, Review 57(3):191-199, 1978. House Committee on Foreign Affairs, 97th 62 Kamsilan, “The Place of Agroforestry in Land- Cong., 1st sess. (Washington, D.C: Govern- Use Planning in Indonesia, ” observations on ment Printing Office, September 1981), pp. Agroforestry on Java, Indonesia, J. F. Wiersum 383-424. (cd.), Department of Forest Management, Uni- 77. Mikola, P. (cd.), Tropical Mycorrhizae Re- versity of Wageningen, The Netherlands, 1981, search (New York: Oxford University Press, pp. 49-55, as cited in Wood, et al., 1982. 1980), 257 pp. 63. Kaul, R, N., Afforestation in Arid Zones (The 78. National Academy of Sciences, Sowing For- Hague, The Netherlands: Junk Publishing, ests From the Air (Washington, D. C.: National 1970), 435 pp., as cited in Wood, et al., 1982. Academy of Sciences, 1981), 61 pp. 64. Keller, W. D., The Principles of Chemical 79. National Academy of Sciences, Firewood Weathering (Washington, D. C.: Lucas Bros. Crops: Shrub and Tree Species for Energy Pro- Publishing Service [Item 990, No. 5967, Janu- duction (Washington, D. C.: National Academy ary 1961], 1962), pp. 540-657. of Sciences, 1980), 237 pp. 65 Kermani, W. A., “Aerial Seed Sowing in River- 80. National Academy of Sciences, Tropical Le- ine Forest Areas of Sind, ” Paper Forestry Con- gumes: Resources for the Future (Washington, ference, Pakistan Forestry Institute, 1974, as D. C.: National Academy of Sciences, 1979), cited in Evans, 1982. 331 pp. 66. King, K. F. S., “Agroforestry and the Utiliza- 81. National Academy of Sciences, Leucaena: tion of Fragile Ecosystems, ” Forest Ecology Promising Forage and Tree Crop for the Trop- Management 2:161-168, 1979. ics (Washington, D. C.: National Academy of 67. Kovda, V. A., “The Management of Soil Fer- Sciences, 1977), 115 pp. tility,” UNESCO, Nature and Resources 8(2): 82. National Academy of Sciences, Underexpioited 2-4, 1972. Tropical Plants With Promising Economic 68. Ladrach, W., forester, Carton de Colombia, Value (Washington, D, C.: National Academy personal communication, 1982. Df Sciences, 1975), 189 pp. 69. Lal, R., and Greenland, O. J. (eds.], Soil Prop- 83. National Research Council, Innovations in erties and Crop Production in the Tropics Tropical Reforestation V: Cailiandra (Wash- (New York: John Wiley & Sons, 1979], 551 pp. ington, D. C.: National Academy Press, in 70. Lambert, D. H., and Cole, H., “Effects of press), Mycorrhizae on Establishment and Perform- 84. National Research Council, Innovations in ance of Forage Species on Mine Spoil, ” Agro- Tropical Reforestation VI: Casuarina (Wash- nomy Journal 72:257-260, 1980. ington, DoC.: National Academy Press, in 71. Laudelot, H,, Dynamics of Tropical Soils in press). Relation to Their Fallowing Techniques, Food 85 National Research Council, Innovations in and Agriculture Organization, 1960, 102 pp. Tropical Reforestation IV: Mangium and 72. Li Jincheng, “Lessons Learned From Heavy Other Acacia of the Humid Tropics (Washing- Floods, ” Mazingira 6[2]:58-62, 1982. ton, D. C.: National Academy Press, in press). 54 ● Background Paper #1: Reforestation of Degraded Lands

86. Nicholson, D. 1., “A Note on Acacia auricul- 99, Read, V. T., Reafforestation in the Markham iforznis A, Cunn. ex Beth in Sabah, ” Malaysian Valley, Papua New Guinea: An Ecological Ap- Forester 28:243-244, 1965, as cited in Wood, praisal of a Study Area in the Upper Markham et al., 1982. Valley With Some Recommendations for Af- 87. Nienstaedt, H., “Tree Improvement and Its forestation, School of Applied Science, Can- Place in Intensive Forest Management,” Proc. berra College of Advanced Education (Belcon- 8th World Forestry Congress, Jakarta, FID- nen), MS., 1980, as cited in Wood, et al., 1982. 1/17-28, 1978, as cited in Evans, 1982. 100. Rice, R, M,, “The Effects of Forest Manage- 88. Nye, R. H., and Greenland, D. J., “The Soil ment on Erosion and Sedimentation Due to Under Shifting Cultivation,” Commonwealth Landslides,” Proc, 8th World Forestry Con- Bureau of Soils, Harpenden, United Kingdom, gress, Jakarta, Indonesia, FFF/5-10, 1978. Tech. Comm. 51., 1960, 156 pp. 101, Rimando, E. F., and Dalmacio, M. V., “Direct 89. OECD, OECD Scheme for the Control of For- Seeding of Ipil-ipil,” Sylvatrop., phillip, For. est Reproductive Material Moving in Interna- Res. Jrn]. 3:171-175, 1976, as cited in Wood, tional Trade (Paris: Organization for Econom- et al., 1982. ic Cooperation and Development, 1974), 21 102. Rudjiman, “Multiple-Purpose Species for pp., as cited in Wood, et al., 1982. Planting on Critical Soils on Java, ” Observa- 90. Office of Technology Assessment, Impacts of tions on Agroforestry on Java, Indonesia, Technology on U.S. Cropland and Rangeland K. F, Wiersum (cd.), Department of Forest Productivity (Washington, D. C.: U.S. Con- Management, University of Wageningen, The gress, Office of Technology Assessment, Netherlands, 1981, pp. 76-89, August 1982), OTA-F-166. 103. Rudolph, V. J., et al., “Forestry in Brazil: An 91. Paul, D. K., “A Handbook of Nursery Practice Awakening Giant,” Journal of Forestry 76(12): for pin us caribaea var. hondurensis and other 784-786, 1978. Conifers in West Malaysia” (Kuala Lumpur, 104. Sanchez, P. A,, Properties and Management Malaysia: UNDP/FAO, 1972], 139 pp., as cited of Soils in the Tropics (New York: John Wiley in Wood, et al., 1982. & Sons, 1976), 618 pp. 92, Pereira, C., “Soil and Water Management 105. Santiago, “Gynecological Aspects of Imperata Technologies for Tropical Countries, ” OTA Weed and Its Practical Implications,” Proceed- commissioned paper, unpublished, 1982, 33 ings of BIOTROP Workshop on Alang-alang, PP. vol. I, Bogor, Indonesia, 1976, pp. 23-34. 93. Pereira, C., Land Use and Water Resources 106. Seubert, C. E., Sanchez, P. A., and Valverde, (London: Cambridge University Press, 1973), C., “Effects of Land Clearing Methods on Soil 246 pp. Properties of an Oltisol and Crop Performance 94. Plant Resources Institute, “Commercial Uses on an Amazon Jungle of Peru, ” Tropical Agri- of Plant Tissue Culture and Potential Impact culture 54:307-321, Trinidad, 1977. of Genetic Engineering on Forestry, ” OTA 107. Sioli, H., “Soils in the Estuary of the Amazon: commissioned paper, unpublished, 1981, 53 UNESCO, ” Scientific problems of the Humid . PP” Tropical Zone-Deltas and Their Implications, 95. Poulsen, G., Man and Tree in Tropical Africa, 1964, PP. 89-96. International Development Research Center 108. Smith, N., “Colonization Lessons From a IIDRC), 1978, 101 pp. Tropical Forest, ” Science 214:755-761, 1981. 96. Qadri, T., professional forester with experi- 109. Soewardi, B,, and Sastradipradja, D., “Alang- ence in India, personal communication, 1982. alang (Imperata cyZindrica [L.] Beauv.) and 97. Ranney, J. W., Cushman, J. H., and Trimble, Animal Husbandry, ” Proceedings of BIOTROP J. L,, “The Short Rotation Woody Crops Pro- Workshop on A]ang-alang, vol. I, Bogor, Indo- gram: A Summary of Research Sponsored by nesia, 1980, pp. 157-158. the Biomass Energy Technology Division of 110. Sukartaatmadia, K., and Siregar, O., “Control Oak Ridge National Laboratory, ” draft, 1982, of Alang-alang by Combinations of Shading 33 pp. With Gliricidia maculata H.B,K, and Dalapon 98. Rae, A. N., “Tissue Culture of Economically Application, ” Contributions of the Weed Soci- Important Plants,” I+oc. of the International ety 1:167-172, Bogor Agricultural University, Symposium, National University of Singapore, Indonesia, 1971, as cited in Wood, et al,, 1982.

Apr. 28-30, 1981, 307 pp. 1110 Synnott, T. J., and Kemp, R. H., “Choosing the References ● 55

Best Silvicultural System, ” Unasy]va 28:14-79, 123. Watters, R. F., Shifting Cultivation in Latin 1976. America, U.N. Food and Agriculture Organi- 112. Tinus, R. W., and McDonald, S. E., “How to zation Forestry Development Paper No. 17, Grow Tree Seedlings in Containers in Green- Rome, 1971, 305 pp. houses, ” General Technical Report RM-60, 124, Wattle Research Institute, Handbook of Euca- USDA Forest Service, 1979, 251 pp. lyptus Growing (Pietermaritzburg, South 113 Tinus, R. W., Stein, W. I., and Balmer, W. E. Africa: Wattle Research Institute, 1972), as (eds.), Proc. North American Containerized cited in Wood, et al., 1982. Forest Trees Seedling Symposium, Great 125. Webb, D. E., Wood, P. J., and Smith, J., “A Plains Agricultural Council Publication No. Guide to Species Selection for Tropical and 81, 1974. Subtropical Plantations, ” Tropical Forestry 114. United Nations, U.N. Conference on Desertifi- Paper No. 15 (Oxford, England: Common- cation: Round-up, Plan of Action, and Resolu- wealth Forestry Institute, 1980), 342 pp., as tions (New York: United Nations, 1978). cited in Wood, et al., 1982. 115, UNEP, “Overview Document, Experts Meet- 126. Weber, F. R., forestry consultant, personal ing on Tropical Forests, ” Nairobi/Libreville, communication, 1982. Feb. 25-Mar. 1, 1980, UNEP/WG.35/4, Nairobi, 127. Weber, F. R., Reforestation in Arid Lands, Kenya, 1980. VITA Publications Manual Series 37E, 1977, 116 UNESCO, “International Working Group on 248 pp. Project 1: Ecological Effects of Increasing 128. Weidelt, H. J. (compiler), “Manual of Reforest- Human Activities on Tropical and Subtropical ation and Erosion Control for the Philippines, ” Forest Ecosystems, ” final report, Programme GTZ, Eschborn, Germany, 1976, 569 pp., as on Man and the Biosphere (MAB) (Paris: cited in Wood, et al,, 1982. UNESCO, 1974), 64 pp., as cited in Wood, et 129. Wiersum, K. F., and Ramlan, A., “Cultivation al., 1982. of Acacia auriculiformis on Java, Indonesia, ” 117 U.S. Department of the Interior, “World Rec- Commonwealth Forestry Review 61:135-145, ord River Flow Measured on Amazon, ” Geolog- 1982. ical Survey News Release, Aug. 10, 1972, p. 3. 130. Wilken, G. C., “Integrating Forest and Small 118. von Maydell, H, J., Baum-und Straucharten Scale Farm Systems in Middle America, ” der Sahelzone unter besonderer Berucksichti- Agroecosystems 3:291-302, 1977, as cited in gung ihrer Nutzungsmoglichkeiten, GTZ, Evans, 1982. Eschborn, Germany, 1981, 526 pp., as cited in 131 Wood, P. J., Burley, J., and Grainger, A., Wood, et al., 1982, “Technologies and Technology Systems for 119. Van Wambeke, A., “properties and Potentials Reforestation of Degraded Tropical Lands, ” of Soils in the Amazon Basin, ” Interciencia OTA commissioned paper, unpublished, 1982, 3(4):233-241, 1978. 114 pp. 120 Venator, C. R., “Directory of Manufacturers 132, World Bank and Food and Agriculture Organi- and Distributors of Containers Suitable for zation, “Forestry Research Needs in Develop- Growing Forest Tree Seedlings,” ITF Research ing Countries—Time for a Reappraisal?” paper Note #15, USDA, Forest Service, 1975. for 17th IUFRO Congress, Kyoto, Japan, Sept. 121 Vergara, N. T., Integral Agroforestry: A Poten- 6-17, 1981, 56 pp. tial Strategy for Stabilizing Shifting Cultivation 133. World Bank, Forestry: Sector Policy Paper and Sustaining Productivity of the Natural En- (Washington, D. C,: World Bank, 1978),65 pp. vironment, Environment and Policy Institute, 134. Yadav, J. S. P., “Salt Affected Soils and Their East-West Center, Honolulu, Hawaii, working Afforestation,” Proceedings of Second All- paper, 1981, 33 pp. India Forestry Conference, Dehra Dun, India, 122 Wadsworth, F., “Secondary Forest Manage- 1980, as cited in Wood, et al., 1982. ment and Plantation Forestry Technologies to 135, Zobel, B., tree geneticist, North Carolina State Improve the Use of Converted Tropical Lands, ” University, Department of Forestry (Professor OTA commissioned paper, unpublished, 1982, Emeritus), personal communication, 1982. 102 pp.

>’? I , . . ‘ ,,’ ] ] ?/] I j ]J 1