Chapter 5
Assisted Natural Regeneration

5.2 Implementing Assisted Natural Regeneration

These steps of ANR implementation in Imperata grasslands are based on experience but can be adjusted depending upon the sites, resources available, and project and community objectives.

5.2.1 Clarify goals and objectives

Be sure that the goals and objectives of any ANR project are clear before it begins. ANR is a technology that may be used by farmers and communities on their own, but ANR may also be promoted and subsidized by a regional or national program addressing watershed or timber goals. Broad goals must be negotiated and agreed upon between the community and those providing assistance from outside (see Section 1.3). Not all goals are compatible, and misunderstanding must be avoided. Here are some examples.

Specific objectives for ANR and land management must also be decided upon ahead of time (watershed, timber, fallow improvement). Implementation and resources needed will depend upon the objectives.

5.2.2 Select appropriate sites

Work in communities that are interested in ANR. Work first with villages or communities that have objectives that can be achieved with ANR, and are willing to organize themselves to prevent fire. Work on lands that the village identifies (see Section 1.3.3).

Choose sites that match the objectives. Also choose objectives that match the sites!

Begin ANR work only in areas that can be protected from fire. Consider labor available to monitor and control fire, and plant and maintain firebreaks.

Consider the stage of plant succession of the site. If little or no natural regeneration has occurred, conventional reforestation would be as effective as ANR. If natural regeneration is advanced and most of the area has a closed canopy and trees that are over 2 m tall, use timber stand improvement techniques (including thinning, Section 5.2.11) instead of ANR. In the middle range, decide what areas to prioritize as follows.

Choose sites with enough natural regeneration already present to meet objectives. Estimate the number of existing woody plants/ha, including seedlings and saplings 15-200 cm tall. Count clumps of seedlings within one square meter as one plant. The guidelines given below are for natural regeneration relatively well spread out regardless of slope. If regeneration is uneven, use an estimate for large areas with less regeneration. To make a more careful estimate, use a tally sheet for sample plots (Appendix F).

Choose sites close to forest patches. Gallery forests, forest edges and patches of forest have seed-bearing plants and seed-dispersing animals. This increases the number of new wildlings that can come into the ANR area. Soil conditions may also be more favorable near forest patches. Grasslands that are far from any remaining forests, and grasslands that have been burned and grazed for a long time, do not have enough natural regeneration to make ANR successful.

After choosing the site, get to know it well. Understand the local people, the history of the area, local species, and local soils and rainfall (Chapters1 and 2).

5.2.3 Protect the area from fire and grazing

The most critical step in ANR is protection of woody plants from fire. Review Chapter 3 carefully. Since ANR is often implemented by communities rather than individual farmers, groups can be organized for fire control. At least a month before the dry season begins, make plans and organize firefighting crews. Review plans and roles when dry season begins. During the dry season, patrol the ANR area to locate fires.

One strategy is to "follow the edges and close the gaps." This means to implement ANR along the edges of forests, agroforests, and other fuelbreaks. Implement ANR in the gaps between areas of forest and agroforest. These adjacent areas will serve as fuelbreaks and sources of seed.

The question of grazing in ANR areas must be addressed by the community. Animals may eat or trample woody seedlings and saplings. However, they may also help spread seeds; for example, cattle eat Albizic saman pods and deposit the seeds in their manure, where they germinate and grow well. Establish a one-year test comparing areas where grazing animals are kept out by a fence to areas where grazing animals are allowed to enter and spread seeds. Compare the results and adopt the better method.

5.2.4 Identify and mark woody plants

All existing woody wildlings hidden in the grass should be located and clearly marked in order to protect them during grass pressing and clearing. This can be done by two workers: the first marks the wildlings with a stake, and the second ringweeds or presses the grasses and weeds with his/her foot.

Mark wildlings. Use stakes only if they are available on the site. The stakes should be visible above the grass, about 1.5-3 cm in diameter and 1.5 m in height. Stakes can often be cut on the site. Do not cut any trees needed to reforest the site. Instead, make stakes from branches pruned from large trees, stems thinned from stumps of fire-hardy species, stems thinned from dense thickets, or thinnings from forests near the ANR area. When cutting stakes from clusters of stems on stumps and in thickets, cut the smaller stems, and leave the largest stems to grow. If stakes are not available, ringweeding will help make the wildlings more visible.

Ring weed. The most efficient procedure is to:

• Press grass away from the base of the wildling, using feet or a pressing board (see Section 3.3.1).

• Pull climbing vines from the trees.

• Slash or uproot ferns, climbing vines, and other weeds within 1/2 m of the stem. Be careful not to damage wildling stems and roots.

• Hand cultivate around the tree, removing grass rhizomes, up to a 1/2 m diameter if labor is available. Slashing may be done instead if it will be repeated often.

After ringweeding, the ANR site will look like this.

Be careful that ringweeding does not take away shade from wildlings that need shade, such as seedlings of climax forest tree species, especially in the dry season.

Identify and count wildlings in sample plots if this was not already done during site selection. Do this at the same time as marking and clearing. Local people may be very helpful in identifying plants, though with local names. Extensionists may also record sizes and tag seedlings for future measurement, to monitor growth and survival.

5.2.5 Suppress the grass layer throughout the site

After fire prevention and control, the most important activity in ANR is suppressing Imperata and other weeds. Imperata must be suppressed efficiently, with minimum use of cash and labor. Usually a combination of methods is used, with cheap and easy methods in open areas and more intensive methods around trees and near forest edges.

Native legumes should be protected and even released from weed competition. They make the soil more fertile and may help suppress Imperata. However, climbing legumes must be kept off of trees and seedlings.

Grass pressing. This is a major ANR technique; review Section 3.3.1 carefully. Its purposes in ANR are to:

• Reduce fuel hazard for fire. Press at the beginning of the dry season and whenever the grass is tall and dry.

• Control Imperata growth and reduce competition with trees. Press during the rainy season when leguminous cover crops and woody species emerge most rapidly.

• Make it easier and faster to move around and work in the ANR area. Press at any time of the year.

• Prepare enrichment planting areas. Press before the planting season.

Herbicides. With ANR, herbicides can be considered if labor is very limited. See the companion manual Imperata Management for Smallholders for practical techniques. However:

• Herbicides are expensive.

• Experience and training is required for safe handling and use.

• A shield must be used to kill only grasses and weeds and not damage woody plants.

• Dead Imperata is still a fuel hazard.

Not recommended:

• Cultivation (plowing)

• Controlled burning

• Brushing (slashing)

Widespread cultivation or plowing is generally not recommended for ANR because it exposes the land to erosion on steep slopes and destroys existing woody plants. Controlled burning is not recommended for ANR because Imperata regrowth is rapid, woody species are killed or damaged, and the soil is exposed to erosion. For grass suppression throughout the site, brushing is not recommended because it takes more work than pressing and stimulates more regrowth of Imperata.

5.2.6 Stimulate new natural regeneration

Brush grass near forests. Near forest edges and tree patches, temperature, moisture, and soil are more favorable for wildlings than in open grasslands. For the purpose of stimulating seed germination, slash or spray herbicide on all grasses and weeds within 5-20 m of the forest edge. Nearby trees and forest wildlife will provide seeds. If trees along the edge of the forest are covered with vines, pull down or slash the vines to release the trees and encourage them to seed.

Protect wildlife. Develop mechanisms within the community and educate children not to kill forest birds and bats. Birds, bats, and pigs can carry seeds into the grasslands.

Consider encouraging weeds that farmers may prefer to Imperata. Spraying glyphosate herbicide can cause increased germination of natural vegetation such as Chromolaena odoratum and Melastoma spp., probably because the dead grass mulches the soil.

5.2.7 Help existing woody plants grow faster

Mark new wildlings as they come in to the area, especially along forest edges.

Ring weed old and new wildlings (see Section 5.2.4).

Fertilize. The decision whether to fertilize depends upon:

• Species. Some species might not grow much faster in response to fertilizer. Before spending much money on fertilizer, test its effects on different species and different age classes in sample plots. Measure size before and after fertilization for both fertilized and unfertilized trees.

• Size of seedling. Newly planted enrichment seedlings or young wildlings will benefit more from a little fertilizer than older trees.

• Soil. Even in Imperata grasslands, some soils are fertile. The use of fertilizers on such soils may not improve tree survival and growth.

• Fire risk. Fertilizer might help trees close canopy sooner.

• Plantation value. Trees providing timber, or other high-value products, might be worth fertilizing.

To apply Fertilizer:

• Apply fertilizer after ringweeding. Make sure it is placed in a hole and covered with soil.

• For seedlings: apply fertilizer in a spot, semi-circle, or circle about 15-20 cm from the tree.

• For nitrogen-fixing seedlings, apply about 10 g P per tree. For other seedlings, apply about 20 g N and 10 g P per tree, or about one tablespoon NPK. These are general recommendations; if recommendations from local soil tests are available, follow them instead.

• For larger trees: apply directly below the edge of the tree canopy, in a circle, semicircle, or three spots.

• Fertilizer will stimulate the growth of lmperata and weeds. Be sure to ring weed and hand cultivate regularly for at least 12 months after fertilization.

Thin. Where two seedlings or saplings are close enough to each other to compete for light, water, and nutrients, remove the one that is smaller, less healthy, or of a less desirable species. When a tree stump has several sprouts, remove all but the 1-3 largest.

Transplant. Make use of planting materials from thinning operations. If thinning takes place during the rainy season, transplant healthy thinned wildlings and cuttings to nearby areas with similar conditions (soil, light, moisture) where there is not enough natural regeneration. If it is near the end of the rainy season, transplant small wildlings of valuable species to a nursery. See Sections 5.2.9 and 5.2.10 for more information on enrichment planting and transplanting wildlings.

5.2.8 Continue to suppress grass

Repeat pressing and ringweeding when Imperata begins to compete with wildlings and trees for light and nutrients. During the rainy season, pressing and ringweeding usually need to be repeated at least once every 1 1/2 months.

During the dry season, pressing should be done if the grass begins to grow tall, usually every 2-3 months. Be careful not to take away shade from species of wildlings that need shade.

During all activities, watch for new natural regeneration to be marked and ringweeded.

5.2.9 Enrich by planting sun-loving species

Enrichment planting can include cover crops (Section 4.3), orchard trees (Section 4.6), and plantation trees (Section 4.7), including nurse trees (Section 4.8).

Possible objectives are to:

• Fill gaps to shade out Imperata and convert the whole area to forest.

• Increase density so that the canopy will close sooner.

• Add trees of species valued for timber, fruit, nuts, or other products.

• Add nitrogen-fixing species as an improved fallow.

Choosing sites and strategies

Plant only as much area as can be maintained in addition to the natural regeneration that is already being ringweeded and cared for.

Strategy: follow the edges and close the gaps. Concentrate efforts where they are most likely to be successful: along the edges of existing forests and plantations, and in gaps between patches of large trees. These areas have more fire protection than open grasslands, more shade, and possibly better soil conditions. Each planting season, follow the edges of recently planted areas, and close gaps between them.

Strategy: plant nurse trees first. To plant high-value species that need shade while young, plant nurse trees first. This is similar to multistory agroforestry (Section 4.8) and tree plantations (Section 4.7).

Species choice

ANR in Imperata grasslands often uses the same species as in simple tree plantations in Imperata: species that can survive harsh conditions, grow quickly and cast heavy shade to suppress Imperata (Section 4.7). But the ANR approach is different from simple tree plantations because it:

• Uses a wider variety of local native species and agroforestry species.

• Has a variety of "microsites" where shrubs and trees provide shade, affect soil moisture, and form windbreaks.

Therefore, instead of choosing a single species, try to use several enrichment species matched to different spots within the ANR area.

Natural regeneration considerations. Include a few local tree species known to provide fruit or food for birds and bats that spread seed. Include local species that are common roosts (sleeping and nesting areas) for birds and bats.

In Imperata, Acacia mangium is a good hardy nurse tree for natural regeneration of native forest species. This is probably because A. mangium fixes nitrogen and provides shade. The shade is important in ANR because it suppresses Imperata and is favorable for shade-tolerant tree species.

Production considerations. For fertile and accessible sites, consider tree crops, multistory agroforestry species, and improved fallow species (Chapter 4). For timber and multipurpose species, choose some that will be harvested within 5-10 years (short rotation) and some high-value species that will be harvested later (medium and long rotation). Having more than one wood or timber species will absorb the loss from a low market price for one species.

Site matching. Information about common reforestation species and agroforestry species is available from foresters and agriculturalists. Information may not be available in books about local native species, but local species should be considered for local cultural, medicinal, wildlife, or other values. To figure out how to match these local species to planting spots:

• Observe surrounding areas and notice where similar species grow well. Notice soil texture and color, soil drainage (wet, dry, variable), topographic position (slope, aspect, hilltops and ridges, streamsides, flood plains), rainfall, elevation, and shade. Consider having a soil test done for fertility.

• Talk with local people to identify potential species, their uses, and habitat requirements.

Plant a few target species in different sites as a test. Observe how they grow or adapt to different conditions. Select the tree species that grow the best for each site.

Implementation

Many planting techniques are the same as those for simple tree plantations (Section 4.7).

Spacing. As a rule of thumb, use a 2m x 3m spacing to close canopy within 3-5 years. For nurse trees, use 3m x 3m, or use a closer spacing and thin later. Other spacings can be used depending upon the species and objectives for the site. Maintain spacing between new trees and existing natural regeneration.

Nursery production. To estimate the amount of planting material needed, subtract the average woody plants/ha already present from the target stocking. For example, a 2m x 3m spacing is about 1670 trees/ha. If there are already 600 wildlings/ha, 1070 seedlings/ha will be needed, plus an allowance for mortality in the nursery, under transport, and in the field.

Site preparation. Cultivate planting areas 1 m in diameter.

5.2.10 Enrich by planting shade-tolerant species

Begin enrichment planting of shade-tolerant trees:

• As soon as nurse trees and existing woody species cast appropriate shade for the shade-tolerant species. Continue to weed and control Imperata.

• Or, wait until nurse trees and existing woody species cast heavy shade and have outcompeted Imperata. Thin or prune nurse trees to allow the right amount of light and shade for the shade-tolerant species. Control Imperata if it begins to grow again.

At the start of the rainy season, plant the high-value tree species between the nurse trees at 3 x 3m or 4 x 4 m spacing, or at the recommended spacing requirements of each species.

Produce seedlings in the nursery, and transplant wildlings from nearby forests. When gathering wildlings, dip the roots in thick mud or a slurry of clay soil and water, and wrap them in leaves to keep them moist while being moved. Mix soil from where they were taken into the mud, slurry or nursery soil, to inoculate them with mycorrhizae and rhizobia to improve their growth. Transplant small wildlings or heavily shaded wildlings to the nursery to grow them larger and gradually accustom them to the right amount of sun.

Agroforestry species, rattans, orchids, and other non-timber forest species can also be planted (Section 4.8).

5.2.11 Thin and prune

Prune branches of nurse trees. Prune nurse trees to gradually increase light for dipterocarps and other species that need shade when young and sun when large.

Thin trees as the forest develops. As the canopy begins to close and trees compete with each other, in some cases it is worth the labor to thin trees.

If an unhealthy, branchy, crooked, or worthless tree is interfering with the growth of a healthy, straight, or valuable tree,

• Cut the unhealthy, branchy, crooked, or worthless tree.

If trees are crowded, and the thinned trees can be used for firewood or other products,

• Cut trees that are shorter, smaller in diameter, or less straight. The remaining trees will grow faster and produce superior seed.

When dipterocarps reach pole diameter,

• Thin enough nurse trees to increase sunlight.

Do not:

• Remove needed shade

• Let Imperata back in

• Damage other trees

Be careful not to cut trees that are still needed for shade of shade-tolerant plants or seedlings. Don't cut so many trees that Imperata returns and becomes a fuel hazard for fire. Finally, cut trees carefully so that they don't damage other trees as they fall.