2003 Annual Report for FW01-091
Luta Windbreak / Agroforestry Project
Summary
OBJECTIVES
Establish a dense, multi-row windbreak/shelterbelt that will protect fragile crops from prevailing and seasonal wind damage and, at the same time, provide a marketable crop.
SUMMARY
Most cash crops of the Commonwealth of the Northern Mariana Islands (CNMI) are susceptible to damage from wind or salt spray. Windbreaks can protect fragile plants from damage, but planting windbreaks on the small farms (average of 1 hectare) can reduce productive farmland. To solve the problem, this SARE-funded project planted fruit and nut trees that could protect banana plants from wind and salt and produce income at the same time.
The banana plantation selected as the project area is on the island of Rota, 45 miles north of Guam, in a cliffside location exposed to prevailing northeast winds. The project team, with seedlings acquired from a local nursery, planted da’ok, a native typhoon-resistant tree that produces an oil-rich nut used in aromatherapy, and various citrus trees, the fruit from which can be sold at local grocery stores and restaurants. Despite poor soil quality that slowed growth, the seedlings were growing well until disaster struck in the form of two typhoons. The first, in July 2002, damaged or killed many of the plants. Just as the survivors were recovering, a second, more fierce typhoon hit in December, damaging or killing all of the plants
Despite the setback, project coordinator Ephram Taimanao says that new seedlings were planted in early 2003, although the dry season was approaching, which may inhibit growth.
RESULTS
The trees were planted in three or four rows, depending on topography, 12 to 15 feet apart at field edges. Calophyllum inophyllum, commonly know as mast wood and called da’ok locally, was planted as the primary row. It is typhoon resistant and, although it grows slowly, it can reach 30 feet, providing excellent shade and wind protection. Various citrus trees were planted in the inside rows, staggered to create a closed wall of leaves at maturity.
Soils are Dandan-Chinen complex characterized by slopes of 5-15%. Slopes on the windbreak layout are 4-8%. The low-fertility soils were supplemented with 16-16-16 fertilizer, as advised by the local forester. Soil depth along the cliff edge is shallow, but da’ok trees grow well in it. Soil depth increases farther into the field, so the fruit trees were planted there between existing rows of banana plants, sheltering the plants from wind and excessive sunlight. As the citrus trees matured, the banana plants would be phased out leaving only healthy citrus.
As expected, seedling mortality was high – 40 to 50% – but acceptable for the site conditions, and ample seedlings were available to replace dead trees. Because planting began during the rainy season, mortality was attributed to soil and site conditions rather than a lack of moisture. Water was supplied to trees near a water line, but was not available to all seedlings evenly.
On July 7, 2002, Typhoon Chata’an, with sustained winds of 85 mph and gusts of 125, caused significant damage, some from large banana plants falling onto seedlings but most from salt spray. Seedlings that survived began showing salt damage the second week after the storm.
Dead and dying seedlings were replaced, but many seedlings in the temporary nursery were also damaged. The da’ok seedlings fared better than the citrus because there were smaller and less susceptible to wind damage.
On Dec. 8, 2002, Super Typhoon Pongsona, unseasonably timed and with wind speeds topping 185 mph, struck just as the surviving seedlings were making a strong comeback from Chata’an five months earlier. A few citrus trees were higher than 3 feet, and most of the da’ok were a foot and a half or less.
“Many seedlings were stripped from the ground, and those that remained were either stripped of leaves or suffered shredded foliage,” says Taimanao. Because of the excessive damage to homes, offices and utilities, project participants were preoccupied with recovery. The windbreak, in addition to wind damage, will have suffered from salt damage, and because the island is entering the dry season, moisture will likely be insufficient to flush salts from the ground or provide a boost to new seedlings.
The disaster will, however, allow the project team to assess which varieties might have survived better than others for future plantings. In addition, the team is considering planting a primary row of Casuarina equisetifolia, or ironwood, which provides a faster-growing windbreak.
“This violates our principle of planting only trees that produce a marketable product,” says Taimanao, “but ironwood is fast growing, readily available and more salt-tolerant than citrus.” The ironwood may provide a salt barrier until citrus trees are mature enough to withstand the harsh cliff line conditions.
POTENTIAL BENEFITS
With effective marketing, the income derived from value-added agroforestry products like da’ok oil could be significant, exceeding that from row crops, although Taimanao says it will not supplant row-crop farming.
“The opportunity for local producers to supplement their income with high-value tree products may allow more farmers to reduce their cultivated areas and afford better conservation practices for their land,” he says. “The environmental benefits of the windbreaks may then go beyond simply wind protection and retained soil moisture.”
RECOMMENDATIONS OR NEW HYPOTHESES
Given the setbacks, it’s too early to assess the project’s success. The potential benefits of producing the windbreaks remain to be seen, and Taimanao says the idea is still worth pursuing. To continue the project beyond its original SARE funding date, an extension has been granted for evaluation and replanting