James B. Friday

Wildfires on degraded grasslands cause extensive soil erosion and cause environmental and economic damage worldwide. We conducted fertilizer, lime, and mulch trials to improve growth of trees planted in acid soils in degraded grasslands on the Micronesian islands of Guam, Rota, and Yap. Fertilizer application had no effect on height growth of Acacia auriculiformis seedlings on a Mollisol on Guam while lime application had a small but significant positive effect on height growth. Fertilizer application had a significant positive effect on height growth of Acacia confusa seedlings planted on an Oxisol on Rota but lime had no effect. Mulch application increased height growth of Swietenia macrophylla seedlings planted on an Oxisol on Yap but lime application had no effect. Collaboration between university researchers and local forestry agencies can improve reforestation success, but researchers need to consider local capabilities and local knowledge.

An important strategy for meeting global landscape restoration goals is nursery production of high-quality seedlings. Growing seedlings with attributes that promote post-planting survival and growth can be dramatically influenced by the nursery container system. In many countries, nurseries produce seedlings in polybags filled with excavated soil. These seedlings often develop deformed roots with limited fibrosity which can lead to poor survival and growth after outplanting. Polybags are initially inexpensive but using these single-use plastic containers accrues expenses that are often untracked. Comparisons among nursery production systems must account for factors such as container longevity, labor efficiency, and seedling field performance. A more holistic approach to account for environmental, economic, social, logistic, and cultural elements in the cost–benefit equation that influences nursery production systems is needed. Converting to a modern container system requires concomitant adjustments in nursery scheduling and culturing matched to the new stock type. Doing so provides an opportunity to align nursery production techniques and resulting seedling attributes with anticipated field conditions. This article describes and discusses the advantages and disadvantages of nursery production systems and provides recommendations and case studies to aid nurseries in improving seedling quality toward meeting restoration goals in a cost-effective and timely manner.

Koa (Acacia koa) forests are found across broad environmental gradients in the Hawai‘ian Islands. Previous studies have identified koa forest health problems and dieback at the plot level, but landscape level patterns remain unstudied. The availability of high-resolution satellite images from the new GeoEye1 satellite offers the opportunity to conduct landscape-level assessments of forest health. The goal of this study was to develop integrated remote sensing and geographic information systems (GIS) methodologies to characterize the health of koa forests and model the spatial distribution and variability of koa forest dieback patterns across an elevation range of 600–1,000 m asl in the island of Kaua‘i, which correspond to gradients of temperature and rainfall ranging from 17–20 °C mean annual temperature and 750–1,500 mm mean annual precipitation. GeoEye1 satellite imagery of koa stands was analyzed using supervised classification techniques based on the analysis of 0.5-m pixel multispectral bands. There was clear differentiation of native koa forest from areas dominated by introduced tree species and differentiation of healthy koa stands from those exhibiting dieback symptoms. The area ratio of healthy koa to koa dieback corresponded linearly to changes in temperature across the environmental gradient, with koa dieback at higher relative abundance in warmer areas. A landscape-scale map of healthy koa forest and dieback distribution demonstrated both the general trend with elevation and the small-scale heterogeneity that exists within particular elevations. The application of these classification techniques with fine spatial resolution imagery can improve the accuracy of koa forest inventory and mapping across the islands of Hawai‘i. Such findings should also improve ecological restoration, conservation and silviculture of this important native tree species.

Questions:Is the introduced timber speciesFraxinus uhdeiinvasive in Hawai'i? Has logging disturbance facilitated the spread ofFraxinusand other alien species?Location:Windward Mauna Kea, island of Hawai'i.Methods:We surveyed 29 plots which were established before selective logging of the native treeAcacia koain 1971 to determine ifFraxinusspread beyond the borders of an existing plantation and if other alien species increased. We created gaps in the canopy of theFraxinusplantation and measured seed rain and regeneration, and we sampled foliar and soil nutrients inside and around the plantation.Results:Basal area ofFraxinusincreased from 0.7 m².ha^‐1in 1971 to 10.8 m².ha^‐1in 2000.Fraxinuswas not found in plots that were located more than 500 m from those where it occurred in 1971 except along a road. Basal area ofAcacia koadecreased after logging but subsequently recovered. Occurrence of the alien vinePassiflora tarminianaand alien grassEhrharta stipoidesdecreased. Seedling regeneration ofFraxinuswas prolific in gaps but did not occur under the canopy. Basal area ofFraxinusdid not correlate with soil nutrient concentrations.Conclusions:Fraxinuswas able to regenerate following logging more rapidly than native tree species. Basal area growth ofFraxinuswas great enough to offset a decline in native trees and cause an increase in forest productivity. If theFraxinusplantation is harvested, managers should plan ways of favoring regeneration of the nativeAcaciawhich is more valuable both for timber and for conservation.