Toward Cost-Effective Restoration: Scaling up Restoration in Ecosystems Degraded by Nonnative Invasive Grass and Ungulates

Table 6.

Summary of Present Value of Restoration Costs for 30 yr Period for Three Classes of 1 ha Sites (Easy, Moderate, Difficult) in an Invasive Grass–Dominated Lowland Ecosystem on O'ahu, Hawai'i

Note: Maintenance is assumed to continue for 30 yr. Present Value is calculated at a 2% annual discount rate.

a Values for the 1 ha Easy site are from the 30 yr 1 ha cost analysis in Table 4. The Easy site is fully accessible by road, ~10 m elevation gradient, fairly rough and rocky terrain, dominated by an invasive grass with few scattered invasive trees, and requiring exclusion of ungulates via fence construction.

b Moderate: ~0.8 km from nearest road, ~20 m elevation gradient, moderate rough and rocky terrain, dominated by dense populations of invasive grass and trees, and requiring exclusion of ungulates. Due to more arduous conditions at the Moderate site, the following baseline parameters identified in Table 3 were affected:

^M1 Clearing: The labor time rate for initial clearing slowed to 240 hr/ha/person.

^M2 Fence: Fence construction labor time rate slowed to 2 m/hr/4-person crew.

^M3 Herbicide: The labor time rate for initial herbicide slowed to 79 hr/ha/person.

^M4 Outplant/Replant: The labor time rate for outplanting/replanting slowed to 15 plants/hr/person, and watering delivery slowed to 88 liters/hr/person.

^M5 Maintenance: The labor time rate for fence maintenance slowed to 75 m/hr/person, clearing maintenance slowed to 20 hr/ha/person, and herbicide maintenance slowed to 17.5 hr/ha/person (even years) and 10 hr/ha/person (odd years).

^c Difficult: ~3.2 km from nearest road, ~20-m elevation gradient, rough, rocky and uneven terrain, dominated by dense populations of invasive grass and trees, and requiring exclusion of ungulates. Due to more arduous conditions at the Difficult site, the following baseline parameters identified in Table 3 were affected:

^D1 Clearing: The labor time rate for initial clearing slowed to 240 hr/ha/person.

^D2 Fence: The labor time rate for fence construction rate slowed to 1.7 m/hr/4-person crew; and fence material costs increased to $49/m, with higher probability of uneven terrain requiring additional materials to accommodate the contour and secure ground pinning.

^D3 Herbicide: The labor time rate for initial herbicide slowed to 157.5 hr/ha/person.

^D4 Outplant/Replant: The labor time rate for outplanting/replanting slowed to 7 plants/hr/person, and watering delivery slowed to 44 liters/hr/person.

^D5 Maintenance: The labor time rate for fence maintenance slowed to 50 m/hr/person, clearing maintenance slowed to 20 hr/ha/person, and herbicide maintenance slowed to 34.5 hr/ha/person (even years) and 20 hr/ha/person (odd years).