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This paper analyses the effects of resin benefit on the optimal rotation age of Simao pine plantation. Timber growth and resin yield functions were first derived, and then an integrated formulation for Hartman rotation was solved by taking both timber and resin benefits into consideration through numerical optimization. Empirical results indicate that: (1) the inclusion of resin benefit results in lengthening optimal rotation age; (2) resin benefit has a greater effect on rotation age when discount rate is low than when it is high, ceteris paribus; (3) with an improvement of site productivity, resin benefit has a decreasing effect on rotation age, other factors being constant. These effects are also true with respect to benefit gains in present value. r 2005 Elsevier GmbH. All rights reserved.Jel Classification: Q230

Watersheds provide numerous ecosystem services to downstream communities often with no cost to them. Although these services are valuable to humans, they do not have monetary values attached to them, making their total economic value quite ambiguous. This ambiguity results in the non-optimal use of the natural resources that leads to the degradation of the watersheds. One approach that could address this issue is payments for ecological services (PES). The main objective of this study was to estimate the willingness-to-pay for improved watershed services by domestic water users within the Layawan Watershed in Oroquieta City. It employed the contingent valuation method to assess the willingness to pay of water users. More than 50% of the respondents voted positively to the referendum question which is whether they are willing to pay a certain amount for the conservation of the Layawan Watershed or not. The computed mean willingness to pay amounts were Php 57.48 and Php 53.89 per month per household for the parametric and non-parametric estimations, respectively. These amounts translate to 0.68% of the average monthly household income of the sample respondents, which is approximately Php 8 198.84. The amounts computed may serve as bases for a water user fee that may be collected from the domestic water users in the Layawan Watershed as buyers of the watershed services.

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Over the years, ecosystem services have been undervalued since regarded as public good.