Keywords
land use change, afforestation, ecosystem services, landscape modelling
Start Date
1-7-2010 12:00 AM
Abstract
Land-use change from pasture to forestry can have multiple effects on the environment. In this project, we assessed the impacts of afforestation on erosion-prone land on several ecosystem services in the Manawatu catchment, New Zealand. For 500 high priority farms requiring soil conservation, the land mapped as highly erodible was assumed to be afforested, with two distinct scenarios: conversion of pasture into pine forest or indigenous shrubland. Several models were used to quantify indicators of different ecosystem services including carbon sequestration, non-CO2 gas emission, sediment yield, nitrate export, natural habitat provision, and water yield. The results showed that the pine forest carbon stocks dropped at time of harvest, but rose rapidly after 50 years to be almost double that of the indigenous shrubland scenario. In both scenarios, the main environmental benefit was a large 50% sediment yield reduction from the catchment. As most afforestation occurred on sheep and beef hill country, where stock density is low, there was only a small decrease in nitrate export, and a small decrease in non-CO2 emission. The provision of natural habitat was slightly lower for pine forest than for indigenous shrubland. The water yield relative to the possible range was reduced by 6% at the catchment scale.
Evaluating ecosystem services of Afforestation on Erosion-prone Land: A Case Study in the Manawatu Catchment, New Zealand
Land-use change from pasture to forestry can have multiple effects on the environment. In this project, we assessed the impacts of afforestation on erosion-prone land on several ecosystem services in the Manawatu catchment, New Zealand. For 500 high priority farms requiring soil conservation, the land mapped as highly erodible was assumed to be afforested, with two distinct scenarios: conversion of pasture into pine forest or indigenous shrubland. Several models were used to quantify indicators of different ecosystem services including carbon sequestration, non-CO2 gas emission, sediment yield, nitrate export, natural habitat provision, and water yield. The results showed that the pine forest carbon stocks dropped at time of harvest, but rose rapidly after 50 years to be almost double that of the indigenous shrubland scenario. In both scenarios, the main environmental benefit was a large 50% sediment yield reduction from the catchment. As most afforestation occurred on sheep and beef hill country, where stock density is low, there was only a small decrease in nitrate export, and a small decrease in non-CO2 emission. The provision of natural habitat was slightly lower for pine forest than for indigenous shrubland. The water yield relative to the possible range was reduced by 6% at the catchment scale.
