Tree planting is one of the easiest and tangible ways to offset your carbon emissions. Trees absorb carbon in the process of making wood and provide other co-benefits for the environment.

Performance characteristics of tree planting as a carbon offset.
As they grow, trees absorb carbon.  For New Zealand native trees, it can take a long period of time for them to reach maturity and their full potential to absorb carbon. This can often be over 200 years.  GreenFleet allows for a conservative sequestration rate of 2 tonnes of C02 per hectare, per year (1). By contrast, Radiata Pine plantation forests can absorb well over 500 tonnes per hectare (2). 

Planting trees as a carbon offset has received some questioning from environmentalists. These have included:
- The length of time it takes for native species to grow and sequester carbon in relation to the need for expediency in addressing climate change. Native trees are slow growing. For this reason, tree planting should be considered as part of a range of sustainability and climate change initiatives that organisations undertake.
- The amount of carbon they sequester compared to other offset methods. Organisations who are working toward carbon reduction or neutrality should work on a range of actions that both reduce and offset carbon emissions. 
- Permanence of planting and the risk of losses through clearing, fire or disease. GreenFleet factors an additional 10% margin to allow for natural mortality and unforseen losses. Tree planting partners are required to monitor planting to ensure undue losses do not occur in the first 2 years.
- Problems associated with plantation planting of monoculture species. GreenFleet planting partners are only permitted to plant New Zealand native species.
- Land rights issues. GreenFleet planting takes place on publicly owned sites (e.g. schools and parks) or on private sites under the supervision of Regional Councils.

Co-benefits of tree planting
As well as absorbing carbon, planting native trees helps maintain and enhance biodiversity, helps improve stream water quality (3) and provide amenity value. Much of the planting done by GreenFleet is in partnership with Trees for Survival and other school groups, providing a educational benefit to schools.

GreenFleet tree planting provides businesses with a perfect fun team-building opportunity that demonstrates real support towards local community initiatives.ÿA number of GreenFleet members have related feedback to this effect. Likewise, planting events are a great occasion for communities to network with businesses.

Additionality
An important aspect of any carbon offset is the concept of additionality or the question would this action or projects have occurred anyway?  GreenFleet works in partnership with other planting groups to achieve its planting requirements and aims to help them overcome funding barriers that would otherwise prevent them from undertaking or completing their planting projects.  For example, GreenFleet funds the annual supplies required by schools participating in the Trees for Survival programmes. Without these supplies, the schools would not be able to develop seedlings to later plant.
 
1 This figure has been reached in consultation with New Zealand research organisation Catalyst R&D.
2 http://www.maf.govt.nz/forestry/pfsi/carbon-sequestration-rates.htm
3 www.arc.govt.nz