NIWA mangrove nutrient limitation experiment

Nitrogen and phosphorus are added to individual plants at Whangapoua and Whitford to determine whether they are nutrient limited. Plants beside channels and away from channels are monitored to determine the difference in fertiliser effect on plants adjacent to channels and distant from channels. Purpose: To evaluate whether NZ mangroves are nutrient limited. Part of a global network of sites that includes Australia, Belize and Florida.

Growth rates of marked branches, height of tree, sediment characteristics

Whitford and Whangapoua Harbour

Whangapoua

First sampling in Whangapoua – January 2003. Whitford – June 2001.

18 trees are selected in two areas (next to channel = fringe; away from channel = dwarf). Every 6 months trees are treated with either nothing, N or P. 200gm of dry fertiliser is added in dialysis tubing (slow release) in two cores within 1m from the trunk. Individual plant height and branch length from marker (5 markers per tree) are measured, and sediment samples for chlorophyl, grain size and organics taken. Frequency of collection: Every 6 months (potentially for 5 years).

Gaps in collection: Not reported

MS Excel Digital Format: MS Excel

Land-based management of run-off

See NIWA Sensitivity/Confidentiality: Report publicly available from Environment Waikato or Department of Conservation. For raw data see NIWA.

Ongoing dependant on funding.

Additional comments: Funding runs out in Sept 2003. Hoping to continue project on for another 5 years. International co-ordinator: Candy Feller, Smithosian Institute, Environmental Centre, Washington. [email protected]