Research objectives

• To classify the understorey vegetation of the Straits enclosure into characteristic communities
• To obtain species composition of the defined communities and monitor seasonal change
• To make a reliable leaf area assessment of each community at four time intervals in the year
• To produce similarly spaced estimates of biomass of the understorey components
• To estimate woody biomass increment for each of the vegetation communities.

Methodology

A qualitative walking survey of the 90 ha woodland block was carried out in May 1999. Four distinct vegetation communities were identified. Three 10 m by 10 m plots were established in each community for random sampling using one square metre ground quadrats. Estimates of cover and abundance according to the Braun-Blanquet system were made, together with additional notes on stem length, seedling and sapling height, and the incidence of flowering and fruiting.

This survey was repeated four times in the year, with above ground biomass harvested from the quadrats and dry weights and specific leaf area (SLA) measured for up to 30 species at each sampling point. Biomass and SLA data enabled the calculation of leaf area index for each of the understorey vegetation communities. For ease of analysis, the species list was grouped into categories of:

• Woody shrubs and trees
• Perennial climbers
• Soft stem herbs (both annual and biennial)
• Grasses and sedges
• Rushes and ferns.