Study Site - Rotokare

Healthy bush is characterised by a deep covering of leaves on the ground (leaf litter) which, together with rotting logs and branches, provide ideal growing conditions for ferns, mosses, lichens and germinating seeds and seedlings. Above the forest floor there should be an understory or shrub layer, and sub-canopy layer, making it difficult to see far into the bush before there is a ‘wall’ of vegetation. Shrubs such as coprosmas, kawakawa, mingimingi and hangehange occupy the layer from a height of approximately 20 cm to 2.5 m. 

Above this, are the taller sub-canopy trees which could include nikau, lancewood, rangiora, mahoe, pate, putaputaweta and pigeonwood,which form a layer between the understory/shrub layer and the canopy. Below the canopy you will also find saplings of various ages waiting to change from juvenile "Christmas tree shaped" to adult "broccoli" forms when gaps are left by older trees as they fall/die etc. A healthy canopy will be almost continuous (except for tree-fall gaps) and will usually comprise a variety of species, with different trees dominating over time as they compete for space in the canopy. Common canopy trees could be rimu, kahikatea, tawa, and titoki When looking up into the canopy you should see climbing vines (such as rata and supplejack) and different species of epiphyte e.g. Astelia (kowharawhara or perching lily) The final layer, the ‘emergents’, are particularly tall trees that tower above the surrounding canopy e.g. kahitakatea, totara and rimu.

Abiotic factors such as light intensity, wind strength, and humidity can all play a role in influencing the growth and success of each plant. Generally, light intensity and wind strength are highest in the emergent and canopy layers, whereas humidity is greatest in the leaf litter and ground cover areas where light is blocked out by the towering trees above.

Different species are always in competition with one another. As the plants grow, they compete with one another for space, sunlight, water, nutrition and pollinators/seed dispersal partners. To reduce this competition, each species has developed different adaptations that allow them to become specialised to live in a particular niche. You can read about the different adaptations at different levels here.