Dry Rainforest Reconstruction Experiments
Funding:
Xstrata Coal Mount Owen Complex
Background:
In our explorations of the steep gullies in the New Forest and the North West and North East offset areas of the Mount Owen Vegetation Complex, we discovered pockets of dry rainforest communities. Seed from a number of species was collected to start a seedling program culminating in the production of tube-stock that is currently being planted back into the offset areas and onto the rehabilitation area.
Aim:
Our goal has been to extend the rainforest areas to increase habitat diversity. Tree guarding and fertilizing were tested to determine whether they will improve survival and, or, growth of the species grown from tube-stock in the shadehouse.
Summary of Results:
Six rainforest species (Melaleuca styphelioides, Melia azedarach, Brachychiton populneus, Hibiscus heterophylla, Pittosporum undulatum and Hymenosporum flavum) were planted on a hillside suspected of previously sustaining a dry rainforest community. Four experimental treatments were applied to them: no treatment control, tree guard (TG), fertilizer (F), or tree guard and fertilizer (TG F). For those species where only a small number of seedlings were available, hot spot plantings were planted to observe survival and provide dispersal sources. Some vines were planted close to undesirable species, such as Olive and Rose bushes, with the aim that the vines would eventually smother them. Additional seedlings were planted in a gully, which divides the site. In total, 1065 seedlings from 18 different species were planted.
|
Species Planted |
Common name |
Ecological value |
|
Acacia implexa Aphaneropetalum resinosum Brachychiton populeus Breynia oblongifolia Citriobatus pauciflorus Clematis glycenoides Clerodendron tomentosum Eremophila debilis Eustrephus latifolius Hibiscus heterophylla Hymenosporum flavum Melaleuca styphelioides Melia azedarach Notelaea microcarpa Pandorea pandorana Pittosporum undulatum Spartothamnaella juncea Strebulus brunonianus |
Hickory wattle Gum vine Kurrajong Coffee bush Orange thorn Head ache vine Downy chance Winter apple Wombat berry Native rosella Native frangipani Prickly-leaved tea tree White cedar Native olive Wonga-wonga vine Sweet Pittosporum none Whalebone |
small tree, nodulator (nitrogen fixation) vine, habitat tree, 20m shrub, bird food small thorny bush, bird nesting, habitat vine, habitat shrub- small tree, bird food, nectar ground cover, bird food vine, bird food tall prickly shrub, showy flowers, habitat tree 20m, nectar. tree 20m, nectar, habitat tree 20m, bird food, habitat, litter small tree, bird food vine, nectar, habitat tree, 10-20m, nectar, fruit. shrub, habitat, bird food tree, 30m , bird food |
Of the hot spot species, 56% survived the first year. Survival had decreased from the 6-month survey, probably due to exceptional grass growth smothering smaller plants. In the gully area, 69.5% of seedlings survived. The growth of vines planted around olive and rose bushes, was very slow and any effect of these vines on the introduced bushes will take some time before it can be evaluated.
In the main experiment, 74% of the plants survived after year 1. There are differences between the species, for example Melaleuca survived in all treatments whereas Hibiscus only survived if protected with tree guards (see figures below). Fertilizer often reduced survival, but increased plant growth.
This experiment has lead to the formulation of some recommendations based on the one-year (1) or six month (2) data of survival and growth so far. The table below shows no treatment effect (0), a positive effect (+) or a negative effect (-) on survival (S) or plant height (H), of adding tree guards or fertilizer.
|
Species |
Effect of treatment |
Planting recommendation |
|||
|
Tree guard |
Fertiliser |
||||
|
S |
H |
S |
H |
||
|
Melaleuca stypheloides1 |
0 |
+ |
0 |
++ |
Direct planting possible, treatments enhance growth |
|
Melia azedarach1 |
+ |
0 |
0 |
+ |
Direct planting possible, minimal treatment effects |
|
Brachychiton populneus1 |
0 |
0 |
- |
0 |
Direct planting |
|
Hibiscus heterophylla1 |
+++ |
0 |
- |
0 |
Tree guarding necessary |
|
Pittosporum undulatum2 |
++ |
+++ |
+ |
++ |
Tree guards and possibly fertilizer |
|
Hymenosporum flavum2 |
+++ |
++ |
+ |
++ |
Tree guards and possibly fertilizer |
Conclusions:
Rainforest establishment has been surprisingly successful so far. The requirement for tree guard or fertilizer addition was found to be species-specific. A site set up on the spoil rehabilitation area has also shown great success so far, with 80% survival overall. These results have encouraged us to continue the seed collection and to grow more seedlings for planting dispersal sources into existing vegetation.