Pittosporum undulatum (Sweet Pittosporum), a South Gippsland native mistaken for a weed.

 

"The pittosporum, called 'native orange' from its leaves having a resemblance to the cultured variety, was very ornamental where it had room to grow. It had a glossy, green leaf and sweet scented flowers; its seed pods were round and about the size of marbles, and in colour and shape resembled miniature oranges"

- Mr G Matheson, a Jumbunna resident describing the local native vegetation during the 1880s -from The Land of the Lyrebird

 

 

The ill-will toward Sweet Pittosporum in South Gippsland in recent times is based on myth.

There are many publications, including the booklet produced by the DNRE /South Gippsland Shire entitled "Weed Identification" which have recklessly described Sweet Pittosporum as an environmental weed. This kind of bad press has led to a range of beliefs in the community. Some believe it is a species, which had invaded from East Gippsland, or escaped from the suburbs of Melbourne. Some believe that they are spread in an unnatural way by introduced blackbirds.  All these beliefs have been encouraged by some publication or other. But Mr Matheson reassures us that the Sweet Pittosporum was indeed a local, and a charming one at that. Many reputable botanical publications back this up and are quoted later in this paper. Disapproval of  this species appears to have begun in Melbourne and Sydney (where these popular suburban trees have the ability to “get away”) and then this thinking spread from the cities back into areas where Sweet Pittosporum actually belong. This area has enough genuine weeds to be getting on with.

 

As Mr Matheson said, Pittosporums are a very attractive tree. They also provide excellent shelter and are very popular with bees and a range of native birds. The ground underneath these trees is virtually weed free. In this district, Pittosporums are not confined to gullies and appear to thrive in exposed areas, given the chance. Like wattles and blackwoods, they re-establish themselves in this district without any human assistance. They are good trees to have around.

 

Warm Temperate Rainforest

Gippsland has the most southern and most western occurrences of Warm Temperate rainforest in Australia. Wilsons Promontory has its own brand of Warm Temperate Rainforest dominated by Lilly Pilly. In the Strzeleckis, it is different in one major way. Instead of Lilly Pilly, it is dominated by Sweet Pittosporum.  These areas are now known as Strzeleckis Warm Temperate Rainforest The forest type is classified as "endangered" due to it having been rare in the first (around 3000 ha existed pre white settlement) then heavily depleted to only about 3% of its original extent, making this one of the most depleted vegetation types in the district. DSE estimate that a mosaic of Strzeleckis Warm Temperate Rainforest and Riparian Forest once existed across a further 2000 ha, but none of that remains.

Some key species of Strzeleckis Warm Temperate Rainforest are Sweet Pittosporum, Blackwood, Austral Mulberry, Wonga Vine, Forest Clematis, Muttonwood, Bluegum, Messmate, Kangaroo Apple, Mountain Grey Gum and a range of ferns including Mother Shield-Fern.

 

Sweet Pittosporum acts as a "pioneer species" for South Gippsland's own unique brand of Warm Temperate Rainforest. If conditions are suitable, over time the Pittosporum overstorey will create conditions which a host of warm temperate rainforest plants depend on, and gradually a forest community develops. In order to begin such a transition, all pioneer plants (regardless of what family they are from) are necessarily aggressive. This invasive behaviour should not be interpreted as a bad thing. Natural re-establishment of Warm Temperate Rainforest should be strongly encouraged, not combated.

 

Bill Peel (NRE)  'Rainforests and Cool Temperate Mixed Forests of Victoria'   January 1999 indicates that Pittosporum undulatum is a key species for Strzeleckis Warm Temperate Rainforest.  “In less disturbed sites, Sweet Pittosporum and Muttonwood are well represented as the primary canopy species’. (p.100)

Peel describes this community as ‘widely scattered on the footslopes and in the lowland valleys around the periphery of the Strzelecki Ranges in South Gippsland’ and says that ‘most sites are disturbed, with some developing within Damp or Wet forest.' (p.86)

'The community is restricted to the lowlands of the Strzelecki Ranges at elevations between 80 and 240 m. where it grows on the slopes adjacent to streams and along minor gullies. Past large-scale clearing for agriculture leaves it unclear whether the community ever grew on the alluvial flats of streams in this district.’(p.99)  Strzeleckis Warm Temperate Rainforest

‘has been significantly depleted throughout its range by agricultural clearing.  Historical accounts such as "The Land Of The Lyrebird" noted that this vegetation was once very common around the footslopes of the Strzelecki Ranges.’ The community ‘is currently re-establishing itself in 'old field scrubs' that have re-invaded land that was initially cleared for agriculture and then abandoned.  If it is to survive, some of these old-field scrubs should be retained in order to facilitate the community's re-establishment throughout its former range.' (p. 101)

 

There is a remnant patch of mature Sweet Pittosporum forest near the "Deep Creek Reserve" not far from Foster and another in the Agnes Falls vicinity, identified by Mr Peel as Strzeleckis Warm Temperate Rainforest. Peel lists further localities for Strzeleckis Warm Temperate Rainforest, including Foster’s Gully in Morwell National Park, Macks Creek, Bodman Creek near Won Wron, the Alberton West Forest, Ness Creek north of Korumburra, Hallston Regional park and Grand Ridge Road near Mirboo North.

 

Wet Forest and Damp Forest

   Sweet Pittosporum is not confined to Warm Temperate rainforest areas. "Gippsland Comprehensive Regional Assessment - Biodiversity Assessment" (1999, Regional Forest Agreement) indicates that in Gippsland, Pittosporum undulatum occurs in Wet Forest and Damp Forest. A great deal of South Gippsland carried these forest types, Wet forest generally occurring at higher altitudes and Damp forest being widespread throughout most of the district, and in association with many other forest types (including Shrubby Foothill Forest; Lowland forest and Herb rich foothill forest).

 In Damp forest, Pittosporum can be found with Mountain Grey Gums, Messmate, Swamp Gum, Silver Wattle and Blackwood, Christmas Bush, and a range of ferns and shrubs.

In Wet Forest, Pittosporums are just one of the many understorey species that live beneath the Eucalypt or Acacia overstorey.

 

In Morwell National Park, Pittosporum undulatum  is one of the main hosts to the rare epiphyte, the Butterfly orchid.  This orchid, along with the Oval Fork Fern, was the main reason why the area was declared a national park.  Yet the 1998 Morwell National Park Management Plan, however, reflects an outdated view of this species. While recognising its importance as a host to the butterfly orchid, it refers to them as a pest species and outlines strategies to eradicate them. 

 

Cochran et al ‘Flowers and plants of Victoria and Tasmania’ 1980  states that Sweet Pittosporum is “Indigenous from Westernport eastwards and is a frequent spreading tree in stream-bank jungles”.

 

Costermans Leon "Native trees and shrubs of South Eastern Australia" (1998 printing) page 180 says that the tree is to be found ‘in sheltered situations (gullies) in forest east of Westernport’.     The accompanying map showing the range of Sweet Pittosporum indicates that this species range along the East coast of Australia through to Westernport Bay, taking in all of South Gippsland

 

The Draft Native Vegetation Plan for West Gippsland has a long term goal to increase the extent of Strzelecki Warm Temperate Rainforest from the current 91 ha. to around 300 ha. This will only happen if we allow large amounts of Pittosporums to grow, and this means we need to completely reverse current attitudes that are completely counter-productive to this goal.

Removal of this species could also contravene both the Flora and Fauna Guarantee Act and the Native Vegetation Retention Controls, yet publications like the DNRE /South Gippsland Shire booklet advises the public to pull out or poison Pittosporums.

 

All the most reliable references agree that  Sweet Pittosporums ranged  as far as Westernport Bay.  For some, the debate continues: Yes, they might range that far, but within that range there must be places where they “belong” and places where they don't? If indeed this question of “belonging” really needs addressing, here again are the clues provided by the references in a nutshell:

Matheson states that they grew, "where there was room"

Costermans said that they grew where there was shelter - particularly in gullies

Cochrane et al said they form "streambank jungles"

Peel says Strzeleckis Warm Temperate Rainforest  was widely scattered on the footslopes and in the lowland valleys around the periphery of the Strzelecki Ranges

Peel states they are a key species of Strzeleckis Warm Temperate Rainforest of which DSE estimates was  fairly rare to begin with but now depleted to around 100 ha.

DSE data  and Bill Peel says that Sweet Pittosporums are also to be found in Wet Forest and Damp Forest

Jumbunna, where Matheson observed Pittosporums growing in the 1880s is an area that carried Wet and Damp, Lowland and Shrubby Foothill forest types. The district is on the edge of the Strzeleckis and straddling the South Gippsland plain. Westernport Bay is about 20 km to the West.

 

From this we can reason that there are many places were they surely “belong”. But what about the other areas, the areas which were once covered by Lowland Forest or Shrubby Foothill Forest.  The references don’t list the Sweet Pittosporum as a key species for these vegetation types, but they don’t discount their possible presence either. We have to draw our own conclusions. It is quite likely that in the times before white settlement, as now, if one was to look hard enough, a Sweet Pittosporum could be found in just about any South Gippsland locality

The various references say that Sweet Pittosporums like Stream banks and Shelter and Foot slopes, but South Gippslanders have all noticed Pittosporums establishing themselves in areas that have none of these qualities. Perhaps Matheson hit the mark when he said that the main thing Pittosporums were relying on was room - a break in the canopy, a bit less competition.  It is true, Sweet Pittosporums show up in areas where they had not been noticed before, as far as anyone can remember. Perhaps there’s nothing wrong with that.  Pittosporums are demonstrating that they can tolerate a fair degree of exposure, and capable of growing in a variety of situations and places around South Gippsland, both within existing forest and on more exposed areas.   Some South Gippslanders have been influenced to interpret this as an unwelcome invasion of a non-indigenous weed and believe that cutting down these trees will be somehow beneficial to the environment. There are several publications which reinforce this thinking, but the most reliable botanical publications give evidence that is quite the contrary.

It takes a certain kind of tree to re-colonise the highly denuded parts of South Gippsland. Among other things, it has to be able to tolerate a lot of exposure. Many of our local tree species which were so prolific in a forest landscape make very limited headway in today’s paddocky landscape, but the Blackwoods, Silver wattles and the Pittosporums stand out among the species most capable of coming back unassisted. Rather than celebrate this good fortune, many people react to this marvellous capability with suspicion.

 

In some areas they are returning much needed tree cover to degraded land, in other areas they will merely co-exist with the compliment of existing plants and will play only a minor role. In certain select areas where conditions are just right, they will successfully initiate a gradual yet complete transformation of the landscape. From this, Warm Temperate Rainforest is the very desirable "end result". Therefore we should rethink the current attitude and management of Pittosporum undulatum in South Gippsland and re-educate the local community about Sweet Pittosporum's rightful native status.

 

Lets get back to waging war on the real weeds and make peace with the Sweet Pittosporum.

 

Kim Devenish and Julie Constable    June 2004

 

References:

 

1.  "Weed Identification"    DNRE /South Gippsland Shire P 2 and P 26

 

2. Costermans L  "Native trees and shrubs of South Eastern Australia" (1998 printing) P. 180

 

3.  "Gippsland Comprehensive Regional Assessment - Biodiversity Assessment"

(1999, Regional Forest Agreement) P 159, P 161

 

4. ‘The Land of the Lyrebird”  First published 1920.   Extract from the reflections of Mr G Matheson P279

 

5. 'Rainforests and Cool Temperate Mixed Forests of Victoria'  Bill Peel (NRE)  January 1999  P 84 and P 86 P 100 and P 99

 

6.  Cochran GR et al ‘Flowers and plants of Victoria and Tasmania’ 1980

 

7.  ‘Flowers and Ferns of Morwell National Park’  Harris K  circa 2002

 

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