There were fifteen coastal gardens. Fourteen were located in the coastal suburb of
Cremorne and one at another coastal suburb in Kingston on the opposite side of the
Derwent River21. Rainfall in Cremorne averages 572 mm per annum, and in
Kingston 711 mm per annum. Kingston is an environmentally diverse suburb, with
some gardens in close proximity to the beach, and others in hilly terrain some
distance from the beach.
The coastal garden type was particularly poor in species richness. Harsh coastal
environmental conditions may have limited the number of species. Species richness
ranged between 25 and 119 species, with the average being 69 (Table 3.4). The
lowest number of species occurred in the gardens of two gardeners who self-
identified as ‘non-gardeners’. These two gardeners were involved in the audit as a
result of snowball selection after neighbours had indicated to them that a garden
survey was being conducted by university researchers. The highest number of
species occurred in the gardens of three ‘passionate’ gardeners with allegiance to
native gardens.
Five species with more than 20 percent frequency (Table 3.3, Appendix 2) were
completely faithful to coastal gardens (a faithful species is confined to a particular
garden type): Tetragonia implexicoma (53% frequency), Einadia nutans and Senecio
21
The Derwent River is a drowned estuary, tidal and considered coastal under the Tasmanian State Coastal Policy, 1996.
pinnatifolius (33%), Lepidosperma gladiatum and Westringia rigida (20%). Marginally faithful species included Eucalyptus morrisbyi (40%), Atriplex cinerea
and Poa rodwayi (33%), and Delairea odorata and Bambusa spp. (27%). Two species were both constant (constancy refers to species being present in most gardens
of a particular type, and across garden types) and faithful: Acacia longifolia ssp.
sophorae (87%), and Rhagodia candolleana (60%). Other species that were highly constant in this garden type were Poa labillardierei (73%), Argyranthemum frutescens (73%), Agapanthus praecox (67%), and Gazania hybrida (60%).
Life form richness (Table 3.5) reflected a trend that was common to six garden types
(the exception being the native garden type), in that evergreen shrubs and herbaceous
perennials constituted the two main life forms. In the coastal garden, 28 percent of
the taxa were evergreen shrubs, and 21 percent herbaceous perennials. Almost 16
percent of species were evergreen trees. Most of the trees were stunted due to the
environmental conditions. The most common trees were Agonis flexuosa, Eucalyptus morrisbyi, E. leucoxylon, E. viminalis, and Schinus terebinthifolius. One gardener even had a Liquidambar styraciflua, barely 50 meters from the beach. The largest percentage of succulents (5% of species) was in this garden type (Table 3.5).
Surprisingly, given the harsh environmental conditions, this garden type also had the
highest percentage (3%) of annuals of all the garden types. No reasons can be
attributed for this high percentage.
An average of 34 percent of species in this garden type was of Australian origin, with
the mean number per garden being 23 species (Table 3.6). Species originating from
South Africa, accounted for ten percent of species in this garden type. Almost 50
percent of the species in these gardens originated from the drier environments of
areas were hardy, salt-resistant and drought-resistant. The remainder of species in
this garden type originated from North America, Asia, and Europe. Three percent of
species were of Tasmanian origin, and of the seven classificatory groups, this type
had the highest percentage of Tasmanian ‘rare or threatened’ species at 3.8 percent
(Table 3.6).
There were two main reasons for including Tasmanian natives as a class in
themselves and distinct from Australian natives. First, gardeners in Tasmania pride
themselves on having species that are specifically native to Tasmania only. Second,
Tasmania boasts a significant number of cool temperate rain forest species
(Buchanan, 2005; Curtis & Stone, 1967) not found on the Australian mainland as
well as species with ancestral links to Gondwanan (Read, 1999) times. Many
Tasmanian gardeners had a sense of wanting to conserve these species and those
deemed as ‘rare or threatened’ species (Buchanan, 2005).
Structural diversity and the physical components of these gardens varied greatly.
Three gardens in this type were not maintained, very overgrown, with invasive exotic
species. There was no structure to these three gardens, with sand flowing in between
plants, smothering some, yet allowing others to dominate. I had to steer a course
through this jungle in order to speak with the gardener. In Barry’s case, the path to
the house wound through a tangle of Delairea odorata, Passiflora mollissima (two invasive species), and tall Aeonium arboreum. He said I know it’s a mess, unkempt and untidy, but I like it this way. Of these three gardeners, two who self identified themselves as non-gardeners, did not like to garden. They only participated in the
survey out of curiosity and hearing about ‘someone from the university’ doing
surveys on gardens. The third gardener just pottered around when he had the time. Their gardens had the lowest number of species: 25, 27 and 33 respectively.
There was a group of five (Cremorne) sites that boasted ‘native conscious’ gardens22
whose gardeners made a point of trying to grow mainly Australian, if not Tasmanian
natives. These gardens also had equal numbers of exotics. According to Tom, I know I have a large number of exotics (which I inherited) but slowly I am trying to replace these with natives. Apart from Al, who regarded himself as a ‘native purist’, the other four research partners in Cremorne also maintained vegetable patches.
These five gardens were informal in structure; their low maintenance was attributed
to these research partners’ attitudes and practices – ecological common sense,
demonstrated by low water inputs, as Al explained. The gardens were bushy and deliberately overgrown; there were layers of grasses, ground covers and procumbent
shrubs, along with canopy of tall coastal shrubs. A thick covering of leaf litter,
mulch, seaweed and hoggings (thick mulch from Eucalypts) was found on bare
patches of ground. Easily navigable paths wound around plants and underneath
canopies. The stated intention of these research partners in having such gardens was
to replicate ‘natural’ bush settings, and be ecologically responsible.
Six gardens in this type were semi-formal and ‘gardenesque’ in structure. Paving
meandered around garden beds and houses; plants were maintained and nurtured.
Gardeners described constant and frustrating battles in their gardens – battles with
the elements but especially the movement of sand. In Joe’s garden, 150 tonnes of
rock was brought in to combat the sand by terracing the dune on which he had
created his garden (Figure B, photo essay); two hundred square metres of paving was
also used to offset the influx of sand. A hedge of Acacia sophorae, a local coastal
22
shrub, was grown along the northern boundary to further protect the house and
garden from sand and wind.
The species composition of these six coastal gardens was also eclectic, with more
shrubby exotics than natives and a range of flowering daisies, hardy Mediterranean
plants, together with a range of conifers. The garden layers tended to be shrubbier
(fewer grasses and procumbent plants) than the five ‘native conscious’ gardens, and
there were also more (small) trees in these gardens. Two of these gardens also
boasted excessively green and well manicured lawns for that time of year (Autumn
April 2004). One lawn surrounded by thick native shrubs could have passed for a
golfing green. The gardener maintained it this way as she did not like to sunbake on
the beach because of the sand.
The last garden in this type, in Kingston, was relatively new. The garden was on a
steep slope, with grassy patches, a few native trees and shrubs, and needing
development. Di, who had only been there less than six months intended to make it a
native garden, totally informal and with lots of grasses, shrubs and ground covers.
She hoped to attract birds and the local fauna to it.