Mt Vaea Digital Nature Trail

Panel 1. Introduction

Geography and Geology

Samoa has had 6 different periods of volcanic activity since the islands were first formed from a geological “hotspot” and the Mt Vaea Nature Reserve is sited on the oldest volcanic lava flow on Upolu. Geologists have named the earliest volcanic series in Samoa the “Fagaloa” volcanic series which are 3-5 million years old and  characterised by steep slopes, deep soils and many rivers and waterfalls. Most of Samoa is composed of younger rock with more gentle slopes and shallower and more rocky soils. 

Mt Vaea is a remnant of a 3 million year old volcano that has eroded away to form the steep ridges covered with the deep, rocky soil that you see today. Younger, less eroded, lava flows surround the mountain and these are characterised by the gentler slopes of Vailima and Avele, on the 750,000 year old Salani volcanic series. The elevation of the reserve ranges from 180m to 470m. One river flows through the reserve, the Loimata o Apaula stream, which has a series of small waterfalls including the small swimming pool used by Robert Louis Stevenson in the 1890’s. From the reserve, the Loimata o Apaula stream flows north through the centre of Apia and into Apia harbour next to the Mulivai Catholic Cathedral.

VEGETATION AND PLANTS

Forest covers three quarters of the reserve, most of it comprising fast growing introduced invasive trees. Originally the mountain was covered with native lowland rainforest, but over the years the forest has been disturbed by human activity and by cyclones. Much of the forest remaining is now called “secondary forest” meaning it has grown up after the original, or “primary forest”, was removed. Since 2008, a restoration project has been underway at Mt Vaea and approximately 12,000 native lowland trees have been planted and a total of around 6 hectares of open and degraded forest has been restored.

At the base of the mountain the forest consists mostly of exotic tree species such as the Sita or the Cigar Box Cedar (Cedrella odorata), Mahoki or Mahogony (Swietenia macrophylla). The lower part of the Mt Vaea reserve was actually a forestry plantation where introduced timber trees were trialled to see how they perform in Samoan conditions.  A number of highly invasive trees such as Tamaligi (Albizzia species), Fa’apasi or African Tulip (Spathodea campanulata) and rubber trees such as Pulu Vao (Funtumia elastica) and Pulu Mamoe (Castilla elastica) have invaded these lower slopes.

Higher up in the reserve small patches of the original lowland rainforest remain. The most common native trees here are: Tava (Pometia pinnata), Ma’ali (Canarium vitiense), Mamalava (Planchonella samoensis), Asi-toa (Syzygium inophylloides) and Maota Mamala (Dysoxyllum samoense). The less common native trees include: Gasu (Palaquium stehlinii), Tamanu (Calophyllum neo-ebudicum), and Au’auli (Diospyros samoensis). There are also a few giant Aoa, or Banyan Trees (Ficus prolixa and Ficus obliqua) on the long trail. These are arguably the most important trees in the Samoan rainforest as they are hosts to myriad species of orchids, ferns and other epiphytic plants and are an important food source and home for native birds and flying foxes.

The ground cover is comprised of a mixture of native and introduced ferns, vines, shrubs and grasses. Look out in particular for the invasive Panama Hat Palms (Carludovica palmata) and the bright red flowers of the Fire Spike (Odontonema tubaeforme) along the trail. While pretty, these and many other introduced garden plants are highly invasive and are spreading into the native forest in Samoa.

Below are some photos and key features of some of the more common native trees in the reserve, many of which have now been labelled with QR codes.

Native Trees of the Reserve – Photos & Key Features

VAILIMA BOTANICAL GARDENS

ANIMALS

The reserve is home to a rich animal biodiversity including birds, flying foxes, lizards, butterflies, snails, insects and freshwater fauna. These animals all have an important ecological role, whether as pollinators or spreaders of native plants, decomposers of rotting vegetation or as food sources for other animals; all contribute to the stability of the forest ecosystem and the complex web of life.

Birds

Many of Samoa’s birds inhabit the Reserve, with around 34 species recorded from the Reserve, including introduced birds, seabirds and shore birds!

Common Birds

The most common native land bird species are shown below with their Samoan name, Common English name and Scientific name. Please click on the sound icon to listen to the bird calls.

Rare Birds

Rare birds such as the Sega ula or Samoan Parrot Finch are occasionally sighted in the reserve and the haunting sound of the Ma’oma’o or Giant Forest Honeyeater can also be heard.

Introduced Birds

Seabirds

Flying Foxes

Samoa has two flying fox species both of which can be seen in the reserve: the Pe’a Fanua or Tongan flying fox (Pteropus tonganus) and the much rarer Pe’a Vao or Samoan flying fox (Pteropus samoensis). The two flying fox species are quite distinctive: the Pe’a Fanua lives in large colonies and is most active at night while the Pe’a Vao is solitary and active during the day. Furthermore, the Pe’a Vao has a light coloured face and broad wings while the Pe’a Fanua has a black face, whitish collar around the neck, narrower wings, and the hind legs stretch out like a tail.

Butterflies

There are 30 species of butterfly known in Samoa with at least 16 of these recorded or expected in the Vailima Botanical Gardens and Mt Vaea Reserve. The  small blue Samoan cerulean butterfly Jamides argentina flies quickly and often high around the margins of shrubs and trees in forest glades as well as darting in and out of shrubs along the tracks.  Its flashing blue-purple colouration is striking even for this small butterfly.  The grass yellow butterfly Eurema hecabe sulphurata flutters along the ground across low herbs among the sun patches on the open flats.

The blue tiger butterfly Tirumula hamata melittula is common in open areas and the vivid orange common vagrant butterfly Vagrans egista bowdenia is a common visitor to the summit near Robert Louis Stephenson’s grave.  Also common is the blue moon Hypolimnas bolinas pallescens and the Evening Brown Melanitis leda hopkinsi. Bright flowers such as Lantana, Blue-rat tail, Ixoras and others attract this and other butterflies to feed on the nectar.

Please visit the butterfly garden in the Vailima Botanical Gardens for more information on our beautiful butterflies.

See if you can find all 16 butterfly species that have been recorded from the Vailima Botanical Gardens and Mt Vaea Reserve! (butterflies circled in green)

Fish/Crustacea

Very little is known about freshwater biodiversity in Samoa.  However, a survey of the Loimata o Apaula Stream was conducted in July 2008 as a part of nationwide preliminary survey (Jenkins et al. 2008).  Three fish species (two species of eel and one species of gobiid) and six macro-crustacean species were recorded in the stream. One of the macro-crustacean species, Macrobrachium aemulum was a new record to Samoa and only found in the Loimata o Apaula Stream.

Rules of the Reserve

• Please stick to the trails. Making new trails causes erosion and damages plants
• Please remember that all plants and animals are protected within the reserve. Nothing must be taken or damaged.
• Please put your litter in the bins provided or take it with you
• Take only photographs and leave only footprints!

Photo credits: Unless otherwise credited plant photos are by Dr Art Whistler, butterfly images are from Eric Edwards, bird photos are by James Atherton, all others as credited. Bird calls are from https://xeno-canto.org

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