I had the pleasure of watching a kaka dig for grubs in a  NZ passionfruit vine (Passiflora tetrandra) at Maungatautari Ecological Island this weekend:  

Epiphytes, vines and mistletoes are important for our native fauna. These plants provide food, nesting materials, habitat and water to many, many species. Consider the above example - the vine is providing habitat for the grub and food for the kaka. 

There are many research opportunities within this topic - most of what we know is from casual observations as no one has yet quantified the diversity or abundance of fauna species that utilise these plants.

One more example for today - a wax eye enjoying the fruit of kiekie (Freycinetia banksii) in Hammond Bush, Hamilton:

Have you ever stumbled across a fallen epiphyte? Did you wonder what caused it to fall? 

Some new research by Cabral, Petter and Zotz, titled: What can fallen branches and vascular epiphytes reveal about the dynamics of epiphyte communities? looked at the influence of branch fall on epiphyte distribution in forests of Brazil and Panama. 

They found that most epiphytes reach the ground after falling off branches rather than with branches. They attributed these falls to shedding bark and noted that large branches do not often fall - around 90% of fallen branches were less than 2 cm in diameter. 

This likely means that the epiphyte populations of large branches are more limited by bark shedding than branch fall while those on the small branches of the outer canopy are the opposite, their distribution is limited by branch fall rather than bark shedding.

Bark shedding is important for epiphyte distribution in New Zealand forests. Trees like kauri and rimu are thought to rid themselves of pesky epiphytes and vines by dropping large bark flakes. The branch-shedding behaviour of kauri trees is also likely to minimise epiphyte loads. When investigating epiphytes on kauri, Sarah Wyse found that small epiphyte and vine species growing on kauri trunks between 0.5 and 3 metres from the ground are surprisingly abundant. This may be because they spread over multiple bark flakes and are too low down to be affected by dropped branches.

Next time you find a fallen epiphyte - have a look to see if it has been shed with a bark flake, dropped with a branch, or knocked off by something else...

I am working on a field guide to New Zealand's epiphytes, vines and mistletoes and I have quite a few photo gaps in my species descriptions. My request to the NZ Epiphyte Network is for any good pictures of our native epiphytes, vines or mistletoes (please!). Sometimes it is the detail that I'm missing such as the sporangia on ferns, the flowers of a vine or fruit of a mistletoe. In other cases I have no photos at all of a particular species. Any photos that are kindly supplied and used in the publication will be correctly credited to the photographer but unfortunately I don’t have access to funding to pay for them. Please email me: [email protected] if you can help! Thanks.

A new research article titled "Evaluating factors that predict the structure of a commensalistic epiphyte–phorophyte network" by Sayago and colleagues has once again highlighted the importance of large host trees for epiphyte populations. 

Many authors have found this relationship and it is usually attributed to three key factors: (1) a greater number of potential habitats provided by large trees than small trees, (2) the lifespan of larger trees providing more time for humus to accumulate and epiphytes to establish, and (3) the better access to light and water in large trees than small trees. 

This relationship gives us another reason to conserve old-growth forest and large trees. Did you know that large trees in west coast forests of the South Island of NZ have been found to host up to 28 vascular species? Dickinson, Mark & Dawkins set this record in 1993 for a 26 metre tall, kahikatea that was 1.45 metres in diameter.

In the kauri forest of Waipoua it is only the really large trees that host epiphytes, as shown in the photo below.