Lea van de Graaf from the University of Leiden, Netherlands and Carolina Madeira from the University of Lisbon, Portugal have recently published an account of rich invertebrate communities in tropical epiphytes. Their study involved sampling 18 elephant ear ferns (Platycerium elephantotis) in Kibale National Park, Uganda to investigate the macroinvertebrate populations on, and within, suspended soil.

The objectives of this study were:

1. to survey the biodiversity and species richness, as well as organisms’ density within these ferns
   
2. to compare macroinvertebrate communities from ferns at different heights and of different weights
   
3. identify patterns of macroinvertebrate assemblages according to the mentioned variables
   

Individual ferns on 18 randomly-selected trees were removed and thoroughly dissected to collect all fauna within. 

They speculate that this epiphyte may be a nursery for macroinvertebrates because they found high numbers of caterpillars, cocoons, pupas and eggs in their samples.

When addressing their second objective they found that there were no significant relationships between invertebrate diversity or abundance and height or weight of the epiphyte. The authors speculate that the diversity and abundance of invertebrates is more likely related to the microhabitat within each fern and suggest that the presence or absence of canopy soil is probably an important factor in determining critter populations.

The authors conclude that invertebrate populations within epiphytes are an overlooked but important component of forest diversity. They state that: 

"There will undoubtedly be other, overlooked, concentrations of invertebrates in the canopy, living in a wide range of habitats other than epiphytes. As further studies are made of the animals both in epiphytes and elsewhere in the canopy, the estimates of total invertebrate biomass will increase and the relative importance of epiphytes may need to be revised."

This conclusion is very similar to that from our recent epiphyte fauna study in NZ, which is: we need to study our forest canopies more!

I'm very excited to announce a new publication on New Zealand epiphytes and the fauna that inhabit them. Hot off the press this week, this paper reports the results of a small exploratory study in the canopy of the temperate Waitakere rainforest. The project was undertaken by NZ Epiphyte Network student Olivia Henwood (who has previously posted on this blog), myself, and entomologist Brian Cutting.

Last summer our team installed cameras in the canopy of Northern rata and kauri trees with the help of Ark in the Park volunteers. The cameras were directed at nest epiphytes (Collospermum and Astelia species) and epiphyte mats (comprised of small mantling species like Cardiomanes reniforme). We also took samples of substrate from within and around the epiphytes. Our goals were to 1) find out what, if any, fauna use epiphytes for habitat or other resources and 2) investigate different canopy research methods to guide future studies.

After a huge processing effort from Olivia and Brian our small study produced 1,003 video sightings from over 200 hours of footage and 794 collected specimens. This was surprising given the low intensity, exploratory sampling design but we were even more surprised by the diversity of organisms recorded. Here is a snapshot of the results:

From the video: the most frequently recorded taxonomic groups were spiders (249), moths (179), cockroaches (172) and weta (156) but the most exciting record was that of a gecko (speculated to be a forest gecko (Mokopirirakau granulatus)) that was sighted on two different nights in the Collospermum hastatum. If you've got good eyes you might be able to spot it in these still shots:

From the samples: samples of organic matter produced 701 invertebrate specimens while samples of phytotelmata (water bodies within epiphytes) produced 93 specimens. The most exciting find was that of the copepod Attheyella lewisae which has only ever been found on mossy stream banks before now.

Methods: we used tree climbing to set up cameras, collect samples and do timed visual surveys. The visual surveys did not return enough samples to process but the other two methods were useful. We speculate that the drought conditions of last summer influenced our results and that different methods may be useful in different forest types and under different climatic conditions. 

This study has provided a useful indication of the diversity of faunal species that inhabit or visit epiphyte communities and we believe that this relatively unknown canopy community certainly needs further investigation. This study has also shown that a range of survey methods is likely to be required to accurately sample the huge range of lifeforms that are present in the canopy.

Here is the link to this paper if you'd like to know more:
Henwood, Kirby, Cutting 2014

Ernesto Gianoli and Fernando Carrasco-Urra from the University of Concepción in Chile have recently achieved the semi-impossible: they've become famous because of a botanical discovery!

The two researchers have published the first record of a plant that can imitate several hosts. Boquila trifoliolata is the only member of the Boquila genus and is a native vine of Chile and Argentina. It is common, vigorous climber with fluted, hairy stems. The most interesting feature of this plant is definitely its ability to grow leaves that match the shape and size of the nearest plant -  usually its host! 

The leaves of this vine are extraordinarily diverse. The biggest ones can be 10 times bigger than the smallest, and they can vary from very light to very dark. In around three-quarters of cases, they’re similar to the closest leaf from another tree, matching it in size, area, length of stalk, angle, and colour. Boquila’s leaves can even grow a spiny tip when, and only when, it climbs onto a shrub with spine-tipped leaves.

“There are some leaf features that are too hard to copy, such as serrated leaf margins,” says Gianoli. “It is common to see cases where Boquila “did her best”, and attained some resemblance, but did not really meet the goal.”

The same vine can even mimic several trees! If it crosses from one plant to another, its leaves change accordingly.

It is not yet clear why or how this species makes these changes. The authors have suggested that it may be avoiding herbivore predators and may utilise airborne chemicals or gene transfer to get the blueprint for the leaf features of their host plant. Its all a bit mind-blowing and exciting, whatever the mechanism. I wonder if there is anything in New Zealand doing this without us noticing?! 

One case of possible NZ plant mimicry has been noticed in matukuroimata (Alseuosmia pusilla), a fairly common forest shrub that appears to be mimicking the famous horopito, or pepper tree (Pseudowintera colorata). These plants are not at all related but often look very similar. It is thought that the matukuroimata is avoiding herbivore browsers my copying the threatening red tinges of the spicy horopito. Click here to read more.

A real kiwi bushman from Northland once showed us some Alseuosmia that were mimicking other shrub species including the long leaves of horoeka and mahoe. I don't have any photos sorry so I guess that one will have to remain a mystery until more investigations are done!

Some wording in this blog came from the excellent Ed Yong at National Geographic.

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:

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.

Nonvascular epiphytes are the mosses, lichens and liverworts that we find growing on other plants. They do not have the plumbing systems that higher plants have to pump water and resources around their stems and leaves. This means no xylem or phloem and a generally small stature.

Nonvascular plants are a very important group epiphytes. They are commonly the first epiphytes to colonise a young, bare host tree and provide substrate that other plants require for attachment. They contribute to forest biodiversity and processes and can be found from the bottom to the very top of host trees.

The trouble with nonvascular epiphytes is that they are hard to identify. This means that they often get overlooked in epiphyte surveys and studies. Dr Kathrin Affeld discussed in her talk at the 2013 NZ Epiphyte Workshop the importance and challenges of including these plants in epiphyte studies. I admit that I know very little about New Zealand’s nonvascular epiphytes and have not found any feasible way to include them in the NZ Epiphyte Survey Programme. I am very interested in any thoughts on this – how can we start paying more attention to nonvascular epiphytes?

Today was the University of Waikato Open Day - an event where prospective students come to see what the University has to offer and what it means to undertake tertiary study (and of course, get lots of free stuff!).

Olivia and I set our ropes up in a Ginko biloba for a tree climbing demonstration. It was very branchy and required some careful manoeuvring around smaller limbs but overall a pretty straight-forward and enjoyable climb. 

We had a few conversations with students but unfortunately the rain seemed to deter most from hanging around. Our goal was really just to let them know what studying biology can lead to - real life adventures! 

Hopefully we sparked the interest of some young minds who could become our next epiphyters :) Here are some photos from today and other tree-climbing expeditions.

I'm Olivia Henwood, a student at the University of Waikato. I have recently spent four weeks carrying out an epiphyte research project in the Waitākere Ranges. Here's brief a snapshot of my trip:

This is a good day in the office! Ascending a rata to install a camera.

Stunning view over the Waitākere Dam and sun-soaked ranges beyond.

Camera ready and waiting to unlock the secrets of the tree canopy...

Sharon Osman, one of the amazing Ark in the Park volunteers happy to get an opportunity to utilise her skills.

Massive Collospermum hastatum nest - this must be at least 4m tall!

Giant cave wēta - close to 30 cm stretched out! Just one of the many treasures living within the epiphytes. More to be revealed soon...

In a new viewpoint article, Professor Gerhard Zotz has clarified the use of ‘hemiepiphyte’ and proposed the rejection of the term ‘secondary hemiepiphyte’.

The current classification of canopy plants typically has three main groups: (1) holoepiphytes; (2) hemiepiphytes; and (3) climbing plants. Holoepiphytes are those that germinate and complete their life cycle on other plants. Climbing plants are vines (also called lianas) that require the structural support of other plants to reach the canopy; these can be further defined as herbaceous or woody categories. Hemiepiphytes are plants that have a root connection with the forest floor at some stage in their life cycle and can be further differentiated into primary and secondary categories:

• Primary hemiepiphytes are plants that establish this connection to the ground after germinating in the canopy 
  

• Secondary hemiepiphytes begin life on the ground, climb to the canopy and then lose their link with the ground. 
  

This is how the current classifications relate to each other (please note that this is my interpretation):

Classification of hemiepiphytes has been confusing for many years – especially secondary hemiepiphytes (SH). Here is a conceptual picture of the difference between primary and secondary hemiepiphytes that I’ve drawn and below that, a list of problems with these classifications.

The problems:

As explained by Zotz (2013), there are multiple problems with the term ‘secondary hemiepiphyte’:

1.      Inconsistent use of SH has resulted in ambiguous application of the term and confusion over which species fit in this group.

2.      It is difficult to determine if any one species is a SH because although the main ground connection may be lost, adventitious roots can re-connect with the soil and these roots can be hard to find and trace.

3.      The term implies a close relationship with primary hemiepiphytes when there are in fact significant functional differences between the two groups, including: the location of germination; the growth form; the source of water and nutrients; and the structural support mechanisms.

A solution:

Zotz (2013) proposes that the use of the term SH is discontinued and that all climbing plants which germinate on the ground and possibly lose parts of their ground connection are instead referred to as ‘nomadic vines’. This change would achieve the following clarification:

1.      It should stop the ambiguous classification of canopy species and facilitate compatibility of data sets in higher-level studies. Also, the use of ‘primary’ with hemiepiphyte will be redundant and ‘hemiepiphyte’ will only refer to species that germinate on another plant and establish a connection with the forest floor.

2.      There will no longer be an implied functional relationship between the primary and secondary hemiepiphytes but instead the similarity of SH with vines/lianas will be highlighted

3.      Species that only sometimes lose their connection with forest soil will fit within ‘nomadic vines’. This new term can also accommodated the occasional germination of these species in the canopy.

This is how the proposed classifications relate to each other when based on the location of germination (please note that this is my interpretation):

What are your thoughts? How does this new classification apply in New Zealand? Do you think any of our species can be classified as nomadic vines?

Kia ora tatou!

Welcome to the first blog on our brand new website. 2013 has so far been a year of firsts for epiphyte researchers. The first NZ epiphyte workshop was held in New Plymouth in February.  The event involved a lot of discussion about our current knowledge of epiphytes, vines and mistletoes in NZ and what we need to do to start filling our rather large knowledge gaps. 

From the workshop, the first network for people interested in these plants was formed - The New Zealand Epiphyte Network. Following on from that was the development of our first facebook page and now our first website!

Please have a look around the site and let us know if you have ideas for what might be a useful addition to the website - all feedback is welcome!

This is the epiphyte network because "the epiphyte, vine, and mistletoe network" was a bit too long-winded. However, we are equally interested in the three plant groups because there are a lot of parallels, including: habitat, distribution, physiological characteristics, host interactions and the challenges of studying them!

These three groups of plants are not well known in New Zealand. This is mainly because of the difficulty of accessing their forest canopy habitat, but trust me... getting up into this area of the forest is well worth it! There is no better way to understand the challenges of living on a tree branch 20 metres above the ground, or to investigate the interactions of mosses, lichens, orchids and nests, than to get up-close and personal. 

Tree climbing might not be your cup of tea... no problem! Just take a minute next time you visit a forest to pause under a big tree and really have a good look at what is up there. Take some binoculars and you might see flowering orchids, buzzing bees, waving fern fronds, or tangled vines; its a fascinating world and well worth some investigation.