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

Epiphytes are, by definition, plants that grow on other plants, but like many aspects of the natural world, they don't quite fit within this box.

Species that most commonly grow on trees can also be found in many other habitat types in New Zealand. Here are some examples:

Maybe a better definition of an epiphyte is a plant that can handle dessication, wind and fluctuating temperatures? They are very hardy plants and have a range of features that help them survive in harsh conditions. This new definition seems to work for these tough characters:

There are other terms that can describe these different lifestyles: a "saxicole" is a plant that grows on rocks and a "halophyte" is a plant that can handle exposure to salt water but maybe these species are best described as "hardy opportunists"? Inhabiting these harsh environments presents an opportunity to thrive and reproduce where other species can't.

While searching for recent literature on epiphytes a paper by Liu et al. 2014 caught my eye. This review looks into the potential for ‘restoration-friendly cultivation’ of an epiphytic Dendrobium species which is used for traditional medicine in China. The fusion of traditional cultural practices within the context of restoration/conservation is a concept that has always intrigued me and one that I believe is gaining increasing traction here in Aotearoa, New Zealand.

China boasts over 1,000 species of native orchids, of which over a quarter of these species are used in traditional medicine or as health food supplements. 

Demand for species with desired traits has in many cases led to diminished wild populations and even localised extinction. The epiphytic medicinal orchid Dendrobium catenatum is no exception. Insatiable market demand for this species has led to rapid decline in wild populations throughout China and neighbouring countries. Moreover, the initiation of mass commercial cultivation has not effectively alleviated the pressure on wild populations because demand is higher for individuals sourced from the wild. 

Liu et al. argue for an unconventional introduction approach, in which populations planted in natural forests are allowed to be sustainably harvested (restoration-friendly cultivation). They claim “adding this restoration-friendly cultivation into the current mix of conservation approaches has the potential to turn deeply-entrenched traditional uses of orchids from a conservation challenge to a conservation success”.

The ethno-botanical use of orchid species in Traditional Chinese Medicine (TCM) is a 2000-year old tradition. Dendrobium catenatum is one of the more popular TCM herbs used in both prescribed medicine and as a health food supplement, it is usually consumed directly as a tea or mixed in a soup. Medicinal benefits include voice protection for vocal artists, cancer prevention and cure, and immune system support.


The pros and pitfalls of a restoration-friendly cultivation proposal for Dendrobium:

Potential pros:

• The epiphytic and lithophytic nature of medicinal Dendrobium species means that they can be reintroduced on tree trunks or bare rocks within natural forests. Plants can be harvested non-destructively (taking older stems that have already flowered and fruited) giving reintroduced individuals a chance to regenerate naturally. 
  

• The proposal promotes the preservation and enhancement of native ecosystems as a viable, profitable alternative to exotic agricultural practices.
  

• Social benefits include the potential for adoption by marginalised populations of older and female rural residents in orchid hotspots due to non-intensive labour and smaller initial investments. The high market value and non-destructive harvesting technique allows for farmers to gain financial independence even in areas of limited arable land.
  
  

Potential pitfalls (which are addressed in the article):

• Inappropriate genetic provenance 
  

• Harmful impact on native ecosystems due to increased cultivation activities
  

• Costly seedlings and difficulty finding appropriate markets for marginalised rural populations

Concluding statement from Liu et al.:

“Adding restoration friendly cultivation to the current mix of conservation offers a scientific solution to the TCM conservation conflict that not only respects, but takes advantage of, deeply-entrenched traditions. Such a new solution to a persisting conservation issue also holds promise for other regions facing similar species conservation issues.”

Exciting times??

Is anyone aware of any research or reviews of a similar nature from a New Zealand perspective that they can share? 

Having had the privilege of recently participating a Rongoa Maori course I can think of many examples of how traditional practices would complement conservation and restoration efforts here in New Zealand, are there any good examples you know of that are already taking place?