Nectar At Highest Concentrations On Native Trees Along NZ’s Dry East Coast – Study

Monique
Steele, Journalist

A new study has found
higher concentrations of nectar from native New Zealand
plant species in the drier eastern parts of the
motu.

Flowers produced high-sugar nectar which fed
birds and insects, and was also collected and processed to
make honey.

Over two years, researchers measured
nectar from more than 4200 flowers off eight native trees in
a number of regions nationwide.

The “Nectar traits of
New Zealand trees vary across climatic zones” study was
published in Frontiers in Plant Science last
month.

The plant species studied included karo
(Pittosporum crassifolium), kōhūhū (Pittosporum
tenuifolium), tarata (Pittosporum eugenioides), kōtukutuku
(Fuchsia excorticata), pōhutukawa (Metrosideros excelsa),
mānuka (Leptospermum scoparium) and kōwhai (Sophora
microphylla) and tī kōuka (cabbage tree).

The
regions were Auckland, Taranaki, Hawke’s Bay and Wellington
in the North Island and Nelson/Tasman, Marlborough,
Canterbury and Dunedin in the South.

Researchers found
trees like kōwhai and pōhutakawa produced the highest
concentrations of nectar in drier areas, while sunnier sites
generally had lower nectar volumes though larger
flowers.

Results from mānuka flowers showed
substantial regional variation in nectar traits, driven by
climate.

University of Waikato researcher Dr Johanna
van Delden said the study could benefit conservationists and
beekeepers, the latter to help them decide the most optimal
locations and nearby trees for their beehives.

“The
trees which produced the most sugar of all the species were
either found in Dunedin, Canterbury or Hawke’s Bay, which
are all on our East Coast,” she said.

“And the nectar
volume, so how much nectar each flower produced, was also in
50 percent of the species coming from Dunedin or Hawke’s
Bay. So I think that was the clearest and easiest result we
could take out of our measurements.”

She said
researchers were surprised by how the plants differed across
climates.

“We found that every plant is really
different. So we could see that some plant traits like
nectar or the flower size was climate-linked, but it really
varied from species to species between 20 and 80 percent,
which is a massive variation.

“It was mostly
associated with sunshine hours and rain amounts to really
simplify the results.”

Van Delden said farmers could
look at the species which performed well in their region to
encourage greater biodiversity around farms.

“When
they are flowering, attracting butterflies and birds, that
could enhance your backyard biodiversity and could be used
also on pastures for shelter.”

She said further
research should explore how the native plants adapted to
local climates across the country.

“If we go one step
further, so the next researcher after me, could have a look
if it’s actually not the location itself having the
influence on the plant, but actually that it’s genetically
driven.

“So that the plants over time have evolved in
that way, that they are adapted to that local climate and
therefore show those adaptations in regards to producing
more sugar, for example, in the South Island and East
Coast.”

Part of the research was funded by the
government’s Endeavour research programme by the Ministry
for Business Innovation and Employment entitled, ‘Building
Resilience and Provenance into an Authentic Māori Honey
Industry’.

It was a joint project with the University
of Waikato, Manaaki Whenua/Landcare Research and the
Auckland University of
Technology.

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