Measuring the impact of herbivory on regeneration of pine-buloke woodlands

Last week, Cindy and I travelled again to Wyperfeld, a national park in the semi-arid mallee of northern Victoria. The reason this time was a pilot study of some vegetation monitoring methods for our kangaroo adaptive management project. Without getting into details of the project itself (I leave that for another blog entry), the basic idea is that if you are trying to manage the impact of overabundant herbivores on vegetation regeneration, you’ll need to have some way of monitoring whether management actions taken are actually working or not! This is important in any kind of management, but necessary by definition for ‘adaptive management’ since otherwise we cannot learn and improve our management over time.

The focus of our project are mixed woodlands of slender cypress-pine Callitris gracilis and buloke Allocasuarina luehmannii, located in some areas of Wyperfeld. The seedlings of these species are being eaten (mostly) by Western grey kangaroos and rabbits when other food sources are scarce, before they are able to recruit as adult trees. These species are not the favourite food for kangaroos, but they’ll resort to them when other food sources have already been depleted.

pine-buloke

Slender cypress-pine (left) and buloke (right)

With this trip, we wanted to get a better understanding of the distribution of pine-buloke regeneration within the park, measure seedling density around mature trees and trial a range of vegetation survey methods to assess their feasibility for ongoing monitoring.

We were joined by a bunch of researchers: plant qaecologists Chris Jones and Dave Duncan directed the surveying, while some volunteers (qaecologists Gurutzeta Guillera-Arroita and Kate Cranney, and Simon West who was visiting our lab) provided the much needed manual labour. Many thanks to all involved!!

Point surveys in a 20x20m plot around a mature pine

Counting seedlings in a 15m radius circle around a pine

Exploring an area looking for seedlings

After the two first days driving around the park, it was clear that pine seedlings were not abundant and many showed signs of herbivory. After summer, when herbivores are at their hungriest levels, the impact on vegetation is most visible.

A couple of sites stood out, with many small seedlings. But we had only found one solitary buloke seedling despite searching several woodland areas.

seedlings

An area of nice pine regeneration (left), although showing some signs of herbovory (right)

Only on the third day, we stumbled upon a large area with many buloke saplings. Sadly, most of this area had been affected by the devastating fire that consumed parts of Wyperfeld this summer. Lightly burn and often chewed on, many of these saplings were still alive… there is hope for a new generation of bulokes in this area!

buloke seedling

Buloke seedling after a recent fire

The trip was very productive, and provided a lot of insight about the situation on the ground. This will help us produce recommendation regarding location and size of grazing exclosures, which will help track the progress towards the long-time objective of pine-buloke woodland regeneration, as well as providing the means of disentangling the effects of herbivory and environmental variation on an annual basis.

exclosure

Any guess about what is inside and outside the kangaroo-proof fence?

J.

PS: For the ornithologically-minded: it was a pleasure to get some nice views of Major Mitchell’s cockatoos and blue bonnets, two beautiful species of parrots from the semi-arid interior!

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3 Responses to Measuring the impact of herbivory on regeneration of pine-buloke woodlands

  1. Pingback: Dbytes #147 (6 May 2014) | Dbytes

  2. Pingback: Adaptive management of kangaroos in Wyperfeld National Park | The Quantitative & Applied Ecology Group

  3. Pingback: We went to Wyperfeld (again) | Cindy E Hauser

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