Flooded gum, leafminers and fire

By Katherine Edwards

In a previous post, Jodi Wildy raised concerns about the health of Flooded Gum, on her land in Boyup Brook and elsewhere. George Matusick has shared his ideas about the role of psyllids in the decline, and below Katherine Edwards, on the basis of her master’s studies, pays attention to some other factors that she thinks may be important explanatory factors.

Thank you Jodi for bringing the important issue of Flooded Gum decline into the spotlight! Relatively little research has been conducted into the causes behind the extensive Flooded Gum decline. Research that has been conducted has tended to focus on the role that phloem-feeding insects (PFI) may be playing in the decline. While George has given abundant information on the psyllids, I wanted to comment on the Perthida leafminer, another important PSI that is abundant on Flooded Gum. An important factor of the history between Flooded Gum and the Flooded Gum species of the Perthida leafminer, is that the abundance and distribution of the leafminer seem to have increased since their first records in the late 1800’s according to a study of herbarium collections. The authors of that study suggested that the increases were linked to the governmental changes to Aboriginal fire regimes around that were in place since the 1850’s, the hypothesis being that Aboriginal burning regimes produced more crown scorch which would kill larvae and abscise the leaves that would have been their food source, and the change to the European burning regime reduced this population control mechanism. The Aboriginal fire regime, compared to the European regime, involved frequent burning of bushland areas with intensity sufficient to reach and scorch the crowns. The European burning regime involved an era (1856-1920) of uncontrolled, intense fires caused by settlers, followed by an era (1921-1965) of fire suppression, followed by the current era (1966-present) of wildfire suppression and prescribed burning.

PFI are an important factor in the decline aetiology of Flooded Gum but, from my observations and the research I have read, are one factor in a complex decline. Fire and understory disturbance may also be important but I fear that changes to rainfall may be the main driver behind this decline, causing the stress that renders the species more susceptible to the horde of organisms (PSI’s, Phytophthora species, heart-rot fungi, mistletoe’s, boring beetles, termites, e.t.c.) that feed on this species.

The decline of Flooded Gum presents some exciting opportunities for further research into ecological interactions, the effect that a changing climate is having on South-Western Australian Eucalypts and the primary cause of the decline of an iconic keystone species. This is one species I am not prepared to lose in the shift to the novel ecosystem state, it is far too important!

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Challenges to biodiversity conservation in urban bushland

Leonie Stubbs, Coordinator, Friends of Paganoni Swamp

MonitorPlots_Seeders

Following a prescribed burn of approximately 90 hectares at Paganoni Swamp Reserve, Katinka, her business manager Annora, myself and Norm (members of Friends of Paganoni Swamp) spent a glorious Friday morning placing markers and erecting seed collectors at thirteen ashbed and control sites. These activities are contributing to research into tuart regeneration following fire that is one of a number of studies being undertaken to improve our knowledge of the impacts of such burns on tuart woodland. Paganoni Swamp Reserve has not been burned for over thirty years and when the Department of Environment and Conservation (DEC) advised that a burn was to take place, staff from Urban Nature (a division of DEC) arranged for all those with an interest in the reserve to meet to discuss how best to obtain the greatest benefit from the burn from an adaptive management perspective. This ranged from those with an interest in weeds, flora, tuart regeneration, the impact on fauna and bird species as well as those working in the reserve such as our Friends group and Regional Parks.

Whilst the pros and cons of prescribed burns can be debated ad infinitum, the protection of biodiversity at Paganoni Swamp Reserve should be the ultimate goal for its managers. The reserve is in good condition as it has been relatively isolated until infrastructure and urban development gradually surrounded it over the past seven years. Only the southern boundary retains unconstricted access to southern swamps and lakes and this area will be developed for housing in the near future. Add to this a drying climate and the ongoing survival of the reserve’s flora and fauna face significant threats. Our goal should be to ameliorate these threats and our Friends group hopes that the research being undertaken from the burn will assist in these endeavours, and that the research outcomes will provide the basis for future management decisions on burning practices at Paganoni Swamp Reserve.

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Flooded Gum: some thoughts on site conditions, psyllid populations, and tree health

In the previous blog posting, Jodi Wildy from Boyup Brook expressed her concerns about the health of Flooded Gums in different conditions. She wondered, for example, if the presence of understory plays an important role. Today George Matusick shares his thoughts, raises some further questions, and invites others to share their observations.

Hey Jodi,

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How can we help stop the decline of Flooded Gums?

By Jodi Wildy

I have been following the blog on tree health with much interest and thought that I must finally ask about an issue that is quite striking and of concern at our patch near Boyup Brook in the Southwest of WA.

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Reptiles neglected in times of climate change?

By Mike Craig

Morethia Obscura

In our drying climate, it is interesting to ponder how our native animals will cope with the decreasing rainfall. For mammals and birds, the loss of productivity associated with the reduction in water availability is likely to have negative impacts but any potential effects on reptiles are less clear. Reptiles tend to be more diverse and abundant in low productivity environments, so will they benefit from the reduction in rainfall? Data from a trapping project suggest that reptile activity, at least, is to a large extent driven by rainfall. Data from the summer of 2009/10 showed that captures during the relatively wet months of October and November 2009 were quite high (5.6 and 7.9 captures per 100 trap nights respectively), but that capture rates dropped significantly (to 3.9 captures per 100 trap nights) in December 2009 due to the lack of rain over the previous month. Trapping in March 2010, just a few days after the storms that caused so much hail damage in Perth probably lead to capture rates jumping back up to 6.0 captures per 100 trap nights that month. The pattern in the summer of 2010/11 was quite different. It started similarly with relatively high numbers of captures in October and November 2010 (3.6 and 4.4 captures per 100 trap nights respectively), but then was even higher in December 2010 (4.6 captures per 100 trap nights), probably due to the small amount of rainfall that fell in December that maintained moisture levels to some extent. In contrast, captures rates in March were extremely low (1.9 captures per 100 trap nights), again probably due to the lack of rainfall in the previous two months. So, does this mean that the drying climate will reduce reptile activity so much that they are no longer able to be active enough to find sufficient food? That scenario is unlikely, but it does suggest that reptiles will not be immune from the effects of climate change. How individual reptile species respond will likely vary greatly between species, with those preferring moist, dense sites being disadvantaged and those preferring open, sunny sites being advantaged. Whatever the response, it is interesting to think about how our activities might ultimately affect our most diverse vertebrate group, a group that is too often neglected when we think about climate change effects.

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What can we learn from the European oak decline?

By Sonja Jakob

Sure, this blog is about forest health but why should we bother about oak decline in Europe – especially since there is a severe decline in eucalypts going on over here! The aim of this blog entry is to show that there are similarities between the two decline phenomenons.

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We ♥ marri

By Cielito Marbus

I’ve spent some time recently reflecting on the amount of attention given to the different tree species we study at the Centre. Particularly, I’ve been pondering why we have funding to spend on researching the decline of all the important south-west tree species, except marri.  Jarrah has long been a focus, and more recently tuart and wandoo, while a funding agreement to examine peppermints came into place just a few months ago. So marri research isn’t funded, yet we receive a lot of calls from concerned community members about marri trees on their block or in their town. Many people are aware of the contribution that marri trees make to our native ecosystems. The canker disease in marri has been known since 1939 and became widespread by the 1970s, while a leaf and flower blight pathogen has become widespread over the last decade or so. I recently completed my honours thesis studying this blight pathogen, and during my field studies I found it difficult to find a truly healthy and happy marri tree.

I touched on a point in my thesis, duly picked up by my examiner, where I commented roughly that marri was not, historically, a valuable timber tree. What I meant was that it was not perceived as a valuable timber, despite the appreciation by some for the interesting results that came from the kino (gum) veins. What I leave to be considered here, is that our appreciation for marri is driven largely by sentimental and intangible values, as opposed to monetary or economic. We love marri for the honkey nuts that we grew up with as kids, for the native, cute and cuddly fauna that the trees support, for the unique ‘flaws’ in the timber, and for the masses of beautiful flowers produced each year. Personally I have fond memories of the Adventures of Snugglepot and Cuddlepie, and Little Ragged Blossom.

May Gibbs brought us the characters and adventure stories of Snugglepot and Cuddlepie

Marri timber is in truth stronger than jarrah, and the honey produced from its flowers has as much nutritional and antimicrobial potential as jarrah honey. I find it interesting also that the production of kino, which has served the tree so well in the past (it has certainly been a strong point in its evolution and adaptation), is now working against it favour. The scarring it leaves in the timber causes us to undervalue the tree, which may have influenced our lack of attention to the species. Should we seek value in economic terms now? Should we glorify the merits of this tree by the dollar value on the furniture we make or the honey it provides? Or can we continue to love it for the good old fashioned reasons.

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Frost Damage to Forestry and Agriculture Under a Warming Climate– Should We Worry?

By George Matusick, Jatin Kala, Tom Lyons

The Intergovernmental Panel on Climate Change (IPCC) predicts that the largest threat to ecosystems in the southwest of WA is diminishing rainfall and increasing average temperatures.  In fact, the southwest of WA is one of the rare regions in the world whereby the vast majority of Global Circulation Models (GCMs) agree on the trends in precipitation and temperature.

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Probing the spectral reflectance of our keystone species: Eucalyptus rudis (Flooded Gum)

By Bradley Evans

Over the last few weeks the following centre members have been out in the field collecting leaf samples for our ‘spectroscopic library’ across our sites. Thanks to; George Matusick, Martin Bader, Jerome Chopard, Cielito Marbus and Katherine Edwards for their help in realizing this projects initial phase. We have been using an Ocean Optics Jaz Spectrometer (Jaz) with the capability to take reflectance measurements, from leaves and other materials, across the visible and through to the beginning of the near infrared range. These measurements can now form the baseline of our understanding of the spectral reflectance properties of our species of interest. In remote sensing studies, i.e. using airborne and satellite imagery as opposed to leaf spectroscopy collected on the ground, these reflectance signatures can be used to un-mix larger combination (leaf/soil/wood) pixels and form the basis of landscape classification. This data is collected into what is known as a ‘Spectral Library’ so it can be used in remote sensing studies.

Jerome and Brad helping KatherineOur Leaf Spectroscopy with the Jaz has created a great opportunity for some real teamwork!

To wet your appetite for spectroscopy I have prepared a sample of E.rudis from Katherine Edwards’ Beeliar site. Figure 1 is a great demonstration of the capabilities of the Jaz and is the starting point of our library entry for this declining species. One interesting observation is that when Eucalypt leaves dry out they generally reflect more light than when living. This is because of the dark green-blue colour. This phenomena tends to be reversed in other types of leaves. Spectroscopy concepts discussed broadly in this posting are explained in ‘The Red Edge’ slideshow.

We will continue to collect leaf samples and increase the robustness of our ‘Spectral Library’ for the benefit of our researchers. You will shortly see more information emerging on the uses of this spectral information.

 

E.rudis Green and Dry Leaves

Figure 1: A comparison of E.rudis green and dry leaves collected by Katherine Edwards from her site in Beeliar Reserve. The green band shows the distinctive ‘Red Edge’ typical of active chlorophyll in leaf cells. The blue signature has a higher reflection because the leaves were very light in colour. The blue, green, red and grey (NIR) bands represent SpecTerra Services Pty Ltd Digital Multispectral Imagery (DMSI) product.

 

The Red Edge

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The difficulties of valueing slime mold versus woylies and numbats

By Bernie Masters

As much as I would like to place a value on nature, I have never seen any successful attempt by economists or others to put a meaningful price on biodiversity, an ecosystem service (other than bees pollinating crops but neither the bees nor the crops were local species but instead were exotics) or on a measurable part of the environment. Using contingent liability assessment methods, many researchers have asked people how much they would be prepared to pay to protect a landscape or a species, but the results either show that the amount people nominate as their acceptable level of payment is pitifully small or, if it is a ‘reasonable’ amount of money, the people then fail to willingly make a payment of the nominated amount when governments announce tax increases.

In my view, the best that can (and should) happen is that people should be informed of the actual benefits that an ecosystem service provides or they should be shown the beauty or uniqueness of our biodiversity, so that they will then support the government when money is allocated from their taxes to protect ecosystem services or species.

The bottom line is this: how can you put a value on a threatened species of slime mold when it is up against woylies and numbats in the race to be ‘cute and cuddly’? How can you put a value on a nice but not outstanding landscape when economic development of a small part of that landscape may produce billions of dollars of income from mining or tourism development which then provides social benefits for hundreds or thousands of people? How can you put a value on the cleaning up of water flowing out of a forested catchment when limited and well managed development (such as logging or mining) may have no measurably adverse impact on water quality and when the risk of adverse impacts is low (remembering that people happily accept the huge risk of death or injury every time they drive their cars)?

Informing people of the aesthetic beauty or uniqueness or rarity of a part of our natural environment is, in my view, the most urgent task facing environmental practitioners and academics.

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