If a tree falls in the forest, and no one hears it…

The demise of long-term population monitoring

Posted by Margaret Stanley @mc_stanley1

“Is there any evidence that an introduced insect – other than a social insect – has caused the decline of a native species in New Zealand?”

A feeling of total frustration and helplessness came over me when I heard those words – while standing before an EPA panel deciding whether to allow a generalist insect predator into New Zealand for biocontrol of a crop pest.

The answer to this is “no”. The frustration comes from the fact that we have no evidence, because there is no long-term monitoring of native insect populations in New Zealand. The Dept. of Conservation (DoC) may have data for a few threatened species (perhaps wetapunga?), but not for common insect species – those that might follow the fate of the passenger pigeon if an additional invasive predator is the thing that tips the balance for that population. The example I gave the EPA in answer to that question was anecdotal – the decline of our native mantis as a result of the invasive South African mantis. There’s certainly no long-term population monitoring that has picked up the demise of the native mantis.

The lack of long-term monitoring for non-charismatic species (e.g. bees) has also been lamented in Europe lately, where a massive decline of insects in Germany over the last few decades has been detected by the Krefeld Entomological Society: a group of mostly amateur entomologists, recording insects since 1905. They have recorded declines of up to 80% since the early 1980s – that’s a lot of bird food (if you care only for vertebrates!).

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Plans for long-term biodiversity monitoring in Germany (Vogel 2007)

Changes in science funding over the last few decades, and the vagaries of politics, means that long-term population monitoring is no longer ‘sexy’ and not worthy of funding (‘Cinderella Science’: unloved and underpaid). These types of datasets are difficult to maintain because they exceed cycles of funding and government administration. In New Zealand we now lament the loss of amazing datasets that have provided the foundation and impetus for some amazing science around ecology, conservation and pest control: e.g. the Orongorongo Valley dataset, and the long term monitoring of wasps, pests and birds in Nelson.

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Seedfall of hinau and hard beech trees in the Orongorongo Valley 1968-1991 (Fitzgerald & Gibb 2001)

DoC and some councils do undertake regular biodiversity monitoring where they can, but on a reduced number of taxa (usually birds and vegetation), not often at a population level (except for threatened species), and the data are often held within these organisations, rather than open access sites. Some scientists also try to sneak in a long-term monitoring project where their (often unfunded) time and resources allow.

Instead, community groups in New Zealand, those groups undertaking pest control and restoring ecosystems, are taking up the slack in long-term ecological monitoring. At least for vegetation and birds, they are the ones undertaking regular and long-term monitoring via vegetation plots and bird counts. There is also the rise of citizen science – with large numbers of people recording biodiversity: counting kereru and garden birds. Although scientists are doing what they can to give community groups technical advice, and make citizen science more robust, will the data being collected be robust enough to understand how disturbance, invasion, and climate change are affecting biodiversity? Community restoration often takes place primarily where people are (close to urban centres), and restoration projects are dominated by lowland coastal forest ecosystems. Hardly representative of New Zealand’s ecosystems.

Needless to say, there was great excitement within the ecological/entomological community with the initiation of NZ’s National Science Challenges. The idea was mooted that we could have a Long Term Ecological Research network (LETR) like that funded by the National Science Foundation (NSF) in the USA. This network of sites provides the research platforms and long-term datasets necessary to document and analyse environmental change. There are numerous papers that summarise the benefits of long-term ecological datasets, such as: (1) quantifying and understanding how ecosystems respond to change; (2) understanding complex ecosystem processes that occur over long time periods; (3) providing core ecological data to develop, parameterise and validate theoretical and simulation models; (4) acting as platforms for collaborative, transdisciplinary research; and (5) providing data and understanding at scales relevant to management (Lindenmayer et al. 2012). Surely gaining an in-depth understanding of New Zealand populations and ecosystems over time would allow us to understand their resilience to the effects of long-term and large-scale drivers like climate change, and even the effects of new invasive species, such as myrtle rust?

However, it was not to be. And although citizen science and community monitoring is valuable in its own right for specific purposes, it doesn’t allow us to respond to the opening salvo.

If an insect goes extinct in the forest, will anyone know?

Postscript: The EPA decided not to allow import of the predatory insect – not so much because the ecological risk was perceived to be particularly high – but the industry benefits were seen as too low relative to the risk.

 

MargaretDr Margaret Stanley is a Senior Lecturer in Ecology, School of Biological Sciences, University of Auckland and is the programme director of the Masters in Biosecurity and Conservation. Her interests in terrestrial community ecology are diverse, but can be grouped into three main research strands: urban ecology; invasion ecology; and plant-animal interactions.

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Kauri and drought – What’s their survival strategy?

Posted by Julia Kaplick @julekap

New Zealand’s future climate is likely to be warmer and dryer and the frequency and duration of drought events is predicted to increase. Drought-induced tree mortality is increasing world-wide, with several instances also reported in New Zealand. So far we know very little about the drought vulnerability of New Zealand forest trees, but due to our research on kauri we are beginning to understand more and more about the drought survival strategy of this forest giant.

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Roots

The roots are integral for trees to extract water from the soil and a good root network is crucial for drought survival. During times of water stress many trees, including kauri, invest in root growth. This allows them to keep up their normal transpiration levels for a little longer. So far it is assumed that kauri roots are very shallow, but sap flow measurements during the 2013 drought suggest otherwise. The upper soil layer during that time was extremely dry, but the trees still used water which suggests that kauri roots must reach a lot deeper than we previously thought allowing access to deeper water stores.

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Kauri roots

Drought avoidance or toleration?

In general, every tree species falls somewhere on the spectrum between drought avoidance and drought toleration. Drought tolerating trees keep up transpiration as long as possible. Drought avoiding species on the other hand start closing their stomata to reduce water loss, when the soil moisture goes down. Both strategies have their downsides. Drought tolerators risk the formation of little air bubbles (xylem embolism) in their conducting tissue. This can lead to hydraulic failure if a drought lasts too long. Drought avoiders protect their hydraulic integrity but risk starvation, because the closure of the stomata also means a reduction of carbon intake. Kauri are clearly drought avoiders. Even under ideal growing conditions kauri are conservative water users, closing their stomata early in the day. They are known to be very susceptible to xylem embolism and protect their hydraulic integrity in that way.

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Kauri cone in a bed of leaf litter

Leaf shedding

During the 2013 drought the kauri in our study plot lost a substantial amount of leaves and twigs. The reduction of leaf area is an effective way to reduce the water-losing surface and consequently the reduction of transpiration and the need for water uptake.

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Base of a kauri stem

Water storage

All components of a tree (roots, stem, branches, leaves) can serve as water storage compartments. This is a drought survival strategy that succulents have perfected. Kauri make use of stored water on daily basis. Water is withdrawn from the stem and branches in the morning when the water starts to transpire from the leaves. During the afternoon and night these stores are refilled again. The massive stem volume paired with deep sapwood seem to make a great water store. During prolonged drought conditions kauri should be able to use the water reserves to their advantage. This is something we are investigation right now, stay tuned.

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Julia Kaplick is a PhD student in the Centre of Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland. She is researching the response of native trees to seasonal variation in climatic conditions using measurements of sap flow, water relations and carbon allocation. Julia is supervised by Cate Macinnis-Ng (University of Auckland) and Mike Clearwater (Waikato University). Julia is supported by funding from the Marsden Fund.  

A Trip to Switzerland to learn some Wood Anatomy Skills

Posted by Julia Kaplick @julekap

In June this year I was lucky enough to escape the Auckland winter weather and learn some new skills at a Wood Anatomy Course in the Swiss Alps. It is a long running course organized by Dr Holger Gärtner, Prof Fritz Schweingruber from the Swiss Federal Institute of Forest, Snow and Landscape Research and Dr Alan Crivellaro from the University of Padua in Italy. The two main aspects of the course are the theoretical basics of the anatomical features of wood and the practical skills needed for sampling and preparing wood thin sections. This might not be obvious to everyone, but I was super excited to go and it was not because it took place in Klosters, where Prince Charles goes on skiing holidays.

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Left: Microscopy with a view of the Swiss Alps. Right: Gentian, the Swiss national flower. Right: Out in the field with Prof Fritz Schweingruber, one of the world’s leading experts in wood anatomy

There are many different scientific applications for wood anatomy, but I am most interested in the connection with tree water relations. Anatomical features like lumen area and cell wall thickness vary seasonally and are strongly influenced by climatic conditions. The wood anatomy also affects hydraulic characteristics of trees. Tree species with larger lumen areas can transport more water, but they are also more likely to suffer from embolism (the formation of air bubbles) during times of drought stress.

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Sample preparation – Top: With a microtome wood samples can be cut into thin section. Bottom: Staining of the sample and baking to create permanent slides

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Thin section of a kauri root – Staining of the wood thin sections makes anatomical structures more visible. Left: unstained. Right: same sample stained with Safranin and Astrablue.

The first day of the week-long course was all about the theoretical background. We spent the day looking at many thin sections under the microscope, starting with simple conifers, and later learned about the more complex structures of angiosperms and even had a glimpse at some crazy looking non-woody species. On the following days we went to some beautiful alpine valleys to try out different sampling techniques and learned how to prepare and stain professional thin sections from our own samples.

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Radial thin sections of rewarewa (left), tanekaha (middle) and nikau (right).

I could have easily spent the whole week cutting and staining my samples, but we also got to go on two little trips. The first one was a walk through a sustainably managed forest area, together with the responsible forester. The second trip was a visit to the Institute of Snow and Avalanche Research in Davos where we got to see the latest fashion accessories on the Swiss skiing field and also got to know a little more about how effective forest is as a protection against avalanches. Another highlight of the week was Helga, the lovely hotel cook who insisted on providing us with two hot meals a day, to keep our brains running. Yes, there was a lot of cheese and chocolate.

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Left: Fancy new avalanche protection. Middle: View of Klosters from above. Right: Happiness after a long day of learning

 

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Julia Kaplick is a PhD student in the Centre of Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland. She is researching the response of native trees to seasonal variation in climatic conditions using measurements of sap flow, water relations and carbon allocation. Julia is supervised by Cate Macinnis-Ng (University of Auckland) and Mike Clearwater (Waikato University). Julia is supported by funding from the Marsden Fund.  

Play time – Scientific toys

Posted by Julia Kaplick @julekap

My research focuses on trees, but when I look at the equipment I fill my car with when I go out to my field site, it looks more like I am an electrician. There are car batteries, cables, a bag full of tools, a laptop and lots more. Only a field notebook to record observations like Darwin or Humboldt have done it, is just not enough anymore. Nowadays most research involves specialised equipment to gather data or samples and advanced technology to physically or chemically analyse all sorts of sample materials. That can be daunting, but mostly it is just great to have so many toys to play with as a researcher.

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Kauri tree with sap flow sensor – nicely wrapped (for sun protection) like toys for christmas

I rely on sensors to gather most of my data. A meteorological station records environmental data for me, sap flow sensors (that I partly built myself) measure how much water my trees are using and I use a little thing called Trephor to collect wood samples (see how in this little video). The newest additions to our toy collection are called radius dendrometers. They will very soon record the expansion and contraction of my study trees’ stems on an extremely fine scale. That will give me an idea about daily patterns of water storage and growth. When the parcel with that equipment arrived I was excited like a little child at Christmas, but very soon the daunting part started. I needed to figure out how to get them working, how to install them and there is always that little bit of anxiety, because all that equipment is ridiculously expensive since it is so specialised and only few people in the world use it.

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Some of the toys I get to play with: Trephor micro corer to collect wood samples, our meteorological station, sap flow sensors (that is how it looks like under the wrapping paper) and data loggers to record measurements (with lots of fun coloured cables)

All these toys are great and playing with them is mostly fun, the harder part is the interpretation of the data they gather. Even though there have been many advances in how to get data the part where you have to make sense out of it to generate knowledge has not actually changed much since Darwin and Humboldt.

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#girlswithtoys, specifically #ecologytoys: Measuring water potential with a pressure bomb and (attempt to) shooting down leaves

To have a look at some cool toys scientists are using check out #girlswithtoys on twitter.

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Julia Kaplick is a PhD student in the Centre of Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland. She is researching the response of native trees to seasonal variation in climatic conditions using measurements of sap flow, water relations and carbon allocation. Julia is supervised by Cate Macinnis-Ng (University of Auckland) and Mike Clearwater (Waikato University). Julia is supported by funding from the Marsden Fund.  

Bush mad in the city

Posted by Samantha Lincoln @slin247

Over the course of this year I have been undertaking intense field work across some of Auckland Councils public parks. Urban ecology is inherently strange; emerging sweat-soaked from a long day’s work, and carrying a small colony of beetles in your hair onto a main road whilst startling local dog walkers and being serenaded by Auckland Zoo’s primates. While not as idyllic as disappearing to the mountains for a week, urban ecology is incredibly important when most of our human population is urban. Connecting with nature is undeniably important for our wellbeing.

Auckland has hundreds of public parks of all sizes, both without and without maintained walking tracks as I have discovered. They are refuges for native species in the middle of our manicured city, but how well do we really look after these spaces? During my field work my volunteers and I have found a range of debris: backyard clippings spreading weeds, Victorian inkwells, a year’s supply of newspapers courtesy of a lazy paperboy, shelters built by those with nowhere else to turn (a growing issue in Auckland) and a pile of books featuring a bunny not often seen during pest control.

Live capture of a rat during a capture-recapture study

Live capture of a rat during a capture-recapture study

As Auckland city grows, more pressure is being placed on these biodiversity refuges and how we value and care for them becomes more important as was noted last month. Will we value and nurture these green spaces, or will they fail under the pressure? Will we continue to use them as personal rubbish dumps, or will we take interest in the other species that use these spaces? I will be a science advocate – we can all lend our voices. To me nothing beats the feeling of following a fantail nest from first cheeps to first awkward flight, as I make my daily visit to the rat trap at the tree’s base.

Sam Ln webSam Lincoln is an MSc student in the Centre for Biodiversity & Biosecurity, School of Biological Sciences, University of  Auckland. She is trying to disentangle interactions between domestic cats and rats in urban environments. She is supervised by Margaret Stanley, John Innes and Al Glen.

A little ode to field work

Posted by Julia Kaplick @julekap

Julia takes aim!Spring is on our doorstep here in Auckland and nature is visibly getting busy. It is the start of the growing season for many plants and the most active time of the year for many animals. For many ecologists it also means that field work season is starting.

I am lucky enough to do my research in a more applied area of ecology. I get to go out into the forest and collect the data that forms the basis of my research myself. It is in fact the part that I enjoy the most and the main reason why I chose to work in ecology. During more than a year of field work in New Zealand, I have been soaking wet, freezing cold and muddy from head to toe, but at the end of the day I went home happy and with pages full of data. I have been hanging 15 metres high in the kauri forest canopy and freezing my feet off while taking predawn measurements in the mangroves.

The view from above.

The view from above.

Field work is challenging and fun. It teaches you to plan and organise, to improvise and to find creative solutions, as things do not always go as originally planned. Who knew that the party supply store around the corner would turn into one of the best sources for field equipment? What else could you possibly do with these metre long party straws than put wood samples into them and there cannot be any other proper use for Styrofoam cups than to use them as a radiation cover for temperature sensors. I also learned that a pressure bomb is a good thing and have significantly increased my electrical skills by building and connecting sensors. You also know that you are working with pretty cool instruments when your supervisor seems to be more worried about the machine dropping out of than canopy than about the PhD student who holds it. All this I have to admit came at a price. I probably lost several litres of blood to mosquitos and a scar on my middle finger will always remind me that soldering irons are extremely hot, not that I really needed that reminder.

Mud pie anyone?

Mud pie anyone?

Field work lets you see the world with different sometimes slightly nerdy eyes. It is exciting and rewarding to see theory come to life, even if it is sometimes unexpected. Someone recently told me that field work can become a little addictive and I can already see why.