Video Podcast – Harper Prize Highly Commended Paper 2015: Jewelweed’s defense against deer herbivory

Last week, we published a blog post written by the winner of the Harper Prize 2015 Yuuya Tachiki, that you can find here. Each year, as well as selecting an overall winner, the Editors of Journal of Ecology also select two highly commended papers. This year we had two fantastic highly commended papers by Laura Martin et al. and Courtney Stepien et al. This week we want to highlight their research and share with you their novel and interesting results through video podcasts.

In the first video podcast, Laura Martin is presenting the findings of her highly commended paper entitled “Historically browsed jewelweed populations exhibit greater tolerance to deer herbivory than historically protected populations”. The video is available below and can also be found on the Journal of Ecology YouTube channel.

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Laura Martin is currently a Ziff Environmental Fellow in the Harvard University Center for the Environment and the Department of the History of Science. She recently obtained her PhD from Cornwell University with the project entitled “Natural and National Recovery: Ecological Restoration in the United States, 1930-1975”. Laura’s research aims at understanding how humans intentionally and unintentionally shape the distribution and diversity of other species. She is thus working at the interplay between environmental history, social and ecological science. Her publications have explored topics as diverse as invasive plants, the indoor biome, and the history of linear regression. In this highly commended Journal of Ecology article, Laura and her colleagues investigate whether a plant that is native and thriving in the eastern United States, jewelweed, has rapidly evolved tolerance to deer herbivory. Laura is currently writing a book on the history of ecological restoration. 

Stay tuned for the second video podcast staring Courtney Stepien and her research on geography, taxonomy and functional group effects on inorganic carbon use patterns in marine macrophytes.

Pierre Mariotte
Blog Editor, Journal of Ecology

Endangered Species Day 2016 – Plants are endangered too!

Today is Endangered Species Day and to mark the occasion the BES journals have put together a Virtual Issue of recent papers on endangered species of various taxa from around the world. Journal of Ecology papers are strongly represented, showing that endangered species day is about more than just lions and tigers!

The papers from Journal of Ecology cover subjects such as the effect of civil war on African savannah tree species; the risks posed by elephant decline to an Asian fruiting tree species and the threat to large native trees posed by large scale agriculture in Costa Rica.

We also highlight a recent Biological Flora of the British Isles account on ash, a comprehensive monograph warning of the duel threat to the species from ash dieback and the emerald ash borer beetle.

But it’s not all bad news – the open source COMPADRE database of plant population matrix models is an important research tool for plant ecology and evolution research and could help provide novel insights into endangered plant species and our recent study of Hawaiian forest communities provides important conservation and management messages.

All the papers are free to access for three months and the full Virtual Issue is available here. Happy reading!

 

Winner of the Harper Prize 2015

Editor’s note

The Harper Prize 2015 for the best paper published in Journal of Ecology by a young author has been awarded to Dr. Yuuya Tachiki, currently postdoctoral researcher at Kyushu University in Japan. His paper entitled “A spatially explicit model for flowering time in bamboos: long rhizomes drive the evolution of delayed flowering” provides novel evolutionary insights into the reproductive strategy of clonal plants by using a spatially explicit mathematical model. This paper was also selected as the Editor’s Choice for Issue 103:3 – check out Associate Editor Richard Shefferson’s interesting commentary here.

Yuuya has kindly agreed to describe his research findings and share his view on the topic in the blog post below “Seeking the peculiar flowering habit of bamboo”. The Editors of Journal of Ecology and myself congratulate Yuuya, Winner of the Harper Prize 2015.

Coming soon: Laura Martin and Courtney Stepien, both authors of highly commended papers for the Harper Prize, will also present their study and research findings through video podcasts.

Pierre Mariotte
Blog Editor, Journal of Ecology


Seeking the peculiar flowering habit of bamboo

Study of demography and phenology of perennial plants requires perpetual effort over many plant generations. Bamboo has long fascinated many ecologists with its distinctive flowering habit – most bamboos are monocarpic and thus die after reproducing, but also reproduce vigorously through clonal propagation before flowering. The study of population ecology over the whole life cycle of bamboo requires surprisingly long-term observations due to the long delay before reproduction. Although exact flowering interval is still unknown in many species, it can be longer than 100 years for some species (Numata 1970), with a record of 120 years for madake (Phyllostachys bambusoides) (Kawamura 1927).

In this blog post, I would like to introduce a field site of bamboo research, where great efforts to reveal bamboo’s demography have been invested. It is situated in an old-growth beech forest located at the South of Lake Towada, Akita prefecture in the northern Honshu Island in Japan. The canopy layer is dominated by beech (Fagus crenata) with the understorey covered by the dwarf bamboo (Sasa kurilensis). A flowering of the bamboo took place in 1995 (Makita et al. 1995), but the exact flowering interval is not known. Although flowering and subsequent withering occurred over a broad spatial range, more than 1,000 ha, some patchy populations did not flower and remained as vegetative growth. The area was therefore ideal to observe the effects of bamboo flowering on the forest ecosystem and regeneration processes. Two decades of long-term observation provided information on several topics, including the changes in light availability, the regeneration of tree canopy (Abe et al. 2002), and the interplay among trees, bamboo, and herbivorous rodents (Abe et al. 2001).

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The first census of dwarf bamboos in Towada in 1996. Bamboos are all withering as far as we can see with beeches covering the canopy layer, credit: Akifumi Makita.

One of the purposes of long-term observation is to understand the evolutionary significance of the extraordinary reproductive strategy in bamboos from a demographic point of view. “Why bamboos wait so long to flower” is the title of an article by Janzen in 1976. After this monumental paper, many ecologists tackled this topic and proposed many hypotheses to explain the advantage of the bamboo’s strategy. For example, the relationship between fire cycle and flowering interval is one of the most famous hypotheses for tropical bamboo (Keeley & Bond 1999). A game theory model that explains the multiplication of flowering interval was also proposed more recently (Veller et al. 2015).

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Yuuya Tachiki during the fieldwork in 2015, credit: Akifumi Makita.

Our study, published in Journal of Ecology, tackles the evolutionary significance of long flowering intervals, but also shows how the geographic cline emerged (Tachiki et al. 2015). Geographic trend in flowering interval, which is short in tropical regions and becomes longer as we move toward north, has long been recognized (Campbell 1985). Interestingly, another correlational geographic tendency has also been reported, in which rhizome extension patterns and resulting spatial arrangements of ramets are also different between tropical and temperate bamboos (Makita 1998). To understand how dispersal traits (i.e. rhizome length, seed dispersal range) affect the evolution of flowering interval, we developed a spatially explicit simulation model. The results of stochastic simulation showed that flowering interval increased with rhizome length but decreased with seed dispersal range. A major cause of this dependence could be intra-genet competition. If a rhizome is short, each genet forms a clumping structure by clonal reproduction. Such structure favours strong intra-genet competition, which can be reduced by early flowering. I believe that our hypothesis on intra-genet competition as mediator of flowering interval should be tested through the study of bamboo demography. This emphasises the importance of long-term field observation and I hope that the findings of our paper will attract more ecologists into the fantastic and unique Asian bamboo forests.

Yuuya Tachiki
Winner of the Harper Prize 2015

Updated Journal Aims and Scope

Following some excellent feedback and comments at our most recent BES Editor’s Strategy Day (see photo below), we have updated the wording of our journal scope. The updated scope reads:

Journal of Ecology publishes original articles on all aspects of the ecology of plants (including algae), in both aquatic and terrestrial ecosystems. We will publish papers concerned solely with cultivated plants and agricultural ecosystems if such articles address important ecological or evolutionary questions. Studies of plant communities, populations or individual species are accepted, as well as studies of the interactions between plants and animals, fungi or bacteria.

We aim to bring important work using any ecological approach (including molecular techniques) to a wide international audience and therefore only publish papers with strong ecological messages that advance our understanding of ecological principles. The research presented must transcend the limits of case studies. Both experimental and theoretical studies are accepted, as are descriptive or historical accounts, providing they offer insights into issues of general interest to ecologists.

Whilst the kinds of submissions we will accept has not changed, the aim in updating our scope is to accentuate the positive, and clarify the types of articles that we are interested in publishing. Rather than say what we don’t publish, the updated scope says what we do publish.

Notice that we retain a primary interest in plants in the broadest sense, but emphasize that papers must ‘address important ecological or evolutionary questions’. This phrase is a key criteria for consideration of papers on cultivated or agricultural plants.

I should add that we are still particularly keen to receive manuscripts that address one or more of the 100 Fundamental Ecological Questions posed by Sutherland et al. (2013) in the Journal, or the 50 Priority Research Questions in Palaeoecology by Seddon et al. (2014).

The Editors look forward to receiving manuscripts that fall within the Journal scope.

 

David Gibson, Executive Editor

Some serious strategizing by BES Editors (Charles Darwin House, London, April 2016)

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New Insights into Size Asymmetry of Resource Competition

Editor’s note

A recently published paper in Journal of Ecology, entitled Size asymmetry of resource competition and the structure of plant communities by DeMalach et al. 2016, garnered a lot of excitement during the review process. Associate Editor James F Cahill kindly agreed to share and comment the novel findings of this paper below.

Pierre Mariotte
Blog Editor, Journal of Ecology


New Insights into Size Asymmetry of Resource Competition

The foundations of modern community ecology lie in the study of competition, coexistence, and exclusion. Many plant ecological research programs have been based upon understand the mechanisms that cause observed relationships between species richness and resource availability (e.g. Fraser et al., 2015), with competitive exclusion due to light limitation a commonly ascribed culprit (Grime 1973). The centrality of competition in classical theory developed by plant ecologists (Grime 1979; Tilman 1982) is not surprising given that the sessile nature of plants make social interactions a chronic aspect of plant-life.

Challenges to the idea that plant-plant interactions are necessarily competitive has come from many fronts, most notably in the context of positive interactions (Bertness & Callaway 1994). However, there has also been an empirically-driven attack against the idea that competition, even when present, necessarily causes species loss and structures communities (Lamb & Cahill 2008; Hautier et al. 2009; Bennett et al. 2013). At the heart of the idea that competition can be both strong, while also not necessarily being a major driver of community assembly, is the issue of competitive size-asymmetry, the degree to which larger individuals gain disproportionate advantages in competitive encounters (Schwinning & Weiner 1998). The general result emerging from experiments is that when competition is belowground, community structure is relatively unaffected, while competition aboveground for light can cause dramatic changes (Lamb et al. 2009; Hautier et al. 2009). This is typically interpreted as root competition being size-symmetric under most conditions, and light competition size-asymmetric (Schwinning & Weiner 1998). Lacking, however, has been a general theory integrating the idea that competitive size-asymmetry may shift depending upon the identity of the limiting resources.

It is in filling this conceptual gap that the paper authored by Niv DeMalach, Eli Zaady, Jacob Weiner and Ronen Kadmon titled Size asymmetry of resource competition and the structure of plant communities (DeMalach et al. 2016) makes a significant contribution to plant community ecology. By extending Tilman’s resource competition model, DeMalach and colleagues are able to test whether size-asymmetric interactions associated with competition for light can generate two fundamental patterns associated with soil resource gradients: decreased species richness and species compositional shifts towards larger and faster growing species with increases in soil resources. Importantly, their model framework includes both growth rate and species diversity components, allowing for a mechanistic understanding of how resource supply can influence patterns in plant communities.

Through a series of permutations to the model framework, DeMalach and colleagues are able to show that size-asymmetric competition for light can generate both patterns.  Critically, this work reinforces the increasing empirical support suggesting competitive size-asymmetry, rather than simply the intensity of competition, can governs its influence in impacting community assembly. Additionally, their model indicates that the plant traits favored under competitive scenarios will vary with the size-asymmetry of competition.  Thus, their work suggests there are no single traits that are advantageous under all competitive regimes, and instead the relative value of a given trait will be contingent upon the size-asymmetry of competition that is occurring.

The work by DeMalach and colleagues opens the doors to greater understanding of plant competition, moving well beyond simple intensity. At a minimum, their work raises significant questions about the biological justification for ignoring size-asymmetry in plant interactions, with implications for both a general understanding of community dynamics as well as more applied studies focusing on biodiversity loss associated with species invasion.  With this novel contribution, we will hopefully see resurgences in field-based tests of the role of plant-plant interactions in structuring natural communities and a better understanding of the traits causing increased fitness under different competitive regimes.

James F Cahill
Associate Editor, Journal of Ecology

Editor’s Choice 104:3

Issue 104:3 is now online and the Editor’s Choice paper from this issue is Bioclimatic envelope models predict a decrease in tropical forest carbon stocks with climate change in Madagascar by Vieilledent et al.

Associate Editor Emily Lines has written a post about the paper below.

Editor’s Choice 104:3

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Tropical moist forest and deforestation patterns in the Tsaratanana mountains, credit: Ghislain Vieilledent

Whether or not forest carbon stores will increase to mitigate anthropogenic climate change is a key question for future climate predictions, and one that attracts a wide range of research approaches. For example, bottom-up process-based dynamic global vegetation models (DGVMs) coupled to general circulation models (GCMs) disagree substantially in their predictions of carbon storage in tropical land in the future, in part due to uncertain responses of vegetation to warming (Cox et al. 2013). Ecological models in temperate regions suggest wood production change will depend on how much and how fast forest structure and species’ composition respond to climate change (Coomes et al. 2014), but these key responses are poorly understood on a global scale. What is clear is that multiple sources of data and research approaches are needed to bound our uncertainties and improve model predictions.

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View on Montagne d’Ambre tropical moist forest. This forest should be strongly impacted by climate change, credit: Ghislain Vieilledent

The Editor’s Choice paper for this issue of the Journal of EcologyBioclimatic envelope models predict a decrease in tropical forest carbon stocks with climate change in Madagascar” by Vieilledent and colleagues combines forest inventory and remote sensing data to produce current and future forest carbon maps for Madagascar using a bioclimatic envelope approach. This type of correlative model is commonly used to predict future species’ ranges but this study adapts the approach to predict future tropical forest carbon stocks.

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Collecting wood samples and weighting trees in the spiny forest of Madagascar (Androy region), credit: Romuald Vaudry.

A set of forest inventory plot measurements collated from data held by multiple institutes and agencies allowed Vieilledent et al. to generate a model of aboveground carbon density (ACD) for Madagascar using satellite-derived vegetation indices, topography and climate as explicative variables, which was implemented using a random forest approach. The results identify the key role played by climate in explaining spatial variability in ACD; the map both produced higher ACD estimates and outperformed global biomass maps which are constructed without climatic information.

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.Measuring tree diameter and inventorying trees in the moist forest of Madagascar (Tsaratanana mountains), credit: Romuald Vaudry

The resulting bioclimatic model predicts that, under the RCP 4.5 and 8.5 climate change scenarios Madagascan forests could lose up to 13 and 17% (respectively) of their total carbon stock by 2080, with moist forests experiencing the largest decline in stocks. These losses are solely the result of increases in temperature, changes in temperature seasonality and decreases in precipitation, and are of the same order of magnitude as projected losses due to deforestation (30%). Declines in these tropical forest stocks are in contrast to recent DGVM-based estimates of tropical forest resilience to climate change (e.g. Huntingford et al., 2013), and Vieilledent et al. suggest that losses may be caused by changes in forest structure and species’ composition. These results add to other research (e.g. Baudena et al. 2015, Coomes et al. 2014) to suggest that models including ecological mechanisms can identify key processes that may strongly influence future changes in forest carbon stocks.

Emily Lines
Associate Editor, Journal of Ecology

REFERENCES

Baudena et al. (2015) Forests, savannas, and grasslands: bridging the knowledge gap between ecology and Dynamic Global Vegetation Models. Biogeosciences, 12, 1833–1848.

Coomes et al. (2014) Wood production response to climate change will depend critically on forest composition and structure. Global Change Biology, 20(12), 3632-3645.

Cox et al. (2013) Sensitivity of tropical carbon to climate change constrained by carbon dioxide variability. Nature, 494, 341-344.

Huntingford et al. (2013) Simulated resilience of tropical rainforests to CO2-induced climate change. Nature Geoscience 6, 268-273.

Virtual Issue: In Honour of Mark Westoby V

Editor’s Note

The Editors of the Journal of Ecology are pleased to honour Professor Mark Westoby in our continuing Eminent Ecologist virtual issue series. The virtual issue is available on the Journal of Ecology website.

Mark has written a number of posts for the blog about the papers in the virtual issue, and the people and stories related to them

Lauren Sandhu
Assistant Editor, Journal of Ecology


How to interpret it when a trait is phylogenetically conservative

Westoby, M., M.R. Leishman and J.M. Lord. 1995. On misinterpreting the “phylogenetic correction”. Journal of Ecology 83:531-534.

Cornwell W, Westoby M, Falster DS, Fitzjohn R, O’Meara B, Pennell M, McGlinn D, Eastman J, Moles A, Reich PB, Tank D, Wright IJ, Aarssen L, Beaulieu J, Kooyman R, Leishman M, Miller E, Niinemets U, Oleksyn J, Ordonez A, Royer D, Mith S, Stevens P, Warman L, Wilf P, Zanne AE. 2014. Functional distinctiveness of major plant lineages. Journal of Ecology 102: 345-356

Westoby et al 1995 was a Forum item, the first paper in a longer exchange (Ackerly & Donoghue 1995; Harvey, Read & Nee 1995a; b; Rees 1995; Westoby, Leishman & Lord 1995a; b; c). It arose from the review process for Leishman et al 1995 (listed above under “seeds, dispersal biology, seedling establishment”). During that process a reviewer asserted that correlations of traits across species were no longer statistically legitimate and had been superseded by correlations of phylogenetic divergences. I wrote a more spelled-out explanation of our position in correspondence to the editor, then Jonathan Silvertown. Although he personally disagreed, he decided to accept the Leishman et al manuscript and to have the issues aired as an exchange. He invited Harvey to contradict us, and various others chimed in as the exchange went along.

Currently it’s again becoming more common to hear the claim that analysis of species trait data is required to be “phylogenetically informed”. You hear it even from editors of BES journals, who ought to know better. The crux of the issue is simple enough. For most traits, variation across species is correlated both with ecology (other traits, or habitat variables) and with phylogeny. That is, families or genera often have distinct ecological propensities. What happens when we consider ecology and phylogeny as potential causes or interpretations? – remembering always that correlation does not by itself prove causation. The important point is that ecology and phylogeny are not mutually exclusive causes.  Species have both a phylogenetic history and an ecological competence in the present day, and correlation with one does not exclude causation by the other. So any analysis that takes phylogenetically conservative trait variation and removes it from consideration as potentially ecologically relevant must be misleading. In effect, such analyses are saying that differences between major clades can not be ecologically meaningful.

Janice Lord was a postdoc in the Macquarie lab working on the phylogenetic pattern in seed size (Lord, Westoby & Leishman 1995) and on accessory costs of seed production (Lord & Westoby 2006, 2012). She is now an academic at U Otago in New Zealand, and has given the Cockayne Memorial Lectures in 2015.

Enderby island Anistome and Dr Megaherb

Janice Lord on subantarctic Enderby Island

Cornwell et al 2014 mapped traits onto phylogeny with a view to describing specifics of evolutionary history, rather than from a perspective of statistically correcting for cross-correlation. It arose from a working group organised by Will Cornwell and Amy Zanne and supported mainly by the US National Evolutionary Synthesis Centre, with a meeting also in Australia supported by Macquarie Uni. At the time the working group got under way, trait data had accumulated for more than 10K species across several traits. The working group compiled a data set that spanned five main traits plus a number of others with lesser coverage, and focused on the question how different traits had radiated in relation to each other. Cornwell et al 2014 identified evolutionary divergences that were most influential for the breadth of trait variation observed in the present day (an idea prefigured in Moles et al. 2005, but using a different index of importance). The effect was to take very traditional knowledge, about the characters and lifestyles of particular clades, and put it on a freshly quantitative basis. For example Proteaceae were ranked 1 for increasing the spread of leaf N and SLA, Magnoliidae ranked 1 for leaf size and 2 seed size.

Macquarie lab people among the authors of Cornwell et al 2014 (besides Wright and Leishman who have already been mentioned) included Cornwell, Zanne and Fitzjohn. Will Cornwell did part of his Stanford PhD working from our lab, and was a frequent visitor as a postdoc though never formally enrolled or employed at Macquarie. He subsequently spent time at U British Columbia and Vrije Universiteit Amsterdam and is now a senior lecturer at U of New South Wales, across the other side of Sydney. Amy Zanne came to Macquarie as a postdoc with NSF International funding. She subsequently went to U Missouri St Louis and is now an Assoc Prof at George Washington U in Washington DC. She has continuing research collaborations in Australia. Both Will and Amy are members of the J Ecol Editorial Board.

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Amy Zanne working on wood decomposition in tropical Queensland

Rich Fitzjohn spent postdoc time at Macquarie on a computing project and is now an app developer in ecology of diseases at Imperial College London.

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Rich Fitzjohn while in Sydney

Falster, Kooyman, Miller and Moles all did PhDs in the Macquarie lab at various times.

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Daniel Falster

Robert-Kooyman

Rob Kooyman

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Angela Moles

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Eliot Miller

Daniel Falster is currently a postdoc at Macquarie and won the 2015 Next-Generation Ecologist Award from Ecological Society of Australia. Rob Kooyman lives in rainforest on the north coast of NSW (his PhD was undertaken after a long career as rainforest expert). He does research both with our lab and with the Royal Bot Gardens in Sydney. Angela Moles is now a professor at U New South Wales, and was Australia’s Life Scientist of the Year in 2013. Eliot Miller is a postdoc at the Cornell Ornithology Lab.

Retrospect

Looking back over this set of papers, they’re actually not too bad a representation of our lab’s interests overall, despite the big chance element about which pieces of work ended up in J Ecol rather than somewhere else. Probably the clearest trajectory corresponds to what’s become known as trait ecology. Of course all ecology and physiology is in some sense about traits (except maybe neutral theory). But the point about comparing trait constellations across many species is to put particular species and mechanisms in a wider context – to ask more quantitatively what “model systems” actually represent.

For us trait ecology began with work focused around seed size and its connections to other traits and to habitat (Jurado et al. 1991; Leishman & Westoby 1992; Hughes et al. 1994; Leishman et al. 1995). In the mid-90s a general agenda was formulated to approach plant strategies via trait axes (Westoby 1998; a paper that proved influential eventually, after being declined as insufficiently interesting by J Ecol and also by Ecology). Our attention expanded to leaf traits (e.g. Wright & Westoby 2002) and subsequently to stem traits (e.g. Falster & Westoby 2005). In parallel we began to assemble data sets to assess consistency across different continents and vegetation types (e.g. Leishman et al. 1995), leading eventually to the global communal-property datasets spanning tens of thousands of species that underpin many recent syntheses.

But the reason traits influence fitness, ultimately, is because of how they shape life histories and demography, and how those mesh with different disturbance regimes. So I’d see the self-thinning rule – how biomass accumulation translates into competitive mortality – as part of the same picture, and also the state-and-transition models for vegetation, and the demography in arid zones. Indeed self-thinning reappears in our recent models of traits in vegetation (e.g. Falster et al. 2011).

And finally I’d just like to apologise for leaving out all the people from our lab who have worked on fish, on mammal habitats, on insect communities, on gene conflict and cooperation, or who for whatever other reason have somehow gotten through life without sending papers to Journal of Ecology.

Prof. Mark Westoby

Literature cited

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Eldridge, D., Westoby, M. & Holbrook, K. (1991) Soil surface characteristics, microtopography and proximity to mature shrubs: effects on survival of several cohorts of Atriplex vesicaria seedlings. J Ecol, 79, 357–364.

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Falster, D.S. & Westoby, M. (2005) Alternative height strategies among 45 dicot rain forest species from tropical Queensland, Australia. Journal of Ecology, 93, 521–535.

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Leishman, M. & Westoby, M. (1992) Classifying plants into groups on the basis of associations of individual traits — evidence from Australian semi-arid woodlands. J Ecol, 80, 417–424.

Leishman, M.R. & Westoby, M. (1994a) The role of seed size in seedling establishment in dry soil conditions – experimental evidence from semi-arid species. Journal of Ecology, 82, 249–258.

Leishman, M.R. & Westoby, M. (1994b) Hypotheses On Seed Size – Tests Using the Semiarid Flora of Western New-South-Wales, Australia. American Naturalist, 143, 890–906.

Leishman, M.R., Westoby, M. & Jurado, E. (1995) Correlates of seed size variation: a comparison among five temperate floras. Journal of Ecology, 83, 517–529.

Lord, J.M. & Westoby, M. (2006) Accessory costs of seed production. Oecologia, 150, 310–317.

Lord, J.M. & Westoby, M. (2012) Accessory Costs of Seed Production and the Evolution of Angiosperms. Evolution, 66, 200–210.

Lord, J., Westoby, M. & Leishman, M. (1995) Seed size and phylogeny in six temperate floras: constraints, niche conservatism, and adaptation. Am. Nat., 146, 349–364.

Moles, A.T., Ackerly, D.D., Webb, C.O., Tweddle, J.C., Dickie, J.B. & Westoby, M. (2005) A brief history of seed size. Science, 307, 576–580.

Moles, A.T., Falster, D.S., Leishman, M.R. & Westoby, M. (2004) Small-seeded species produce more seeds per square metre of canopy per year, but not per individual per lifetime. Journal of Ecology, 92, 384–396.

Moles, A.T. & Westoby, M. (2004) Seedling survival and seed size: a synthesis of the literature. Journal of Ecology, 92, 372–383.

Noy-Meir, I. (1973) Desert ecosystems: environment and producers. Annual Review of Ecology and Systematics, 4, 25–51.

Rees, M. (1995) EC-PC Comparative Analyses? Journal of Ecology, 83, 891–893.

Saverimuttu, T. & Westoby, M. (1996) Seedling longevity under deep shade in relation to seed size. Journal of Ecology, 84, 681–689.

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Vesk, P.A. & Westoby, M. (2004) Sprouting ability across diverse disturbances and vegetation types worldwide. Journal of Ecology, 92, 310–320.

Watson, I.W., Westoby, M. & Holm, A.M. (1997a) Demography of two shrub species from an arid grazed ecosystem in Western Australia 1983-93. Journal of Ecology, 85, 815–832.

Watson, I.W., Westoby, M. & Holm, A.M. (1997b) Continuous and episodic components of demographic change in arid zone shrubs: models of two Eremophila species from Western Australia compared with published data from other species. Journal of Ecology, 85, 833–846.

Westoby, M. (1980) Relations between genet and tiller population dynamics: tiller survival under clipping in Phalaris tuberosa. J Ecol, 68, 683–870.

Westoby, M. (1981) The place of the self-thinning rule in population dynamics. Amer. Nat., 118, 581–587.

Westoby, M. (1982) Frequency distributions of plant size during competitive growth of stands: the operation of distribution-modifying-functions. Ann. Bot., 50, 733–735.

Westoby, M. (1984) The self-thinning rule. Advances in Ecological Research, 14, 167–226.

Westoby, M. (1998) A leaf-height-seed (LHS) plant ecology strategy scheme. Plant and Soil, 199, 213–227.

Westoby, M. & Howell, J. (1981) Self-thinning: the effect of shading on glasshouse populations of silver beet (Beta vulgaris). J Ecol, 69, 359–366.

Westoby, M. & Howell, J. (1986) The influence of population structure on self-thinning. J Ecol, 74, 343–359.

Westoby, M., Leishman, M. & Lord, J.M. (1995a) Further remarks on phylogenetic correction. J. Ecol., 83, 727–734.

Westoby, M., Leishman, M.R. & Lord, J.M. (1995b) On misinterpreting the “phylogenetic correction.” J. Ecol., 83, 531–534.

Westoby, M., Leishman, M.R. & Lord, J.M. (1995c) Issues of interpretation after relating comparative datasets to phylogeny. J. Ecol., 83, 892–893.

Westoby, M., Moles, A.T. & Falster, D.S. (2009) Evolutionary coordination between offspring size at independence and adult size. Journal of Ecology, 97, 23–26.

Wright, I.J., Reich, P.B. & Westoby, M. (2002) Convergence towards higher leaf mass per area in dry and nutrient-poor habitats has different consequences for leaf lifespan. Journal of Ecology, 90, 534–543.

Wright, I.J., Reich, P.B., Westoby, M., Ackerly, D.D., Baruch, Z., Bongers, F., Cavender-Bares, J., Chapin, T., Cornelissen, J.H.C., Diemer, M., Flexas, J., Garnier, E., Groom, P.K., Gulias, J., Hikosaka, K., Lamont, B.B., Lee, T., Lee, W., Lusk, C., Midgley, J.J., Navas, M.L., Niinemets, U., Oleksyn, J., Osada, N., Poorter, H., Poot, P., Prior, L., Pyankov, V.I., Roumet, C., Thomas, S.C., Tjoelker, M.G., Veneklaas, E.J. & Villar, R. (2004) The worldwide leaf economics spectrum. Nature, 428, 821–827.

Wright, I.J. & Westoby, M. (1999) Differences in seedling growth behaviour among species: trait correlations across species, and trait shifts along nutrient compared to rain gradients. Journal of Ecology, 87, 85–97.

Wright, I.J. & Westoby, M. (2002) Leaves at low versus high rainfall: coordination of structure, lifespan and physiology. New Phytologist, 155, 403–416.

Yoda, K., Kira, T., Ogawa, H. & Hozumi, H. (1963) Self-thinning in overcrowded pure stands under cultivated and natural conditions. J Inst Polytech Osaka City Univ Series D, 14, 107–129.

Zammit, C. & Westoby, M. (1988) Predispersal seed losses and the survival of seeds and seedlings of two serotinous Banksia shrubs in burnt and unburnt heath. J Ecol, 76, 200–214.

Virtual Issue: In Honour of Mark Westoby IV

Editor’s Note

The Editors of the Journal of Ecology are pleased to honour Professor Mark Westoby in our continuing Eminent Ecologist virtual issue series. The virtual issue is available on the Journal of Ecology website.

Mark has written a number of posts for the blog about the papers in the virtual issue, and the people and stories related to them

Lauren Sandhu
Assistant Editor, Journal of Ecology


Nutrients, rainfall, stress

Wright, I.J. and M. Westoby. 1999. Differences in seedling growth behaviour among species: trait correlations, and trait shifts along nutrient compared to rainfall gradients. Journal of Ecology 87: 85-97.

Fonseca, C.R., J. McC. Overton, B. Collins and M. Westoby. 2000. Shifts in trait-combinations along rainfall and phosphorus gradients. Journal of Ecology 88: 964-977.

Wright, I.J., Westoby, M. & Reich, P.B. 2002. Convergence towards higher leaf mass per area in dry and nutrient-poor habitats has different consequences for leaf lifespan. Journal of Ecology 90:534-543

From the 1970s onward a key idea in thinking about plant strategies has been stress or adversity and how species adapt to it. This is most apparent in Grime’s CSR triangle (Grime 1979), where one of the two axes is about coping with stress, meaning conditions that permit only slow growth. The question is whether there is indeed a common trait syndrome that confers advantage under low soil nutrient, cold climate, shading by competitors, low rainfall, heavy metal contamination and any number of other stresses. Or alternatively, are distinctive trait syndromes expected to arise for each of these stressors? In Australia drought versus low nutrients is an important manifestation of this general question. Traditionally in the northern hemisphere, sclerophyll foliage has been seen mainly as drought adaptation. But along the east coast of Australia many sclerophyll shrublands occur under quite high rainfall without a distinct dry season. Beadle’s papers (Beadle 1954, 1962) began a shift to the now widespread view that sclerophylly can also be an adaptation to low nutrients. The historical evolution of sclerophylly is also connected to this debate. Australia was climatically rainforest through most of the Tertiary up to about 15 Mya, but some sclerophyll features appear in Australian clades much earlier than that (Hill 1998).

During the second half of the 1990s several studies in our lab took advantage of the circumstance that working from Sydney, vegetation on high vs low nutrient sites can be contrasted at different rainfall levels, and also high vs low rainfall sites can be contrasted at different nutrient levels. Our nutrient indicator was total P, since our interest was in the mixture of species traits in vegetation constructed at a site over tens to hundreds of years not in physiology over weeks to months. Phosphorus in natural soil arises from the rock type plus local redistribution of fine particles, unlike nitrogen which arises largely from N-fixation by the vegetation itself. Three of these studies were published in J Ecol. It’s also worth noting Cunningham et al (1999) which selected species to form phylogenetically independent divergences along both nutrient and rainfall dimensions.

Ian Wright’s first work in our lab addressed seedling relative growth rate. Slow potential RGR of seedlings, measured during exponential growth and under favourable conditions, had been established as an attribute of species occupying slow-growth situations since Grime and Hunt (1975). Wright and Westoby (1999) confirmed that specific leaf area SLA was the strongest single predictor of potRGR (as had been demonstrated during the 1980s especially by a fine body of Netherlands work (Lambers & Poorter 1992)). In particular, Wright & Westoby 1999 showed that the SLA-potRGR correlation applied across species within sites and also across both rainfall and nutrient contrasts. (This is not always the case – trait correlations across sites can arise from different selective forces and can behave differently compared to correlations within sites.)

Fonseca et al (2000) looked at many more species across more sites, but with only field-measured traits. Starting from high-nutrient volcanic soil sites in high rainfall near the coast, it was possible to group sites to form trajectories towards lower nutrient and towards lower rainfall. The question was whether these trajectories behaved similarly in site-mean trait-space. As might perhaps have been expected, the answer was partly yes and partly no. Combinations of SLA with leaf width behaved rather similarly along the two trajectories. But comparing at a common SLA, low nutrient sites were running at taller plant heights than low rainfall sites.

Wright et al (2002) showed another sort of exception to the proposition that traits would adjust similarly to different stresses. The downshift in SLA has different leaf morphology, and different consequences, at low rainfall compared to on low-nutrient soils. At low nutrient the SLA downshift confers mechanical strengthening and longer leaf lifespan, but at low rainfall it is associated with more nitrogen and photosynthetic capacity per leaf area, with stronger drawdown of internal CO2 concentration during photosynthesis, and consequently with higher water use efficiency.

Ian Wright joined the Macquarie lab initially as a research assistant after completing honours at U Melbourne, then shifted to a PhD. As a postdoc he coordinated the “glopnet” collaboration, known for the leaf economic spectrum (Wright et al. 2004). The citation impact from that work persuaded Macquarie’s administration to offer him a continuing position. He is currently an Assoc Prof at Macquarie.

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Ian Wright’s lab in 2014; Ian in red shirt on left

Carlos Fonseca and Jake Overton were postdocs from Brasil (via Imperial College London) and USA respectively.

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Carlos Fonseca in field in Australia in 1990s

Carlos, with his wife Gislene Ganade who was also at Macquarie, are now professors at Universidade Federal do Rio Grande do Norte in Natal Brasil. Jake Overton is with Landcare Research in New Zealand, and is currently seconded to Panthera, a carnivore survey program in Zambia.

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Jake Overton (white t-shirt and hat) discussion carnivore surveys in Zambia

Bronwyn Collins was a research assistant while at Macquarie. She is now at the Australian National Herbarium in Canberra, coordinating the curation process and also student internships.

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Bronwyn Collins in 2015; photo provided by CSIRO

Prof. Mark Westoby

 

Virtual Issue: In Honour of Mark Westoby III

Editor’s Note

The Editors of the Journal of Ecology are pleased to honour Professor Mark Westoby in our continuing Eminent Ecologist virtual issue series. The virtual issue is available on the Journal of Ecology website.

Mark has written a number of posts for the blog about the papers in the virtual issue, and the people and stories related to them

Lauren Sandhu
Assistant Editor, Journal of Ecology


Arid-zone demography

Watson, I.W., M. Westoby and A. McR. Holm. 1997b. Continuous and episodic components of demographic change in arid zone shrubs: models of two Eremophila species from Western Australia compared with published data from other species. Journal of Ecology 85: 833-846.

Vesk, P.A. and Westoby, M. 2004. Sprouting ability across diverse disturbances and vegetation types worldwide. Journal of Ecology 92:310-320

During my PhD I had been a research assistant in the US/IBP Desert Biome programme. From that program there developed a “pulse-reserve paradigm” (Noy-Meir 1973) for arid ecosystems. This emphasized the importance of episodic events rather than continuous balance between recruitment and mortality. Through the 1970s and 1980s the idea that ecosystems were heavily driven by episodic events and disturbances became a new orthodoxy (and this was a trend across ecology as a whole, not just for arid zones). Many anecdotes were available about mass recruitment in exceptional years giving rise to even-aged stands.

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Ian Watson

Ian Watson came to our lab from Western Australia Dept of Agriculture (WADA), bringing with him long-term plot data from the WA Rangelands Monitoring Scheme. Measurements in these data runs were yearly, and they spanned a serious drought and a year of exceptional rainfall, as well as more commonplace years. This made possible a serious quantification of the extent to which for recruitment and mortality were actually concentrated into episodes vs occurring continuously year to year (Watson, Westoby & Holm 1997a; b). The second of these papers also gathered together literature data to the extent possible. As might perhaps have been expected, both episodic and continuous processes were influential. For Eremophila for example, 50-70% of all recruitment was concentrated into high-recruitment years, meaning that 30-50% occurred more continuously.

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Peter Vesk teaching vegetation management and conservation

Peter Vesk switched from his MSc in microscopy and freshwater biology in order to undertake a PhD with us on dynamics of terrestrial vegetation. He focused on resprouting or vegetative regeneration, especially after grazing and fire. He published a variety of papers from field experiments and data syntheses. Vesk and Westoby (2004) looked at percentages of individuals that resprouted following different types of damage in different settings. Plant species response to stem-killing fire was indeed dichotomous – as implied by the widely-used distinction between resprouters and obligate-seeders – but the most common outcomes were not at 100% and 0% of individuals surviving fire, but at 79% and 13%. Response to other types of damage such as windthrow were more of a continuum. It’s a continuing problem for plant growth models to deal satisfactorily with damage that falls short of mortality.

 After completing his PhD, Ian Watson went back to WADA initially. Later he moved to CSIRO, where he is currently leader of their Tropical Landscapes Joint Venture (joint with James Cook U in Townsville). He says his main claim to fame is that son Jay plays synth with Tame Impala. Peter Vesk is now an Assoc Prof at U Melbourne, with focus on landscape reconstruction and environmental decisions, and a member of the J Ecol Editorial Board. David Eldridge (Eldridge, Westoby & Holbrook 1991) is a researcher in soil conservation and arid zone ecology with NSW Office of Environment and Heritage and is also honorary faculty at University of New South Wales.

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David Eldridge at Belaley

Prof. Mark Westoby

Virtual Issue: In Honour of Mark Westoby II

Editor’s Note

The Editors of the Journal of Ecology are pleased to honour Professor Mark Westoby in our continuing Eminent Ecologist virtual issue series. The virtual issue is available on the Journal of Ecology website.

Mark has written a number of posts for the blog about the papers in the virtual issue, and the people and stories related to them

Lauren Sandhu
Assistant Editor, Journal of Ecology


Seeds, dispersal biology, seedling establishment

Hughes, L., M. Dunlop, K. French, M. Leishman, B. Rice, L. Rodgerson and M. Westoby. 1994. Predicting dispersal spectra: a minimal set of hypotheses based on plant attributes. J. Ecol. 82:933-950.

Leishman, M.R., E. Jurado and M. Westoby. 1995. Correlates of seed size variation: a comparison among five temperate floras. J. Ecol. 83:517-530.

During the 1980s we were interested in myrmecochory, plant species whose seeds bear an oil-body that motivates ants to disperse them. (None of that work appeared in J Ecol, however.) In low-nutrient sclerophyll vegetation in Australia, commonly 30-40% of species use this dispersal morphology. By 1990 we were still working on seed biology and seed size (e.g. in J. Ecol. Jurado, Westoby & Nelson 1991; Jurado & Westoby 1992; Leishman & Westoby 1992, 1994a; Saverimuttu & Westoby 1996) but moving to the broader question how different plant traits went together in constellations. Sometimes particular trait combinations may not be mechanically or developmentally possible. But mutation and evolution over tens of millions of years can make many things possible, so other times trait correlations across species arise because some combinations are more competent or competitive than others.

One outcome was Hughes et al (1994), which was written as a group project in the lab. Rather than simply writing a review about how dispersal morphology, seed size, plant growth form and habitat went together, we thought a more interesting challenge would be to write down a semi-quantitative a set of rules for predicting what dispersal morphology a plant species should be selected to adopt. This paper has been quite widely cited as a review, but so far as we know no-one has yet taken the opportunity to test how well the proposed rules predict evolutionary transitions between one dispersal morphology and another.

Seed size has big consequences for seedling establishment and for seed output as well as for dispersal modes. By the early 1990s we were interested to move beyond studies of tens to hundreds of species in particular floras and to assess the consistency of patterns at world scale. Leishman et al (1995) was our first compilation in this direction.

The review process for Leishman et al 1995 also brought into the open a debate about “phylogenetic correction”, which appears in a separate section below.

Hughes, Dunlop, Rodgerson and Leishman were all students at Macquarie, completing their PhDs during 1990-93. Lesley Hughes’s PhD was on the ant behaviour involved in myrmecochory. Then at postdoc stage she shifted to impacts of climate change, working initially on plant-insect interactions. She has become very visible in science communication and science policy via IPCC and Climate Commission. She has won the Australian Ecology Research Award and a Eureka Prize for science communication. She was Head of Department of Biological Sciences at Macquarie for a while and is now Pro-VC for Research.

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Lesley Hughes in 2015

Lou Rodgerson completed her PhD on myrmecochory at Macquarie and then taught at U Wollongong for some years (she was a notably passionate teacher and developed new curriculum). She then married Mike Dunlop, moved to Canberra and had three sons. Currently she is active through the Stephanie Alexander Foundation that integrates kitchen gardens, cooking and science in schools. Mike Dunlop joined CSIRO and works on future scenarios for Australian landscapes and rural industries. Michelle Leishman spent postdoc time at Imperial College London, then returned to Macquarie having won a postdoc from Australian Research Council, and after a while won a faculty position. She is currently Head of the Dept of Biological Sciences, and a member of the Editorial Board of J Ecol. Kris French came from a background in bird ecology. She was a postdoc in our lab 1988-90 in order to work on dispersal of fleshy fruits. She subsequently went to U Wollongong and is now a professor there. She was president of Ecological Society of Australia 2011-13.

Lou Rodgerson

Lou Rodgerson

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Michelle Leishman in 2015

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Kris French in 2013

Barbara Rice was Mark Westoby’s wife. She was an honorary associate at Macquarie, backbone of our lab over more than 30 years, and elder sister and mentor to many postgrads. She passed away in 2009. She is remembered through two activities. There are prizes at Macquarie University for the best postgrad field research, recalling her enjoyment and self-reliance in remote fieldwork. There is a Rice Memorial Poster Session at Ecological Society of Australia meetings, recalling her very sincere dislike of public speaking.

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Barbara Rice in field

Other J Ecol papers from our lab dealing with seeds and seedlings were (Zammit & Westoby 1988; Jurado et al. 1991; Leishman & Westoby 1994b; Saverimuttu & Westoby 1996; Moles et al. 2004; Moles & Westoby 2004; Westoby, Moles & Falster 2009).

Prof. Mark Westoby