Wednesday, September 14, 2011

BES day 2: Plants, plants and way more plants

From Sept 13

I attended the Journal of Ecology Centenary symposium all morning, where the talks were broad overviews of select areas in plant ecology. They were quite good; I really do feel that I was informed about recent research advances.

In the first talk of the morning, Sandra Lavorel gave a tour de force about how plant functional traits scale up to ecosystem services. She recognizes that there are trade offs in services, where one service (say agricultural value) is in direct conflict with a noter service (say species richness). She very cleverly asks whether these services are constrained by ecological trade offs or traits. It is known that functional traits affect ecosystem functions and services, and it is also known that there are strong tradeoffs in plant traits such as explained by the world wide leaf economic spectrum. Where plants have these tradeoffs they affect productivity and litter decomposition. Height for example affects productivity and other trophic levels supported. Abiotic gradients affect traits like height or leaf N, and these traits affect ecosystem function such as biomass or litter. Multiple service such as agronomic value, pollination, cultural value, richness, etc. To understand how traits relate to tradeoffs in services.

Next was Angela Moles who talked about how the study of invasions has progressed and whether there were important future directions. The have been 10,000 studies on invasions over the last 30 years and she recognizes that the fact that species evolve in their new ranges to be a critical future research need. Specifically, she asked: do exotics evolve to be more similar or different tha natives? And, can differences be predicted by environmental differences between home and away range. Most interestingly she brought up the point that if on-going change produce new species, should they then be conserved as natives? She went on to say that broad generalizations about trait differences between natives and exotics have produced largely idiosyncratic results, and so other priorities such take the forefront. She went on to say that impact on natives is actually an understudied problem, which needs to be rectified. Finally, she showed us that there is a generally positive relationship between disturbance and invasion. But invasions are favored when there is a change in disturbance rate, since natives are likely adapted to historical disturbance regime. She showed some relatively weak evidence that change in disturbance better predictor of invader richness and abundance then the amount of disturbance, but more work is needed.

Yadvinder Malhi talked about how productivity and metabolism were related to biomass in tropical forests. He sowed us that a small proportion of primary production is turned into biomass. Thus small changes in various pathways could have large consequences. In exhaustive studies in the tropics, he showed that increases in GPP (gross primary production) occurred with soils nutrient quality, and decreases with elevation, likely because of temperature effects on photosynthesis. He also showed that carbon use efficiency is lower than thought, about 30% of carbon turned to biomass. Further, higher productivity is associated with lower residence times, and he hypothesized that rapid growth leads to earlier senescence or less defences if trade offs exist. Biomass appears to be increasing with climate change, but potentially greater mortality and turnover.

Then James Bullock talked about where we are at with understanding seed dispersal. There has been a long history of not understanding long distance dispersal, LDD. The main empirical approaches have grown rapidly lately: tracking seeds, molecular methods and marking seeds or to track dispersers. But at the same time spread models have appeared and advanced. However, Bullock really supports mechanistic models for wind-dispersed species, and these models seem to really provide insights. He then compared a handful of models for invasive and scarce natives, and did mechanistic modeling with climate change. Changes in future wind speeds may result in even larger changes in spread rates. Only Ailanthus appears to have dispersal rates at or faster than the rate of climate change, most species do not appear to be able to move fast enough (except animal dispersed species). Movement on shoes major dispersal vector.

Hans Jacquemyn was the final speaker, and talked about evolution and habitat fragmentation. He studies calcareous grasslands, forests and heathlands in Belgium that have increasingly become isolated and fragmented. Observed declines in genetic diversity in populations, as they get smaller in size. More recent fragmentations have less loss of genetic diversity compared to older fragments. Reduced seed output in small populations for self-incompatible species, results in reduced population growth rates. To counteract plants can increase floral displays or increase selfing rates, which they observed. Also, he has observed changes in timing of flowering and investing more in nectar.

*Some thoughts about the BES. It is a great Society, and a great meeting. It is relatively small and it is nice to see how many members know each other. For those of us in North America, I think it is a great experience to go to one of these meetings.

**I also participated in the BESdigital workshop on communicating science in a digital era. I will have a post about this tomorrow –I've been without internet connection at both the Sheffield dorm and various airports.

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