Links across ecological scales: Plant biomass responses to elevated CO.

The degree to which elevated CO concentrations (e[CO ]) increase the amount of carbon (C) assimilated by vegetation plays a key role in climate change. However, due to the short-term nature of CO enrichment experiments and the lack of reconciliation between different ecological scales, the effect of e[CO ] on plant biomass stocks remains a major uncertainty in future climate projections. Here, we review the effect of e[CO ] on plant biomass across multiple levels of ecological organization, scaling from physiological responses to changes in population-, community-, ecosystem-, and global-scale dynamics.

Field experiments underestimate aboveground biomass response to drought.

Researchers use both experiments and observations to study the impacts of climate change on ecosystems, but results from these contrasting approaches have not been systematically compared for droughts. Using a meta-analysis and accounting for potential confounding factors, we demonstrate that aboveground biomass responded only about half as much to experimentally imposed drought events as to natural droughts. Our findings indicate that experimental results may underestimate climate change impacts and highlight the need to integrate results across approaches.

Rethinking the Plant Economics Spectrum for Annuals: A Multi-Species Study.

The plant economics spectrum hypothesizes a correlation among resource-use related traits along one single axis, which determines species' growth rates and their ecological filtering along resource gradients. This concept has been mostly investigated and shown in perennial species, but has rarely been tested in annual species. Annuals evade unfavorable seasons as seeds and thus may underlie different constraints, with consequences for interspecific trait-trait, trait-growth, and trait-environment relations.

Experimental simulation of environmental warming selects against pigmented morphs of land snails.

In terrestrial snails, thermal selection acts on shell coloration. However, the biological relevance of small differences in the intensity of shell pigmentation and the associated thermodynamic, physiological, and evolutionary consequences for snail diversity within the course of environmental warming are still insufficiently understood. To relate temperature-driven internal heating, protein and membrane integrity impairment, escape behavior, place of residence selection, water loss, and mortality, we used experimentally warmed open-top chambers and field observations with a total of >11,000 naturally or experimentally colored individuals of the highly polymorphic species (O.

Species selection under long-term experimental warming and drought explained by climatic distributions.

Global warming and reduced precipitation may trigger large-scale species losses and vegetation shifts in ecosystems around the world. However, currently lacking are practical ways to quantify the sensitivity of species and community composition to these often-confounded climatic forces. Here we conducted long-term (16 yr) nocturnal-warming (+0.

A comprehensive test of evolutionarily increased competitive ability in a highly invasive plant species.

Background And Aims: A common hypothesis to explain plants' invasive success is that release from natural enemies in the introduced range selects for reduced allocation to resistance traits and a subsequent increase in resources available for growth and competitive ability (evolution of increased competitive ability, EICA). However, studies that have investigated this hypothesis have been incomplete as they either did not test for all aspects of competitive ability or did not select appropriate competitors.

Methods: Here, the prediction of increased competitive ability was examined with the invasive plant Lythrum salicaria (purple loosestrife) in a set of common-garden experiments that addressed these aspects by carefully distinguishing between competitive effect and response of invasive and native plants, and by using both intraspecific and interspecific competition settings with a highly vigorous neighbour, Urtica dioica (stinging nettle), which occurs in both ranges.

Middle-Eastern plant communities tolerate 9 years of drought in a multi-site climate manipulation experiment.

For evaluating climate change impacts on biodiversity, extensive experiments are urgently needed to complement popular non-mechanistic models which map future ecosystem properties onto their current climatic niche. Here, we experimentally test the main prediction of these models by means of a novel multi-site approach. We implement rainfall manipulations--irrigation and drought--to dryland plant communities situated along a steep climatic gradient in a global biodiversity hotspot containing many wild progenitors of crops.

Fine-scale community and genetic structure are tightly linked in species-rich grasslands.

Recent evidence indicates that grassland community structure and species diversity are influenced by genetic variation within species. We review what is known regarding the impact of intraspecific diversity on grassland community structure, using an ancient limestone pasture as a focal example. Two genotype-dependent effects appear to modify community structure in this system.

A study of crop-to-crop gene flow using farm scale sites of fodder maize (Zea mays L.) in the UK.

From 2000 to 2003 a range of Farm Scale Evaluation (FSE) trials were established in the UK to assess the effect of the release and management of herbicide tolerant (HT) crops on arable weeds and invertebrates. The FSE trials for maize were also used to investigate crop-to-crop gene flow and to develop a statistical model for the prediction of gene flow frequency that can be used to evaluate current separation distance guidelines for GM crops. Seed samples were collected from the non-GM half of 55 trial sites and 1,055 were tested for evidence of gene flow from the GM HT halves using a quantitative PCR assay specific to the HT (pat) gene.

Crop-to-crop gene flow using farm scale sites of oilseed rape (Brassica napus) in the UK.

From 2000-2003 a range of Farm Scale Evaluation (FSE) trials were established in the UK to assess the effect of the release and management of herbicide tolerant (HT) crops on the abundance and diversity of farmland wildlife compared with their conventionally managed non-GM-equivalents. The objective of this research project was to investigate gene flow within the winter (WOSR) and spring oilseed rape (SOSR) FSE trials and to develop a statistical model for the prediction of cross-pollination frequency that can be used to evaluate current separation distance guidelines. Seed samples were collected from the non-GM half of the trial sites and were tested for evidence of cross-pollination from the GM HT halves using a quantitative PCR assay specific to the HT (bar) gene.