396 research outputs found
Natural carbon solutions are not large or fast enough
No full textResponse letter: we thank Griscom et al. for their thoughtful letter to the editor (https://doi.org/10.1111/gcb.14612), responding to our paper (Baldocchi & Penuelas, 2019, https://doi.org/10.1111/gcb.14559) and expressing the opinion "we need both natural and energy solutions to stabilize our climate." We agree with tha
Lianas decelerate tropical forest thinning during succession
No full textThe well-established pattern of forest thinning during succession predicts an increase in mean tree biomass with decreasing tree density. The forest thinning pattern is commonly assumed to be driven solely by tree-tree competition. The presence of non-tree competitors could alter thinning trajectories, thus altering the rate of forest succession and carbon uptake. We used a large-scale liana removal experiment over 7years in a 60- to 70-year-old Panamanian forest to test the hypothesis that lianas reduce the rate of forest thinning during succession. We found that lianas slowed forest thinning by reducing tree growth, not by altering tree recruitment or mortality. Without lianas, trees grew and presumably competed more, ultimately reducing tree density while increasing mean tree biomass. Our findings challenge the assumption that forest thinning is driven solely by tree-tree interactions; instead, they demonstrate that competition from other growth forms, such as lianas, slow forest thinning and ultimately delay forest succession
Thinner bark increases sensitivity of wetter Amazonian tropical forests to fire
No full textUnderstory fires represent an accelerating threat to Amazonian tropical forests and can, during drought, affect larger areas than deforestation itself. These fires kill trees at rates varying from < 10 to c. 90% depending on fire intensity, forest disturbance history and tree functional traits. Here, we examine variation in bark thickness across the Amazon. Bark can protect trees from fires, but it is often assumed to be consistently thin across tropical forests. Here, we show that investment in bark varies, with thicker bark in dry forests and thinner in wetter forests. We also show that thinner bark translated into higher fire-driven tree mortality in wetter forests, with between 0.67 and 5.86 gigatonnes CO2 lost in Amazon understory fires between 2001 and 2010. Trait-enabled global vegetation models that explicitly include variation in bark thickness are likely to improve the predictions of fire effects on carbon cycling in tropical forests
Genetic effects of chronic habitat fragmentation in a wind-pollinated tree
No full textHabitat fragmentation poses a serious threat to plants through genetic changes associated with increased isolation and reduced population size. However, the longevity of trees, combined with effective seed or pollen dispersal, can enhance their resistance to these effects. The European beech (Fagus sylvatica) dominates forest over large regions of Europe. We demonstrate that habitat fragmentation in this species has led to genetic bottlenecks and the disruption of the species' breeding system, leading to significantly elevated levels of inbreeding, population divergence, and reduced genetic diversity within populations. These results show that, in contrast with the findings of previous studies, forest fragmentation has a negative genetic impact, even in this widespread, wind-pollinated tree. The identification of significant effects of forest fragmentation in beech demonstrates that trees are not at reduced risk from environmental change. This should be accounted for in the management of remaining natural and seminatural forest throughout the world
Environmental change and the option value of genetic diversity
No full textRapid anthropogenic environmental change is altering selection pressures on natural plant populations. However, it is difficult to predict easily the novel selection pressures to which populations will be exposed. There is heavy reliance on plant genetic diversity for future crop security in agriculture and industry, but the implications of genetic diversity for natural populations receives less attention. Here, we examine the links between the genetic diversity of natural populations and aspects of plant performance and fitness. We argue that accumulating evidence demonstrates the future benefit or ‘option value’ of genetic diversity within natural populations when subject to anthropogenic environmental changes. Consequently, the loss of that diversity will hinder their ability to adapt to changing environments and is, therefore, of serious concern
Running to stand still: adaptation and the response of plants to rapid climate change
No full textClimate is a potent selective force in natural populations, yet the importance of adaptation in the response of plant species to past climate change has been questioned. As many species are unlikely to migrate fast enough to track the rapidly changing climate of the future, adaptation must play an increasingly important role in their response. In this paper we review recent work that has documented climate-related genetic diversity within populations or on the microgeographical scale. We then describe studies that have looked at the potential evolutionary responses of plant populations to future climate change. We argue that in fragmented landscapes, rapid climate change has the potential to overwhelm the capacity for adaptation in many plant populations and dramatically alter their genetic composition. The consequences are likely to include unpredictable changes in the presence and abundance of species within communities and a reduction in their ability to resist and recover from further environmental perturbations, such as pest and disease outbreaks and extreme climatic events. Overall, a range-wide increase in extinction risk is likely to result. We call for further research into understanding the causes and consequences of the maintenance and loss of climate-related genetic diversity within populations
Natural carbon solutions are not large or fast enough
No full textResponse letter: we thank Griscom et al. for their thoughtful letter to the editor (https://doi.org/10.1111/gcb.14612), responding to our paper (Baldocchi & Penuelas, 2019, https://doi.org/10.1111/gcb.14559) and expressing the opinion "we need both natural and energy solutions to stabilize our climate." We agree with tha
Decreasing efficiency and slowdown of the increase in terrestrial carbon-sink activity
No full textAnthropogenic fertilization of the Earth with increasing concentrations of atmospheric CO2 and nitrogen inputs has enhanced plant photosynthesis and carbon sinks of terrestrial ecosystems. Several signals now suggest, however, that this carbon-sink activity is slowing its rate of increase because of limitations of nutrients, water, and heat, among other factors
Exploring the limits: Long-term observations on terrestrial carbon sink efficiency
No full textIn this talk, I will examine the long-term capabilities of plants to mitigate climate change, focusing on the weakening efficiency of terrestrial carbon sinks. I will address the slowdown in the increase of terrestrial carbon-sink activity. Anthropogenic activities, such as elevated atmospheric CO2 and nitrogen inputs, have historically enhanced plant photosynthesis and the carbon sequestration capabilities of vegetation. However, the analysis of long-term observations and experiments provide evidence suggesting that the effectiveness of these carbon sinks is diminishing due to limitations in nutrients, water, and heat, as well as other factors like fires, pollution, and reduced vegetation carbon residence time. These findings are consistent with the five laws of life proposed by Peñuelas and Baldocchi (2019):the law of the conservation of mass,energy cannot be created or destroyed in an isolated system,the entropy of any isolated system always increases,the information content is a power of the material size of its store with an exponent larger than one, andbasic mechanisms such as natural selection, self-organization, and random processes (not driven by selection) drive evolution, generating the huge complexity of organisms and ecosystems.Long-term data has underscored the critical role terrestrial plants have historically played in mitigating climate change by assimilating a significant portion of CO2 emissions, thus buffering against more severe warming. Yet, these data also raise pressing concerns about how long this mitigation effect can persist as the efficiency of carbon sinks seems to be declining. The potential deceleration in atmospheric carbon fixation and its long-term implications for climate change mitigation are not well studied, and current models may overestimate the capacity of carbon sinks and underestimate the severity of future climate warming if such factors are not thoroughly accounted for. Therefore, in this talk I will advocate for more comprehensive, long-term studies and updated models that consider the evolving structure and functioning of plants to better predict and manage the planet's carbon balance and climate change mitigation efforts over extended periods
The altitude-for-latitude disparity in the range retractions of woody species
No full textIncreasing temperatures are driving rapid upward range shifts of species in mountains. An altitudinal range retreat of 10 m is predicted to translate into a ~10 km latitudinal retreat, based on the rate at which temperatures decline with increasing altitude and latitude, yet reports of latitudinal range retractions are sparse. Here we examine potential climatic, biological, anthropogenic and methodological explanations for this disparity. We argue that the lack of reported latitudinal range retractions stems more from a lack of research effort, compounded by methodological difficulties, rather than from their absence. Given the predicted negative impacts of increasing temperatures on wide areas of the latitudinal distributions of species, the investigation of range retractions should become a priority in biogeographical research
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