Leaf senescence in winter deciduous species signals the transition from the active to the dormant stage. The purpose of leaf senescence is the recovery of nutrients before the leaves fall. ...Photoperiod and temperature are the main cues controlling leaf senescence in winter deciduous species, with water stress imposing an additional influence. Photoperiod exerts a strict control on leaf senescence at latitudes where winters are severe and temperature gains importance in the regulation as winters become less severe. On average, climatic warming will delay and drought will advance leaf senescence, but at varying degrees depending on the species. Warming and drought thus have opposite effects on the phenology of leaf senescence, and the impact of climate change will therefore depend on the relative importance of each factor in specific regions. Warming is not expected to have a strong impact on nutrient proficiency although a slower speed of leaf senescence induced by warming could facilitate a more efficient nutrient resorption. Nutrient resorption is less efficient when the leaves senesce prematurely as a consequence of water stress. The overall effects of climate change on nutrient resorption will depend on the contrasting effects of warming and drought. Changes in nutrient resorption and proficiency will impact production in the following year, at least in early spring, because the construction of new foliage relies almost exclusively on nutrients resorbed from foliage during the preceding leaf fall. Changes in the phenology of leaf senescence will thus impact carbon uptake, but also ecosystem nutrient cycling, especially if the changes are consequence of water stress.
Aim: Potassium (K) is the second most abundant nutrient in plant photosynthetic tissues after nitrogen (N). Thousands of physiological and metabolic studies in recent decades have established the ...fundamental role of K in plant function, especially in water-use efficiency and economy, and yet macroecological studies have mostly overlooked this nutrient. Methods: We have reviewed available studies on the content, stoichiometry and roles of in the soil–plant system and in terrestrial ecosystems. We have also reviewed the impacts of global change drivers on K content, stoichiometry and roles. Conclusions: The current literature indicates that K, at a global level, is as limiting as N and phosphorus (P) for plant productivity in terrestrial ecosystems. Some degree of K limitation has been seen in up to 70% of all studied terrestrial ecosystems. However, in some areas atmospheric K deposition from human activities is greater than that from natural sources. We are far from understanding the K fluxes between the atmosphere and land, and the role of anthropogenic activities in these fluxes. The increasing aridity expected in wide areas of the world makes K more critical through its role in water-use efficiency. N deposition exerts a strong impact on the ecosystem K cycle, decreasing K availability and increasing K limitation. Plant invasive success is enhanced by higher soil K availability, especially in environments without strong abiotic stresses. The impacts of other drivers of global change, such as increasing atmospheric CO₂ or changes in land use, remain to be elucidated. Current models of the responses of ecosystems and carbon storage to projected global climatic and atmospheric changes are now starting to consider N and P, but they should also consider K, mostly in arid and semi-arid ecosystems.
Potassium, mostly as a cation (K
), together with calcium (Ca
) are the most abundant inorganic chemicals in plant cellular media, but they are rarely discussed. K
is not a component of molecular or ...macromolecular plant structures, thus it is more difficult to link it to concrete metabolic pathways than nitrogen or phosphorus. Over the last two decades, many studies have reported on the role of K
in several physiological functions, including controlling cellular growth and wood formation, xylem-phloem water content and movement, nutrient and metabolite transport, and stress responses. In this paper, we present an overview of contemporary findings associating K
with various plant functions, emphasizing plant-mediated responses to environmental abiotic and biotic shifts and stresses by controlling transmembrane potentials and water, nutrient, and metabolite transport. These essential roles of K
account for its high concentrations in the most active plant organs, such as leaves, and are consistent with the increasing number of ecological and agricultural studies that report K
as a key element in the function and structure of terrestrial ecosystems, crop production, and global food security. We synthesized these roles from an integrated perspective, considering the metabolic and physiological functions of individual plants and their complex roles in terrestrial ecosystem functions and food security within the current context of ongoing global change. Thus, we provide a bridge between studies of K
at the plant and ecological levels to ultimately claim that K
should be considered at least at a level similar to N and P in terrestrial ecological studies.
Pharmaceuticals and personal-care products (PPCPs) derived from agricultural, urban, and industrial areas accumulate in plants at concentrations (ng to μg kg−1) that can be toxic to the plants. ...Importantly, the dietary intake of these PPCP-contaminated plants may also pose a risk to human health, but currently little is known about the fate of PPCPs in plants and their effect on or risk to the ecosystem. In this Opinion article we propose that in-depth research on the use of plants as a monitoring device for assessing the use and environmental presence of PPCPs is warranted. The toxicity of PPCPs to plants and their microbiota needs to be established, as well as any toxic effects on herbivores including humans.
PPCPs derived from municipal, agricultural, and industrial wastewater are frequently detected anthropogenic contaminants in the environment.
Plants take up, accumulate, and metabolize PPCPs at concentrations that can be toxic to plants, plant microbiota, and soil microorganisms, affecting plant–microorganism symbiosis.
The dietary intake of these PPCP-contaminated plants may pose a risk to ecosystems and humans.
Owing to the lack of data on the fate of PPCPs in the environment and their toxicity to plants and humans, no regulations exist for most PPCPs in irrigation water, biosolids, or manure before these are reused for agriculture or in supplies of drinking water, vegetables, and other food to be commercialized.
Challenges to food security under conditions of global change are forcing us to increase global crop production. Focussing on belowground plant traits, especially root exudation, has great promise to ...meet this challenge. Root exudation is the release of a vast array of compounds into the soil. These exudates are involved in many biotic and abiotic interactions. Wild relatives of crops provide a large potential source of information and genetic material and have desirable traits that could be incorporated into modern breeding programs. However, root exudates are currently underexploited. Here, we highlight how the traits of root exudates of crop wild relatives could be used to improve agricultural output and reduce environmental impacts, particularly by decreasing our dependence on pesticides and fertilisers.
Root exudates are the compounds that roots release into the soil.Root exudates show a large amount of variation in composition between species.Crop wild relatives contain different root exudate traits compared with crops.Exploitation of root exudate traits in crop wild relatives offers opportunities to reduce the use of fertilisers and pesticides.
Background Rhizodeposition is the release of organic compounds from plant roots into soil. Positive relationships between rhizodeposition and soil microbial biomass are commonly observed. ...Rhizodeposition may be disrupted by increasing drought however the effects of water stress on this process are not sufficiently understood. Scope We aimed to provide a synthesis of the current knowledge of drought impacts on rhizodeposition. The current scarcity of well-defined studies hinders a quantitative meta-analysis, but we are able to identify the main effects of water stress on this process and how changes in the severity of drought may produce different responses. We then give an overview of the links between rhizodeposition and microbial communities, and describe how drought may disrupt these interactions. Conclusions Overall, moderate drought appears to increase rhizodeposition per gram of plant, but under extreme drought rhizodeposition is more variable. Concurrent decreases in plant biomass may lessen the total amount of rhizodeposits entering the soil. Effects on rhizodeposition may be strongly species-dependant therefore impacts on soil communities may also vary, either driving subsequent changes or conferring resilience in the plant community. Advances in the study of rhizodeposition are needed to allow a deeper understanding of this plant-soil interaction and how it will respond to drought.
Root exudates are well-known ‘labile’ sources of soil carbon that can prime microbial activity. Recent investigations suggest that the stability of labile carbon inputs in soil mostly depends upon ...the physical, chemical, and biological properties of the surroundings. Here, we propose that, in some ecosystems, such as forests and grasslands, root exudates can function as a source of soil organic carbon (SOC) that can be stabilized through various mechanisms leading to long-term sequestration. Increasing soil carbon sequestration is important for capturing atmospheric CO2 and combating climate change issues. Thus, there is an urgent need to preserve existing ecosystems and to adopt strategies such as afforestation, reforestation, and establishment of artificial grasslands to foster carbon sequestration through higher root exudate inputs in the soil.
Soil and plants are pivotal to the processes important for maintaining the integrity of biogeochemical cycles, such as the carbon cycle. Over the past few decades, anthropogenic activities have disturbed the atmospheric carbon cycle, leading to severe CO2 emissions into the atmosphere.Soil carbon sequestration by plant root exudates is an important means for net removal of CO2 content from the atmosphere.The rhizosphere environment in natural ecosystems, such as forests and grasslands, can help to stabilize root exudates in soil, while conditions in croplands do not appear favorable to stabilize root exudates as a soil organic carbon (SOC) source.Thus, preserving forests and grasslands with plant species secreting a high amount of carbon compounds might increase the SOC content in the soil of these ecosystems.
Forest ecosystems in the Mediterranean Basin are mostly situated in the north of the Basin (mesic). In the most southern and dry areas, the forest can only exist where topography and/or altitude ...favor a sufficient availability of water to sustain forest biomass. We have conducted a thorough review of recent literature (2000–2021) that clearly indicates large direct and indirect impacts of increasing drought conditions on the forests of the Mediterranean Basin, their changes in surface and distribution areas, and the main impacts they have suffered. We have focused on the main trends that emerge from the current literature and have highlighted the main threatens and management solution for the maintenance of these forests. The results clearly indicate large direct and indirect impacts of increasing drought conditions on the forests of the Mediterranean Basin. These increasing drought conditions together with over-exploitation, pest expansion, fire and soil degradation, are synergistically driving to forest regression and dieback in several areas of this Mediterranean Basin. These environmental changes have triggered responses in tree morphology, physiology, growth, reproduction, and mortality. We identified at least seven causes of the changes in the last three decades that have led to the current situation and that can provide clues for projecting the future of these forests: (i) The direct effect of increased aridity due to more frequent and prolonged droughts, which has driven Mediterranean forest communities to the limit of their capacity to respond to drought and escape to wetter sites, (ii) the indirect effects of drought, mainly by the spread of pests and fires, (iii) the direct and indirect effects of anthropogenic activity associated with general environmental degradation, including soil degradation and the impacts of fire, species invasion and pollution, (iv) human pressure and intense management of water resources, (v) agricultural land abandonment in the northern Mediterranean Basin without adequate management of new forests, (vi) very high pressure on forested areas of northern Africa coupled with the demographic enhancement, the expansion of crops and higher livestock pressure, and the more intense and overexploitation of water resources uses on the remaining forested areas, and (vii) scarcity and inequality of human management and policies, depending on the national and/or regional governments and agencies, being unable to counteract the previous changes. We identified appropriate measures of management intervention, using the most adequate techniques and processes to counteract these impacts and thus to conserve the health, service capacity, and biodiversity of Mediterranean forests. Future policies should, moreover, promote research to improve our knowledge of the mechanisms of, and the effects on, nutrient and carbon plant-soil status concurrent with the impacts of aridity and leaching due to the effects of current changes. Finally, we acknowledge the difficulty to obtain an accurate quantification of the impacts of increasing aridity rise that warrants an urgent investment in more focused research to further develop future tools in order to counteract the negative effects of climate change on Mediterranean forests.
BVOCs and global change Peñuelas, Josep; Staudt, Michael
Trends in plant science,
03/2010, Volume:
15, Issue:
3
Journal Article
Peer reviewed
Biogenic volatile organic compounds (BVOCs) produced by plants are involved in plant growth, reproduction and defense. They are emitted from vegetation into the atmosphere and have significant ...effects on other organisms and on atmospheric chemistry and physics. Here, we review current knowledge on the alteration of BVOC emission rates due to climate and global changes: warming, drought, land use changes, high atmospheric CO
2 concentrations, ozone and enhanced UV radiation. These alterations are very variable depending on the doses, timing, BVOC and species, but in overall terms are likely to increase BVOC emissions. These changed emissions can lead to unforeseeable consequences for the biosphere structure and functioning, and can disturb biosphere feedback on atmospheric chemistry and climate with a direction and intensity that warrants in-depth investigation.
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