Senescence: Is It Universal or Not?

Munné‐Bosch, Sergi

doi:10.1016/j.tplants.2015.07.009

Cited by 34 publications

(26 citation statements)

References 48 publications

(55 reference statements)

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“…Higher survival in the highest population may be associated with improved soil and leaf water contents despite being exposed to higher light intensity. Furthermore, plants from this species seem to escape from increased size-dependent mortality, as it has been shown in other plant species, mostly woody perennials (shrubs and trees), in which increased plant size make larger individuals more vulnerable to environmental constraints (Mencuccini et al, 2005(Mencuccini et al, , 2007Baudisch et al, 2013;Salguero-Gomez et al, 2013;Munné-Bosch, 2014, 2015. This was not observed here in either studied population.…”

Section: Non-clonal Clonalsupporting

confidence: 59%

Adaptation of the Long-Lived Monocarpic Perennial, Saxifraga longifolia to High Altitude

et al. 2016

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Global change is exerting a major effect on plant communities, altering their potential capacity for adaptation. Here, we aimed at unveiling mechanisms of adaptation to high altitude in an endemic long-lived monocarpic, Saxifraga longifolia, by combining demographic and physiological approaches. Plants from three altitudes (570, 1100, and 2100 m above sea level [a.s.l.]) were investigated in terms of leaf water and pigment contents, and activation of stress defense mechanisms. The influence of plant size on physiological performance and mortality was also investigated. Levels of photoprotective molecules (a-tocopherol, carotenoids, and anthocyanins) increased in response to high altitude (1100 relative to 570 m a.s.l.), which was paralleled by reduced soil and leaf water contents and increased ABA levels. The more demanding effect of high altitude on photoprotection was, however, partly abolished at very high altitudes (2100 m a.s.l.) due to improved soil water contents, with the exception of a-tocopherol accumulation. a-Tocopherol levels increased progressively at increasing altitudes, which paralleled with reductions in lipid peroxidation, thus suggesting plants from the highest altitude effectively withstood high light stress. Furthermore, mortality of juveniles was highest at the intermediate population, suggesting that drought stress was the main environmental driver of mortality of juveniles in this rocky plant species. Population structure and vital rates in the high population evidenced lower recruitment and mortality in juveniles, activation of clonal growth, and absence of plant sizedependent mortality. We conclude that, despite S. longifolia has evolved complex mechanisms of adaptation to altitude at the cellular, whole-plant and population levels, drought events may drive increased mortality in the framework of global change.

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Section: Non-clonal Clonalsupporting

confidence: 59%

Adaptation of the Long-Lived Monocarpic Perennial, Saxifraga longifolia to High Altitude

et al. 2016

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“…Additionally, tree age could diminish resprouting vigor, particularly in those with older and larger stems, due to the increasing costs of respiratory maintenance with size and to hormonal changes (Juvany et al. , Munné‐Bosch ). This lack of consensus on the limits to resprouting is hindering efforts toward modeling post‐fire vegetation dynamics.…”

Section: Fire Resistance At Individual Tree Levelmentioning

confidence: 99%

“…Moreover, drought acts as a weakening agent that increases the probability of attacks by pests and pathogens, which would substantially hamper tree resprouting (Oliva et al 2014). Additionally, tree age could diminish resprouting vigor, particularly in those with older and larger stems, due to the increasing costs of respiratory maintenance with size and to hormonal changes (Juvany et al 2015, Munn e-Bosch 2015. This lack of consensus on the limits to resprouting is hindering efforts toward modeling postfire vegetation dynamics.…”

Section: Resistance To Fire Induced Mortality Through Resproutingmentioning

confidence: 99%

Fire‐induced deforestation in drought‐prone Mediterranean forests: drivers and unknowns from leaves to communities

Karavani

Boer

Baudena

et al. 2018

Ecological Monographs

110

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Over the past 15 years, 3 million hectares of forests have been converted into shrublands or grasslands in the Mediterranean countries of the European Union. Fire and drought are the main drivers underlying this deforestation. Here we present a conceptual framework for the process of fire‐induced deforestation based on the interactive effects of fire and drought across three hierarchical scales: resistance in individuals, resilience in populations, and transitions to a new state. At the individual plant level, we review the traits that confer structural and physiological resistance, as well as allow for resprouting capacity: deforestation can be initiated when established individuals succumb to fire. After individuals perish, the second step toward deforestation requires a limited resilience from the population, that is, a reduced ability of that species to regenerate after fire. If individuals die after fire and the population fails to recover, then a transition to a new state will occur. We document trade‐offs between drought survival and fire survival, as embolism resistance is negatively correlated with fire tolerance in conifers and leaf shedding or drought deciduousness, a process that decreases water consumption at the peak of the dry season, temporally increases crown flammability. Propagule availability and establishment control resilience after mortality, but different hypotheses make contrasting predictions on the drivers of post‐fire establishment. Mycorrhizae play an additional role in modulating the response by favoring recovery through amelioration of the nutritional and water status of resprouts and new germinants. So far, resprouter species such as oaks have provided a buffer against deforestation in forests dominated by obligate seeder trees, when present in high enough density in the understory. While diversifying stands with resprouters is often reported as advantageous for building resilience, important knowledge gaps exist on how floristic composition interacts with stand flammability and on the “resprouter exhaustion syndrome,” a condition where pre‐fire drought stress, or short fire return intervals, seriously restrict post‐fire resprouting. Additional attention should be paid to the onset of novel fire environments in previously fire‐free environments, such as high altitude forests, and management actions need to accommodate this complexity to sustain Mediterranean forests under a changing climate.

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“…However, relatively little is known about aging in plants, including whether plants generally undergo demographic senescence, a deterioration in fecundity and/or survival with advancing age (but see Gibson et al. , Munné‐Bosch , Dahlgren and Roach ). If plants show demographic, or “whole‐plant” senescence, then it is likely that this influence of age on demographic (vital) rates needs to be accounted for in studies of plant life history and drivers of plant population dynamics.…”

Section: Introductionmentioning

confidence: 99%

Demographic senescence and effects on population dynamics of a perennial plant

Edelfeldt

Bengtsson

Dahlgren

2019

Ecology

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Citation: Edelfeldt, S., K. Bengtsson, and J. P. Dahlgren. 2019. Demographic senescence and effects on population dynamics of a perennial plant. Ecology 100 (8):Abstract. Demographic rates in plants are usually assumed to be more stage or size dependent than age dependent, and aging is therefore not considered in demographic models. However, little is known about the effect of age on demographic rates, as there still are few studies based on long-term individual-based plant population data that consider both individual age and size. In addition, little is known about how aging of individuals may affect population dynamics. We present analyses of demographic data for three populations of Fumana procumbens collected 1985-2013, on individuals with known year of germination. We modeled age-and size-dependence of the vital rates of survival, growth, fruiting probability, and fruit number using thin plate spline regressions, and constructed an age 9 size integral projection model (IPM) to project population-level effects of aging. We found strong correlations between age and vital rates in solely age-based vital rate models, where vital rates initially increased with age, after which they stabilized and, in some cases, eventually declined. In survival models with both age and size, the effects of age were statistically significant, whereas size effects were insignificant at two of the sites. For other vital rates, most of the effect of age could be explained by size alone. In addition, including the age effects on survival in the IPM led to lower population growth rates compared to predictions of a size-only IPM. These results illustrate that demographic senescence does occur in perennial plants, which has only been demonstrated clearly in a few recent detailed studies. Moreover, we show that population projections may be overly optimistic if they do not consider plant age. We conclude that the possibility of demographic senescence should be considered in demographic population models, such as those used in viability analyses of threatened species.

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Senescence: Is It Universal or Not?

Cited by 34 publications

References 48 publications

Adaptation of the Long-Lived Monocarpic Perennial, Saxifraga longifolia to High Altitude

Adaptation of the Long-Lived Monocarpic Perennial, Saxifraga longifolia to High Altitude

Fire‐induced deforestation in drought‐prone Mediterranean forests: drivers and unknowns from leaves to communities

Demographic senescence and effects on population dynamics of a perennial plant

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