The role of demographic compensation in stabilising marginal tree populations in North America

Yang, Xianyu; Angert, Amy L.; Zuidema, Pieter A.; He, Fangliang; Huang, Shongming; Li, Shouzhong; Li, Shou‐Li; Chardon, Nathalie Isabelle; Zhang, Jian

doi:10.1111/ele.14028

Cited by 13 publications

(7 citation statements)

References 81 publications

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“…The combination of all these three effects could explain the rebound effect in NDVI following the 1994-95 drought. However, compensation mechanisms have recently been shown to commonly fail in marginal tree populations in the long term, as has been reported in a study comprising more than fifty North American tree species (Yang et al, 2022).…”

Section: Fixed Factorsmentioning

confidence: 73%

Unexpected resilience in relict Abies pinsapo Boiss forests to dieback and mortality induced by climate change

et al. 2022

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Acute and early symptoms of forest dieback linked to climate warming and drought episodes have been reported for relict Abies pinsapo Boiss. fir forests from Southern Spain, particularly at their lower ecotone. Satellite, orthoimages, and field data were used to assess forest decline, tree mortality, and gap formation and recolonization in the lower half of the altitudinal range of A. pinsapo forests (850-1550 m) for the last 36 years (1985-2020). Field surveys were carried out in 2003 and in 2020 to characterize changes in stand canopy structure and mortality rates across the altitudinal range. Time series of the Normalized Difference Vegetation Index (NDVI) at the end of the dry season (derived from Landsat 5 and 7 imagery) were used for a Dynamic Factor Analysis to detect common trends across altitudinal bands and topographic solar incidence gradients (SI). Historical canopy cover changes were analyzed through aerial orthoimages classification. Here we show that extensive decline and mortality contrast to the almost steady alive basal area for 17 years, as well as the rising photosynthetic activity derived from NDVI since the mid-2000s and an increase in the forest canopy cover in the late years at mid and high altitudes. We hypothesized that these results suggest an unexpected resilience in A. pinsapo forests to climate change-induced dieback, that might be promoted by compensation mechanisms such as (i) recruitment of new A. pinsapo individuals; (ii) facilitative effects on such recruitment mediated by revegetation with other species; and (iii) a ‘release effect’ in which surviving trees can thrive with fewer resource competition. Future research is needed to understand these compensation mechanisms and their scope in future climate change scenarios.

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Section: Fixed Factorsmentioning

confidence: 73%

Unexpected resilience in relict Abies pinsapo Boiss forests to dieback and mortality induced by climate change

et al. 2022

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“…This approach let us overcome the challenge of modelling recruitment from forest inventory data alone and improve on previous tree population models that assume a fixed recruitment rate across all individuals (e.g. Yang et al, 2022).…”

Section: Methodsmentioning

confidence: 99%

Estimating the net effect of functional traits on fitness across species and environments

Siefert

Laughlin

2023

Methods Ecol Evol

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Functional traits affect the demographic performance of individuals in their environment, leading to fitness differences that scale up to drive population dynamics and community assembly. Understanding the links between traits and fitness is, therefore, critical for predicting how populations and communities respond to environmental change. However, the net effects of traits on species fitness are largely unknown because we have lacked a framework for estimating fitness across multiple species and environments. We present a modelling framework that integrates trait effects on demographic performance over the life cycles of individuals to estimate the net effect of traits on species fitness. This approach involves (1) modelling trait effects on individual demographic rates (growth, survival and recruitment) as multidimensional performance surfaces that vary with individual size and environment and (2) integrating these effects into a population model to project population growth rates (i.e., fitness) as a function of traits and environment. We illustrate our approach by estimating performance surfaces and fitness landscapes for trees across a temperature gradient in the eastern United States. Functional traits (wood density, specific leaf area and maximum height) interacted with individual size and temperature to influence tree growth, survival and recruitment rates, generating demographic trade‐offs and shaping the contours of fitness landscapes. Tall tree species had high survival, growth and fitness across the temperature gradient. Wood density and specific leaf area had interactive effects on demographic performance, resulting in fitness landscapes with multiple peaks. With this approach it is now possible to empirically estimate the net effect of traits on fitness, leading to an improved understanding of the selective forces that drive community assembly and permitting generalizable predictions of population and community dynamics in changing environments.

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“…Recently, several studies have assessed how population dynamics drive tree species distributions using National Forest Inventories (NFIs) (Kunstler et al, 2021; Le Squin et al, 2021; Purves, 2009; Schultz et al, 2022; Thuiller et al, 2014; Yang et al, 2022). However, to our knowledge, there have been no systematic tests of the respective roles of demographic and environmental stochasticity for range limits of tree species (but for shrub response to fire disturbance in South Africa, see Pagel et al, 2020), probably because most studies either ignored recruitment or assumed that it was independent of climate (Kunstler et al, 2021; Le Squin et al, 2021; but see Purves, 2009).…”

Section: Introductionmentioning

confidence: 99%

Beyond mean fitness: Demographic stochasticity and resilience matter at tree species climatic edges

Guyennon

Reineking

Salguero‐Gómez

et al. 2023

Global Ecol Biogeogr

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Aim Linking local population dynamics and species distributions is crucial to predicting the impacts of climate change. Although many studies focus on the mean fitness of populations, theory shows that species distributions can be shaped by demographic stochasticity or population resilience. Here, we examine how mean fitness (measured by invasion rate), demographic stochasticity and resilience (measured by the ability to recover from disturbance) constrain populations at the edges compared with the climatic centre. Location Europe: Spain, France, Germany, Finland and Sweden. Period Forest inventory data used for fitting the models cover the period from 1985 to 2013. Major taxa Dominant European tree species; angiosperms and gymnosperms. Methods We developed dynamic population models covering the entire life cycle of 25 European tree species with climatically dependent recruitment models fitted to forest inventory data. We then ran simulations using integral projection and individual‐based models to test how invasion rates, risk of stochastic extinction and ability to recover from stochastic disturbances differ between the centre and edges of the climatic niches of species. Results Results varied among species, but in general, demographic constraints were stronger at warm edges and for species in harsher climates. Conversely, recovery was more limiting at cold edges. In addition, we found that for several species, constraints at the edges were attributable to demographic stochasticity and capacity for recovery rather than mean fitness. Main conclusions Our results highlight that mean fitness is not the only mechanism at play at the edges; demographic stochasticity and population capacity to recover also matter for European tree species. To understand how climate change will drive species range shifts, future studies will need to analyse the interplay between population mean growth rate and stochastic demographic processes in addition to disturbances.

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The role of demographic compensation in stabilising marginal tree populations in North America

Cited by 13 publications

References 81 publications

Unexpected resilience in relict Abies pinsapo Boiss forests to dieback and mortality induced by climate change

Unexpected resilience in relict Abies pinsapo Boiss forests to dieback and mortality induced by climate change

Estimating the net effect of functional traits on fitness across species and environments

Beyond mean fitness: Demographic stochasticity and resilience matter at tree species climatic edges

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