scholarly journals Intraspecific root and leaf trait variation with tropical forest successional status: consequences for community-weighted patterns

2019 ◽  
Author(s):  
J. Aaron Hogan ◽  
Oscar J. Valverde-Barrantes ◽  
Qiong Ding ◽  
Han Xu ◽  
Christopher Baraloto

SummaryQuantifying the dimensions and magnitude of intraspecific root trait variation is key to understanding the functional trade-offs in the belowground plant strategies of tropical forest trees. Additionally, accurately measuring how belowground functional trait variation relates to soil environment and forest age is crucial to tropical forest modeling efforts.We sampled leaf and root morphologies from 423 juvenile trees of 72 species from 14 Angiosperm families along a 6.6 km transect that corresponded to an environmental gradient in decreasing soil fertility and texture with increasing forest age.We observed within-lineage conservative functional trait-shifts in root and leaf morphological traits along the transect. From secondary to primary forest, average leaf area increased 7 cm2and average root system diameter increased 0.4 mm. Mean specific leaf area decreased by 0.8 m2kg−1, specific root length decreased by 3.5 m kg−1, and root branching intensity decreased by 0.3 tips cm−1. Leaf thickness and root tissue density showed no change.We coupled trait measurements to a network of 164 1/16th-ha plots across a Chinese tropical forest reserve, to scale individual trait measurements up to the community-level, accounting for forest age.For most traits, intraspecific trait variation negatively covaried with species compositional turnover between plots in younger versus older forest to compound and create greater community-weighted differences in trait values than would be observed if intraspecific variation in traits with forest age was not accounted for.SummaryRoot morphologies are variable with local scale variation in soil fertility and texture. Accurately understanding broader (i.e. forest)-scale patterns in root functional traits, requires attention to underlying environmental variation in soil resources, which interacts with environmental filtering of plant communities.

2021 ◽  
Author(s):  
J. Aaron Hogan ◽  
Han Xu ◽  
Christopher Baraloto

Abstract Accounting for intraspecific trait variation (ITV) is central to plant ecology and crucial for vegetation modeling efforts. ITV can be substantial; however, it remains unclear how ITV influences community-weighted mean (CWM) trait estimates. We use leaf and root trait data from 423 trees of 72 species from 15 Angiosperm families in combination with community data from 164 small plots comprising 582 species to evaluate the contribution of ITV to CWMs, comparing unlogged, primary forest to selectively-logged and clear-cut secondary forest. We examine the effect of gap-filling missing trait values via phylogenetic generalized linear modeling (PhyloPars) on CWMs. For six of seven traits, ITV negatively covaried with species turnover to generate larger CWM differences than observed if ITV was not integrated. For example, plot average CWM specific leaf area was 10.7 and 10.4 m2 kg− 1 for primary and secondary forest, not accounting for ITV, but shifted to 9.8 and 11.1 m2 kg− 1 after doing so. Specific root length showed a similar trend. Our results from 72-species assemblages were supported by the results from the gap-filled analysis using the entire community, where the contribution of ITV to CWMs ranged from 25 to 75%, with nearly all trait variation due to forest type attributable to ITV. Therefore, CWM trait estimates became more-conservative with forest age, whereas ITV for many traits showed an acquisitive shift, and because of negative covariation between ITV and species turnover, forest age-related CWM differences increased. Differences were unaffected, if not strengthened, by gap-filling incomplete functional trait matrices.


2018 ◽  
Author(s):  
Elias Ehrlich ◽  
Nadja J. Kath ◽  
Ursula Gaedke

Functional trait compositions of communities can adapt to altered environmental conditions ensuring community persistence. Theory predicts that the shape of trade-offs between traits crucially affects these trait dynamics, but its empirical verification from the field is missing. Here, we show how the shape of a defense-growth trade-off governs seasonal trait dynamics of a natural community, using high-frequency, long-term measurements of phytoplankton from Lake Constance. As expected from the lab-derived concave trade-off curve, we observed an alternating dominance of several fast-growing species with intermediate defense levels and gradual changes of the biomass-trait distribution due to seasonally changing grazing pressure. By combining data and modelling, we obtain mechanistic insights on the underlying fitness landscape, and show that low fitness differences can maintain trait variation along the trade-off curve. We provide firm evidence for a frequently assumed trade-off and conclude that quantifying its shape allows to understand environmentally driven trait changes within communities.


2012 ◽  
Vol 28 (5) ◽  
pp. 527-530 ◽  
Author(s):  
Carl F. Salk

Plants have an inherent flexibility to respond to different environmental conditions. One axis of plant ecophysiological strategy is seen in the spectrum of leaf functional traits. Flexibility in these traits would be suggestive of plants’ phenotypic plasticity in response to environmental changes. This research seeks to identify differences between leaves of sprout and non-sprout shoots of a broad ecological range of neotropical tree species. Using a functional-trait approach, this study assesses a large pool of species for within-species physiological flexibility. Leaf mass per area (LMA) and leaf area were measured for plants of sprout and non-sprout origin for 26 tree species grown in a reforestation plantation in Panama. Sprouts had a consistently lower LMA than non-sprouts, but there was no consistent pattern for leaf area. These trends show that sprouts are more like pioneer species than conspecific saplings, a finding in general agreement with fast sprout growth seen in previous studies. Further, later-successional (high LMA) species showed a greater reduction of LMA in sprouts. These results show that tropical tree species adjust physiologically to changing ecological roles and suggest that certain species may be more resilient than realized to changing climate and disturbance patterns.


2021 ◽  
Vol 118 (37) ◽  
pp. e2103162118 ◽  
Author(s):  
Olivia L. Cope ◽  
Ken Keefover-Ring ◽  
Eric L. Kruger ◽  
Richard L. Lindroth

All organisms experience fundamental conflicts between divergent metabolic processes. In plants, a pivotal conflict occurs between allocation to growth, which accelerates resource acquisition, and to defense, which protects existing tissue against herbivory. Trade-offs between growth and defense traits are not universally observed, and a central prediction of plant evolutionary ecology is that context-dependence of these trade-offs contributes to the maintenance of intraspecific variation in defense [Züst and Agrawal, Annu. Rev. Plant Biol., 68, 513–534 (2017)]. This prediction has rarely been tested, however, and the evolutionary consequences of growth–defense trade-offs in different environments are poorly understood, especially in long-lived species [Cipollini et al., Annual Plant Reviews (Wiley, 2014), pp. 263–307]. Here we show that intraspecific trait trade-offs, even when fixed across divergent environments, interact with competition to drive natural selection of tree genotypes corresponding to their growth–defense phenotypes. Our results show that a functional trait trade-off, when coupled with environmental variation, causes real-time divergence in the genetic architecture of tree populations in an experimental setting. Specifically, competitive selection for faster growth resulted in dominance by fast-growing tree genotypes that were poorly defended against natural enemies. This outcome is a signature example of eco-evolutionary dynamics: Competitive interactions affected microevolutionary trajectories on a timescale relevant to subsequent ecological interactions [Brunner et al., Funct. Ecol. 33, 7–12 (2019)]. Eco-evolutionary drivers of tree growth and defense are thus critical to stand-level trait variation, which structures communities and ecosystems over expansive spatiotemporal scales.


2021 ◽  
Author(s):  
Florian Hofhansl ◽  
Eduardo Chacón‐Madrigal ◽  
Åke Brännström ◽  
Ulf Dieckmann ◽  
Oskar Franklin

Ecology ◽  
2019 ◽  
Vol 100 (3) ◽  
Author(s):  
Ian R. McFadden ◽  
Megan K. Bartlett ◽  
Thorsten Wiegand ◽  
Benjamin L. Turner ◽  
Lawren Sack ◽  
...  

Author(s):  
Henrique Fürstenau Togashi ◽  
Owen K. Atkin ◽  
Keith J. Bloomfield ◽  
Matt Bradford ◽  
Kunfang Cao ◽  
...  

2013 ◽  
Vol 10 (11) ◽  
pp. 6769-6781 ◽  
Author(s):  
E. Lobo ◽  
J. W. Dalling

Abstract. Treefall gaps are the major source of disturbance in most tropical forests. The frequency and size of these gaps have important implications for forest ecosystem processes as they can influence the functional trait distribution of tree communities, stand-level aboveground biomass and productivity. However, we still know little about the relative importance of environmental drivers of gap disturbance regimes because existing studies vary greatly in criteria used for defining gaps, in the spatial extent of the study area, and the spatial resolution of canopy height measurements. Here we use lidar (light detecting and ranging) to explore how forest age, topography and soil type affect canopy disturbance patterns across a 1500 ha tropical forest landscape in central Panama. We characterize disturbance based on the frequency distribution of gap sizes (the "gap size distribution"), and the area of the forest affected by gaps (the "gap area fraction"). We found that slope and forest age had significant effects on the gap size distribution, with a higher frequency of large gaps associated with old-growth forests and more gentle slopes. Slope and forest age had similar effects on the gap area fraction, however gap area fraction was also affected by soil type and by aspect. We conclude that variation in disturbance patterns across the landscape can be linked to factors that act at the fine scale (such as aspect or slope), and factors that show heterogeneity at coarser scales (such as forest age or soil type). Awareness of the role of different environmental factors influencing gap formation can help scale up the impacts of canopy disturbance on forest communities measured at the plot scale to landscape and regional scales.


2021 ◽  
Vol 12 ◽  
Author(s):  
Caishuang Huang ◽  
Yue Xu ◽  
Runguo Zang

Understanding how environmental change alters the composition of plant assemblages is a major challenge in the face of global climate change. Researches accounting for site-specific trait values within forest communities help bridge plant economics theory and functional biogeography to better evaluate and predict relationships between environment and ecosystem functioning. Here, by measuring six functional traits (specific leaf area, leaf dry matter content, leaf nitrogen, and phosphorus concentration, leaf nitrogen/phosphorus, wood density) for 292 woody plant species (48,680 individuals) from 250 established permanent forest dynamics plots in five locations across the subtropical evergreen broadleaved forests (SEBLF) in China, we quantified functional compositions of communities by calculating four trait moments, i.e., community-weighted mean, variance, skewness, and kurtosis. The geographical (latitudinal, longitudinal, and elevational) patterns of functional trait moments and their environmental drivers were examined. Results showed that functional trait moments shifted significantly along the geographical gradients, and trait moments varied in different ways across different gradients. Plants generally showed coordinated trait shifts toward more conservative growth strategies (lower specific leaf area, leaf N and P concentration while higher leaf nitrogen/phosphorus and wood density) along increasing latitude and longitude. However, trends opposite to the latitudinal and longitudinal patterns appeared in trait mean values along elevation. The three sets of environmental variables (climate, soil and topography) explained 35.0–69.0%, 21.0–56.0%, 14.0–31.0%, and 16.0–30.0% of the variations in mean, variance, skewness, and kurtosis across the six functional traits, respectively. Patterns of shifts in functional trait moments along geographical gradients in the subtropical region were mainly determined by the joint effects of climatic and edaphic conditions. Climate regimes, especially climate variability, were the strongest driving force, followed by soil nutrients, while topography played the least role. Moreover, the relationship of variance, skewness and kurtosis with climate and their geographical patterns suggested that rare phenotypes at edges of trait space were selected in harsher environments. Our study suggested that environmental filtering (especially climate variability) was the dominant process of functional assembly for forest communities in the subtropical region along geographical gradients.


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