The Influence of Ecosystem and Phylogeny on Tropical Tree Crown Size and Shape

1ABSTRACTThe sizes and shapes of tree crowns are of fundamental importance in ecology, yet understanding the forces that determine them remains elusive. A cardinal question facing ecologists is the degree to which general and non-specific versus ecological and context-dependent processes are responsible for shaping tree crowns. Here, we test this question for the first time across diverse tropical ecosystems. Using trees from 20 plots varying in elevation, precipitation, and ecosystem type (savanna-forest transitions) across the paleo- and neo-tropics, we test the relationship between crown dimensions and tree size. By analyzing these scaling relationships across environmental gradients, biogeographic regions, and phylogenetic distance, we extend Metabolic Scaling Theory (MST) predictions to include how local selective pressures shape variation in crown dimensions. Across all sites, we find strong agreement between mean trends and MST predictions for the scaling of crown size and shape, but large variation around the mean. While MST explained approximately half of the observed variation in tree crown dimensions, we find that local, ecosystem, and phylogenetic predictors account for the half of the residual variation. Crown scaling does not change significantly across regions, but does change across ecosystem types, where savanna tree crowns grow more quickly with tree size than forest tree crowns. Crowns of legumes were wider and larger than those of other taxa. Thus, while MST can accurately describe the central tendency of tree crown size, local ecological conditions and evolutionary history appear to modify the scaling of crown shape. Importantly, our extension of MST incorporating these differences accounts for the mechanisms driving variation in the scaling of crown dimensions across the tropics. These results are critical when scaling the function of individual trees to larger spatial scales or incorporating the size and shape of tree crowns in global biogeochemical models.

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The Influence of Ecosystem and Phylogeny on Tropical Tree Crown Size and Shape

Frontiers in Forests and Global Change ◽

10.3389/ffgc.2020.501757 ◽

2020 ◽

Vol 3 ◽

Cited By ~ 1

Author(s):

Alexander Shenkin ◽

Lisa Patrick Bentley ◽

Imma Oliveras ◽

Norma Salinas ◽

Stephen Adu-Bredu ◽

...

Keyword(s):

Tropical Tree ◽

Tree Crown ◽

Size And Shape ◽

Crown Size

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Deriving Tree Size Distributions of Tropical Forests from Lidar

Remote Sensing ◽

10.3390/rs13010131 ◽

2021 ◽

Vol 13 (1) ◽

pp. 131

Author(s):

Franziska Taubert ◽

Rico Fischer ◽

Nikolai Knapp ◽

Andreas Huth

Keyword(s):

Size Distribution ◽

Spatial Scales ◽

Basal Area ◽

Tree Height ◽

Tree Size ◽

Diameter Distribution ◽

Forest Inventories ◽

Allometric Relations ◽

Lidar Measurements ◽

Derived Data

Remote sensing is an important tool to monitor forests to rapidly detect changes due to global change and other threats. Here, we present a novel methodology to infer the tree size distribution from light detection and ranging (lidar) measurements. Our approach is based on a theoretical leaf–tree matrix derived from allometric relations of trees. Using the leaf–tree matrix, we compute the tree size distribution that fit to the observed leaf area density profile via lidar. To validate our approach, we analyzed the stem diameter distribution of a tropical forest in Panama and compared lidar-derived data with data from forest inventories at different spatial scales (0.04 ha to 50 ha). Our estimates had a high accuracy at scales above 1 ha (1 ha: root mean square error (RMSE) 67.6 trees ha−1/normalized RMSE 18.8%/R² 0.76; 50 ha: 22.8 trees ha−1/6.2%/0.89). Estimates for smaller scales (1-ha to 0.04-ha) were reliably for forests with low height, dense canopy or low tree height heterogeneity. Estimates for the basal area were accurate at the 1-ha scale (RMSE 4.7 tree ha−1, bias 0.8 m² ha−1) but less accurate at smaller scales. Our methodology, further tested at additional sites, provides a useful approach to determine the tree size distribution of forests by integrating information on tree allometries.

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The Effect of Crown Dimensions on Stem Profile for Dahurian Larch, Korean Spruce, and Manchurian Fir in Northeast China

Forests ◽

10.3390/f12040398 ◽

2021 ◽

Vol 12 (4) ◽

pp. 398

Author(s):

Amna Hussain ◽

Muhammad Khurram Shahzad ◽

Lichun Jiang

Keyword(s):

Northeast China ◽

Least Squares Method ◽

Model Fitting ◽

Nonlinear Least Squares ◽

Dahurian Larch ◽

Fit Statistics ◽

Crown Length ◽

Crown Shape ◽

Natural Stands ◽

Crown Dimensions

Crown architecture has long been evaluated for its impact on taper modeling. However, most of the research has focused on a limited number of crown dimensions. This study examined the effect of adding several crown dimensions in improving the diameter and volume estimates of Dahurian larch, Korean spruce, and Manchurian fir in northeast China. The crown dimensions included crown length, crown ratio, crown width, height to live crown base, diameter at the crown base, and crown shape. A well-known taper model of Clark et al. (1991) was fitted to the data of 276 trees from natural stands. To adjust the inherent autocorrelation in the data, we added a third-order continuous-time error structure in the model fit. Model fitting was carried out with the NLMIXED procedure (Non-linear Mixed Procedure), followed by the MODEL procedure of SAS using the generalized nonlinear least-squares method. Fit statistics and graphical assessments were used to evaluate the original and modified models. Above 98% of the total variance of d was explained by the models for all species. The addition of crown variables showed slight improvements for root mean square error (RMSE) values in the analyzed species. The RMSE plots indicated that the models with crown variables slightly improved the diameter and volume predictions for the species but only for the upper stem (>50%–90%). The study demonstrated that crown dimensions influence the stem taper, but the original model of Clark et al. (1991) reasonably realized that effect.

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Estimating tree crown dimensions using digital analysis of vertical photographs

Agricultural and Forest Meteorology ◽

10.1016/s0168-1923(99)00138-0 ◽

2000 ◽

Vol 100 (2-3) ◽

pp. 199-212 ◽

Cited By ~ 14

Author(s):

P.L. Brown ◽

D. Doley ◽

R.J. Keenan

Keyword(s):

Digital Analysis ◽

Tree Crown ◽

Crown Dimensions

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Substantial hysteresis in emergent temperature sensitivity of global wetland CH4 emissions

Nature Communications ◽

10.1038/s41467-021-22452-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Kuang-Yu Chang ◽

William J. Riley ◽

Sara H. Knox ◽

Robert B. Jackson ◽

Gavin McNicol ◽

...

Keyword(s):

Temperature Sensitivity ◽

Spatial Scales ◽

Biogeochemical Model ◽

Spatial And Temporal Variability ◽

Biogeochemical Models ◽

Model Parameterization ◽

Machine Learning Model ◽

Meta Analyses ◽

The Relationship ◽

Global Carbon

AbstractWetland methane (CH4) emissions ($${F}_{{{CH}}_{4}}$$ F C H 4 ) are important in global carbon budgets and climate change assessments. Currently, $${F}_{{{CH}}_{4}}$$ F C H 4 projections rely on prescribed static temperature sensitivity that varies among biogeochemical models. Meta-analyses have proposed a consistent $${F}_{{{CH}}_{4}}$$ F C H 4 temperature dependence across spatial scales for use in models; however, site-level studies demonstrate that $${F}_{{{CH}}_{4}}$$ F C H 4 are often controlled by factors beyond temperature. Here, we evaluate the relationship between $${F}_{{{CH}}_{4}}$$ F C H 4 and temperature using observations from the FLUXNET-CH4 database. Measurements collected across the globe show substantial seasonal hysteresis between $${F}_{{{CH}}_{4}}$$ F C H 4 and temperature, suggesting larger $${F}_{{{CH}}_{4}}$$ F C H 4 sensitivity to temperature later in the frost-free season (about 77% of site-years). Results derived from a machine-learning model and several regression models highlight the importance of representing the large spatial and temporal variability within site-years and ecosystem types. Mechanistic advancements in biogeochemical model parameterization and detailed measurements in factors modulating CH4 production are thus needed to improve global CH4 budget assessments.

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Spatial scale-dependent land–atmospheric methane exchanges in the northern high latitudes from 1993 to 2004

Biogeosciences ◽

10.5194/bg-11-1693-2014 ◽

2014 ◽

Vol 11 (7) ◽

pp. 1693-1704 ◽

Cited By ~ 20

Author(s):

X. Zhu ◽

Q. Zhuang ◽

X. Lu ◽

L. Song

Keyword(s):

Spatial Heterogeneity ◽

Spatial Scale ◽

Water Table ◽

Spatial Scales ◽

Grid Cell ◽

High Latitudes ◽

Atmospheric Methane ◽

Ch4 Emissions ◽

Biogeochemical Models ◽

Macro Scale

Abstract. Effects of various spatial scales of water table dynamics on land–atmospheric methane (CH4) exchanges have not yet been assessed for large regions. Here we used a coupled hydrology–biogeochemistry model to quantify daily CH4 exchanges over the pan-Arctic from 1993 to 2004 at two spatial scales of 100 km and 5 km. The effects of sub-grid spatial variability of the water table depth (WTD) on CH4 emissions were examined with a TOPMODEL-based parameterization scheme for the northern high latitudes. We found that both WTD and CH4 emissions are better simulated at a 5 km spatial resolution. By considering the spatial heterogeneity of WTD, net regional CH4 emissions at a 5 km resolution are 38.1–55.4 Tg CH4 yr−1 from 1993 to 2004, which are on average 42% larger than those simulated at a 100 km resolution using a grid-cell-mean WTD scheme. The difference in annual CH4 emissions is attributed to the increased emitting area and enhanced flux density with finer resolution for WTD. Further, the inclusion of sub-grid WTD spatial heterogeneity also influences the inter-annual variability of CH4 emissions. Soil temperature plays an important role in the 100 km estimates, while the 5 km estimates are mainly influenced by WTD. This study suggests that previous macro-scale biogeochemical models using a grid-cell-mean WTD scheme might have underestimated the regional CH4 emissions. The spatial scale-dependent effects of WTD should be considered in future quantification of regional CH4 emissions.

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Simulating natural carbon sequestration in the Southern Ocean: on uncertainties associated with eddy parameterizations and iron deposition

Biogeosciences ◽

10.5194/bg-14-1561-2017 ◽

2017 ◽

Vol 14 (6) ◽

pp. 1561-1576 ◽

Cited By ~ 3

Author(s):

Heiner Dietze ◽

Julia Getzlaff ◽

Ulrike Löptien

Keyword(s):

Carbon Sequestration ◽

Southern Ocean ◽

Ocean Circulation ◽

Spatial Scales ◽

Carbon Uptake ◽

Comprehensive Understanding ◽

Biogeochemical Models ◽

Anthropogenic Carbon ◽

Natural Carbon ◽

Oceanic Carbon

Abstract. The Southern Ocean is a major sink for anthropogenic carbon. Yet, there is no quantitative consensus about how this sink will change when surface winds increase (as they are anticipated to do). Among the tools employed to quantify carbon uptake are global coupled ocean-circulation–biogeochemical models. Because of computational limitations these models still fail to resolve potentially important spatial scales. Instead, processes on these scales are parameterized. There is concern that deficiencies in these so-called eddy parameterizations might imprint incorrect sensitivities of projected oceanic carbon uptake. Here, we compare natural carbon uptake in the Southern Ocean simulated with contemporary eddy parameterizations. We find that very differing parameterizations yield surprisingly similar oceanic carbon in response to strengthening winds. In contrast, we find (in an additional simulation) that the carbon uptake does differ substantially when the supply of bioavailable iron is altered within its envelope of uncertainty. We conclude that a more comprehensive understanding of bioavailable iron dynamics will substantially reduce the uncertainty of model-based projections of oceanic carbon uptake.

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Spatial analysis of phylogenetic community structure: New version of a classical method

10.7287/peerj.preprints.927 ◽

2015 ◽

Author(s):

Carlo Ricotta ◽

Eszter EA Ari ◽

Giuliano Bonanomi ◽

Francesco Giannino ◽

Duncan Heathfield ◽

...

Keyword(s):

Community Structure ◽

Spatial Scales ◽

Point Pattern ◽

Maximum Deviation ◽

Individual Plant ◽

Phylogenetic Distance ◽

Phylogenetic Structure ◽

Phylogenetic Community Structure ◽

Point Patterns ◽

Wide Range

The increasing availability of phylogenetic information facilitates the use of evolutionary methods in community ecology to reveal the importance of evolution in the species assembly process. However, while several methods have been applied to a wide range of communities across different spatial scales with the purpose of detecting non-random phylogenetic patterns, the spatial aspects of phylogenetic community structure have received far less attention. Accordingly, the question for this study is: can point pattern analysis be used for revealing the phylogenetic structure of multi-species assemblages? We introduce a new individual-centered procedure for analyzing the scale-dependent phylogenetic structure of multi-species point patterns based on digitized field data. The method uses nested circular plots with increasing radii drawn around each individual plant and calculates the mean phylogenetic distance between the focal individual and all individuals located in the circular ring delimited by two successive radii. This scale-dependent value is then averaged over all individuals of the same species and the observed mean is compared to a null expectation with permutation procedures. The method detects particular radius values at which the point pattern of a single species exhibits maximum deviation from the expectation towards either phylogenetic aggregation or segregation. Its performance is illustrated using data from a grassland community in Hungary and simulated point patterns. The proposed method can be extended to virtually any distance function for species pairs, such as functional distances.

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Tree crowns grow into self-similar shapes controlled by gravity and light sensing

Journal of The Royal Society Interface ◽

10.1098/rsif.2017.0976 ◽

2018 ◽

Vol 15 (142) ◽

pp. 20170976 ◽

Cited By ~ 5

Author(s):

Laurent Duchemin ◽

Christophe Eloy ◽

Eric Badel ◽

Bruno Moulia

Keyword(s):

Tree Growth ◽

Initial Conditions ◽

Tree Crown ◽

Tree Crowns ◽

Light Sensing ◽

The Core ◽

Long Period ◽

Self Similar ◽

Wind Loading on Scaled Down Fractal Tree Models of Major Urban Tree Species in Singapore

Forests ◽

10.3390/f11080803 ◽

2020 ◽

Vol 11 (8) ◽

pp. 803

Author(s):

Woei-Leong Chan ◽

Yong Eng ◽

Zhengwei Ge ◽

Chi Wan Calvin Lim ◽

Like Gobeawan ◽

...

Keyword(s):

Wind Tunnel ◽

Tree Species ◽

Experimental Studies ◽

Velocity Profiles ◽

Aerodynamic Load ◽

Tree Crowns ◽

Urban Tree ◽

Crown Shape ◽

Optical Porosity ◽

Tree Models

Estimation of the aerodynamic load on trees is essential for urban tree management to mitigate the risk of tree failure. To assess that in a cost-effective way, scaled down tree models and numerical simulations were utilized. Scaled down tree models reduce the cost of experimental studies and allow the studies to be conducted in a controlled environment, namely in a wind or water tunnel, but the major challenge is to construct a tree model that resembles the real tree. We constructed 3D-printed scaled down fractal tree models of major urban tree species in Singapore using procedural modelling, based on species-specific growth processes and field statistical data gathered through laser scanning of real trees. The tree crowns were modelled to match the optical porosity of real trees. We developed a methodology to model the tree crowns using porous volumes filled with randomized tetrahedral elements. The wind loads acting on the tree models were then measured in the wind tunnel and the velocity profiles from selected models were captured using particle image velocimetry (PIV). The data was then used for the validation of Large Eddy Simulations (LES), in which the trees were modelled via a discretized momentum sink with 10–20 elements in width, height, and depth, respectively. It is observed that the velocity profiles and drag of the simulations and the wind tunnel tests are in reasonable agreement. We hence established a clear relationship between the measured bulk drag on the tree models in the wind tunnel, and the local drag coefficients of the discretized elements in the simulations. Analysis on the bulk drag coefficient also shows that the effect of complex crown shape could be more dominant compared to the frontal optical porosity.

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