Tree diversity in relation to tree height: alternative perspectives

Givnish, Thomas J.

doi:10.1111/ele.12693

Cited by 4 publications

(5 citation statements)

References 24 publications

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“…This initial positive trend up to a certain threshold has been reported in many studies at different scales [19,60], while the negative decline after this threshold for excessive water supply was observed and reported in others [12]. Herein, the results confirm the findings of [12], who used space LiDAR to examine the same relationship on a global scale and inventory data at national scale; these authors depicted a peak of maximum height at 680 mm P-PET gradient (compared with 800 mm in our study) and a declining trend at higher P-PET.…”

Section: Water Availabilitysupporting

confidence: 76%

Analyzing Canopy Height Patterns and Environmental Landscape Drivers in Tropical Forests Using NASA’s GEDI Spaceborne LiDAR

et al. 2022

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Canopy height is a fundamental parameter for determining forest ecosystem functions such as biodiversity and above-ground biomass. Previous studies examining the underlying patterns of the complex relationship between canopy height and its environmental and climatic determinants suffered from the scarcity of accurate canopy height measurements at large scales. NASA’s mission, the Global Ecosystem Dynamic Investigation (GEDI), has provided sampled observations of the forest vertical structure at near global scale since late 2018. The availability of such unprecedented measurements allows for examining the vertical structure of vegetation spatially and temporally. Herein, we explore the most influential climatic and environmental drivers of the canopy height in tropical forests. We examined different resampling resolutions of GEDI-based canopy height to approximate maximum canopy height over tropical forests across all of Malaysia. Moreover, we attempted to interpret the dynamics underlining the bivariate and multivariate relationships between canopy height and its climatic and topographic predictors including world climate data and topographic data. The approaches to analyzing these interactions included machine learning algorithms, namely, generalized linear regression, random forest and extreme gradient boosting with tree and Dart implementations. Water availability, represented as the difference between precipitation and potential evapotranspiration, annual mean temperature and elevation gradients were found to be the most influential determinants of canopy height in Malaysia’s tropical forest landscape. The patterns observed are in line with the reported global patterns and support the hydraulic limitation hypothesis and the previously reported negative trend for excessive water supply. Nevertheless, different breaking points for excessive water supply and elevation were identified in this study, and the canopy height relationship with water availability observed to be less significant for the mountainous forest on altitudes higher than 1000 m. This study provides insights into the influential factors of tree height and helps with better comprehending the variation in canopy height in tropical forests based on GEDI measurements, thereby supporting the development and interpretation of ecosystem modeling, forest management practices and monitoring forest response to climatic changes in montane forests.

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Section: Water Availabilitysupporting

confidence: 76%

Analyzing Canopy Height Patterns and Environmental Landscape Drivers in Tropical Forests Using NASA’s GEDI Spaceborne LiDAR

et al. 2022

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“…When Givnish () suggests that analyses of the effects of tree height on tree diversity should control for environmental covariates of both, he appears to have misunderstood our approach. We did not argue that tree height has a direct effect on tree diversity, but rather that environmental harshness limits both tree diversity and maximum tree height in parallel ways, thus making tree height a good proxy for environmental harshness.…”

Section: Pearson Correlation Coefficients Of 100 × 100 Km2 Grid Cell mentioning

confidence: 99%

Section: Pearson Correlation Coefficients Of 100 × 100 Km2 Grid Cell mentioning

confidence: 99%

“…Givnish () agrees that greater maximum height is associated with an increase in the available trait space, but disagrees that this will necessarily result in more species coexisting, as a few dominant species may exclude others. Givnish () further argues that classic research by Whittaker (, ) is inconsistent with the harshness hypothesis because it shows a rise and then a decline in tree species richness with moisture. We argue that the harshness hypothesis predicts a decline in richness on the most hydric sites with soil hypoxia, as well as on late‐successional mesic sites in which the dense overstory has resulted in deep understory shade, an endogenously created environmental stress that can prevent seedling recruitment of some species (Marks et al .…”

Section: Pearson Correlation Coefficients Of 100 × 100 Km2 Grid Cell mentioning

confidence: 99%

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Tree diversity in relation to maximum tree height: evidence for the harshness hypothesis of species diversity gradients

2017

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“…A significant positive relation between tree species diversity and tree height, as a proxy for forest volume, was found, explaining a limited amount of the variance in tree species diversity within the USA and on a global scale (Marks et al 2016, Gatti et al 2017. However, Givnish (2017) objects that the use of just forest height leads to deceptive results since it only provides information on the potential trait space (volume below canopy) that could be occupied, but does not measure the occupation of this trait space. In this study we address this caveat by exploring the relation between tree species diversity and the vertical vegetation structure; hereafter referred to as the structure-diversity relationship.…”

Section: Introductionmentioning

confidence: 99%

Exploring the relation between remotely sensed vertical canopy structure and tree species diversity in Gabon

Marselis

Tang

Armston

et al. 2019

Environ. Res. Lett.

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Mapping tree species diversity is increasingly important in the face of environmental change and biodiversity conservation. We explore a potential way of mapping this diversity by relating forest structure to tree species diversity in Gabon. First, we test the relation between canopy height, as a proxy for niche volume, and tree species diversity. Then, we test the relation between vertical canopy structure, as a proxy for vertical niche occupation, and tree species diversity. We use large footprint full-waveform airborne lidar data collected across four study sites in Gabon (Lopé, Mabounié, Mondah, and Rabi) in combination with in situ estimates of species richness (S) and Shannon diversity (H′). Linear models using canopy height explained 44% and 43% of the variation in S and H′ at the 0.25 ha resolution. Linear models using canopy height and the plant area volume density profile explained 71% of this variation. We demonstrate applications of these models by mapping S and H′ in Mondah using a simulated GEDI-TanDEM-X fusion height product, across the four sites using wallto-wall airborne lidar data products, and across and between the study sites using ICESat lidar waveforms. The modeling results are encouraging in the context of developing pan-tropical structurediversity models applicable to data from current and upcoming spaceborne remote sensing missions.

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Tree diversity in relation to tree height: alternative perspectives

Cited by 4 publications

References 24 publications

Analyzing Canopy Height Patterns and Environmental Landscape Drivers in Tropical Forests Using NASA’s GEDI Spaceborne LiDAR

Analyzing Canopy Height Patterns and Environmental Landscape Drivers in Tropical Forests Using NASA’s GEDI Spaceborne LiDAR

Tree diversity in relation to maximum tree height: evidence for the harshness hypothesis of species diversity gradients

Exploring the relation between remotely sensed vertical canopy structure and tree species diversity in Gabon

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