No abstract

The ability to accurately assess liana (woody vine) infestation at the landscape level is essential to quantify their impact on carbon dynamics and help inform targeted forest management and conservation action. Remote sensing techniques provide potential solutions for assessing liana infestation at broader spatial scales. However, their use so far has been limited to seasonal forests, where there is a high spectral contrast between lianas and trees. Additionally, the ability to align the spatial units of remotely sensed data with canopy observations of liana infestation requires further attention. We combined airborne hyperspectral and LiDAR data with a neural network machine learning classification to assess the distribution of liana infestation at the landscape-level across an aseasonal primary forest in Sabah, Malaysia. We tested whether an object-based classification was more effective at predicting liana infestation when compared to a pixel-based classification. We found a stronger relationship between predicted and observed liana infestation when using a pixel-based approach (RMSD = 27.0% AE 0.80) in comparison to an object-based approach (RMSD = 32.6% AE 4.84). However, there was no significant difference in accuracy for object-versus pixel-based classifications when liana infestation was grouped into three classes; Low [0-30%], Medium [31-69%] and High [70-100%] (McNemar's χ 2 = 0.211, P = 0.65). We demonstrate, for the first time, that remote sensing approaches are effective in accurately assessing liana infestation at a landscape scale in an aseasonal tropical forest. Our results indicate potential limitations in object-based approaches which require refinement in order to accurately segment imagery across contiguous closed-canopy forests. We conclude that the decision on whether to use a pixel-or object-based approach may depend on the structure of the forest and the ultimate application of the resulting output. Both approaches will provide a valuable tool to inform effective conservation and forest management.

mate attraction [ 35 ] and predator deterrents. [ 33,[36][37][38] In fl owers, structural color is hypothesized to function in relation to attracting potential pollinators. [ 20 ] However, in organisms such as algae the function of structural color remains unclear.Marine macroalgae (red, brown and green seaweeds) represent a large, diverse group of organisms within the marine kingdom. To date, around 11,000 species of marine algae have been described, however it is suggested that around 10,000 species are still undescribed (Mike Guiry pers. comm.; see further in ref. [ 39 ] ). Red (Rhodophyta) and green (Chlorophyta) algae originated from the primary endosymbiosis of cyanobacteria around 1500 Mya. [ 40 ] In comparison, the divergence of the brown algae (Phaeophyceae), as a consequence of secondary endosymbiosis, occurred relatively recently, at around 200 Mya ( Figure 1 ). [ 41 ] Marine algae play a major role in the functionality of coastal ecosystems, [ 42 ] provide a signifi cant contribution towards global carbon fi xation, [ 43 ] contribute to stable food sources, [ 44 ] and are employed in various health [ 45 ] and medicinal [ 46 ] products. Considering the global importance of marine algae and the current declines that many populations face as a result of environmental degradation, [47][48][49] understanding their structural color may reveal adaptation strategies useful in relation to global environmental change. For example, similarly to leaves, [ 50,51 ] structural color in algae may serve to protect species from ultraviolet radiation which may be benefi cial considering continual ozone damage. Assuming this hypothesis, structural color may be useful in predicting marine species composition in the future.Despite the lack of understanding on the biological purpose of structural color, marine algae have received very little attention within this fi eld, most likely as their colors do not function for a communicative purpose. [ 32 ] Subsequently, only a few studies have attempted to work on and identify the mechanisms responsible for producing structural color and they have mainly focused on the red algae (Rhodophyta), where intracellular [ 52 ] and extracellular [ 29 ] structures have been observed. For example, in the red alga, Chondrus crispus Stackhouse [ 53 ] (Rhodophyta), it has been shown that structural color is produced by a multilayered structure in the cuticle with refractive-index periodicity. [ 29 ] Furthermore, virtually no studies have attempted to investigate the vivid and diverse array of structural color patterns found within the brown algae (Phaeophyceae). It has been suggested that intracellular quasi-ordered spherical inclusions in the epidermal cells termed 'iridescent bodies' are responsible for the observed structural color, [ 54 ] however there is no clear experimental evidence that correlates these bodies with the optical appearance.In this progress report, we describe the mechanisms of color production in marine algae and compare them to those Structural coloration is widespread ...

The factors that limit the maximum height of trees, whether ecophysiological or mechanical, are the subject of longstanding debate. Here, we examine the role of mechanical stability in limiting tree height and focus on trees from the tallest tropical forests on Earth, in Sabah, Malaysian Borneo, including the recently discovered tallest tropical tree, a 100.8 m Shorea faguetiana named Menara. We use terrestrial laser scans, in situ strain gauge data and finite element simulations, to map the architecture of tall tropical trees and monitor their response to wind loading. We demonstrate that a tree's risk of breaking due to gravity or self‐weight decreases with tree height and is much more strongly affected by tree architecture than by material properties. In contrast, wind damage risk increases with tree height despite the larger diameters of tall trees, resulting in a U‐shaped curve of mechanical risk with tree height. Our results suggest that the relative rarity of extreme wind speeds in north Borneo may be the reason it is home to the tallest trees in the tropics. Abstract in MALAY is available with online material.