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- Muscarella, Robert, et al.
(författare)
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The global abundance of tree palms
- 2020
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 29:9, s. 1495-1514
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Tidskriftsartikel (refereegranskat)abstract
- AimPalms are an iconic, diverse and often abundant component of tropical ecosystems that provide many ecosystem services. Being monocots, tree palms are evolutionarily, morphologically and physiologically distinct from other trees, and these differences have important consequences for ecosystem services (e.g., carbon sequestration and storage) and in terms of responses to climate change. We quantified global patterns of tree palm relative abundance to help improve understanding of tropical forests and reduce uncertainty about these ecosystems under climate change.LocationTropical and subtropical moist forests.Time periodCurrent.Major taxa studiedPalms (Arecaceae).MethodsWe assembled a pantropical dataset of 2,548 forest plots (covering 1,191 ha) and quantified tree palm (i.e., ≥10 cm diameter at breast height) abundance relative to co‐occurring non‐palm trees. We compared the relative abundance of tree palms across biogeographical realms and tested for associations with palaeoclimate stability, current climate, edaphic conditions and metrics of forest structure.ResultsOn average, the relative abundance of tree palms was more than five times larger between Neotropical locations and other biogeographical realms. Tree palms were absent in most locations outside the Neotropics but present in >80% of Neotropical locations. The relative abundance of tree palms was more strongly associated with local conditions (e.g., higher mean annual precipitation, lower soil fertility, shallower water table and lower plot mean wood density) than metrics of long‐term climate stability. Life‐form diversity also influenced the patterns; palm assemblages outside the Neotropics comprise many non‐tree (e.g., climbing) palms. Finally, we show that tree palms can influence estimates of above‐ground biomass, but the magnitude and direction of the effect require additional work.ConclusionsTree palms are not only quintessentially tropical, but they are also overwhelmingly Neotropical. Future work to understand the contributions of tree palms to biomass estimates and carbon cycling will be particularly crucial in Neotropical forests.
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- Lawes, Simon D. A., et al.
(författare)
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Performance of fullerene-like CNx coatings for automotive valve-train applications
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The design of internal combustion engines is evolving in order to provide greater efficiency and lower harmful emissions. There has been a move to lower component masses, higher engine temperatures, lower viscosity oils and low SAPS (sulphated ash, phosphor and sulphur) oils. With the transition to low density, low hardness materials and new lubrication conditions, come issues of component wear. Surface engineering techniques such as thin-film coating technologies present a possible solution. Thin-film coating development in recent years has often focused on achieving a high hardness, which often leads to high elastic modulus. However, there are potential benefits of less stiff and more elastic coatings. A number of wear mechanism are directly related to the ratio of hardness (H) and elastic modulus (E) and higher H/E ratios can be beneficial. This work therefore investigates the potential for using a highly elastic, experimental fullerene-like carbon nitride (FL-CNx) coating in a valve-train environment. Two FL-CNx coatings of differing nitrogen content were investigated using microscopy, wear testing, nanoindentation testing and in an experimental cam-tappet testing rig. The two FL-CNx coatings had similar adhesion to the substrate and hardness. The FL-CNx coating with the higher value of H/E also showed greater durability in the valve-train testing.
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