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62 results for “Eucalypt”

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dryad36/100

Native herbivore browsing alters plant physical and chemical traits in a eucalypt forest understory

Macropods exhibit selective herbivory on plant traits within and between species and hence can alter plant trait variation. In this study we asked, what are the effects of macropod herbivory on intraspecific variation in plant traits of forest understorey species? We tested the effects of herbivory by macropods on eight plant traits, in nine understorey species using a herbivore exclusion experiment. Generalised linear mixed models were used to test for differences between herbivory treatments in trait means as well as variation within species and at the community level. Macropod herbivory resulted in differences in either the mean trait value or trait variance within a species for seven of the eight tested plant traits. Macropod exclusion resulted in larger dimensions of size for most species, as well as changes in specific leaf area, moisture content, and carbon content of leaves. Further, community-weighted means of specific leaf area, moisture content, and leaf nitrogen were lower in the presence of macropods. Plant trait variance was altered for three of the seven community weighted traits. This study demonstrates a mechanism through which macropods can drive changes in the traits of understorey plant species. Plant traits have been linked to various larger scale ecological processes including ecosystem flammability, nutrient cycling, response to global change and habitat suitability for other organisms. Therefore, herbivore-induced changes in plant trait variation and community composition could have important flow on effects for other environmental processes and hence should be considered in management decisions regarding fire-prone ecosystems.

opencc-zeroNov 2023View details →

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Differential effects of ecosystem engineering by the superb lyrebird Menura novaehollandiae and herbivory by large mammals on floristic regeneration and structure in wet eucalypt forests

Ecosystem engineers that modify soil and ground-layer properties exert a strong influence on vegetation communities in ecosystems worldwide. Understanding the interactions between animal engineers and vegetation is challenging when in the presence of large herbivores, as many vegetation communities are simultaneously affected by both engineering and herbivory. The superb lyrebird Menura novaehollandiae, an ecosystem engineer in wet forests of south-eastern Australia, extensively modifies litter and soil on the forest floor. The aim of this study was to disentangle the impacts of engineering by lyrebirds and herbivory by large mammals on the composition and structure of ground-layer vegetation. We carried out a two-year, manipulative exclusion experiment in the Central Highlands of Victoria, Australia. We compared three treatments: fenced plots with simulated lyrebird foraging; fenced plots excluding herbivores and lyrebirds; and open controls. This design allowed assessment of the relative impacts of engineering and herbivory on germination rates, seedling density, vegetation cover and structure, and community composition. Engineering by lyrebirds enhanced the germination of seeds in the litter layer. After two years, more than double the number of germinants were present in 'engineered' than 'non-engineered' plots. Engineering did not affect the density of seedlings, but herbivory had strong detrimental effects. Herbivory also reduced the floristic richness and structural complexity (< 0.5 m) of forest vegetation, including the cover of herbs. Neither process altered the floristic composition of the vegetation within the 2-year study period. Ecosystem engineering by lyrebirds and herbivory by large mammals both influence the structure of forest-floor vegetation. The two-fold increase in seeds stimulated to germinate by engineering may contribute to the evolutionary adaptation of plants by allowing greater phenotypic expression and selection than would otherwise occur. Over long timescales, engineering and herbivory likely combine to maintain a more-open forest floor conducive to ongoing ecosystem engineering by lyrebirds.

opencc-zeroJan 2023View details →

dryad36/100

Perianth evolution and implications for generic delimitation in the Eucalypts (Myrtaceae): DNA sequences, morphological data

Eucalyptus was traditionally defined by the operculate perianth—hence the generic name (Latin, meaning "well-covered"). But after previous phylogenetic analysis placed Angophora, which has free sepals and petals, as sister to the bloodwood eucalypts, the latter were segregated into a new genus, Corymbia. We made a targeted capture of 101 low-copy nuclear exons from 392 samples representing 329 species-level taxa. The phylogeny was estimated using maximum likelihood (IQtree and RAxML) and the multi-species coalescent (Astral). We tested alternative relationships between four genera within Eucalypteae (Arillastrum, Angophora, Eucalyptus, Corymbia) at each of two nodes critical to generic delimitation using Shimodaira's Approximately Unbiased (AU) test. Monophyly of Arillastrum + (Corymbia + Angophora) relative to Eucalyptus sensu stricto was supported whereas monophyly of Corymbia relative to Angophora was decisively rejected. These results indicate that either Eucalyptus should be expanded to include all four genera or Corymbia should be split into two. All of the alternative relationships among the four currently recognised genera imply homoplasy in perianth evolution, specifically with respect to origins of the bud cap (operculum or calyptra), which has been traditionally used to define Eucalyptus. Inferred evolutionary transitions in perianth traits are generally congruent with divergences between major clades with a single exception: expression of separate sepals and petals in Angophora, which is nested within the operculate genus Corymbia, appears prima facie to be a reversal to the plesiomorphic perianth structure. Strictly, this is not a reversal because the petals of Angophora and Corymbia have a novel compound keel-and-limb structure that is absent in the outgroups. This structure is evident in early development, irrespective of whether the petals remain free or later become part of an operculum. Many of the currently recognised infrageneric taxa down to sectional level (and below in some cases) are well-supported by the sequence data and definable by morphological traits. Inclusion of Angophora within Eucalyptus was formally proposed two decades ago but did not gain acceptance. Here instead, we formally raise Corymbia subg. Blakella to genus rank and make the relevant new combinations.

opencc-zeroFeb 2023View details →

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DaRT-seq raw data of Eucalyptus spp for the genetic assessment of the value of restoration planting within an endangered eucalypt woodland

Assessment of woodland restoration often focusses on stand demographics, but genetic factors likely influence long-term stand viability. We examined the genetic composition of Yellow Box (Eucalyptus melliodora) trees in endangered Box-Gum Grassy Woodland in SE Australia, some 30 years after planting with seeds of reportedly local provenance. Using DArT sequencing for 1406 SNPs, we compared genetic diversity and population structure of planted E. melliodora trees with remnant bushland trees, paddock trees, and natural recruits. Genetic patterns imply that natural stands and paddock trees had historically high gene flow (among group pairwise FST = 0.04–0.10). Genetic diversity was highest among relictual paddock trees (He = 0.17), while diversity of revegetated trees was identical to natural bushland trees (He = 0.14). Bayesian clustering placed the revegetated trees into six genetic groups with four corresponding to genotypes from paddock trees, indicating that revegetated stands are mainly of genetically diverse, local provenance. Natural recruits were largely derived from paddock trees with some contribution from planted trees. A few trees have likely hybridised with other local eucalypt species which are unlikely to compromise stand integrity. We show that paddock trees have high genetic diversity and capture historic genetic variety and provide important foci for natural recruitment of genetically diverse and outcrossed seedlings.

opencc-zeroApr 2023View details →

zenodo36/100

Steam explosion of eucalypt sawdust for ethanol production within a biorefinery approach - Supplementary Material

Supplementary Material to the manuscript entitled "Steam explosion of eucalypt sawdust for ethanol production within a biorefinery approach", which has been revised according to the reviewers' comments and submitted for publication in Processes MDPI (July 18, 2023).

opencc-by-4.0Jul 2023View details →

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Dataset for: Population decline in a Pleistocene refugium: stepwise, drought-related dieback of a South Australian eucalypt

Refugia can facilitate the persistence of species through long-term environmental change, but it is not clear if Pleistocene refugia will remain functional under anthropogenic climate change. Dieback of species within refugia therefore raises concerns about their long-term persistence. Using repeat field surveys, we investigate dieback patterns of an isolated population of Eucalyptus macrorhyncha during two droughts and discuss prospects for its continued persistence in a Pleistocene refugium. We first confirm that the Clare Valley in South Australia has constituted a long-term refugium for the species, with the population being genetically highly distinct from other conspecific populations. However, the population lost >40% of individuals and biomass through the two droughts, with mortality being just below 20% after the Millennium Drought (2000–2009) and almost 25% after the Big Dry (2017-2019). The best predictors of mortality differed after each drought. While the north-facing aspect of a sampling location was a significant positive predictor after both droughts, biomass density and slope were significant negative predictors only after the Millennium Drought, and distance to the north-west corner of the park, which intercepts hot, dry winds, was significant after the Big Dry only. This suggests that more marginal sites with low biomass and located on exposed, flat plateaus were more vulnerable initially, but that heat-stress was an important driver of dieback during the Big Dry. Therefore, the causative drivers of dieback may change during population decline. Regeneration occurred predominantly on southern and eastern aspects, which would receive the least solar radiation. Occurrence in a refugium did not protect this population from dieback. However, gullies with lower solar radiation are continuing to support relatively healthy, regenerating stands of red stringybark, providing hope for persistence in small pockets. Monitoring and managing these pockets during future droughts will be essential to ensure the persistence of this isolated and genetically unique population.

opencc-zeroSep 2023View details →

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