Biodiversity in Dead Wood Stokland, Jogeir N; Siitonen, Juha; Jonsson, Bengt Gunnar
04/2012
eBook, Book
Fossils document the existence of trees and wood-associated organisms from almost 400 million years ago, and today there are between 400,000 and 1 million wood-inhabiting species in the world. This ...is the first book to synthesise the natural history and conservation needs of wood-inhabiting organisms. Presenting a thorough introduction to biodiversity in decaying wood, the book studies the rich diversity of fungi, insects and vertebrates that depend upon dead wood. It describes the functional diversity of these organisms and their specific habitat requirements in terms of host trees, decay phases, tree dimensions, microhabitats and the surrounding environment. Recognising the threats posed by timber extraction and forest management, the authors also present management options for protecting and maintaining the diversity of these species in forests as well as in agricultural landscapes and urban parks.
Signals of species interactions can be inferred from survey data by asking if some species occur more or less often together than what would be expected by random, or more generally, if any ...structural aspect of the community deviates from that expected from a set of independent species. However, a positive (or negative) association between two species does not necessarily signify a direct or indirect interaction, as it can result simply from the species having similar (or dissimilar) habitat requirements. We show how these two factors can be separated by multivariate logistic regression, with the regression part accounting for species-specific habitat requirements, and a correlation matrix for the positive or negative residual associations. We parameterize the model using Bayesian inference with data on 22 species of wood-decaying fungi acquired in 14 dissimilar forest sites. Our analyses reveal that some of the species commonly found to occur together in the same logs are likely to do so merely by similar habitat requirements, whereas other species combinations are systematically either over- or underrepresented also or only after accounting for the habitat requirements. We use our results to derive hypotheses on species interactions that can be tested in future experimental work.
The biosynthetic origins of the structurally related racemic isoxazolidine Papaveraceae alkaloids Setigerumine I, Dactylicapnosinine and Dactylicapnosine have remained elusive since their original ...isolation over two decades ago. Herein we report the first biosynthetic hypothesis for their formation and, inspired by it, the first synthesis of (±)‐Setigerumine I with accompanying computational rationale. Based on the results, these isoxazolidine alkaloids arise from racemizing oxidative rearrangements of prominent isoquinoline alkaloids Noscapine and Hydrastine. The key steps featured in this synthesis are a room temperature Cope elimination and a domino oxidation/inverse‐electron demand 1,3‐dipolar cycloaddition of an axially chiral, yet configurationally unstable, intermediate. The work opens this previously inaccessible family of natural products for biological studies.
The first synthesis of (±)‐Setigerumine I, an isoxazolidine Papaveraceae alkaloid, is realized through a biomimetic strategy. The synthesis sheds light to the possible biosynthetic origins of these elusive natural product family members.
We report the first direct catalytic enantioselective allylation of acyclic α-ketiminoesters to afford α-allyl-α-aryl and α-allyl-α-trifluoromethyl amino esters in excellent isolated yield (91–99%) ...and with high optical purity (90–99+% ee). The allylation proceeds on a gram scale with 5–10 mol % of indium(I) iodide and commercially available BOX-type ligands. The allylated products are easily converted to enantiomerically enriched α-substituted proline derivatives.
A short formal synthesis of ent-Cephalotaxine is achieved. The approach features a new Lewis acid-mediated 2,3-Stevens rearrangement of N-allylated prolineamide to generate a key quaternary ...stereogenic center. Additionally, a one-pot Parham–aldol sequence was developed to rapidly assemble two of the four rings in the cephalotaxine core.
1. The loss of suitable habitats is one of the main causes behind the loss of species and communities. Habitat fragmentation, that is, the division of the remaining habitat into small and isolated ...fragments, often co-occurs with the process of habitat loss. The spatial division of habitats decreases connectivity among local populations and generally has a negative effect on population viability, but it can also have a positive effect for some species, for example, due to released competition pressure. 2. In both animals and plants, certain characteristics such as low dispersal ability and narrow ecological niche are known to be associated with fragmentation vulnerability, but in fungi, systematic analyses have so far been lacking. With their small and highly dispersive spores, fungi could be mainly resource-limited, not dispersal-limited. 3. In this study, we analysed spatial occurrence data on 119 species of wood-inhabiting fungi to identify the species characteristics that are associated with high extinction risk and fragmentation vulnerability in particular. We modelled resource use and connectivity dependence separately for each species using the presence-absence data on 98 318 dead trees in 496 sites located on a gradient in the duration and intensity of land use in eastern Fennoscandia. We then related species' responses to connectivity to their resource-use patterns, life-history characteristics and red-list status. 4. Our results show that red-listed species are highly specialized in their resource use and suffer from loss of connectivity at three spatial scales: along the large-scale gradient, at the landscape scale and at the scale of a forest stand. In contrast, many of the non-red-listed generalist species are actually more likely to occur (per resource unit) in fragmented managed forests than well-connected natural forests. 5. Synthesis. We show that the expected number of red-listed species per a fixed amount of similar resources (dead trees) can be even more than 10 times higher in well-connected than in fragmented surroundings, and thus, protecting high-quality areas that are well connected is conservationally more effective than protecting small fragments distributed across the landscape.
Total synthesis of isatindigotindoline C Siitonen, Juha H; Lira, Sherlin; Yousufuddin, Muhammed ...
Organic & biomolecular chemistry,
03/2020, Letnik:
18, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Total synthesis of isatindigotindoline C, a 3,3'-spiropyrrolidine oxindole alkaloid, is achieved in two steps using an exo-selective decarboxylative 1,3-dipolar cycloaddition as the key step. The ...synthesis verifies the originally assigned relative anti-stereochemistry for the bis-oxindole core of isatindigotindoline C.
Intensive forest management has drastically reduced the amount and diversity of dead wood resulting in population decline of saproxylic species. Forestry practices can also disrupt spatiotemporal ...continuity of dead wood habitats. We studied the effects of stand- and landscape-level densities of host trees on the incidence (proportion of occupied trees) of saproxylic beetles inhabiting recently dead standing Scots pines, a common host-tree type both in natural and managed boreal forests. We compared the occurrence patterns of eight rare specialist and eight common generalist species. Saproxylic beetles were collected from a total of 315 trees in 67 forest stands, including both managed and natural forests, located in three regions which form a gradient in forest-use intensity. Species richness of the entire community at tree and stand level did not respond to the stand- and landscape-level host-tree density. The incidence of six common generalist species did not depend on the stand-level host-tree density, whereas the incidences of four rare specialist species increased with increasing host-tree density. Five out of eight rare specialist species were either significantly less common or absent from the region with the lowest landscape-level density of host trees. We conclude that rare specialist species living in recently dead pines are susceptible to changes in spatiotemporal dynamics of their host trees. To conserve rare early-successional species, it is necessary to ensure continuous input of dying trees by prolonging rotation times in mature forests, regenerating stands using seed-tree cutting and leaving as many permanent retention trees as possible.
O-Unprotected keto- and aldoximes are readily C-allylated with allyl diisopropyl boronate in the presence of arylboronic acid catalysts to yield highly substituted N-α-secondary and tertiary ...homoallylic hydroxylamines. The method was used in the total synthesis of the trace alkaloid N-Me-Euphococcine.
A stereoselectivity model inspired by the total synthesis of stemona alkaloids is developed to explain why enolate-derived 3,4-fused butyrolactones are methylated with a preference for
alkylation. ...The model shows how conformational locking present in nonplanar enolate structures favors
over
methylation, due to less significant structural distortions in the
pathway. The developed model was also successfully used to rationalize selectivities of previously documented methylation reactions.
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