The importance of the Mujechineup wetland for biodiversity: an evaluation of habitat quality and ecosystem service value

Landscape and Ecological Engineering - Wetlands are important multifunctional systems that provide various ecological services for animal populations, particularly with regard to regulation and...     

Trapping of peptide-based surrogates in an artificially created channel of cytochrome c peroxidase

As recently described, the deliberate removal of the proposed electron transfer pathway from cytochrome c peroxidase resulted in the formation of an extended ligand-binding channel. The engineered channel formed a template for the removed peptide segment, suggesting that synthetic surrogates might be introduced to replace the native electron transfer pathway. This approach could be united with the recent development of sensitizer-linked substrates to initiate and study electron transfer, allowing access to unresolved issues about redox mechanism of the enzyme. Here, we present the design, synthesis, and screening of a peptide library containing natural and unnatural amino acids to identify the structural determinants for binding this channel mutant. Only one peptide, (benzimidazole-propionic acid)-Gly-Ala-Ala, appeared to interact, and gave evidence for both reversible and kinetically trapped binding, suggesting multiple conformations for the channel protein. Notably, this peptide was the most analogous to the removed electron transfer sequence, supporting the use of a cavity-template strategy for design of specific sensitizer-linked substrates as replacements for the native electron transfer pathway.     

Early response of Abies balsamea seedlings to artificially created openings

Abstract. Small-scale canopy openings are being increasingly recognized for their importance in boreal forest stand development. Yet more work is necessary to understand their effects on seedling growth. This study investigated the effect of different degrees of canopy opening (all trees cut, conifers cut, conifers girdled and control quadrats) in different stand types on Abies balsamea seedling recruitment, growth and architecture. The lack of a treatment effect on seedling establishment suggests that gaps primarily affect advance regeneration. In the first year after treatment the seedlings in the cut blocks (both conifer cut and all trees cut) responded with an increase in height growth. Changes in the leader to lateral branch ratio were also significant. Continued architectural change in terms of number of branches produced did not occur until after two years had passed. Although not significantly different from the control, increases can be observed in all measurements for the girdled treatment. It is therefore concluded that the growth response of advance regeneration is more important following canopy opening than new seedling recruitment and that seedling performance is greatest where degree of opening is greatest.     

Density mapping of decaying wood using X-ray computed tomography

Wood biodegradation is a central process at the crossroads of several disciplines. It is not only important for carbon storage in forests, but it is also important for wood conservation, wood protection and wood transformation products. Many methods already exist for studying wood biodegradation; however, they present several drawbacks, being time-consuming or destructive. Moreover, they provide little information regarding the complexity of the degradation process and the heterogeneity of the wood substrate. Based on a kinetic study of the biodegradation of Fagus sylvatica by the white-rot fungus Phanerochaete chrysosporium, we developed an X-ray computed tomography method coupled with an in-house plugin for fast, non-destructive and accurate measurement of the density variations of decaying wood. This method allowed us to examine the spatial heterogeneity of woody decayed material at the millimeter scale, providing information about the fungal pattern of degradation. Thus, X-ray computed tomography is an efficient tool that can be used for measuring the degradation of a variety of wood substrates ranging from small normalized wood blocks to fallen logs in the forest.     

Characterization of the Bacillus subtilis motile system driven by an artificially created proton motive force.

Transient swimming was induced in energy-depleted cells of Bacillus subtilis by an artificial proton motive force, which was created by valinomycin addition and a pH reduction. This system did not require any ions except protons in the medium. The size of the induced motility was strongly influenced by changes in the size of either the K+ diffusion potential or the pH gradient. A rough estimation indicated that a proton motive force higher than -100 mV was required for induction of translational swimming of the cell. Corresponding with the transient appearance of swimming, a rapid but transient efflux of K+ and influx of H+ were observed. With decreases in the rate of H+ influx, the amount of motility decreased. A rate of H+ influx higher than 0.2 mumol/s per ml of cell water gave translational swimming. These results suggest direct coupling of H+ influx to rotation of bacterial flagella.     

生境破碎化对生物多样性的影响

生境破碎化对生物多样性和生态系统功能的影响是当前国内外生态学家研究的热点问题之一。生境破碎化导致原生境的总面积减小,产生隔离的异质种群,从而影响个体行为特性、种群间基因交换、物种间相互作用及生态过程。生境破碎化的过程引起栖息地内部食物、繁殖场所、局部小气候、边缘效应等生物和非生物条件的变化,从而影响植物种群的大小和灭绝速率、扩散和迁入、遗传和变异以及存活力等,影响动物种群的异质种群动态、适宜生境比例、灭绝阈值、种间关系等。随着景观生态学与农业科学的融合,探索利用景观布局控制害虫发生将是人类利用生境破碎化为人类服务的一条新途径。     

Larvae of Aenetus virescens (Lepidoptera: Hepialidae) in decaying wood

Abstract

Larvae of Aenetus virescens (Doubleday) have previously been recorded only from the wood of live trees or shrubs. This paper describes the circumstances in which larvae occupy decaying wood in the forest habitat. Young larvae are considered to exist in dead wood for no more than a year. They then disperse to live trees, in which development is completed.     

Improving national habitat specific biodiversity indicators using relative habitat use for common birds

It has recently been stated that the global goal of halting the loss of biodiversity by 2010 has not been met highlighting the urgent need to monitor trends in biodiversity. Our study suggests that existing indicators of bird biodiversity in Denmark are inaccurate and we present a new objective method for accurately assessing trends in specific habitats using common bird species. Bird species were selected for creating habitat specific indicators by calculating their relative habitat use (RHU) in nine different habitat categories. RHU indicates the degree to which a habitat is preferred (RHU > 2) or avoided (RHU < 0.5) by a species, relative to other habitats. Indicator sets were constructed for each habitat type using species with an RHU > 2 and revealed that existing habitat indicators, based on species lists from the Pan-European Common Bird Monitoring Scheme (PECBMS), often included species that did not in fact have preferences for those particular habitats in Denmark. Habitat specific indicators based on the new species selection method showed significant negative trends in three of nine habitat categories: coniferous forest, bog/marsh and heath. Habitat classes were further combined to create overall indicators for forest, farmland and freshwater. A comparison of these indicators with the existing indicators revealed a negative overall trend for forest habitat, which had previously been overlooked, suggesting that species selection is crucial for the development of informative indicators. The habitat specific farmland indicator confirmed the negative trend in the current farmland indicator. The methodology for indicator species selection presented here could potentially be applied for use in a global context for a wider range of taxonomic groups.     

A new species of yeast isolated from decaying insect-invaded wood

A yeast strain was isolated from an insect-tunnelled piece of wood from Equatorial Africa. This sporogenous yeast is aPichia sensu stricto:Pichia heimii.

---

Resume Une levure a été isolée d'un morceau de bois creusé de galeries d'insectes et provenant d'Afrique équatoriale. Cette levure, sporogène, appartient au genre Pichia s.str.: Pichia heimii.

---

---

The author wishes to thank Professor J. Boidin for furnishing the Central African material and for his comments upon this work, and Mrs. S. Poncet for her aid in the application of the mathematical method.     

A sixth‐level habitat cascade increases biodiversity in an intertidal estuary

Many studies have documented habitat cascades where two co‐occurring habitat‐forming species control biodiversity. However, more than two habitat‐formers could theoretically co‐occur. We here documented a sixth‐level habitat cascade from the Avon‐Heathcote Estuary, New Zealand, by correlating counts of attached inhabitants to the size and accumulated biomass of their biogenic hosts. These data revealed predictable sequences of habitat‐formation (=attachment space). First, the bivalve Austrovenus provided habitat for green seaweeds (Ulva) that provided habitat for trochid snails in a typical estuarine habitat cascade. However, the trochids also provided habitat for the nonnative bryozoan Conopeum that provided habitat for the red seaweed Gigartina that provided habitat for more trochids, thereby resetting the sequence of the habitat cascade, theoretically in perpetuity. Austrovenus is here the basal habitat‐former that controls this “long” cascade. The strength of facilitation increased with seaweed frond size, accumulated seaweed biomass, accumulated shell biomass but less with shell size. We also found that Ulva attached to all habitat‐formers, trochids attached to Ulva and Gigartina, and Conopeum and Gigartina predominately attached to trochids. These “affinities” for different habitat‐forming species probably reflect species‐specific traits of juveniles and adults. Finally, manipulative experiments confirmed that the amount of seaweed and trochids was important and consistent regulators of the habitat cascade in different estuarine environments. We also interpreted this cascade as a habitat‐formation network that describes the likelihood of an inhabitant being found attached to a specific habitat‐former. We conclude that the strength of the cascade increased with the amount of higher‐order habitat‐formers, with differences in form and function between higher and lower‐order habitat‐formers, and with the affinity of inhabitants for higher‐order habitat‐formers. We suggest that long habitat cascades are common where species traits allow for physical attachment to other species, such as in marine benthic systems and old forest.     

Effects of soil and wood depletion on biodiversity

Human depletion of soil and wood resources is dramatically altering the biodiversity of both terrestrial and aquatic ecosystems. This paper provides an overview of the numerous linkages between the depletion of soil and wood resources and the loss of biodiversity. While some of these linkages are well documented, others remain speculative or unexplored. In order to understand the full ramifications of resource depletion on biodiversity, additional research is required.