Growth and crown morphological responses of boreal conifer seedlings and saplings with contrasting shade tolerace to a gradient of light and height

The effects of gradients in light levels and tree height on growth and crown attributes of six conifer species were studied in eastern and western Canada. Three conifers were studied in British Columbia (Abies lasiocarpa (Hook.) Nutt., Picea glauca (Moench) Voss x Picea engelmannii Parry ex Engelm., and Pinus contorta Dougl. ex Loud. var. latifolia Engelm.), and three in Quebec (Abies balsamea (L.) Mill., Picea glauca, and Pinus banksiana Lamb.). For several growth and morphological parameters, conifers reacted strongly to both an increase in light and tree height. Significant or nearly significant interactions between light classes and height were found for height and diameter growth of most species as well as for many crown attributes for both Abies and Picea. These interactions usually indicated that growth or morphological changes occurred with increasing height from a certain light level. Within a single genus, both eastern and western tree species showed the same overall acclimation to light and height. As generally reported, Pinus species showed less variation in growth and morphological responses to light than Abies and Picea species

Morphological indicators of growth response of coniferous advance regeneration to overstorey removal in the boreal forest

Regeneration of forest stands through the preservation of existing advance regeneration has gained considerable interest in various regions of North America. The effectiveness of this approach relies on the capacity of regeneration to respond positively to overstory removal. Responses of advance regeneration to release is dependent on tree characteristics and site conditions interacting with the degree of physiological shock caused by the sudden change in environmental conditions. This paper presents a review of the literature describing the relationships between morphological indicators and the advance regeneration response to canopy removal. It focuses primarily on the following species: jack pine (Pinus banksiana Lamb.), lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), black spruce (Picea mariana (Mill.) B.S.P.), interior spruce (Picea glauca x engelmannii), white spruce (Picea glauca (Moench) Voss), balsam fir (Abies balsamea (L.) Mill.), and subalpine fir (Abies lasiocarpa (Hook.) Nutt). Pre-release height growth has been found to be a good indicator of post-release response for many species. Live-crown ratio also appears to be a good indicator of vigour for shade-tolerant species. The ratio of leader length to length of the longest lateral at the last whorl could serve to describe the degree of suppression before harvest for shade-tolerant species. Number of nodal and internodal branches or buds has been found to be related with vigour for many species. Logging damage has been shown to be an important determinant of seedling response to overstory removal. In contrast, height/diameter ratio has limited value for predicting response to release since it varies with site, species and other factors. No clear relationship between age, height at release and response to release could be demonstrated. This paper also suggests the use of combined indicators and critical threshold values for these indicators

Evaluation of multiple protein docking structures using correctly predicted pairwise subunits

<p>Abstract</p> <p>Background</p> <p>Many functionally important proteins in a cell form complexes with multiple chains. Therefore, computational prediction of multiple protein complexes is an important task in bioinformatics. In the development of multiple protein docking methods, it is important to establish a metric for evaluating prediction results in a reasonable and practical fashion. However, since there are only few works done in developing methods for multiple protein docking, there is no study that investigates how accurate structural models of multiple protein complexes should be to allow scientists to gain biological insights.</p> <p>Methods</p> <p>We generated a series of predicted models (decoys) of various accuracies by our multiple protein docking pipeline, Multi-LZerD, for three multi-chain complexes with 3, 4, and 6 chains. We analyzed the decoys in terms of the number of correctly predicted pair conformations in the decoys.</p> <p>Results and conclusion</p> <p>We found that pairs of chains with the correct mutual orientation exist even in the decoys with a large overall root mean square deviation (RMSD) to the native. Therefore, in addition to a global structure similarity measure, such as the global RMSD, the quality of models for multiple chain complexes can be better evaluated by using the local measurement, the number of chain pairs with correct mutual orientation. We termed the fraction of correctly predicted pairs (RMSD at the interface of less than 4.0Å) as <it>fpair </it>and propose to use it for evaluation of the accuracy of multiple protein docking.</p

Direct visualization reveals dynamics of a transient intermediate during protein assembly

Interactions between proteins underlie numerous biological functions. Theoretical work suggests that protein interactions initiate with formation of transient intermediates that subsequently relax to specific, stable complexes. However, the nature and roles of these transient intermediates have remained elusive. Here, we characterized the global structure, dynamics, and stability of a transient, on-pathway intermediate during complex assembly between the Signal Recognition Particle (SRP) and its receptor. We show that this intermediate has overlapping but distinct interaction interfaces from that of the final complex, and it is stabilized by long-range electrostatic interactions. A wide distribution of conformations is explored by the intermediate; this distribution becomes more restricted in the final complex and is further regulated by the cargo of SRP. These results suggest a funnel-shaped energy landscape for protein interactions, and they provide a framework for understanding the role of transient intermediates in protein assembly and biological regulation

Black pitch, carved histories: radiocarbon dating, wood species identification and strontium isotope analysis of prehistoric wood carvings from Trinidad's Pitch Lake

We report on the results of a multi-disciplinary project (including wood identification, radiocarbon dating and strontium isotope analysis) focused on a collection of pre-Columbian wooden carvings and human remains from Pitch Lake, Trinidad. While the lake's unusual conditions are conducive to the survival of organic artefacts, they also present particular challenges for analysis. There is a loss of any contextual association beyond that of the lake, and specific methodologies are required to deal with pitch contamination. A surprising taxonomic range of woods was employed for the various utilitarian and ceremonial items recovered. The 14C results range from ca. 3200 BCE to ca. 700 CE, and include the earliest known wooden carvings in the entire Caribbean. The strontium isotope results - interpreted with the aid of an isoscape developed for the project, based on extensive samples of modern trees across Trinidad and Tobago - indicate that most carvings are consistent with the site's immediate environs; however, a ‘weaving tool’ came from a more radiogenic region that is unlikely to be found on Trinidad, suggesting links with the South American mainland

Editorial: Influence of environmental variability on climate change impacts in marine ecosystems

multiple drivers, environmental variability, Climate change, marine heatwaves, stressmemory, Ecological memory, Thermal performance curves, acclimatio

Early above- and below-ground responses of subboreal conifer seedlings to various levels of deciduous canopy removal

We examined the growth of understory conifers, following partial or complete deciduous canopy removal, in a field study established in two regions in Canada. In central British Columbia, we studied the responses of three species (Pseudotsuga menziesii var. glauca (Beissn.) Franco, Picea glauca (Moench) Voss x Picea engelmannii Parry ex Engelm., and Abies lasiocarpa (Hook.) Nutt.), and in northwestern Quebec, we studied one species (Abies balsamea (L.) Mill.). Stem and root diameter and height growth were measured 5 years before and 3 years after harvesting. Both root and stem diameter growth increased sharply following release but seedlings showed greater root growth, suggesting that in the short term, improvement in soil resource capture and transport, and presumably stability, may be more important than an increase in stem diameter and height growth. Response was strongly size dependent, which appears to reflect greater demand for soil resources as well as higher light levels and greater tree vigour before release for taller individuals. Growth ratios could not explain the faster response generally attributed to true fir species or the unusual swift response of spruces. Good prerelease vigour of spruces, presumably favoured by deciduous canopies, could explain their rapid response to release