scholarly journals Modeling tree diversity, stand structure and productivity of northern temperate coniferous forests of Mexico

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7051 ◽  
Author(s):  
José Návar
Keyword(s):  
Stand Structure ◽  
Canopy Structure ◽  
Three Dimensional ◽  
Quantitative Information ◽  
Tree Diversity ◽  
Coniferous Forests ◽  
Dimensional Structure ◽  
Long Term Effects ◽  
Stand Productivity ◽  
Statistical Relationships

There is increasing evidence complex forest structure and tree diversity correlates positively with the productivity of forest ecosystems. However, there is little quantitative information regarding the effect of these factors on stand productivity of northern temperate coniferous forests of Mexico. This study aimed to test the hypothesis tree diversity and canopy structure positively associates with forest productivity. Parameterization of tree diversity, stand structure and productivity were carried out on dasometric data from 36 permanent sampling plots re-measured in 1982, 1993, and 2004. Statistical analysis of stand parameters tested the null hypothesis. Statistical relationships revealed well-balanced canopy strata and imbalanced diameter structures positively correlated with stand productivity. Tree diversity was also positively linked with stand productivity, but the effect appeared to be most important in the early to intermediate stages of succession. Further research is required to understand the long-term effects of tree diversity and canopy structure on stand productivity. These preliminary observations stress the importance of prescribing silvicultural practices that maintain the three-dimensional structure of stands and diversity of forest canopies that aim to preserve ecosystem function, diversity, and productivity.

scholarly journals Topography and Three-Dimensional Structure Can Estimate Tree Diversity along a Tropical Elevational Gradient in Costa Rica

2018 ◽  
Vol 10 (4) ◽  
pp. 629 ◽  
Author(s):  
Chelsea Robinson ◽  
Sassan Saatchi ◽  
David Clark ◽  
Johanna Hurtado Astaiza ◽  
Anna Hubel ◽  
...  
Keyword(s):  
Costa Rica ◽  
Three Dimensional ◽  
Elevational Gradient ◽  
Tree Diversity ◽  
Dimensional Structure ◽  
Three Dimensional Structure

Canopy light transmittance in a chronosequence of mixed-species deciduous forests

1994 ◽  
Vol 24 (8) ◽  
pp. 1694-1703 ◽  
Author(s):  
Martin J. Brown ◽  
Geoffrey G. Parker
Keyword(s):  
Leaf Area ◽  
Geometric Mean ◽  
Canopy Structure ◽  
Three Dimensional ◽  
Distinct Pattern ◽  
Light Transmittance ◽  
Dimensional Structure ◽  
Stand Age ◽  
Area Index ◽  
Frequency Distributions

We measured the photosynthetically active radiation transmitted through the canopies of 24 Maryland forest stands, each around midday in midsummer. We then compared the observed values of PAR transmittance with stand age and measures of canopy structure. Generally, transmittance was low, with positively skewed frequency distributions. The geometric mean transmittance followed a distinct pattern with stand age. It was lowest (about 1%) in the youngest stands, increased to about 2.5% as forests approached ages of about 50 years, and then declined with age in the oldest sites (65–340 years). Transmittance was not significantly correlated with many simple measures of forest structure, including estimated aboveground biomass and leaf area index. Better predictions of transmittance used information on the vertical arrangement of the canopy, such as leaf area density. The results are contrary to the common assumptions that forests get consistently darker through time, and that transmittance is inversely proportional to the sheer mass or leaf area of the canopy. The Beer–Lambert extinction coefficient, k, changed with stand age and structure and was especially high in very young stands. We suggest that the variation in light transmittance, and k, can be explained by successional changes in the three-dimensional structure of the canopy.

Shipping of water on a two-dimensional structure. Part 2

2007 ◽  
Vol 581 ◽  
pp. 371-399 ◽  
Author(s):  
M. GRECO ◽  
G. COLICCHIO ◽  
O. M. FALTINSEN
Keyword(s):  
Three Dimensional ◽  
Quantitative Information ◽  
Front Velocity ◽  
Green Water ◽  
Dimensional Structure ◽  
Two Dimensional ◽  
Incoming Wave ◽  
Water On Deck ◽  
Type Water ◽  
Water Front

The water-shipping problem is modelled in a two-dimensional framework and studied experimentally and numerically for the case of a fixed barge-shaped structure. The analysis represents the second step of the research discussed in Greco et al. (J. Fluid Mech., vol. 525, 2005, p. 309). The numerical investigation is performed by using both a boundary element method and a domain-decomposition strategy. The model tests highlight the occurrence of dam-breaking-type water on deck, (a) with and (b) without an initial plunging phase, and (c) an unusual type of water shipping connected with blunt water–deck impacts here called a hammer-fist type event never documented before. Cases (a) and (c) are connected with the most severe events and the related features and green-water loads are discussed in detail. A parametric analysis of water-on-deck phenomena has also been carried out in terms of the local incoming waves and bow flow features. We classify such phenomena in a systematic way to provide a basis for further investigations of water-on-deck events. The severity of (a)-type water-on-deck events is analysed in terms of initial cavity area and water-front velocity along the deck. The former increases as the square power of the modified incoming-wave (front-crest) steepness while the latter scales with its square-root. The two-dimensional investigation gives useful quantitative information in terms of water-front velocity for comparison with three-dimensional water-on-deck experiments on fixed bow models interacting with wave packets.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

Electron Microscopy of Cytoplasmic Contractile Proteins

1978 ◽  
Vol 36 (3) ◽  
pp. 606-614 ◽  
Author(s):  
T.D. Pollard ◽  
P. Maupin
Keyword(s):  
Electron Microscopy ◽  
Actin Filaments ◽  
Three Dimensional ◽  
Uranyl Acetate ◽  
Contractile Proteins ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
Cytoplasmic Matrix ◽  
Computer Image Processing ◽  
Nonmuscle Cells

In this paper we review some of the contributions that electron microscopy has made to the analysis of actin and myosin from nonmuscle cells. We place particular emphasis upon the limitations of the ultrastructural techniques used to study these cytoplasmic contractile proteins, because it is not widely recognized how difficult it is to preserve these elements of the cytoplasmic matrix for electron microscopy. The structure of actin filaments is well preserved for electron microscope observation by negative staining with uranyl acetate (Figure 1). In fact, to a resolution of about 3nm the three-dimensional structure of actin filaments determined by computer image processing of electron micrographs of negatively stained specimens (Moore et al., 1970) is indistinguishable from the structure revealed by X-ray diffraction of living muscle.

A New 1000kv Electron Microscope

1969 ◽  
Vol 27 ◽  
pp. 100-101
Author(s):  
J.L. Williams ◽  
K. Heathcote ◽  
E.J. Greer
Keyword(s):  
Electron Microscope ◽  
Direct Observation ◽  
High Voltage ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Specimen Thickness ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
Dynamic Experiments ◽  
Conventional Instrument

High Voltage Electron Microscope already offers exciting experimental possibilities to Biologists and Materials Scientists because the increased specimen thickness allows direct observation of three dimensional structure and dynamic experiments on effectively bulk specimens. This microscope is designed to give maximum accessibility and space in the specimen region for the special stages which are required. At the same time it provides an ease of operation similar to a conventional instrument.

High-voltage electron microscopy of maxillary gland of spirochete-infected brine shrimp: lesion of efferent tubule

1988 ◽  
Vol 46 ◽  
pp. 362-363
Author(s):  
G. E. Tyson ◽  
M. J. Song
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Brine Shrimp ◽  
Natural Populations ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Infected Adult

Natural populations of the brine shrimp, Artemia, may possess spirochete- infected animals in low numbers. The ultrastructure of Artemia's spirochete has been described by conventional transmission electron microscopy. In infected shrimp, spirochetal cells were abundant in the blood and also occurred intra- and extracellularly in the three organs examined, i.e. the maxillary gland (segmental excretory organ), the integument, and certain muscles The efferent-tubule region of the maxillary gland possessed a distinctive lesion comprised of a group of spirochetes, together with numerous small vesicles, situated in a cave-like indentation of the base of the tubule epithelium. in some instances the basal lamina at a lesion site was clearly discontinuous. High-voltage electron microscopy has now been used to study lesions of the efferent tubule, with the aim of understanding better their three-dimensional structure.Tissue from one maxillary gland of an infected, adult, female brine shrimp was used for HVEM study.

Mitochondrial Reconstructions Based on Serial Thick Sections and HVEM

1975 ◽  
Vol 33 ◽  
pp. 286-287
Author(s):  
Jerome J. Paulin
Keyword(s):  
Imaging Techniques ◽  
Three Dimensional ◽  
Posterior Pole ◽  
Dimensional Structure ◽  
Stereo Imaging ◽  
Thin Sections ◽  
Anatomical Features ◽  
The Past ◽  
Cellular Components ◽  
Mitochondrial Reticulum

Within the past decade it has become apparent that HVEM offers the biologist a means to explore the three-dimensional structure of cells and/or organelles. Stereo-imaging of thick sections (e.g. 0.25-10 μm) not only reveals anatomical features of cellular components, but also reduces errors of interpretation associated with overlap of structures seen in thick sections. Concomitant with stereo-imaging techniques conventional serial Sectioning methods developed with thin sections have been adopted to serial thick sections (≥ 0.25 μm). Three-dimensional reconstructions of the chondriome of several species of trypanosomatid flagellates have been made from tracings of mitochondrial profiles on cellulose acetate sheets. The sheets are flooded with acetone, gluing them together, and the model sawed from the composite and redrawn.The extensive mitochondrial reticulum can be seen in consecutive thick sections of (0.25 μm thick) Crithidia fasciculata (Figs. 1-2). Profiles of the mitochondrion are distinguishable from the anterior apex of the cell (small arrow, Fig. 1) to the posterior pole (small arrow, Fig. 2).

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