Quadrat Size Research Articles

How can seed removal rates of zoochoric tree species be assessed quickly and accurately?

The quantification of seed dispersal and predation processes has been gaining increased importance in the assessment of forest responses to anthropogenic disturbance, but also in developing an understanding of forest dynamics facing particular reproductive strategies. Seed removal rate is a reliable estimator of animal activities relating to these processes and can be quickly and easily estimated using a rapid assessment method (RAM) described by Lermyte and Forget (2009) and Boissier et al. (2014). This method consists in selecting trees reaching a given fruit crop in plots of interest and estimating, under each tree, the proportion of removed seeds in a single quadrat among the places having the highest crops; the proportion of removed seeds is obtained by enumeration of fruit scraps and intact fruits and estimation of their seed contents. The objective of this work is to evaluate the reliability of this method and to propose alternative estimation protocols (APs) in order to obtain an index of animal interaction with seeds.To do so, we estimated produced and removed seed numbers in up to 30 random 1sq.m. quadrats under a total of 19 trees of Afzelia bipindensis, Dialium pachyphyllum/zenkeri and Xylopia staudtii. Secondly, we investigated the influence of tree size and fruit production on seed removal rate using a generalized linear mixed model. Thirdly, we used a generalized linear mixed model and a bootstrap procedure to test if RAM and APs are biased. Then, we compared their accuracy throughout their mean squared error, also obtained with a bootstrap approach.Despite its interesting accuracy, we showed that the RAM is positively biased. Removal rate was obviously influenced by canopy size and fruit production whereas the quadrats with higher fruit production have higher seed removal rates. Thus, trees with representative sizes and crops of the studied plots have to be sampled. Secondly, as an AP, random selection of several quadrats was found to be the best method. Based on these results, we recommend using the mean of three random quadrats per tree to estimate seed removal rate. It is an unbiased estimator, more accurate and more time efficient than the RAM. However, attention should be paid to select a proper quadrat size, in line with seed and fruit numbers, since the accuracy of the methods depends on these quantities. Such a choice could be made using a mean squared error criterion obtained from a preliminary intensive sampling of some specimens of the focal species.

Spatial Clustering and Ecological Crowding of Valley Oak (Quercus lobata, Née) Associated with Shifts in Recruitment Establishment Sites in Southern California

Premise of research. Valley oak (Quercus lobata, Nee) has received much attention due to concerns about regeneration failure and, more recently, compositional and structural community changes associated with this foundation species. Changes in the structure and spatial distribution of valley oak stands, as examined in this article, are likely affecting ecological processes and interactions throughout communities where it is found.Methodology. We used quadrat-based methods of spatial analysis, Morisita’s index of aggregation (IM), and a derived index (IMr) to examine patterns of clustering, intensity of crowding, and changes in the probability of crowding as the definition of crowding (stems/area) is changed. Saplings, defined as stems with a diameter at breast height (dbh) greater than 1 cm and less than 10 cm (1 cm ≤ dbh < 10 cm) and adults (dbh ≥ 10 cm) were analyzed using four quadrat sizes. We mapped clusters of stems on the basis of spatial autocorrelation of dbh using Anselin’s local Moran’s I to id...

Eco-Floristic studies of native plants of the Beer Hills along the Indus River in the districts Haripur and Abbottabad, Pakistan.

The present study was conducted to elaborate vegetation composition structure to analyze role of edaphic and topographic factors on plant species distribution and community formation during 2013–14. A mixture of quadrat and transect methods were used. The size of quadrat for trees shrubs and herbs were 10 × 5, 5 × 2, 1 × 1 meter square respectively. Different phytosociological attribute were measured at each station. Primary results reported 123 plant species belong to 46 families. Asteraceae and Lamiaceae were dominant families with 8 species each. PCORD version 5 were used for Cluster and Two Way Cluster Analyses that initiated 4 plant communities within elevation range of 529–700 m from sea level. Indicator species analyses (ISA) were used to identify indicator species of each community. CANOCO Software (version 4.5) was used to measure the influence of edaphic and topographic variables on species composition, diversity and community formation. Whereas Canonical Correspondence Analysis (CCA) was used to measure the effect of environmental variables which showed elevation and aspect were the stronger environmental variable among topographic and CaCO3 contents, electric conductivity, soil pH were the stronger edaphic factors in determination of vegetation and communities of the Bheer Hills. Grazing pressure was one of the main anthropogenic factors in this regard.

On the dimension of matrix embeddings of torsion-free nilpotent groups

Since the work of Jennings (1955), it is well-known that any finitely generated torsion-free nilpotent group can be embedded into unitriangular integer matrices UTN(Z) for some N. In 2006, Nickel proposed an algorithm to calculate such embeddings. In this work, we show that if UTn(Z) is embedded into UTN(Z) using Nickel's algorithm, then N≥2n/2−2 if the standard ordering of the Mal'cev basis (as in Nickel's original paper) is used. In particular, we establish an exponential worst-case running time of Nickel's algorithm.On the other hand, we also prove a general exponential upper bound on the dimension of the embedding by showing that for any torsion free, finitely generated nilpotent group the matrix representation produced by Nickel's algorithm has never larger dimension than Jennings' embedding. Moreover, when starting with a special Mal'cev basis, Nickel's embedding for UTn(Z) has only quadratic size. Finally, we consider some special cases like free nilpotent groups and Heisenberg groups and compare the sizes of the embeddings.

Structure and Natural Regeneration Status of Woody Plants of Berbere Afromontane Moist Forest, Bale Zone, South East Ethiopia; Implication to Biodiversity Conservation

The study was conducted on Berbere Forest in Bale Zone of Oromia Regional State, south east of Ethiopia with the objective of determining the structural analysis and natural regeneration status of the forest. Systematic sampling method was used to collect vegetation data. Seventy two nest quadrat sizes of 400 m2 (20 m × 20 m) for trees and shrubs were used. Within the main quadrat, two opposite side of each sub-quadrat of 25 m2 (5 m × 5 m) for sapling, 4 m2 (2 m × 2 m) for seedling of woody plants. The diameter and height were measured for all individual trees and shrubs having DBH (Diameter at Breast Height) ≥ 10 cm thick and ≥2 m height by using a diameter tape or caliper and clinometer respectively. For description and analysis of vegetation structure Diameter at Breast Height (DBH), basal area, tree density, height, frequency and important value index were used. Structural analysis of some selected tree species was revealed four different population patterns (bell shaped, inverted J-shaped, irregular and U-shaped). The total basal area of Berbere forest was 87.49 m2/ha, but most of the basal area was contributed by few large sized Moraceae family (Ficus vasta, Ficus ovate and Ficus thonningii) plant species. Analysis of regeneration status of woody plants in the forest showed 37.09% trees/shrubs species exhibited “good”, 19.35% showed “fair”, 6.45% showed “poor” and 25.81% trees/shrubs species were “not regenerating” at all and 11.29% trees/shrubs species were available only in sapling or seedling stage. Studies on the structure and regeneration of the forest indicated that there are species that require urgent conservation measures. Therefore, based on the results of this study, we recommended detail regenerating studies of seed bank in relation to various environmental factors such as soil type and properties.

Floristic Composition and Community Analysis of Berbere Forest, Bale Zone, South East Ethiopia

The study was conducted on Berbere forest in Bale Zone of Oromia National Regional State, South east of Ethiopia with the objective of determining the floristic composition and community type of the forest. Systematic sampling method was used to collect vegetation data. Seventy two quadrat size of 400 m² (20 m x 20 m) for trees, shrubs and lianas and five 1 m² (1 m x 1 m) for herbs one at each corner and one at the center of the main plot were used. In each of these quadrants, all vascular plant species were collected and brought to National Herbarium, Addis Ababa University for identification. Vegetation classification was performed using PC-ORD software packages. Sorensens’s similarity coefficient and Shannon-Wiener diversity index were also used to detect similarities among communities and to compute species richness and evenness between the plant communities’ respectively. A total of two hundred one plant species in 157 genera and 65 families were identified from the forest. Fabaceae and Asteraceae are the dominant families in terms of species richness. Based on the results of vegetation classification, three plant communities (Terminalia brownie-Psydrax schimperiana, Warburgia ugandensis - Podocarpus falcatus, and Euclea racemosa subsp. schimperi-Combretum molle) were recognized and described. Ethnobotanical studies to explore indigenous knowledge on the diverse uses of plants, and sound management and monitoring as well as maintenance of biodiversity that promote sustainable use of the forest and its products are recommended.

Bone-forming cells with pronounced spread into the third dimension in polymer scaffolds fabricated by two-photon polymerization.

The main aim of this work was to stimulate bone‐forming cells to produce three‐dimensional networks of mineralized proteins such as those occurring in bones. This was achieved by a novel approach using a specific type of mesenchymal progenitor cells (i.e., primary fibroblast cells from human hair roots) seeded on to polymer scaffolds. We wrote polymer microstructures with one or more levels of quadratic pores on to a flexible substrate by means of two‐photon polymerization using a Ti‐sapphire femtosecond laser focused into a liquid acrylate‐based resin containing a photoinitiator. Progenitor cells, differentiated into an osteogenic lineage by the use of medium supplemented with biochemical stimuli, can be seeded on to the hydrophilic three‐dimensional scaffolds. Due to confinement to the microstructures and/or mechanical interaction with the scaffold, the cells are stimulated to produce high amounts of calcium‐binding proteins, such as collagen type I, and show an increased activation of the actin cytoskeleton. The best results were obtained for quadratic pore sizes of 35 µm: the pore volumes become almost filled with both cells in close contact with the walls of the structure and with extracellular matrix material produced by the cells. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 891–899, 2017.

Optimal Subdivision for Treatment and Management of Catastrophic Landslides in a Watershed Using Topographic Factors.

Recent extreme rainfall events led to many landslides due to climate changes in Taiwan. How to effectively promote post-disaster treatment and/or management works in a watershed/drainage basin is a crucial issue. Regarding the processes of watershed treatment and/or management works, disaster hotspot scanning and treatment priority setup should be carried out in advance. A scanning method using landslide ratio to determine the appropriate outlet of an interested watershed, and an optimal subdivision system with better homogeneity and accuracy in landslide ratio estimation were developed to help efficient executions of treatment and/or management works. Topography is a key factor affecting watershed landslide ratio. Considering the complexity and uncertainty of the natural phenomenon, multivariate analysis was applied to understand the relationship between topographic factors and landslide ratio in the interested watershed. The concept of species-area curve, which is usually adopted at on-site vegetation investigation to determinate the suitable quadrate size, was used to derive the optimal threshold in subdivisions. Results show that three main component axes including factors of scale, network and shape extracted from Digital Terrain Model coupled with areas of landslide can effectively explain the characteristics of landslide ratio in the interested watershed, and a relation curve obtained from the accuracy of landslide ratio classification and number of subdivisions could be established to derive optimal subdivision of the watershed. The subdivision method promoted in this study could be further used for priority rank and benefit assessment of landslide treatment in a watershed.

Matchings of quadratic size extend to long cycles in hypercubes

Ruskey and Savage in 1993 asked whether every matching in a hypercube can be extended to a Hamiltonian cycle. A positive answer is known for perfect matchings, but the general case has been resolved only for matchings of linear size. In this paper we show that there is a quadratic function $q(n)$ such that every matching in the $n$-dimensional hypercube of size at most $q(n)$ may be extended to a cycle which covers at least $\frac34$ of the vertices.

Ecological Assessment of Plant Communities and Associated Edaphic and Topographic Variables in the Peochar Valley of the Hindu Kush Mountains

This study quantified the effect of environmental variables on plant species composition in the Peochar Valley, located in the Hindu Raj mountains of the Hindu Kush. A mixture of quadrat and transect methods were used. Quadrat sizes were 10 × 10 m, 2 × 5 m, and 1 m2 for trees, shrubs, and herbs, respectively, determined using the minimal area method. Twenty-seven stations were established along 6 elevation transects on slopes with various aspects. Density, cover, and frequency were recorded for all species in each quadrat. Aspect, elevation, rock types, soil nature, and grazing pressure were also considered as edaphic and topographic variables. Preliminary results showed that the Peochar Valley hosts 120 species. Presence/absence data for these species were analyzed with cluster and 2-way cluster techniques to elaborate species composition in the study area; this resulted in 4 plant communities. Species abundance and environmental data matrices were developed to evaluate the ecological gradient of vegetat...

Effects of wheat source and particle size in meal and pelleted diets on finishing pig growth performance, carcass characteristics, and nutrient digestibility.

Two experiments were conducted to test the effects of wheat source and particle size in meal and pelleted diets on finishing pig performance, carcass characteristics, and diet digestibility. In Exp. 1, pigs (PIC 327 × 1050; = 288; initially 43.8 kg BW) were balanced by initial BW and randomly allotted to 1 of 3 treatments with 8 pigs per pen (4 barrows and 4 gilts) and 12 pens per treatment. The 3 dietary treatments were hard red winter wheat ground with a hammer mill to 728, 579, or 326 μm, respectively. From d 0 to 40, decreasing wheat particle size decreased (linear, < 0.033) ADFI but improved (quadratic, < 0.014) G:F. From d 40 to 83, decreasing wheat particle size increased (quadratic, < 0.018) ADG and improved (linear, < 0.002) G:F. Overall from d 0 to 83, reducing wheat particle size improved (linear, < 0.002) G:F. In Exp. 2, pigs (PIC 327 × 1050; = 576; initially 43.4 ± 0.02 kg BW) were used to determine the effects of wheat source and particle size of pelleted diets on finishing pig growth performance and carcass characteristics. Pigs were randomly allotted to pens, and pens of pigs were balanced by initial BW and randomly allotted to 1 of 6 dietary treatments with 12 replications per treatment and 8 pigs/pen. The experimental diets used the same wheat-soybean meal formulation, with the 6 treatments using hard red winter or soft white winter wheat that were processed to 245, 465, and 693 μm and 258, 402, and 710 μm, respectively. All diets were pelleted. Overall, feeding hard red winter wheat increased ( < 0.05) ADG and ADFI when compared with soft white winter wheat. There was a tendency ( < 0.10) for a quadratic particle size × wheat source interaction for ADG, ADFI, and both DM and GE digestibility, as they were decreased for pigs fed 465-μm hard red winter wheat and were greatest for pigs fed 402-μm soft white winter wheat. There were no main or interactive effects of particle size or wheat source on carcass characteristics. In summary, fine grinding hard red winter wheat fed in meal form improved G:F and nutrient digestibility, whereas reducing particle size of wheat from approximately 700 to 250 μm in pelleted diets did not influence growth or carcass traits. Finally, feeding hard red winter wheat improved ADG and ADFI compared with feeding soft white winter wheat.

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Forest structure, diversity and regeneration potential along altitudinal gradient in Dhanaulti of Garhwal Himalaya

Aim of the study: The aim of the present study was to understatnd the forest composition, structure, diversity and regeneration potential along altitudinal gradient.Area of study: The study was carried out in Dhanaulti forest which falls under temperate region of Garhwal Himalaya in Uttarakhand state, India.Material and Methods: Vegetation analysis was carried out using 10 quadrats at each altitude using a quadrate size of 10×10 m2. In each quadrate, categories of trees &gt;30 cm cbh were considered as trees, 10-30cm cbh as saplings and &lt;10 cm cbh as seedlings. The data were quantitatively analyzed.Main results: In upper and middle altitudes, Cedrus deodara was reported dominant tree whereas, in lower altitude Quercus leucotrichophora was reported dominant. Tree density was highest in lower altitude which reduced middle and upper altitudes whereas, total basal cover increased with increasing altitude. The increasing total basal cover with altitude could be because of the presence of Cedrus deodara trees having higher girth classes. In tree, sapling and seedling layers, diversity (H) and equitabiltiy (EC) decreased with increasing altitude. However, concentrations of dominace (CD) and beta diversity (BD have shown reverse trend with H and EC which increased with increasing altitudes, in each layer of tree, sapling and seedling.The distribution pattern of most species in all layers of trees, saplings and seedlings was contagious. The regeneration potential of the species has shown that some of the species in the absence of tree layer are still regenerating particularly, Rhododendron arboreum, Benthamidia capitata, Neolitsea pallens etc. It indicates that most of the species are shifting upward as they are getting suitable conditions.Research highlights: Altitude influence species composition, diversity and regeneration potential of species.Key words: Distribution pattern; tree diversity; regeneration; mountains; temperate; Himalaya.

Scale-dependent effect of biotic interactions and environmental conditions in community assembly: insight from a large temperate forest plot

In forested ecosystems, it remains unclear whether environmental conditions, resource competition or their joint effects explain non-randomly distributed species pattern. Recently, trait-based approaches have been recognized as an important tool to infer processes governing community assembly patterns. In this study, we quantify patterns of functional composition and diversity to study how tree species coexistence is influenced by abiotic factors and biotic interactions in a species-rich temperate old-growth forest. In a 25 ha (500 × 500 m) fully mapped forest plot, we calculated functional composition (community weighted mean) and diversity of five key traits considering two spatial scales (20 × 20 and 50 × 50 m quadrats). We compared the observed patterns in functional diversity with randomly generated null communities to test for the presence of non-random patterns in community assembly, and studied the variation of functional composition and diversity along gradients of soil conditions to test for the shift in assembly processes along resource gradients. Functional diversity differed from null expectations depending on the spatial scale considered. In broad-scale quadrats (50 × 50 m), functional diversity in wood specific gravity (WSG) and leaf area (LA) was lower than expected by chance, whereas functional diversity in specific root length (SRL) was greater than expected. In small quadrats (20 × 20 m), functional diversity was lower than expected by chance in specific leaf area (SLA) and when considering all traits in combination. Functional composition and diversity varied along the soil resource gradient but the results were dependent on the scale considered. We found an increase in functional composition in maximum height (H) and WSG and a reduction in the functional diversity in most of traits suggesting an increase in competition with the increase in soil water content at small scale. The trait dispersion pattern for all traits in combination had no directional changes with some of individual traits generating more clear dispersion trend when the dominant competitor Pinus koraiensis was removed from the community dataset. The results presented here suggest that community assembly is governed by non-random processes in the studied forests. Interestingly, the choice of quadrat size seems to be crucial to describe community patterns and infer the forces governing community assembly. The consideration of different traits and environmental gradients allowed us to discover that different assembly mechanisms operate simultaneously in the studied forest.

Biogeomorphic disturbance: A case study on associations and methods after fire within the alpine treeline ecotone

Biogeomorphology is an increasingly popular field of study, but the approaches to biogeomorphic research and methods are not yet well developed. This research evaluated ecologic and geomorphic interactions after fire within the alpine treeline ecotone of Glacier National Park, Montana. Associations between soil conditions and vegetation, the effect of vegetation edges on soil characteristics, and the influence of quadrat size on select vegetation and soil variables were evaluated with the use of fieldwork and statistics. Of the 11 ecologic/soil variables compared, three were significantly correlated – soil compaction and krummholz density, soil loss and percent vegetation, and soil loss and burn severity. The ecologic edge between burned and unburned krummholz had significant influence on soil compaction, clast size, and effective soil depth patterns. Quadrat size did not have much influence on average results for either soil or vegetation variables. These findings highlight both the potential biogeomorphic interactions as well as interesting results that were not significant, and will contribute to the advancement of biogeomorphology. The results also provide novel information on alpine treeline ecotone response after fire.

A probability distribution model of small -scale species richness in plant communities

We devised a probability distribution model that best expressed species richness per quadrat in grassland communities, and clarified the mechanism by which the mean richness per quadrat was always larger than the variance among quadrats. Our model will aid in the understanding of community structures, and allow comparisons among different communities. The model was constructed based on relatively simple theoretical assumptions about the mechanisms in play in target communities. We assumed in the model that the number of species occurring in an actual quadrat, j, is the sum of “the fundamental number of species”, k (constant), and “a fluctuating number of species”, i (a Poisson variate with the mean of μ); that is, j=k+i, where i, j and k are non-negative integers. The probability that j species occur in a quadrat is given by a Poisson-like distribution (extended Poisson), with two parameters k and μ. The mean species richness in the probability distribution is expressed by λ (=k+μ), and the variance is λ−k. The proposed model afforded a good fit for the observed frequency distribution of species richness per quadrat. If even one species is common among many quadrats, the mean number of species per quadrat is greater than the variance. The greater the number of common species among quadrats is, the larger is the value of k, and then the more pronounced is the difference between the mean and the variance (although the variance does not change). We fitted the model to 55 datasets collected by ourselves from grasslands in various locations (Tibet, Inner Mongolia, Slovakia, or Japan), with varying quadrat size (0.25, 0.0625, or 0.01m2), and under differing management status (various stocking densities).

A Type-Directed Negation Elimination

In the modal mu-calculus, a formula is well-formed if each recursive variable occurs underneath an even number of negations. By means of De Morgan's laws, it is easy to transform any well-formed formula into an equivalent formula without negations -- its negation normal form. Moreover, if the formula is of size n, its negation normal form of is of the same size O(n). The full modal mu-calculus and the negation normal form fragment are thus equally expressive and concise. In this paper we extend this result to the higher-order modal fixed point logic (HFL), an extension of the modal mu-calculus with higher-order recursive predicate transformers. We present a procedure that converts a formula into an equivalent formula without negations of quadratic size in the worst case and of linear size when the number of variables of the formula is fixed.

Linear-time version of Holub's algorithm for morphic imprimitivity testing

Stepan Holub (Discr. Math., 2009) gave the first polynomial-time algorithm deciding whether a given word is a nontrivial fixed point of a morphism. His algorithm works in quadratic time for large alphabets. We improve the algorithm to work in linear time. Our improvement starts with a careful choice of a subset of rules used in Holub's algorithm that is necessary to grant correctness of the algorithm. Afterwards we show how to choose the order of applying the rules that allows to avoid unnecessary operations on sets. We obtain linear time using efficient data structures for implementation of the rules. Holub's algorithm maintains connected components of a graph corresponding to specially marked positions in a word. This graph is of quadratic size for large alphabet. In our algorithm only a linear number of edges of this conceptual graph is processed. A preliminary version of this paper appeared at LATA 2013 conference [11].

Fabrication of highly porous glass filters using capillary suspension processing

We present a novel, capillary suspension based processing route for sintered glass filters with porosities ⩾50% at average pore sizes between 1 and 50μm. This new kind of glass filters exhibits narrow pore size distribution and uniform pore structure. Pores are exceptionally smooth and round. Accordingly, permeability and mechanical strength of these filters excel that of similarly processed ceramic and commercial glass filters significantly.Mechanical strength at a given porosity is much higher than that of commercial glass filters and reaches values similar to that of ceramic filters with distinctly higher matrix strength. Absolute values are well predicted by the Gibson & Ashby model σc/σf,0=B0(1−ɛ)z with B0=0.8. Liquid permeability varies with pore size according to Darcy’s law but absolute values are clearly higher than that for ceramic filters at given pore size as expected from the smoother pore structure. Gas permeability is especially high at pore sizes <10μm and exceeds that of ceramic and commercial glass filters significantly. Moreover, this results in a weaker than quadratic pore size dependence. This is presumably due to slip effects occurring especially in small pores and narrow necks of the novel glass filters.

Analyzing the Distribution Patterns of Nutmeg (Myristica spp.) in Busama Forest Area Using Quadrat Size Technique

Trees in natural forests are scattered across and along altitudinal gradients. The mode of dispersion varies within a natural forest and is influenced by natural translocation phenomena of biotic and abiotic factors acting on the environment. It is understood that dispersion in a natural forest can be in random, uniformed or clumped and assumed to be in random at a certain degree. This study was carried out in Busama forest area in a permanent sampling plot to describe the distribution pattern of trees within the forest area with Myristica spp. used because of its dominance within the forest. The index of dispersion technique was used to assess and analyze the distribution patterns of Myristica spp. where quadrat sizes are increased from 1m2 to 2,500m2 using Microsoft EXCEL to generate subplots within the PSP and f – test was used to test the significance of the departure or closeness of the distribution to randomness at F0.01 ≥ 1.36 (at 1% level of significance). It was found that as the quadrat size increase the distribution pattern of Myristica spp. becomes random and also the population density increases but it is predicted that it will become random but in clumps (F0.01 ≥ 1.36), as the quadrat size increased to about 200m² and above, there is a significant departure from the randomness of closeness. However, the distribution pattern of Myristica species in this case is general and can be applied to other tree species in other locales.