Strip Tree Research Articles

Planting trees in buffer strips for attenuating phosphorus runoff in Jiangsu Province, China

AbstractIn the last four decades, the Jiangsu province, like the rest of China, has undergone rapid economic development coupled with a rapid increase in environmental pollution. Freshwater ecosystems have been particularly affected. In Lake Tai, China's third‐largest freshwater lake by volume, water quality has been severely reduced. There is a renewed interest in establishing riparian buffer strips in China as a conservation practice for mitigating agricultural non‐point source pollution. To study the effect of riparian buffers on phosphorus attenuation, eight 50 m × 20 m plots were established between a rice farm and the shore of Lake Tai in China, with the 20 m width facing the lake shore. They were planted with hybrid poplar (Populus deltoides × euramericana), hybrid cypress (Taxodium ascendens × mucronatum), or a mixture of both at densities of 2 m × 3 m, 2 m × 5 m, or 5 m × 5 m, while one plot was left as a control. Samples collected from soil, tree leaves, and groundwater during 2014–2018 were analyzed for multiple forms of phosphorus. Results indicated that riparian buffer width and time (year) were the most significant factors of phosphorus attenuation on all plots. Tree density had a minor effect, with medium density being the most effective, and we found negligible differences among hybrid tree species on attenuating phosphorus. Farmers should use densely vegetated buffer strips at least 15 m wide to ensure a significant reduction in nutrient runoff. Species selection should be based on market value and ecological benefits.

Фитомасса березовых древостоев придорожных защитных лесных полос Северного Казахстана

Фитомасса березовых древостоев придорожных защитных лесных полос Северного Казахстана

Counterculture, Property, Place, and Time: Nimbin, 1973

Counterculture, Property, Place, and Time: Nimbin, 1973

Efeito alelopático do extrato aquoso de sabiá na germinação de sementes de fava

The Mimosa caesalpiniaefolia Benth. is a medicinal plant that can be used in agroforestry systems, is also employed in the composition of pasture trees in strips between fields, to enrich brush fields and as a hedge. The Phaseolus lunatus L. is one of four species of the genus Phaseolus exploited commercially; its use is preferably in the form of green beans cooked or in canned form. The aim of the present research was to evaluate aqueous extracts of Mimosa caesalpiniaefolia on the germination of seeds and initial growth of broad beans seedlings. The seeds of bean were sowed into vermiculite in boxes and placed in a germinador at 25 °C under continuous light. The substrate was moistened with the aqueous extract of young leaves of Mimosa caesalpiniaefolia in concentrations of 25%; 50%; 75%, 100%, and a control treatament whose substrate was moistened only with distilled water. The parameters evaluated were: percentage, first count, the index of germination speed and length of the primary root. The experimental design was completely randomized design with four replications of 25 seeds each. The data were subjected to analysis of variance and regression polynomial. In the study of polynomial regression (p < 0,05) equation was used to best fit the data. The values in percentage were transformed in arc sen (n/100) 0,5 . It was concluded that different

Modified Arc tree based hierarchical representation of digital curve

We modify the general Arc tree for better hierarchical representation of digital curve. The proposed method finds tree vertices at only dominant points. Experimental results illustrate superiority of our modified Arc tree over simple Arc tree, Strip tree and Equal error tree.

Hierarchical representation of digitized curves through dominant point detection

Hierarchical data structures play a key role in representation of spatial data. This paper proposes an algorithm for constructing hierarchical representations of digitized curves based on the dominant points of the curve. The comparison of the proposed scheme with the other hierarchical representation schemes viz. Arc Tree and Strip Tree reveals that the proposed algorithm is generally better than the Arc Tree and compares well with the Strip Tree scheme.

A comparison of forest structure among old-growth, variable retention harvested, and clearcut peatland black spruce (Picea mariana) forests in boreal northeastern Ontario

Harvesting techniques that retain structural elements of the original forest may help to preserve the characteristic ecological features and biological diversity of old-growth forests. Harvesting with advance regeneration protection (HARP) is one such technique practised in the Lake Abitibi Model Forest of northeastern Ontario on peatland sites. In this system, winter harvesting operations clear trees in strips about 5–7 m wide and using a minimum diameter limit cut extract trees from the adjacent residual forest rows, 5–9 m wide. In order to assess the effectiveness of HARP in retaining forest structure, we quantified forest and understorey structural features in 24 1.65-ha plots spanning a wide range of forest retention, including clearcuts, three levels of HARP, and the edge and interior of unharvested forest (logging had occurred 2.5–3.5 years before the study). Mean tree age, diameter, and height in HARP forests in all cases exceeded 68% of the mean values found in unharvested forest, which was strikingly higher than the percent retention of basal area (20–43%). Also, unlike clearcuts, HARP forests retained the inverse-J curves between stem density and size class observed in unharvested forests, although stem densities in all size classes were lower. The percentage of black spruce regeneration originating from seed versus vegetative layering was directly related to the amount of forest basal area retained, averaging 2–5% in unharvested forests, 9–38% in HARP forests, and 67% in clearcuts. Many understorey characteristics closely followed the harvest intensity gradient, with amounts of moss, lichen, and Ledum highest at the unharvested end of the gradient and amounts of decaying moss, coarse and fine downed woody debris, exposed soil, and sedge highest at the clearcut end of the gradient. When the structural features were combined into a single composite variable using Principal Components Analysis (PCA) and the scores plotted against basal area, the relationship was curvilinear, with HARP treatments retaining greater amounts of structural characteristics than expected based solely on the basal area of wood harvested. This research suggests that the retention and redevelopment of old-growth features in peatland black spruce forests will be better under a HARP system than under a traditional clearcut system. Longer-term research, specifically on the edge habitats created by the HARP system, is required. Key words: boreal, peatland, black spruce, alternative harvesting methods, forest ecology

Approximating Parametric Curves With Strip Trees Using Affine Arithmetic

Abstract We show how to use affine arithmetic to represent a parametric curve with a strip tree. The required bounding rectangles for pieces of the curve are computed by exploiting the linear correlation information given by affine arithmetic. As an application, we show how to compute approximate distance fields for parametric curves. ACM CSS: I.3.3 Computer Graphics—Curve, surface, solid, and object representations, G.1.2 Numerical Analysis—Approximation of surfaces and contours, G.1.0 Numerical Analysis—Interval arithmetic

Growth and herbage productivity of Gliricidia in Panicum maximum pasture as influenced by seedbed preparation, planting and weed control techniques

Interplanting Gliricidia (Gliricidia sepium [Jacq.] Walp.) into poor quality native grass can improve the quality of pasture. But information on methods to establish the tree legume into existing pasture is scarce. This study was designed to compare the effects of disc-ploughing, hoeing, or rotary tillage operations, and direct seeding or planting out potted seedlings on growth and dry matter yields of Gliricidia in grass pasture. The Guinea grass (Panicum maximum) pasture was first mowed to a height of 10 cm. Then the seedbed was prepared by either hoeing 0.5 m strip or rototilling 0.5 m strip with a 2-wheel tractor or disc-ploughing 1.0 m strip with a 4-wheel tractor. Eight weeks old potted seedlings were planted or seeds were sown direct. At 6 months after planting (MAP), trees in disc-ploughed strips averaged 81 cm in height, about 35% taller than trees in hoed- or rotary-tilled strips. Potted seedlings (average height 77 cm) grew 37% taller than direct-seeded trees. At 12 MAP trees in disc-ploughed strips yielded 95% more leaf DM (1170 vs. 600 kg/ha) than trees in hoed- or rotary-tilled strips. In order to intercrop Gliricidia into existing Guinea grass pasture, it is necessary to plant potted seedlings previously raised in nursery into 1.0 m wide strips disc-ploughed with 4-wheel tractor. Weed control is necessary.

The Palcazu Project

The Palcazu Project among the Yanesha native Amazonian Indians of eastern Peru is a pilot project in natural forest management using the strip shelter-belt system. The system allows for harvesting of all trees in strips 30-40 wide. Timber is processed locally. The plan consists of identification of forest land and fields of harvestable stands location of logging roads and layout of the narrow harvest strips. The advantages of the strip shelter-belt system are described in comparison to conventional selective cutting or extensive clear cutting schemes. The focus of discussion is on ecological and historical background and current operations. The relationship between the Indians and the project and the land holding patterns are presented. The project is considered socially and ecologically unique. The assumptions are that community participation is important in appropriate land management of Amazon forests that land ownership means self interest in preservation that investment must involve small landholders that longterm investment is necessary and that communities must repeat the economic returns in managing their natural resources. The forestry cooperative has survived 5 years of national and regional political upheaval due to a strong sense of ownership and commitment by the Yanesha. Project staff at the onset determined that inviting an entrepreneur to invest in the equipment needed for cutting and processing wood would not be desirable. Local colonists were also excluded. Involving the Yanesha community had advantages. There was an existing road through their communities. There was limited deforestation. The Yanesha valued the forest as forest and had expertise in tree felling. The communities were organized and communication channels were already established within and between communities. The Yanesha were also the most disadvantaged. The solutions to problems in banking and establishing infrastructure evolved through several years of dialogue. assessment of future sustainability is in part dependent on funding training and the political situation in Peru.

疎な距離情報と形状モデルとの階層的照合による２次元物体の認識

In this paper, we discuss a matching method of objects from range data measured more sparsely than the size of object's local structure. In such a case, observed data differ from models in several reasons; 1) occlusion of hollow part, 2) omission of feature elements, 3) bluntness of edges, 4) isolation of observed points, and 5) inconsistency with general knowledges. The aim of the paper is to develop a way to compare sparse imcomplete data with complete model description in hierarchical manner using strip tree, and the validity of the algorithm is demonstrated for 2-D examples. We also discuss 3-D matching of depth images by extending strip tree.

Short-term effects of changes in soil management and nitrogen fertilizer application on ‘Bramley’s Seedling’ apple trees.

Soil managment in a ‘Bramley’s Seedling’ orchard, established in a system of herbicide treated tree rows and mown grass alleys, was changed to provide three treatments: complete grass cover, overall herbicide and a continuation of the existing system. Differential rates of N fertilizer (nil, 62.5 kg ha-1) were applied to each soil management regime. In comparison with herbicide strips, complete grass was intensely competitive, particularly with nil application of N fertilizer, reducing tree growth and yield and greatly decreasing leaf N. Leaves from trees in complete grass (nil N) plots contained higher concentrations of P, K and B but lower ones of Ca, Mn and Cu. Compared with the change from herbicide strip to complete grass management, effects of changing to overall herbicide were smaller. There were slight increases in leaf N concentration but no increases in tree growth or fruit yield. Leaf Mn concentration was increased in overall herbicide. Although application of N fertilizer to grass plots increased leaf N concentration by 0.4% and the three-year girth increment, yield was less than that of trees in herbicide strips. Nitrogen fertilizer applied to herbicide strips or overall herbicide plots slightly increased leaf N content but there was no effect on yield or girth increase. Applying N fertilizer to complete grass plots reduced the concentration of P, K and B in leaves but increased leaf Ca, Mn and Cu.

Short-term effects of changes in soil management and nitrogen fertilizer application on ‘Bramley’s Seedling’ apple trees.

Nitrogen concentration of fruits was reduced and P and B concentrations increased by changing from an orchard system of herbicide tree rows and mown grass alleys (66% bare soil) to complete grass cover. There was a tendency for higher Ca concentrations in the generally smaller fruits from trees in complete grass plots and, in one year, these fruits developed less bitter pit during air and CA (9% Co2 + 12% O2) storage than those from trees in herbicide strips. Fruits from complete grass plots, particularly those which had received nil N fertilizer, were firmer, redder with a more yellow background colour at harvest than those from strip plots. After CA storage fruits from grass plots remained firmer and tended to be less green. Changing from herbicide strip to overall herbicide management reduced fruit P (in the third year of the experiment) and B, and tended to reduce fruit Ca concentration; the latter effect was due to small increases in mean fruit weight. Fruits from overall herbicide plots tended to develop more bitter pit during storage. Fruit from herbicide strips and overall herbicide were of similar red coloration, greenness and firmness both at harvest and after CA storage. Increases in fruit N which resulted from application of N fertilizer (62.5 kg ha-1) to herbicide strip or overall herbicide plots were small compared with those which occurred in complete grass. Nitrogen fertilizer application to complete grass and herbicide strip plots reduced fruit P more than when applied to overall herbicide. Fruit B concentrations were reduced by N application particularly in complete grass. Nitrogen fertilizer applied to complete grass plots reduced fruit red colour, firmness and increased greenness. There was little effect of N application on the quality of fruit from herbicide strip or overall herbicide plots.

Strip trees: a hierarchical representation for curves

The use of curves to represent two-dimensional structures is an important part of many scientific investigations. For example, geographers use curves extensively to represent map features such as contour lines, roads, and rivers. Circuit layout designers use curves to specify the wiring between circuits. Because of the very large amount of data involved and the need to perform operations on this data efficiently, the representation of such curves is a crucial issue. A hierarchical representation consisting of binary trees with a special datum at each node is described. This datum is called a strip and the tree that contains such data is called a strip tree. Lower levels in the tree correspond to finer resolution representations of the curve. The strip tree structure is a direct consequence of using a special method for digitizing lines and retaining all intermediate steps. This gives several desirable properties. For curves that are well-behaved, intersection and point-membership (for closed curves) calculations can be solved in 0(log n ) where n is the number of points describing the curve. The curves can be efficiently encoded and displayed at various resolutions. The representation is closed under intersection and union and these operations can be carried out at different resolutions. All these properties depend on the hierarchical tree structure which allows primitive operations to be performed at the lowest possible resolution with great computational time savings. Strip trees is a linear interpolation scheme which realizes an important space savings by not representing all the points explicitly. This means that even when the overhead of the tree indexing is added, the storage requirement is comparable to raster representations which do represent most of the points explicitly.