No description available.

No description available.

Although manipulation of the light regime is a common goal of silvicultural treatments, the specific light conditions created are poorly documented for many forest types and geographic locations. To help quantify effects of silivicultural treatments on light conditions, basal area, canopy structure, and photosynthetically active radiation (PAR), collected both instantaneously and across time, were measured in central hardwood forests following silvicultural treatments. These measurements were used to: 1.) investigate the magnitudes of differences in understory percent ambient PAR following implementation of shelterwood and thinning treatments; 2.) document the specific amount and variability of understory percent ambient PAR in shelterwood treatments (mean residual basal area=21 ft2/ac [4.8 m2/ha]), thinning (78 ft2/ac [17.9 m2/ha]), and untreated controls (18 ft2/ac[4.1 m2/ha); and 3.) Examine relationships between: basal area and canopy cover; basal area and measured percent ambient PAR; and canopy cover and measured percent ambient PAR. It was found that greater light levels resulted from greater canopy removals. Indexes of variability in light across time and among locations within a stand were higher in the shelterwood and thinning treatments than in the uncut control. Simple linear regression relationships were observed between basal area and PAR (r2= 0.8784 for instantaneous measurements, r2= 0.9697 for continuous measurements), and basal area and canopy cover (r2=0.8479). Such relationships provide a means for including light management in forest planning and application of silivicultural treatments.

An inclined point frame was used to measure leaf area indicies in an alpine tundra Kobresia stand and Deschampsia meadow on Niwot Ridge, Colorado. Measurements were made throughout the summer of 1971 at vi various heights in the canopy and for each species in the two communities. Maximum leaf area indices of 2.2 and 2.0 occurred in the Kobresia and Deschampsia sites, respectively. The Kobresia site was characterized by a single dominant species, Kobresia myosuroides, and a predominance of vegetation within 2.5 cm of mean ground level. The Deschampsia site had no single dominant species. The region of maximum foliage shifted from the 2.5 to 5 cm height zone in June to the 5 to 10 cm zone in early August. Phenological observations revealed a greater number of vegetative contacts in the Deschampsia site on all sampling dates. Certain shared species varied in their phenological patterns. It is suggested that differences in the duration of snow cover and surface melt-water may be related to the variation in phenological patterns in the two sites. In both communities, maximum LAI occurred when flower and fruit production overlapped. Arctic tundra LAI values, measured using similar methods, were less than half the maximum LAI values reached in the alpine communities examined here.

Understory light environments are inherently heterogeneous and therefore difficult to characterize. Numerous methods to measure understory light have been assessed in closed-canopied forests; however, the reliability of these methods has not been addressed for open-canopied forests. Therefore, the first objective of this study, presented in Chapter 3, was to test the accuracy and precision of various light measurement techniques at different time scales and sky conditions. The methods assessed performed differently depending on the sky condition and time of year when the sample was taken. To estimate annual photosynthetic photon flux density transmittance (annual %PPFD), the use of a 10-minute average of PPFD measured on an overcast day (%PPFDovercast) was effective, but accuracy decreased with decreasing solar altitude (ie season change). Hemispherical photographs used to estimate weighted canopy openness and gap fraction were effective methods, but gap light index (GLI) also derived from hemispherical photographs performed better. Accuracy of daily %PPFD estimates using %PPFDovercast, weighted canopy openness, and gap fraction were strongly affected by solar altitude and sky condition. Gap light index was very effective in estimating daily %PPFD for all sky conditions and time periods. The second objective of this study, presented in Chapter 4, was to characterize the relationship between canopy structure and spatial distribution of light by using three replicates of one uncut treatment and three harvest treatments: single tree, small gap (0.1 ha), and large gap (0.2 ha). Each harvest retained similar residual basal area but with different spatial patterns of the residuals, ranging from uniformly dispersed (single tree) to different degrees of aggregation (small and large gap). Average stand level light availability increased 12-22% when the same residual basal area of trees was distributed in clusters versus a uniform distribution. The variation of light availability increased as stands became more aggregated and larger amounts of the variation was explained by the spatial pattern of the canopy structure. Spatial autocorrelation range was twice as large in the small gap harvest then the other harvest treatments. It is suggested that seedling growth response to these differences in spatial patterns of light may differ between the different harvests. / Master of Science

Made available in DSpace on 2017-07-10T17:37:28Z (GMT). No. of bitstreams: 1 Marcelo Angelo Campagnolo.pdf: 1417290 bytes, checksum: 5c4258f560372c956838d25a4574f101 (MD5) Previous issue date: 2008-09-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of the present work was to study the effect of number of productive branches and lopping system in the development and green fig tree yield of Roxo de Valinhos in organic system. The experiment using four year-old plants, with spacing 3 x 2 m, was carried out between July/2007 and March/2008 in Quatro Pontes-PR (24o35 42 South latitude and 53o59 54 West longitude, altitude of 472 m and Cfa Koppen climate, with annual maximum medium temperature of 28.5oC and minimum of 16.6oC). The design utilized was randomized blocks with four replicates, and the treatments arranged in a 5 x 2 factorial scheme, taking as factors number of lopping (one, two, three or four, besides the control without lopping) and number of productive branches (plants conducted with six or twelve branches). In the lopping system, after the emission of the 16th leaf, the branch was blunted (removed the apical bud), being selected two sprouting by productive branches. New lopping was accomplished later on, always after the emission of the sixth leaf. In each plot, made up of three useful plants, data concerning the cropping cycles of 2007/08 were collected. Fig production under organic system is technically viable. The highest green fig yield (2,208 g planta-1) and dear productivity (3,681 Kg ha-1) was observed in the treatment which had plants conducted with twelve branches, with three lopping. There was a prolongation of the crop in the plants were made more lopping. Besides the increase in the production and prolongation of the crop, the lopping plants presented fruits with larger diameter and uniformity in relation to the witness. That uniformity allows to concentrate the crop and to decrease like this the use of cupric products / O objetivo deste trabalho foi estudar a influencia do numero de ramos produtivos e do sistema desponte sobre o desenvolvimento e producao de figos verdes Roxo de Valinhos em cultivo organico. O experimento utilizando plantas de quatro anos de idade, com espacamento 3 x 2 m, foi conduzido de julho de 2007 a marco de 2008 em Quatro Pontes-PR (24o35 42 latitude Sul e 53o59 54 longitude Oeste, altitude de 472 m e clima Cfa Koppen, com temperatura media maxima anual de 28,5oC e minima de 16,6oC). O delineamento utilizado foi em blocos ao acaso, com quatro blocos e os tratamentos arranjados em esquema fatorial 5 x 2, tomando por fatores o numero de despontes (um, dois, tres ou quatro, alem do controle sem desponte) e numero de ramos produtivos (plantas conduzidas com seis ou doze ramos). No sistema desponte, apos a emissao da 16o folha, o ramo foi despontado (gema apical removida), selecionando-se duas brotacoes por ramo produtivo. Novos despontes foram realizados posteriormente, sempre apos a emissao da sexta folha. Em cada parcela, constituida de tres plantas uteis, foram coletados dados no ciclo de producao 2007/08. A maior producao (2.208 g planta-1) e produtividade estimada (3.681 Kg ha-1) observada de figos verdes, foram obtidas quando as plantas foram conduzidas com doze ramos produtivos, efetuando-se tres despontes. Houve um prolongamento da colheita nas plantas onde se efetuaram mais despontes. Alem do aumento na producao e prolongamento da safra, as plantas despontadas apresentaram frutos com maior diametro e uniformidade em relacao a testemunha. Essa uniformidade permite concentrar a colheita e diminuir assim o uso de produtos cupricos

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第17902号 / 農博第2025号 / 新制||農||1017(附属図書館) / 学位論文||H25||N4798(農学部図書室) / 30722 / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 德地 直子, 教授 吉岡 崇仁, 准教授 長谷川 尚史 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

No description available.

A commercially available, tripod mounted, ground-based laser scanner was used to assess forest canopies and measure individual tree parameters. The instrument is comparable to scanning airborne light detection and ranging (lidar) technology but gathers data at higher resolution over a more limited scale. The raw data consist of a series of range measurements to visible surfaces taken at known angles relative to the scanner. Data were translated into three dimensional (3D) point clouds with points corresponding to surfaces visible from the scanner vantage point. A 20 m x 40 m permanent plot located in upland deciduous forest at Coweeta, NC was assessed with 41 and 45 scans gathered during periods of leaf-on and leaf-off, respectively. Data management and summary needs were addressed, focusing on the development of registration methods to align point clouds collected from multiple vantage points and minimize the volume of the plot canopy occluded from the scanner's view. Automated algorithms were developed to extract points representing tree bole surfaces, bole centers and ground surfaces. The extracted points served as the control surfaces necessary for registration. Occlusion was minimized by combining aligned point clouds captured from multiple vantage points with 0.1% and 0.34% of the volume scanned being occluded from view under leaf-off and leaf-on conditions, respectively. The point cloud data were summarized to estimate individual tree parameters including diameter at breast height (dbh), upper stem diameters, branch heights and XY positions of trees on the plot. Estimated tree positions were, on average, within 0.4 m of tree positions measured independently on the plot. Canopy height models, digital terrain models and 3D maps of the density of canopy surfaces were created using aligned point cloud data. Finally spatially explicit models of the horizontal and vertical distribution of plant area index (PAI) and leaf area index (LAI) were generated as examples of useful data summaries that cannot be practically collected using existing methods. / Ph. D.

<div>The accelerating expansion of agricultural and urban areas fragments and degrades forests</div><div>and their capacity to provide essential ecosystem services while increasing physiological stress</div><div>and mortality rates of trees growing near forest edges. Previous studies have documented that</div><div>edges are hotter and drier than forest interiors and trees nearer the edge grow slower. However,</div><div>the physical structure of a forest’s canopy may serve to mitigate to these effects. This study</div><div>quantifies forest fragmentation across the Central Hardwoods Region (CHR; containing Missouri,</div><div>Illinois, and Indiana) and characterizes structural differences between the canopies of forest edges</div><div>and forest interiors. Importantly, we distinguish between edges that neighbor developed land and</div><div>agricultural lands since these landcover types may impose distinct effects on forest structure. We</div><div>characterized forest canopy structure in a subset of the CHR region using the 2016-2020 Indiana</div><div>3DEP Lidar Program data. Our findings indicate edge forest (forests within 30m of an edge) makes</div><div>up 29.8% of the total forest in our study extent, with urban and agricultural edges accounting for</div><div>17.8% and 72.8% of the edge edges in the region, respectively. Analysis of 15 separate structural</div><div>metrics derived from aerial laser scanning (ALS) showed no significant structural differences</div><div>between developed and agricultural edge canopies but did find differences between structure of</div><div>canopies in forest cores and those in forest edges of any kind. As developed and agricultural lands</div><div>increase so too will forest fragmentation and the creation of new forest edges. If there are no</div><div>significant differences between forest edge types, then we could begin to treat edges without</div><div>distinction. This could lead to simplified management practices for foresters and urban foresters</div><div>alike to protect and preserve forest fragments.</div>