The main study objective was to develop robust processing and analysis techniques to facilitate the use of small-footprint lidar data for estimating forest biophysical parameters measuring individual trees identifiable on the three-dimensional lidar surface. This study derived the digital terrain model from lidar data using an iterative slope-based algorithm and developed processing methods for directly measuring tree height, crown diameter, and stand density. The lidar system used for this study recorded up to four returns per pulse, with an average footprint of 0.65 m and an average distance between laser shots of 0.7 m. The lidar data set was acquired over deciduous, coniferous, and mixed stands of varying age classes and settings typical of the southeastern United States (37° 25' N, 78° 41' W). Lidar processing techniques for identifying and measuring individual trees included data fusion with multispectral optical data and local filtering with both square and circular windows of variable size. The window size was based on canopy height and forest type. The crown diameter was calculated as the average of two values measured along two perpendicular directions from the location of each tree top, by fitting a four-degree polynomial on both profiles. The ground-truth plot design followed the U.S. National Forest Inventory and Analysis (FIA) field data layout. The lidar-derived tree measurements were used with regression models and cross-validation to estimate plot level field inventory data, including volume, basal area, and biomass. FIA subplots of 0.017 ha each were pooled together in two categories, deciduous trees and pines. For the pine plots, lidar measurements explained 97% of the variance associated with the mean height of dominant trees. For deciduous plots, regression models explained 79% of the mean height variance for dominant trees. Results for estimating crown diameter were similar for both pines and deciduous trees, with R2 values of 0.62-0.63 for the dominant trees. R2 values for estimating biomass were 0.82 for pines (RMSE 29 Mg/ha) and 0.32 for deciduous (RMSE 44 Mg/ha). Overall, plot level tree height and crown diameter calculated from individual tree lidar measurements were particularly important in contributing to model fit and prediction of forest volume and biomass. / Ph. D.

To understand the impact of N management on harvestable cover crop systems, seven research trials compared: 1) standard intensive management (SIM) (both fall and spring N application), 2) No fall N, a single spring N application, and 3) Cover N (no N application) effects on winter barley (Hordeum vulgare L.) plant biomass (PB), plant N uptake (PNU), grain yield, residual soil nitrate (RSN), and ammonium (RSA). In general, at winter dormancy, SIM resulted in increased PB and PNU but not RSN or RSA. At cover crop termination; SIM and the No fall N practices increased PNU, and at harvesting stage; they produced higher grain yields than the Cover N practice with little significant effect on RSN or RSA values, under normal climatic conditions. While overall yields for the No fall N treatment were lower (8%) than SIM yields, partial net return was similar due to decreased fertilizer input. Nitrogen use efficiency (NUE) of soft red winter wheat (SRWW) can be improved by characterizing genotypes for NUE using canopy spectral reflectance [(CSR), a cheap, rapid and non-destructive remote sensing tool]. The other objectives of this study were to evaluate the predictive potential of vegetative reflection indices for wheat nitrogen use efficiency (NUE) by genotype and the appropriate stages of CSR sensing. An elite panel of 281 regionally developed SRWW genotypes was screened under low and normal N regimes in two crop seasons for grain yield, N uptake, nitrogen use efficiency for yield (NUEY) and nitrogen use efficiency for protein (NUEP). The best models incorporating CSR data at wheat heading explained a significant proportion of total variation in grain yield, N uptake, NUEY and NUEP. Based on the best linear unbiased predictor values, genotypes were ranked and grouped into quartiles and the most efficient and responsive genotypes were identified. A significant proportion of the genotypes with high NUEY under high N conditions also had high NUEY under N stress; however, this was not the case for NUEP. Similarly, a significant proportion of genotypes with high NUEY also had high NUEP under both normal and low N conditions. / Ph. D.

Prohexadione-calcium (P-ca), as ApogeeTM, was evaluated in 2000 and 2001 for impact to grape vegetative and reproductive development. In 2000, P-ca (250 mg/L) was applied to Seyval, Cabernet Sauvignon, and Cabernet franc (125, 250, and 375 mg/L). P-ca reduced primary shoot growth for all cultivars and decreased cane pruning weight of Seyval. P-ca (375 mg/L) increased Cabernet franc canopy gaps but increased Cabernet Sauvignon lateral leaf area and leaf layer number. P-ca reduced components of yield for all cultivars. In 2001, P-ca (250 mg/L) was applied singularly at weekly intervals to Cabernet Sauvignon clusters and pre and post-bloom to Cabernet franc and Chardonnay canopies. Application at E-L stages 21 and 23 decreased Cabernet Sauvignon fruit set whereas application at E-L stages 26, 27, and 29 reduced berry weight without impacting fruit set. Berry weight reduction correlated to higher color intensity (420+520 nm), anthocyanins, total phenols and phenol-free glycosyl-glucose (PFGG). Cabernet franc vegetative and reproductive development was generally not affected yet treatment increased absorbance at 280, 420, and 520 nm, color intensity, anthocyanins and total phenols. Pre-bloom applications inhibited Chardonnay vegetative development, and reduced components of yield, and fruit chemistry values: hydroxycinnamates, total phenols, flavonoids, PPFG and absorbance at 280 and 320 nm. Post-bloom applications did not affect Chardonnay vegetative or reproductive development, yet increased PFGG. Treatment did not affect Chardonnay wine chemistry but two post-bloom applications increased Cabernet franc wine anthocyanins and total phenols. Wine aroma and flavor triangle difference tests did not indicate significant treatment differences. / Master of Science

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

Urban tree canopy cover is important because it mitigates negative impacts of urbanization such as urban heat and stormwater. Land development leads to canopy loss through tree removal, but some localities have regulations in place that require trees to be retained or replanted during development. The goal of these regulations is to preserve tree cover. Since 2009, Fairfax County, Virginia has had an ordinance that requires parcels to reach a certain amount of canopy 10 years post-development. However, it was unknown if the requirements of this ordinance were being met. To investigate this issue, we determined which developed parcels met their required canopy using remotely-sensed tree canopy cover data from 2021. We then conducted an additional analysis on a sample of developed parcels using their site plans to compare the canopy proposed by developers to the measured canopy from the geospatial data. These results were then compared to potential predictors of ordinance compliance to determine if there were certain attributes of a parcel that may drive ordinance compliance. Of all 482 parcels in Fairfax County that were developed from 2009 to 2011, 79.46% met their canopy requirements by 2021. For the sample of 151 developed parcels, 70% reached the proposed amount of canopy by 2021. The results suggest that Fairfax County's ordinance is promoting preservation of tree canopy cover in developed areas as intended. Zoning type, amount of canopy required, parcel size, impervious cover, and pre-existing canopy were all found to have a significant relationship with ordinance compliance. These findings could improve the understanding of the efficacy of tree ordinances in other localities. / Master of Science / Trees in cities provide residents with many benefits including absorbing stormwater, reducing pollutants entering waterways from runoff, filtering air pollutants, and lessening soil erosion. However, the removal of trees during construction reduces the number of trees, which reduces the benefits trees provide. One way municipalities are combating this issue is through creating policies that protect canopy in areas undergoing development. Fairfax County, Virginia has a policy that requires developers to ensure the land they develop has a certain amount of tree canopy 10 years after construction. This policy has been in effect in Fairfax County since 2009, but until now the county did not know if developed areas were meeting the required amount of tree canopy 10 years after construction. We used measurements of tree canopy cover as well as information from the construction plans of developed areas to determine where tree canopy requirements were being met and where they were not. Of all 482 parcels in Fairfax County that were developed from 2009 to 2011, 79.46% met their canopy requirements by 2021. We also investigated if certain attributes of a developed area may impact if that area will reach its required canopy in 10 years. Zoning type, amount of canopy required, parcel size, impervious cover, and pre-existing canopy were all identified as factors that may impact policy compliance. These findings could help other localities protect tree canopy cover using land development policies.

This bachelor thesis investigates nitrogen and carbon stable isotopes in Ireland during the Mesolithic and Neolithic. In recent years, the understanding of subsistence strategies in Northwestern Europe has improved and it has shown that the dietary stable isotope data of Neolithic Ireland is an extreme outlier in the region. The aim is to examine the manuring and canopy effect that have often been suggested to be possible contributing factors for this difference. There is no certainty whether this difference is due to diet, land use or any other cause while these effects remain uninvestigated. The effects are studied by comparing dietary isotopes with sources about land use, such as pollen and geochemical data, for four sites: Carrowkeel, Poulnabrone, Knowth and the Mound of Hostages (Duma na nGiall), which together comprise c. 80% of the Neolithic Irish stable isotope record. The manuring effect is not visible in the current stable isotope, pollen, geochemical, zoological and archaeobotanical record. The canopy effect may be reflected in that same dataset. If the canopy effect is indeed the cause of the difference between Irish and Southern British δ13C values, a detailed comparison between the pollen data close to the origin of the carbon stable isotope samples and the carbon stable isotope samples in another area, such as Southern Britain, may explain the outlier position of Ireland in North-western Europe. / Denna C-uppsats undersöker kväve-och kolisotoper i det neolitiska och mesolitiska Irland. Genom en stor tillväxt av data har det blivit tydligt att de irländska kväve- och kolvärdena är extrema jämfört med resten av britannien. Gödslingseffekten och trädskiktseffekten är två effekter som har misstänkts att orsaka denna skillnad. Syftet är att undersöka dessa effekter genom att leta efter samband mellan markbruk och stabila isotoper. Fyra begravningsplatser har valts ut till detta syfte: Knowth, Carrowkeel, Poulnabrone och Duma na nGiall (Mound of Hostages). 80% av alla stabila kol- och kväveisotopvärden härstammar från dessa begravningsplatser. Gödslingseffekten gick inte att identifiera i datasamlingen som innehåller stabila isotopvärden, pollen, zoologisk data, arkeobotanisk och geokemisk data. Trädskiktseffekten möjligtvis bekräftas av datasammanställningen. För att kunna förklara den fullständiga skillnaden mellan syd-brittiska och irländska δ13C-värden behövs en studie som även inkluderar detaljerad data av neolitiskt markbruk från Brittiska ön.

Wheat canopies were grown at either 330 or 1200 μmol mol-1 CO2 in sealed controlled environments, where carbon fluxes and radiation interception were continuously and nondestructively measured during their life cycles. The effects of elevated CO2 on daily growth rates, canopy quantum yield, canopy and root carbon use efficiencies, and final dry mass were calculated from carbon flux measurements in an open gas exchange system. Dry biomass at harvest was predicted from the gas exchange data to within ± 8%. The greatest effect of elevated CO2 occurred in the first 15d after emergence; however, several physiological processes were enhanced throughout the life cycle. Elevated CO2 increased average net photosynthesis by 30%, average shoot respiration by 10%, and average root respiration by 40%. Crop growth rate, calculated from gas exchange data, was 30% higher during both vegetative growth and reproductive growth. Elevated CO 2 did not affect radiation interception, but increased average canopy quantum yield from 0.039 to 0.051 (31%). Average canopy carbon use efficiency was increased by 12%. Although harvest index was unaffected, these increases in the physiological determinants of yield by elevated CO2 resulted in a 14% increase in seed yield.

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Invasive plants, animals, insects, and pathogens are a significant problem for land managers and conservationists as they can cause irreparable damage to local ecosystems. The emerald ash borer (EAB), an invasive beetle from China, was discovered in the U.S. in 2002, and has decimated ash populations throughout Michigan. It continues to move through Midwestern and some eastern states, usually killing a tree within 2-4 years of infection. Using a Global Positioning System (GPS) and Geographic Information System (GIS), all trees ≥ 45 cm and all ash ≥ 30 cm in diameter were measured and mapped within a 160 acre old-growth deciduous forest in northern Indiana. EAB was detected in 14 trees throughout the forest. A canopy map was generated, estimating 6.6 percent canopy loss due to EAB. Because of this research, the entire spread of EAB within this forest can now be documented and mapped. The methodological framework used in this research can assist land managers and property owners monitor their land by enabling them to: track changes in tree health more accurately; assess damage by creating forest inventory and canopy maps; and model potential damage over time. / Department of Natural Resources and Environmental Management

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