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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The recovery of tropical lowland rainforest after clearfell logging in the Gogol Valley, Papua New Guinea

Saulei, Simon M. January 1985 (has links)
Recovery of tropical rain forest in Gogol Valley, Papua New Guinea was monitored for 2 years following clear-fel1ing in the wet and dry seasons. Further redevelopment, reconstructed by measurements of regrowth of known ages from 1.5-10.8 years, were compared with forest heavily disturbed by fire 55 years ago and primary forest. The vegetation, survey was assessed principally by Counting and measuring trees. Because of the importance of soil seed bank in influencing vegetation recovery processes, special attention was given to the spatial and temporal changes in the soil seed bank and the seed rain which supplies it. The major findings were: (1) vegetation recovery was rapid and 97% of all colonizing trees regenerated from seeds while 3% were resprouts; (2) regrowth after felling in the dry-season differed from that following wet-season felling in having lower density, slower growth and mostly comprised resprouting tree species; (3) after 10 years, regrowth is composed principally of large pioneer trees (65% of basal area or 64% of stems); (4) the 55 year-old forest also had many (48%) pioneer trees: much of the forest in the area is of this kind and may be classified as advanced secondary forest; (5) forest soil seed bank following felling was rapidly depleted due to germination, but was rapidly replaced as early pioneer herbs matured and set seed. Trees in soil seed bank do not approach that of primary forest until after 10 years of regrowth; (6) the intensity of pioneer trees' seed rain was correlated with the fecundity of nearby parent trees and clearly controlled soil seed bank redevelopment. There was evidence of dispersal of pioneer seeds several hundred metres into an isolated area of closed forest; (7) trees left uncut following felling contribute significantly to seed rain and therefore to soil seed bank.
2

Estimating the Economic Value of forest ecosystem services using stated preference methods: the case of Kakamega forest, Kenya

Diafas, Iason 24 July 2014 (has links)
No description available.
3

Les a jeho proměny v průběhu roku / Forest and its Changes During the Year

Mrvová, Petra January 2013 (has links)
(Forest and its changes during the year) The major objective of this thesis is to propose concrete possibilities of using the surrounding forests of Moravská Třebová in the educational process of pupils at primary schools. The current valid Framework Education Programme for Elementary Education, which focuses attention on this topic in several areas, was the starting point. Subsequently, the analysis of textbooks for primary education was conducted with the aim to find out the way of presentation of the subject matter. In the next section, the topical information related to the topic was obtained. It has made use of materials provided by the staff of the Department of the Environment of the municipality of Moravská Třebová and the local forest district of the state-owned company Forest of the Czech Republic. In the next stage of the thesis, the survey was conducted to find out what teachers think about the issue. The teachers of all primary schools in the town were involved in this research. Based on the evaluation of these findings, the possibilities of using forests and other woody areas for the educational process of pupils from primary schools in the town of Moravská Třebová were proposed. Some parts of the project were verified in the selected primary school in the town.
4

The Future of Fir

Vice President Research, Office of the January 2008 (has links)
Adam Wei is employing homegrown UBC technology to help manage the sustainability of China’s fir trees.
5

Partitioning soil CO₂ efflux through vertical profiles of manipulated forests in MOFEP /

Henderson, Rachel. January 2007 (has links)
Thesis (M.S.)--University of Toledo, 2007. / Typescript. "Submitted as partial fulfillment of the requirements for the Master of Science in Biology." Bibliography: leaves 35-38.
6

Bayesian spatial analysis with application to the Missouri Ozark Forest ecosystem project

Zhang, Jing, January 2008 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 3, 2009) Vita. Includes bibliographical references.
7

Individual tree detection and modelling above-ground biomass and forest parameters using discrete return airborne LiDAR data

Wan Mohd Jaafar, Wan Shafrina Binti January 2018 (has links)
Individual tree detection and modelling forest parameters using Airborne Laser Scanner data (Light Detection and Ranging (LiDAR) is becoming increasingly important for the monitoring and sustainable management of forests. Remote sensing has been a useful tool for individual tree analysis in the past decade, although inadequate spatial resolution from satellites means that only airborne systems have sufficient spatial resolution to conduct individual tree analysis. Moreover, recent advances in airborne LiDAR now provide high horizontal resolution as well as information in the vertical dimension. However, it is challenging to fully exploit and utilize small-footprint LiDAR data for detailed tree analysis. Procedures for forest biomass quantification and forest attributes measurement using LiDAR data have improved at a rapid pace as more robust and sophisticated modelling used to improve the studies. This thesis contains an evaluation of three approaches of utilizing LiDAR data for individual tree forest measurement. The first explores the relationship between LiDAR metrics and field reference to assess the correlation between LiDAR and field data at the individual-tree level. The intention was not to detect trees automatically, but to develop a LiDAR-AGB model based on trees that were mapped in the field so as to evaluate the relationships between LiDAR-type metrics under controlled conditions for the study sites, and field-derived AGB. A non-linear AGB model based on field data and LiDAR data was developed and LiDAR height percentile h80 and crown width measurement (CW) was found to best fit the data as evidenced by and Adj-R2 value of 0.63, the root mean squared error of the model of 14.8% and analysis of the residuals. This paper provides the foundation for a predictive LiDAR-AGB model at tree level over two study sites, Pasoh Forest Reserve and FRIM Forest Reserve. The second part of the thesis then takes this AGB-LiDAR relationship and combines it with individual tree crown delineation. This chapter shows the contribution of performing an automatic individual tree crown delineation over the wider forest areas. The individual tree crown delineation is composed of a five-step framework, which is unique in its automated determination of dominant crown sizes in a forest area and its adaption of the LiDAR-AGB model developed for the purpose of validation the method. This framework correctly delineated 84% and 88% of the tree crowns in the two forest study areas which is mostly dominated with lowland dipterocarp trees. Thirdly, parametric and non-parametric modelling approaches are proposed for modelling forest structural attributes. Selected modelling methods are compared for predicting 4 forest attributes, volume (V), basal area (BA), height (Ht) and aboveground biomass (AGB) at the species level. The AGB modelling in this paper is extracted using the LiDAR derived variables from the automated individual tree crown delineation, in contrast to the earlier AGB modelling where it is derived based on the trees that were mapped in the field. The selected non-parametric method included, k-nearest neighbour (k-NN) imputation methods: Most Similar Neighbour (MSN) and Gradient Nearest Neighbour (GNN), Random Forest (RF) and parametric approach: Ordinary Least Square (OLS) regression. To compare and evaluate these approaches a scaled root mean squared error (RMSE) between observed and predicted forest attribute sampled from both forest site was computed. The best method varied according to response variable and performance measure. OLS regression was to found to be the best performance method overall evidenced by RMSE after cross validation for BA (1.40 m2), V (1.03 m3), Ht (2.22 m) and AGB (96 Kg/tree) respectively, showed its applicability to wider conditions, while RF produced best overall results among the non-parametric methods tested. This thesis concludes with a discussion of the potential of LiDAR data as an independent source of important forest inventory data source when combined with appropriate designed sample plots in the field, and with appropriate modelling tools.
8

Soil microbial assembly and their ecosystem functions associated to tree diversity in European forests

Prada Salcedo, Luis Daniel 19 October 2021 (has links)
Investigating forest soil biodiversity is essential to increase our understanding of ecosystem functions, assess potential consequences of global change, and thus optimize future decision-making processes. This cumulative PhD thesis contributes to this field by elucidating responses of bacterial and fungal forest soil communities, and their associated functions, in relation to tree diversity using a trait-based ecological approach with a focus on microbial living strategies. The three main chapters investigated microbial communities, using PCR-amplicon molecular methods, bioinformatics and novel statistics in the frame of the SoilForEUROPE project funded through the 2015–2016 BiodivERsA COFUND call for research proposals. Links between above-belowground biodiversity are crucial to understand forest functionality. For instance, studies on relationships of tree diversity and tree identity with microbial diversity reveal shifts in litter decomposition, nutrient cycling, primary production and the regulation of greenhouse gas emissions. These kinds of studies commonly compare microbial populations of different tree taxonomical groups. However, the effects of different tree taxa on microorganisms are mediated by tree morphology, physiology, phenology and genetics. Therefore, the use of specific plant traits to study biodiversity has become more frequent, adding a mechanistic understanding of compositional or functional shifts and interactions with soil microbial communities. This generalizable approach provides a common currency to compare similar microbial communities from different regions or environments with few microbial taxa in common. Microbial communities are also filtered by other processes such as global drivers, stochastic events, abiotic and biotic factors in addition to the mentioned tree traits. This environmental filtering process results in a functional microbial community structure, also with their own set of traits to increase their population size through higher performance and as response the capacity to affect their own ecosystem. Furthermore, it is expected that a particular set of microbial traits represents the life history strategies that favored a particular community under specific environmental conditions. This thesis correlates tree traits with bacterial and fungal communities by using a wide-ranged European forest platform with 64 plots of four different latitudinal regions. The SoilForEUROPE design also included multispecies and monospecific forests comprising 13 main tree species and 33 different tree species compositions. All these conditions supplied a diversity of environments to improve our knowledge of microbial soil diversity and above-belowground interactions. The here presented thesis encompasses five individual chapters. Chapter 1 provides the research context, project presentation and the main approach used. The Chapters 2 and 3 were developed in association with colleagues from the University of Freiburg and investigate four major European forest types: boreal forests (Finland), hemi‐boreal forests (Poland), mountainous beech forests (Romania) and thermophilous deciduous forests (Italy). Chapter 4 focuses purely on temperate forest plots and Chapter 5 compiles and concludes the results and presented ecological meanings. In particular, Chapter 2 evaluated the influence of tree species composition and diversity on fungal diversity and community composition, and highlights the relationships of fungal guilds and enzymatic activities with tree traits in detail, while also taking environmental variables into account. We demonstrated, how guilds like fungal saprotrophs mirror the litter quality, while tree root traits are often linked to an increasing number of fungal symbiotrophs. We found that forest types of higher latitudes, which are dominated by fast tree communities, correlated with high carbon‐cycling enzymatic activities. In contrast, Mediterranean forests with slow tree communities showed high enzymatic activities related to nitrogen and phosphorus cycles. In Chapter 3, we investigated links between bacterial communities, their functionality and root trait dispersion. Bacterial diversity revealed no major changes across the root functional dispersion gradient. In contrast, predicted gene profiles linked to plant growth activities suggested an increasing bacterial functionality from monospecific to multispecies forest. We also exposed that in multispecies forests, the bacterial functionality declines with the increasing functional dispersion of the roots. We further revealed important effects of the tree species identity on bacterial community composition, but we did not find significant relationships with root functional dispersion. However, bacterial network analyses indicated that multispecies forest have a higher complexity in their bacterial communities, which points towards more stable forest systems with greater functionality. Chapter 4 aimed to explore microbial communities of different soil depths from 0 to 30 cm across forests covering deciduous, evergreen and mixtures plots. Microbial abundance and diversity were especially affected by soil depth and by the presence of evergreen trees. Results showed higher accuracy to detect niche preference by using taxonomy levels than metabolic pathways or fungal guilds as features of a machine learning model. We found that bacterial communities are primarily shaped by soil depth in contrast to fungal community, which were rather influenced by the forest composition. Results also supported the importance of mixed forest to maintain nutrient cycling and a broad diversity of metabolites compared to monospecific forest and this differences where particular perceived in the upper 10 cm of soil. Chapter 5 concludes the thesis and presents a few remarks highlighting microbial strategies that might be favored under a particular soil forest composition. Overall, this thesis not only revealed the ecological patterns of soil forest microbial communities, but also provides a practical tool with necessary information to support decision-making and enlarge the schemes to conserve soil biodiversity.
9

Exploring Potential Utilities of Forest Ecosystem Services and Local Resources Towards Livelihood Improvement- The Case of Bach Ma National Park and its Buffer Zones in Vietnam / 森林生態系サービスと地域資源の生業改善に資する潜在的有用性の検討-ベトナム・バックマー国立公園とその緩衝地域における事例

NGUYEN, THI HONG 23 September 2020 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第22816号 / 地環博第203号 / 新制||地環||39(附属図書館) / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)教授 西前 出, 教授 柴田 昌三, 准教授 落合 知帆 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM
10

Mercury Speciation in Temperate Tree Foliage

Tabatchnick, Melissa Danielle 28 October 2010 (has links)
No description available.

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