A functional trait analysis of successional pathway dynamics

The study of plant community re-assembly following disturbances in anthropogenically managed landscapes is a necessity in today’s climate. The measurement of plant functional traits is a tool that can be of great help in understanding how individual plants and entire communities respond to shifts in disturbance regimes and environmental characteristics that are directly or indirectly under human influence. In Eastern Newfoundland, two distinct successional pathways may be initiated depending on fire severity. Fires of high severity in Picea mariana-dominated forests will initiate a forest succession; fires of low severity can cause a state shift where an ericaceous heath dominated by Kalmia angustifolia will succeed where a P. mariana-dominated forest once stood. To enhance understanding of community response to varying disturbance regimes, I applied a functional trait analysis to two distinct successional pathways with the aim of (i) assessing the functional diversity (FD) of both pathways, (ii) identifying the causes of the observed FD, and (iii) using the functional traits of both communities to predict future successional pathways. Alpha functional diversity (α-FD) was calculated as functional dispersion (FDis) and beta functional diversity (β-FD) was mean pairwise distance (DPW) and mean distance to nearest neighbour (DNN). Identifying significant drivers of FD in both communities was performed by linking soil characteristics with plant traits via a combine RLQ-fourth corner approach. Finally, prediction of post-fire succession was made possible by constructing a model based on fuzzy logic that incorporated community flammability and regeneration strategy of dominant plants, along with environmental variables

Risk Management in Environment, Production and Economy

The term "risk" is very often associated with negative meanings. However, in most cases, many opportunities can present themselves to deal with the events and to develop new solutions which can convert a possible danger to an unforeseen, positive event. This book is a structured collection of papers dealing with the subject and stressing the importance of a relevant issue such as risk management. The aim is to present the problem in various fields of application of risk management theories, highlighting the approaches which can be found in literature

Modelling of microbial populations in biofilm reactors for nitrogen removal from wastewater

The removal of nitrogen from wastewater is essential to prevent algae blooms and fish death in aquatic systems. Conventional biological nitrogen removal is based on nitrification, i.e., the conversion of ammonium to nitrite by ammonia-oxidizing bacteria (nitritation) and nitrite to nitrate by nitrite-oxidizing bacteria (nitratation). Biofilm reactors, in which the bacteria grow in a microbial layer attached to a carrier, are typically applied to prevent the slow-growing nitrifying bacteria from being washed out of the reactor. In this doctoral research, the influence of microbial competition and coexistence, besides operational conditions, on biological nitrogen removal in biofilm reactors was studied through mathematical modelling and simulation. Microbial diversity and competition were incorporated in dynamic biofilm models considering spatial gradients perpendicular to the carrier. Insights were gained on the influence of (1) microbial diversity on steady state and dynamic behaviour of nitrifying biofilms and (2) microbial characteristics, process conditions, and biofilm characteristics on microbial competition. It was demonstrated that species performing the same function typified by a trade-off between their growth rate and affinity were able to coexist in the biofilm at steady state due to the diffusional substrate gradients creating different niches in the biofilm

Quantitative Techniques in Participatory Forest Management

Forest management has evolved from a mercantilist view to a multi-functional one that integrates economic, social, and ecological aspects. However, the issue of sustainability is not yet resolved. Quantitative Techniques in Participatory Forest Management brings together global research in three areas of application: inventory of the forest variables that determine the main environmental indices, description and design of new environmental indices, and the application of sustainability indices for regional implementations. All these quantitative techniques create the basis for the development of scientific methodologies of participatory sustainable forest management