Model forest system: even-aged Douglas fir plantation with invasive Rhododendron

This thesis investigated the ecology and dynamics of Douglas fir (Pseudotsuga menziesii var. menziesii) dominated plantations at Coed-y-Brenin, Wales, whose transformation to continuous cover forestry has been delayed due to the presence of non-native invasive rhododendron (Rhododendron ponticum L). The literature review highlighted the complementary evolution of silviculture and modelling concepts to meet societal expectations and advance knowledge and understanding. It highlighted the development of hybrid, individual-based models, facilitated by advances in technology and complex systems theory to address contemporary pressures on forests. Three permanent sample plots of different ages, collectively covering 1.6ha of forest, were resurveyed in 2011, producing a 5-year growth series of mensuration data to parameterise an individual-based spatially-explicit forest growth model, SORTIE-ND. Vegetation, soil and light were surveyed to construct a statistical model of rhododendron seedling establishment and determine Ecological Site Classification. The limiting factors identified by the ecological site classification were a slightly dry Soil Moisture Regime and a poor Soil Nutrient Regime with moderate to high phosphorus and low nitrogen availability. SORTIE-ND was successfully parameterised using a maximum likelihood technique and simulated annealing. Parameterised relationships achieved an excellent level of fit to the data (R2 of 0.785 to 0.971), and the stand simulations produced DBH density plots comparable to observed size distributions. A Bayesian statistical model of rhododendron seedling establishment was produced. The cross-validated model predicted 81.3% of 24 survey stations with rhododendron seedlings, and 75% of 16 stations without seedlings, with an overall accuracy of 77.5%. Seedling establishment probability increased with soil O layer depth and decreased with increasing summed tree height in a 12x12 m neighbourhood. SORTIE-ND was then parameterised, using published literature, for the rhododendron lifecycle, to highlight knowledge gaps and as the novel first step towards full parameterisation from field data and the creation of decision support systems enabling foresters to interrogate the impact of different harvest regime scenarios on rhododendron invasion vulnerability

Model forest system: even-aged Douglas fir plantation with invasive Rhododendron

This thesis investigated the ecology and dynamics of Douglas fir (Pseudotsuga menziesii var. menziesii) dominated plantations at Coed-y-Brenin, Wales, whose transformation to continuous cover forestry has been delayed due to the presence of non-native invasive rhododendron (Rhododendron ponticum L). The literature review highlighted the complementary evolution of silviculture and modelling concepts to meet societal expectations and advance knowledge and understanding. It highlighted the development of hybrid, individual-based models, facilitated by advances in technology and complex systems theory to address contemporary pressures on forests. Three permanent sample plots of different ages, collectively covering 1.6ha of forest, were resurveyed in 2011, producing a 5-year growth series of mensuration data to parameterise an individual-based spatially-explicit forest growth model, SORTIE-ND. Vegetation, soil and light were surveyed to construct a statistical model of rhododendron seedling establishment and determine Ecological Site Classification. The limiting factors identified by the ecological site classification were a slightly dry Soil Moisture Regime and a poor Soil Nutrient Regime with moderate to high phosphorus and low nitrogen availability. SORTIE-ND was successfully parameterised using a maximum likelihood technique and simulated annealing. Parameterised relationships achieved an excellent level of fit to the data (R2 of 0.785 to 0.971), and the stand simulations produced DBH density plots comparable to observed size distributions. A Bayesian statistical model of rhododendron seedling establishment was produced. The cross-validated model predicted 81.3% of 24 survey stations with rhododendron seedlings, and 75% of 16 stations without seedlings, with an overall accuracy of 77.5%. Seedling establishment probability increased with soil O layer depth and decreased with increasing summed tree height in a 12x12 m neighbourhood. SORTIE-ND was then parameterised, using published literature, for the rhododendron lifecycle, to highlight knowledge gaps and as the novel first step towards full parameterisation from field data and the creation of decision support systems enabling foresters to interrogate the impact of different harvest regime scenarios on rhododendron invasion vulnerability

Evidence for alternate stable states in an Ecuadorian Andean Cloud Forest

Tree diversity inventories were undertaken. The goal of this study was to understand changes in tree community dynamics that may result from common anthropogenic disturbances at the Reserva Los Cedros, a tropical montane cloud forest reserve in northern Andean Ecuador. The reserve shows extremely high alpha and beta tree diversity. We found that all primary forest sites, regardless of age of natural gaps, are quite ecologically resilient, appearing to return to a primary-forest-type community of trees following gap formation. In contrast, forests regenerating from anthropogenic disturbance appear to have multiple possible ecological states. Where anthropogenic disturbance was intense, novel tree communities appear to be assembling, with no indication of return to a primary forest state. Even in ancient primary forests, new forest types may be forming, as we found that seedling community composition did not resemble adult tree communities. We also suggest small watersheds as a useful basic spatial unit for understanding biodiversity patterns in the tropical Andes that confound more traditional Euclidean distance as a basic proxy of dissimilarity. Finally, we highlight the conservation value of Reserva Los Cedros, which has managed to reverse deforestation within its boundaries despite a general trend of extensive deforestation in the surrounding region, to protect a large, contiguous area of highly endangered Andean primary cloud forest

Pioneer species ecology: co-existence and ecological differences amongst contrasting species

<p>Ecological differences were investigated for two co-existing pioneer species from the Cecropia family for variation of first branch height and canopy width across old field and old-growth forest habitats and within habitat variation between species. Forest enumeration data was collected, on all trees >5 cm DBH, from 4 study sites, each containing 9 old-growth forest and 4 old field plots, within the Los Cedros reserve, Ecuador. Cecropia species 1 was not locally more abundant but was found to be more spatially distributed at 32 of the 52 plots; Cecropia sp. 2 was only present at 7 of the 52 plots. Coefficients of variation and allometric relationships were investigated within species and between habitats. No significant variation was found for either species between habitats. For investigations of first branch height Cecropia species 1 was significantly lower than Cecropia sp. 2 in comparisons of actual first branch height (old-growth forest, p</p

A strategy to achieve development through research based on local perceptions in Riberalta, Bolivia

<p>This investigation was realised over 9 weeks in Riberalta, Beni, in the Northern<br>Bolivian Amazon. Interviews and group exercises were carried out in local communities<br>(Palmira, 26 de Octubre, Warnes, 7 de Julio, Santa Maria, Berlin and Popechi) and with<br>local practitioners; primarily with the workers from the three teams (Agroforestry,<br>Forestry and Social) of IPHAE, but also with personnel from ForLive and PROMAB<br>the constituent parts of the Instituto de Investigaciones Forestales de la Amazonía<br>(IIFA).</p

Detection and characterisation of Black Death burials by multi-proxy geophysical methods

The construction of the new Crossrail railway discovered 25 well preserved skeletons shallowly buried in Central London in 2013. Subsequent carbon dating and aDNA analysis confirmed the archaeological age and presence of the Yersinia pestis “Black Death” plague epidemic strain. Here we present the non-invasive multi-proxy geophysical survey of the adjacent Charterhouse Square, rapidly undertaken to detect any further burials and characterise the site. Historical records suggested the area was a burial ground for Black Death plague victims, before subsequent cemetery and urban land use. Following initial trial surveys, surveys imaged ∼200 isolated and similar-sized burials in the south-west of the site. There were also two contrasting burial orientations present at various depths which suggested a series of controlled phased burials. A well-defined eastern burial boundary, taking the form of a ditch and bank, was also discovered. Geophysical surveys also identified a subsequent complex site history with multiple-aged features. This study revises knowledge of Black Death aged-burials and provides important implications for successful geophysical burial detection with significant time- and space-limited site constraints

The Rise and Fall of a Collaboration: Reflections on the benefits, challenges and lessons learned from a joint England-China teaching initiative

UK Higher Education Institutions are increasingly working with overseas institutions as a means of increasing numbers of international students. Transnational education (TNE) initiatives can take many forms, from overseas campuses, ‘flying faculty’ delivering teaching overseas, to arrangements giving advanced standing for students from a particular overseas programme to enter higher years of a programme in the UK (e.g. a 3+1 programme). This paper describes a model where ‘flying faculty’ from an English university deliver teaching at an overseas institution as part of years two and three of a student’s degree. The students then study at the English university for the fourth (final) year. This initiative was the first of its kind for the English university and in a discipline area with limited previous experience in international teaching collaborations. This paper reflects on the different stages of the lifecycle of this collaboration from its establishment, its management and delivery, to its eventual termination. The paper identifies some of the benefits and challenges of the initiative and the solutions devised by the programme team

How robust are future projections of forest landscape dynamics? Insights from a systematic comparison of four forest landscape models

Projections of landscape dynamics are uncertain, partly due to uncertainties in model formulations. However, quantitative comparative analyses of forest landscape models are lacking. We conducted a systematic comparison of all forest landscape models currently applied in temperate European forests (LandClim, TreeMig, LANDIS-II, iLand). We examined the uncertainty of model projections under several future climate, disturbance, and dispersal scenarios, and quantified uncertainties by variance partitioning. While projections under past climate conditions were in good agreement with observations, uncertainty under future climate conditions was high, with between-model biomass differences of up to 200 t ha−1. Disturbances strongly influenced landscape dynamics and contributed substantially to uncertainty in model projections (~25–40% of observed variance). Overall, model differences were the main source of uncertainty, explaining at least 50% of observed variance. We advocate a more rigorous and systematic model evaluation and calibration, and a broader use of ensemble projections to quantify uncertainties in future landscape dynamics.ISSN:1364-8152ISSN:1873-672