Dissertations / Theses on the topic 'Forest resilience – Climatic factors'

Climate change is expected to drastically change the environmental conditions which forests depend. Lags in tree species movements will likely be outpaced by a more rapidly changing climate. This may result in species extirpation, a change in forest structure, and a decline in resistance and resilience (i.e., the ability to persist and recover from external perturbations, respectively). In the northern Great Lakes region of North America, an ecotone exists along the boreal-temperate transition zone where large changes in species composition exist across a climate gradient. Increasing temperatures are observed in the more southern landscapes. As climate change is expected to substantially affect mid-continental landscapes, this region is especially vulnerable to climate change. My research assessed the effects of climate change under business as usual (BAU) management as well as alternative management strategies. To do so, I simulated forest change in two landscapes (northeastern Minnesota and northern lower Michigan) under three climate change scenarios (current climate, low emissions, and high emissions), and four management scenarios (BAU, modified silviculture, expanded reserves, and climate suitable planting) with a spatially-explicit forest simulation model from year 2000 to year 2150. Specifically, I explored how climate change would affect relationships between tree species diversity and productivity; how expanded reserves and modified silviculture may affect aboveground biomass (AGB) and species diversity; how climate suitable planting may affect functional diversity, and AGB; and how alternative management may affect the resistance and resilience of forests to multiple disturbances interacting with climate change. Under the BAU management scenario, I found that current and low emissions climate scenarios did not affect the relationship between species diversity and productivity; however, under a high emissions climate scenario, a decline in simulated productivity was coupled with a stronger positive relationship between diversity and productivity. Under the high emissions climate scenario, overall productivity declined in both landscapes with specific species declines projected for boreal species such as balsam fir (Abies balsamea) and black spruce (Picea mariana). Under alternative management scenarios, I simulated a limited ability to increase tree species and functional diversity, AGB, and net primary productivity under climate change. The limits of management were especially apparent under the high emissions climate scenario. In a novel approach to measuring resilience, I plotted the recovery of both initial species composition and AGB to stochastic fire events for each simulation. This approach assessed both a general response (i.e. AGB) with a more specific response (i.e. species composition). My results suggest that climate change will reduce the resilience of northern Great Lake forest AGB and species composition and that management effects will be largely outweighed by the declines expected due to climate change. My results highlight the necessity to consider even more innovative and creative solutions under climate change (e.g., planting species from even further south than I simulated).

The Kyoto Protocol of UNFCCC (United Nations Framework Convention on Climate Change) postulated that anthropogenic causes are the main drivers of global climate change. This Kyoto Protocol was ratified by South Africa, with South Africa accepting all the binding commitments. Since then South Africa has promulgated legislations which cater for the environment and the reduction of the greenhouse gases respectively, with the aim of promoting sustainable development. The South African constitution has recognised the environment in Section 24. This is the birth place of the “Environmental Clauses” which do not only speak to the national government but are also broken down to the provincial and local government. This study was grounded within the field of Development studies and undertook a case study of improving the socio-ecological resilience strategies of climate changes in Nelson Mandela Bay Metropole (NMBM). The study employed the use of semi-structure interviews whereby a questionnaire was used to guide the researcher in the interview process. A total of 23 officials were interviewed, ranging from governmental departments (municipality) through civil societies to private consultants, in order to avoid the generation of biases. The data obtained from respondents were presented, analysed, and discussed. From the data collected, it was possible to single out certain barriers to climate change resilience initiative in NMBM. Some of these barriers include the lack of awareness of climate change resilience issues, lack of political will, lack of funding, and the poor concern given to climate change issues since the municipality does not consider it a core issue. Based on the study findings, the main recommendation offered to NMBM was the creation of a Sustainable Development Framework, which will provide a perfect platform for development, acknowledge the threat posed by the negative effects of climate change, and enhance opportunities to execute climate change projects in NMBM.

The total mangrove area cover in South Africa is 1631.7 ha, with the largest area cover in a few estuaries in the KwaZulu-Natal Province (1391.1 ha) and the remainder recorded in the Eastern Cape Province with 240.6 ha. This represents 0.05 percent of Africa‟s mangrove area cover and although small adds irreplaceable value to the biodiversity of South Africa. Mangroves are threatened by over-utilization through harvesting for firewood and building materials as well as excessive browsing and trampling by livestock. The objective of this study was to investigate the response of mangroves to different stressors from natural change as well as anthropogenic pressures. This was done by identifying pressures, measuring area cover, population structure and environmental parameters such as sediment characteristics. Mangroves in 17 estuaries along the east coast were investigated. Population structure and the area covered by mangroves in 2011/2012 were compared with data from the same area for 1999. Detailed studies were conducted in St. Lucia Estuary to investigate the response of mangroves to reduced tidal flooding; mangrove expansion at a latitudinal limit in a protected area at Nahoon Estuary was studied and the effect of cattle browsing on mangroves was measured at Nxaxo Estuary. The St. Lucia Estuary (28°S; 32°E) represented a unique study site as the mouth has been closed to the sea since 2002 and the mangrove habitats have been non-tidal. St. Lucia Estuary is both a Ramsar and World Heritage site and therefore understanding the response of mangroves to changes in the environment is important. In 2010 sediment characteristics and mangrove population structure were measured at four sites which were chosen to represent different salinity and water level conditions. The site fringing the main channel had the highest density of mangrove seedlings and saplings. The dry site had a lower density of mangroves with mostly only tall adult trees and few saplings. Mangrove tree height and density increased at sites with high sediment moisture and low surface sediment salinity. Few seedlings and saplings were found at sites with dry surface sediment and high salinity. Long term data are needed to assess the influence of mouth closure on recruitment and survival of the mangrove forest at St. Lucia Estuary; however this study has shown that sediment characteristics are unfavourable for mangrove growth at sites now characterized by a lack of tidal flooding. It is not known when exactly the mangroves were planted in Nahoon Estuary (32°S; 27° E), East London, but it is suspected that this was in the early 1970s. Avicennia marina (Forrsk.)Vierh. was planted first, followed a few years later by the planting of Bruguiera gymnorrhiza (L.) Lam. and Rhizophora mucronata (L.) among the larger A. marina trees. Surprisingly the mangrove population appears to be thriving and this study tested the hypothesis that mangroves have expanded and replaced salt marsh over a 33 year period. This study provides important information on mangroves growing at higher latitudes, where they were thought to not occur naturally due to lower annual average temperatures. It further provides insights on future scenarios of possible shifts in vegetation types due to climate change at one of the most southerly distribution sites worldwide. The expansion of mangroves was measured over a 33 year period (1978 - 2011) using past aerial photographs and Esri ArcGIS Desktop 10 software. In addition, field surveys were completed in 2011 to determine the population structure of the present mangrove forest and relate this to environmental conditions. The study showed that mangrove area cover increased linearly at a rate of 0.06 ha-1 expanding over a bare mudflat area, while the salt marsh area cover also increased (0.09 ha-1) but was found to be variable over time. The mangrove area is still small (< 2 ha) and at present no competition between mangroves and salt marsh can be deduced. Instead the area has the ability to maintain high biodiversity and biomass. Avicennia marina was the dominant mangrove species and had high recruitment (seedling density was 33 822 ± 16 364 ha-1) but only a few Bruguiera gymnorrhiza and Rhizophora mucronata individuals were found (< 10 adult trees). The site provides opportunities for studies on mangrove / salt marsh interactions in response to a changing climate at the most southern limit of mangrove distribution in Africa. This research has provided the baseline data, permanent quadrats and tagged trees to be used in future long-term monitoring of population growth and sediment characteristics. At Nxaxo Estuary (32°S; 28°E) the response of mangrove trees (Avicennia marina) to cattle browsing and trampling was investigated by using cattle exclusion plots. Exclusion plots were established by fencing in five 25 m2 quadrats and adjacent to each experimental quadrat a control quadrat (not fenced in, 25 m2) was set-up. Trees were tagged and measured annually from 2010 to 2012. Sediment salinity, pH, moisture, organic content, compaction as well as sediment particle size was also measured in each quadrat. Sediment characteristics did not vary between control and experimental plots but did show changes between the years. The mangrove trees in the cattle exclusion plots grew exponentially over a period of two years. There was a significant increase in mean plant height (5.41 ± 0.53 cm), crown volume (0.54 ± 0.01 m3) and crown diameter (7.09 ± 0.60 cm) from 2010 to 2012. Trees in the control plots had significantly lower growth (p < 0.05). There was a decrease in plant height (-0.07 ± 0.67cm1) and only small increases in crown volume (0.14 ± 0.1 m3) and crown diameter (2.03 ± 2.61 cm). The research showed that browsing on mangroves by cattle stunts growth and causes a shrubby appearance as a result of coppicing. The browsed trees were dwarfed with horizontal spreading of branches and intact foliage close to the ground while the plants in the cattle exclusion plots showed an increase in vertical growth and expansion. In the cattle exclusion plots there was a significantly higher percentage of flowering (67 percent) and fruiting (39 percent) trees in 2012 compared to the control sites where 34 percent of the plants were flowering and 5.4 percent of the plants carried immature propagules. Observations in the field also indicated that cattle had trampled a number of seedlings thus influencing mangrove survival. The study concluded that browsing changes the morphological structure of mangrove trees and reduces growth and seedling establishment. This is an additional stress that the mangroves are exposed to in rural areas where cattle are allowed to roam free. Seventeen permanently open estuaries provide habitat for mangrove forests along the former Transkei coast. This part of the Eastern Cape is mostly undeveloped and difficult to access. Mangrove area cover, species distribution, population structure and health of the mangrove habitat were compared with results from previous studies in 1982 and 1999. The mangrove Bruguiera gymnorrhiza had the densest stands and was widely distributed as it was present in 13 of the 17 estuaries. Avicennia marina was dominant in those estuaries which had the largest area cover of mangroves and was present in 10 estuaries, while Rhizophora mucronata was rare and only present in five estuaries. Anthropogenic and natural impacts were noted within the mangrove habitats in each of these estuaries. Harvesting of mangrove wood, livestock browsing and trampling and footpaths occurred in most of the estuaries (> 70 percent). It was observed that browsing on trees resulted in a clear browse-line and browsing on propagules mainly by goats resulted in reduced seedling establishment in most of the estuaries except those in protected areas. Mangroves had re-established in estuaries where they had been previously lost but mouth closure due to drought and sea storms resulted in the mass die back of mangroves in the Kobonqaba Estuary. There was a total loss of 31.5 ha in mangrove area cover in the last 30 years and this was a total reduction of 10.5 ha (11 percent) for every decade. This is high considering that the present total mangrove area cover is only 240.6 ha for all the Transkei estuaries. In this study it was concluded that the anthropogenic impacts such as livestock browsing and trampling as well as harvesting in these estuaries contributed most to the mangrove degradation as these are continuous pressures occurring over long periods and are expected to increase in future with increasing human population. Natural changes such as sea storms occur less frequently but could result in large scale destruction over shorter periods. Examples of these are mouth closure that result in mangrove mass mortality as well as strong floods which destroy forest by scouring of the banks.

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São poucos os estudos que abordam a floração e frutificação em espécies filogeneticamente relacionadas. Myrtaceae é uma das famílias de plantas mais abundantes nas matas brasileiras, em especial na floresta pluvial atlântica. O presente estudo teve como objetivos principais: 1) analisar a fenologia reprodutiva de 38 espécies de Myrtaceae, verificando os padrões fenológicos, relação com os fatores climáticos e previsibilidade das fenofases; e 2) avaliar as teorias propostas para explicar a fenologia de espécies aparentadas e a relação entre a fenologia e o tamanho do fruto. O estudo foi desenvolvido em área de floresta atlântica no Parque Estadual Intervales, Base Saibadela (24°14'08S e 48°04'42W), município de Sete Barras, estado de São Paulo, Brasil. As fenofases botão, antese, fruto imaturo e maduro foram observadas mensalmente durante seis anos nãoconsecutivos (abril/1994 a março/1997 e abril/1999 a março/2002) em 285 indivíduos. As maiores porcentagens de indivíduos e espécies apresentando botões e flores abertas ocorreram sempre na estação mais quente e chuvosa (outubro a março), e produzindo frutos imaturos e maduros principalmente ao longo da estação menos quente e úmida (abril a setembro). As correlações de Spearman foram significativas entre a floração e o comprimento do dia e a temperatura, e correlações significativas foram raras entre a frutificação e o clima. A análise estatística circular mostrou que as datas de início e pico das fenofases reprodutivas em Myrtaceae foram sazonais para a maioria dos anos estudados. Todas as fenofases apresentaram valores altos de previsibilidade de ocorrência...
There are few studies approaching flower and fruit patterns among phylogenetically related species. Myrtaceae is one of the most abundant plant families in the Brazilian forests, especially in the Atlantic Rain Forest. The present study had the main objectives: 1) to analyze the reproductive phenology of 38 Myrtaceae species, checking the phenological patterns, the relationship with the climatic factors and the predictability of the phenophases; and 2) to evaluate the proposed theories to explain the phenology of related species and the relation between phenology and fruit size. The study was carried out in an Atlantic forest area at Parque Estadual Intervales, Base Saibadela (24°14'08S and 48°04'42W), municipality of Sete Barras, São Paulo State, Brazil. The phenophases bud flower, open flowers, unripe and ripe fruits were observed monthly for six nonconsecutive years (April/1994 to March/1997 and April/1999 to March/2002) in 285 individuals. The largest percentages of individuals and species presenting buds and open flowers always occurred during the wetter and hotter season (October to March), and unripe and ripe fruits were produced mainly over the less humid and colder season (April to September). The Spearman correlations were significant between flowering and the day length and the temperature, and significant correlations were rare between fruiting and climate. The circular statistical analysis showed that the first date and peak date of the reproductive phenophases in Myrtaceae were seasonal for most of the years. All the phenophases showed high predictability scores... (Complete abstract, click electronic adress below)

Orientador: Leonor Patrícia Cerdeira Morellato
Banca: Marco Antônio Portugal Luttembarck Batalha
Banca: Isabel Cristina Sobreiro Machado
Resumo: São poucos os estudos que abordam a floração e frutificação em espécies filogeneticamente relacionadas. Myrtaceae é uma das famílias de plantas mais abundantes nas matas brasileiras, em especial na floresta pluvial atlântica. O presente estudo teve como objetivos principais: 1) analisar a fenologia reprodutiva de 38 espécies de Myrtaceae, verificando os padrões fenológicos, relação com os fatores climáticos e previsibilidade das fenofases; e 2) avaliar as teorias propostas para explicar a fenologia de espécies aparentadas e a relação entre a fenologia e o tamanho do fruto. O estudo foi desenvolvido em área de floresta atlântica no Parque Estadual Intervales, Base Saibadela (24°14'08"S e 48°04'42"W), município de Sete Barras, estado de São Paulo, Brasil. As fenofases botão, antese, fruto imaturo e maduro foram observadas mensalmente durante seis anos nãoconsecutivos (abril/1994 a março/1997 e abril/1999 a março/2002) em 285 indivíduos. As maiores porcentagens de indivíduos e espécies apresentando botões e flores abertas ocorreram sempre na estação mais quente e chuvosa (outubro a março), e produzindo frutos imaturos e maduros principalmente ao longo da estação menos quente e úmida (abril a setembro). As correlações de Spearman foram significativas entre a floração e o comprimento do dia e a temperatura, e correlações significativas foram raras entre a frutificação e o clima. A análise estatística circular mostrou que as datas de início e pico das fenofases reprodutivas em Myrtaceae foram sazonais para a maioria dos anos estudados. Todas as fenofases apresentaram valores altos de previsibilidade de ocorrência... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: There are few studies approaching flower and fruit patterns among phylogenetically related species. Myrtaceae is one of the most abundant plant families in the Brazilian forests, especially in the Atlantic Rain Forest. The present study had the main objectives: 1) to analyze the reproductive phenology of 38 Myrtaceae species, checking the phenological patterns, the relationship with the climatic factors and the predictability of the phenophases; and 2) to evaluate the proposed theories to explain the phenology of related species and the relation between phenology and fruit size. The study was carried out in an Atlantic forest area at Parque Estadual Intervales, Base Saibadela (24°14'08"S and 48°04'42"W), municipality of Sete Barras, São Paulo State, Brazil. The phenophases bud flower, open flowers, unripe and ripe fruits were observed monthly for six nonconsecutive years (April/1994 to March/1997 and April/1999 to March/2002) in 285 individuals. The largest percentages of individuals and species presenting buds and open flowers always occurred during the wetter and hotter season (October to March), and unripe and ripe fruits were produced mainly over the less humid and colder season (April to September). The Spearman’ correlations were significant between flowering and the day length and the temperature, and significant correlations were rare between fruiting and climate. The circular statistical analysis showed that the first date and peak date of the reproductive phenophases in Myrtaceae were seasonal for most of the years. All the phenophases showed high predictability scores... (Complete abstract, click electronic adress below)
Mestre

The relationships between the tree-rings of the white fir (Abies alba Mill.) and climate in the French internal Alps are indicated by correlation functions. This fir shows an accurate response to climate as well as long term persistence for at least six years (MS =0.18, R1 =0.65, and R6= 0.27). Its growth is strongly influenced by the previous year's climate, especially by prior August rainfall, which enhances ring size, or by high temperatures, which show the opposite effect. The most critical period extends from prior July to prior September. This species responds positively to warm temperature from current January to April, followed by rainfall in May and June, which leads to a longer growth period. A favorable water balance seems to be decisive. Abies alba can be affected by frost and seems to prefer a low thermal amplitude as demonstrated by the analysis of the extreme temperature data. Moreover, even a few days of excessive heat can reduce its growth.

Accurate estimation of Net Primary Productivity (NPP), which is a key component of the terrestrial carbon cycle, is very important in studies of global climate. Ecosystem models have been used for NPP estimates. Determining how much each source of uncertainty contributes to modeled NPP is veiy important before ecosystem models can be used with confidence over larger areas and time periods. This research has systematically evaluated the boreal ecosystem productivity simulator (BEPS) carbon model in mountainous terrain, Kananaskis, Alberta. After parameterization of the model, sensitivity analysis was conducted as a controlled series of experiments involving sensitivity simulations with BEPS by changing a model input value in separate model runs. The results showed that NPP was sensitive to most model inputs measured in the study area, but that the most important input variables for BEPS were LAI and forest species. In addition, the NPP uncertainty resulting from topographic influence was approximately 3.5 %, which is equivalent to 140 kg C ha"1 yr"1. This suggested that topographic correction for the model inputs was also important for accurate NPP estimation. Using the topographically corrected data, the carbon dynamics were simulated, and average annual NPP production by forests in Kananaskis was estimated at 4.01 T ha"1 in 2003.
xix, 117 leaves : col. ill. ; 29 cm.

A Área de Proteção Ambiental (APA) Capivari-Monos no sul do município de São Paulo, sub-distrito de Parelheiros, é uma área de Mata Atlântica que abriga importantes mananciais. Devido à urbanização desorganizada, alterações das condições ecológicas naturais dessa área propiciam o contato entre humanos, patógenos e culicídeos. Pouco se sabe sobre a ecologia de mosquitos vetores de patógenos nessa localidade, o que instigou a pesquisa na região. Nesse sentido, o presente estudo investigou a fauna culicídeos presentes em ambiente silvestre e antrópico na APA Capivari-Monos, determinando-se indicadores de biodiversidade e relacionando-os a fatores ambientais. Para tal, por 12 meses foram capturados mensalmente culicídeos adultos e imaturos de ambiente silvestre e antrópico usando-se diferentes técnicas de captura. Foram utilizados indicadores de diversidade para avaliar a riqueza, dominância, abundância e equabilidade dos diferentes ambientes. Um total de 9.403 mosquitos adultos foram capturados de maio de 2009 a junho de 2010. As espécies prevalentes entre as coletadas no ambiente silvestre foram Anopheles (Kerteszia) cruzii, Culex (Melanoconion) seção Melanoconion e Aedes serratus, enquanto as mais comuns no ambiente antrópico foram Coquillettidia chrysonotum / albifera, Culex (Culex) grupo coronator e An. (Kerteszia) cruzii. A riqueza de mosquitos adultos foi semelhante entre os ambientes, e a abundância variou entre as espécies. Ao comparar os padrões de diversidade entre os ambientes, a região antrópica apresentou maior riqueza e uniformidade, o que sugere que o estresse ambiental aumentou o número de nichos favoráveis para culicídeos e promoveu maior diversidade. A espécie An. cruzii apresentou correlação positiva com pluviosidade e temperatura no ambiente antrópico, mas no ambiente silvestre essa espécie não esteve associada aos fatores climáticos. Dos 2443 mosquitos imaturos coletados, 1507 (61,7 por cento ) foram encontrados no ambiente antrópico e 936 (38,3 por cento ) no ambiente silvestre. Os mosquitos imaturos foram distribuídos em 62 categorias taxonômicas, e sua riqueza e abundância foram maiores no ambiente antrópico que no silvestre. Os indivíduos Culex (Microculex) grupo Imitator foram os que apresentaram maior abundância e foram encontrados com maior frequência no ambiente antrópico e silvestre.
The Environmental Protection Area (APA) Capivari-Monos in the Parelheiros sub-district, in South São Paulo, is an Atlantic Forest area that comprises important springs. Owing to the disorganized urbanization, changes in the natural ecological conditions of the APA promoted human-Culicidae-pathogen contact. The lack of information on the ecology of mosquito vectors in the APA motivated the present study, which investigated the Culicidae fauna wild and anthropic zones of the Capivari-Monos APA, determining biodiversity indicators and relating them to environmental factors. To that end, adult and immature Culicidae were monthly collected from the wild and from the anthropic zones for 12 months and using different capture techniques. Diversity indicators were used to assess richness, dominance, evenness and abundance in the different environments. A number of 9,403 adult mosquitoes were collected from May 2009 to June 2010. The main species collected in the wild environment were Anopheles (Kerteszia) cruzii, the Melanoconion section of Culex (Melanoconion) and Aedes serratus, whereas the most common species in the anthropic zone were Coquillettidia chrysonotum/albifera, Culex (Culex) Coronator group and An. (Ker.) cruzii. Mosquito richness was similar between the zones, and their abundance varied according to the species. Compared to the wild zone, the anthropic zone exhibited higher richness and evenness, suggesting that environmental stress increased the number of favorable niches for culicids, promoting diversity. An. cruzii occurrence was positively correlated with rainfall and temperature in the anthropic zone, but in the wild zone it was not associated with climatic factors. From the 2,443 immature mosquitoes collected, 1,507 (61.7 per cent ) were found int the anthropic zone and 936 (38.3 per cent ) in the wild zone. The immature mosquitoes were distributed into 62 taxonomic categories, and their richness and abundance were higher in the anthropic than in the wild zone. Culex (Microculex) Imitator group was the prevailing species in both environments.

The Eastern Cape contains the majority of the remaining forested areas in South Africa (95.8 percent Coastal forests and 47.6 percent Afromontane forests), however these occur in fragments. Due to the rapid rise in the human population and its needs, conversion of forests to agricultural land and the extraction of timber increases, natural vegetation are lost and this therefore leads to forests becoming fragmented into small forest patches. One of the main consequences of forest fragmentation is loss of contiguous habitat, which is the dominant threat to species globally as it negatively affects both species richness and genetic diversity. This research investigates the effects that forest fragmentation has on small mammal diversity and abundance. The study sampled small mammals in Southern Mistbelt Afromontane forest patches in the Eastern Cape. The first aim of this study was to identify which environmental variable, or combinations of variables, affect the diversity and abundance of small mammals in fragmented forest patches in the Eastern Cape during the austral summer. The second aim was to compare seasonal changes in small mammal diversity and abundance at a forest edge compared to the forest core at Beggars Bush, an Afromontane forest in the Eastern Cape, South Africa. To identify the environmental impacts that different forests have on small mammals, nine different forests were chosen in the Eastern Cape and sampled during the summer in 2013. These nine forests were: Fort Fordyce Forest, Thaba Ndoda Forest, Hogsback Forest, Dassie Kraans Forest, Langeni Forest, Burchell’s Reserve Forest, Maiden Dam Forest and Kagaberg Forest. At each site, three transects of 30 Sherman Traps each were used. Trapping periods within each forest patch lasted between three to five consecutive nights and traps were inspected once a day in the morning. Nine environmental variables were initially identified and after being tested for normality and colinearity, five variables were chosen. These variables were Altitude, Mean Annual Temperature, Gradient, Patch Size and Mean annual potential evaporation. The number of individuals captures and species richness were then incorporated as dependent variables for best subset multiple regression model selection using the Akaike Information Criterion (AIC). For the second aim, the same trapping methods were used when comparing seasonal changes to diversity and abundance within the forest core. However at the forest edge, due to the small size of the forest, only 20 Sherman traps were used in each transect with five traps (25 percent) placed in the grassland and 15 (75 percent) placed in the forest along each transect. This study was one of few to survey small mammal diversity and abundance in fragmented forests in the Eastern Cape. Gradient, patch size and mean annual potential evaporation were the variables that best predicted the individual number of small mammal captures while only gradient best explained species richness. It does however, need to be noted that capture rates and species richness were very low and this would therefore effect the analysis of environmental variables. Future studies should have a larger sample size of forest patches and include more microhabitat environmental variables to determine their effects on small mammal diversity and abundance. However, it should be noted that through climatic extinction filtering, forest mammals are resilient generalists that can tolerate fragmentation effects. Furthermore, it was found that forest edges appear to play a significant role in small mammal diversity and abundance in the Beggars Bush Afromontane forest. Some species were habitat specialists such as Rhabdomys pumilio preferring the grassland habitat and Graphiurus murinus and Aethomys namaquensis the forest habitat, while Myosorex varius was the only species that was not habitat dependant. It was found that there was a greater diversity and abundance at the forest edge compared to within the forest core throughout most of the seasons. One possible flaw was that the sampling methods were different at the edge and within the forest and therefore future studies should ensure that the method stays uniform throughout the study.

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Understanding the effects of climate change is one of the cardinal issues within the natural resource management circles. Increased droughts are part of these changes. Afrotemperate forests, as well as their drier Afromontane counterparts suffer from periodic and seasonal droughts respectively. To better understand the effect of droughts on these forests, three key species namely Olea capensis (Iron wood), Podocarpus latifolius (Common Yellow wood) and Pterocelastrus tricuspidatus (Candle wood), were analysed using dendroecologic techniques. Two sites in the Southern Cape were selected according to a West-to-East moisture gradient, with the drier site being close to George and the medium moist site at the Diepwalle estate in the vicinity of Knysna. Growth ring measurements from each of the species were used to calculate basal area and basal area increment during the lifetime of the trees. Drought years for the sites were then selected based on the Standardised Precipitation and Evapotranspiration Index (SPEI), also indicated by the growth during the drought periods. Differences in growth patterns for all three species were observed. An event analysis was then used to quantify the difference in the resistance (Rt), recovery (Rc), resilience (Rs) and relative resilience (RRs). With values standardised around one (Rt, Rc and Rs) and zero (RRs), it was seen that the Candle wood had the highest (~0.92) resistance and the Yellow wood had the highest (~1.3) recovery after the drought. Iron wood stood apart from the other two species in the sense that it only reacted negatively towards the drought one year after the event in most cases. It was concluded that each of the species were significantly different in their reactions towards drought. This specific difference in drought reaction can give way to the possibility that the species together adapted to relieve the stress of a short drought by splitting the available resources over a longer period.
AFRIKAANSE OPSOMMING: Dit is van uiterse belang vir bestuur doeleindes om die veranderende klimaat oor die wêreld te verstaan, insluitend die droogtes wat daarmee gepaard gaan. Die Afrotemperate woud-tipe, asook sy droeër teenstaander, die Afromontane, lei gereeld aan sporadiese en seisonale droogtes. Om hierdie woud-tipe se reaksie tot droogtes beter te verstaan, was drie boom spesies naamlik Ysterhout (Olea capensis), Kershout (Pterocelastrus tricuspidatus) en gewone Geelhout (Podocarpus latifolius), gekies vir die gebruik in ‘n dendro-ekologiese studie. Twee areas was gekies van ‘n wes-tot-oos droogte gradient, met die droeër blok in die George omgewing en die meer vogtige een naby aan Knysna. Die jaarring metings van elke boom was gebruik om beide die basale oppervlakte en die basale oppervlak groei per jaar aan te teken. ‘n Gestandardiseerde reenval en evapotranspirasie indeks (SPEI) was gebruik om vas te stel jare waarin matige tot sterk droogtes gebeur het. Hierdie gekose jare het aanduiding gegee dat daar wel ‘n verskil waargeneem was in die groei patrone van elke spesie gedurende die droogtes. ‘n Gebeurtenis analise is gebruik om ‘n kwantitatiewe verskil te kon sien in die weerstand (Rt), herstel (Rc), weerstandbiedendheid (Rs) en relatiewe weerstandbiedendheid (RRs). Die was waargeneem dat Kerhout die hoogste weerstand (0.92) toon, terwyl die Geelhout ‘n hoër herstel waarde (1.3) gehad het. Ysterhout het apart van die ander twee spesies gestaan in dìe dat dit eers een jaar na die droogte ‘n reaksie getoon het teenoor die droogte. Dit was dus gevind dat daar spesifieke verskil is tussen al drie van die spesies teen opsigte van stres reaksies was. Hierdie verskil kan dan wel ook moontlik aandui dat hierdie spesies en woud-tipe op so ‘n anier aangepas is dat dit die stress gedurende ‘n kort droogte versprei oor ‘n langer tydperk.

Thesis (MScFor)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: The aim of this project was to determine the site effect- especially water availability - and the effect of cambial age on selected anatomical properties of Pinus radiata, in order to be able to predict possible changes in wood quality due to an expected change in climate. A second objective was to correlate ring and fibre properties, in order to determine, if ring properties could be used as a proxy to describe wood quality. The samples consisted of 12 trees, sampled at an age of 1 to 16 from six selected sites in the Western Cape, which ranged from water stressed to moist. Apart from the water availability all other external factors, such as elevation etc. were kept as equal as possible. Anatomical wood properties such as fibre length and fibre diameter, lumen diameter, cell wall thickness, ring width and earlywood/latewood ratio were determined and their change with cambial age and water availability was evaluated. Fibre length, fibre diameter and cell wall thickness increased with increasing cambial age, and ring width and earlywood/latewood ratio decreased with increasing cambial age. No significant correlations were found between any of the ring or fibre properties and water availability. Most of the fibre properties were significantly correlated with ring width and earlywood/latewood ratio when age was not considered as covariate, but showed no correlation when the age effect was excluded.
AFRIKAANSE OPSOMMING: Die doel van die projek was om die perseel se effek te bepaal, veral water beskikbaarheid, ten opsigte van die effek van kambium ouderdom en geselekteerde anatomiese eienskappe van Pinus radiata, om sodoende die moontike verandering in hout kwaliteit as gevolg van verwagte klimaatsverandering te voorspel. ‘n Tweede doelwit was om die ring en vesel eienskappe te korreleer en ook te bepaal of ring eienskappe gebruik kan word om hout kwaliteit te beskryf. Die monsters het bestaan uit bome van ses geselekteerde persele in die Wes Kaap en het gevarieer van ‘n water tekort na klam. Behalwe vir water beskikbaarheid is al die ander eksterne faktore, soos hoogte ens., konstant gehou waar moontlik. Anatomiese hout eienskappe soos vesel lengte en deursnee, sel deursnee, selwand dikte, ring wydte en E/L verhouding was bepaal asook die verandering met kambium ouderdom en water beskikbaarheid. Vesel lengte , vesel deursnee en selwand dikte het toegeneem met toename in kambium ouderdom, en ring wydte en E/L verhouding het afgeneem met toename in kambium ouderdom. Toename in water beskikbaarheid het gelei to afname in vesel lengte en selwand dikte, waar vesel deursnee, sel deursnee, E/L verhouding en ring wydte toegeneem het. Meeste van die vesel eienskappe het betekenisvol gekorrelleer met ring wydte en E/L verhouding wanneer ouderdom nie as ko-variant gebruik is nie.

Contemporary peacekeeping missions are complex, demanding, and potentially hazardous. There is general agreement that psychological factors are crucial to effective individual and collective performance of the military personnel deployed in support of these missions. This research has examined the human dimensions associated with capability, functioning, and health across the deployment cycle. The aim of this research was to increase understanding of the psychological issues associated with peace support operations at the individual, group, and organisational levels. The study applied precepts of the transactional model of stress (Lazarus & Folkman, 1984) to the context of military deployment on peace support operations. The overarching Human Dimensions of Operations model for this research incorporated stressor, buffer, and outcome components within the multi-level structure of the military organisation and across the stages (pre, peri, post) of deployment. Participants were Canadian and Australian military personnel deployed on Peace Support Operations. The dissertation comprised seven chapters. Chapter One provided an introduction to the psychological challenges posed by peace support operations and the research opportunities these missions afford. The second chapter detailed the methodology and psychometric evaluation of several measurement scales that were developed as part of this research in order to address the unique characteristics of peace support operations. Each of the six scales examined proved to have a meaningful component structure and adequate subscale reliabilities. The third chapter was devoted to an examination of the psychometric properties of a measure of psychological climate factors, the Unit Climate Profile (UCP), which was the cornerstone instrument of this research. The UCP demonstrated a robust, multi-dimensional structure that was conceptually concordant with its theoretical development and design. In addition, the component structure of the UCP changed in meaningful ways according to its level of analysis - individual or group. The next three chapters examined human dimension constructs at different stages of deployment, notably psychological readiness for operations, psychological resilience during deployment, and readjustment following return from deployment. In Chapter Four, the most compelling structural model that examined collective psychological readiness demonstrated that perceptions of readiness at the group level, along with effective senior leadership, could significantly impact morale. The results in Chapter Five revealed that leadership both buffered the immediate impact of stressors, and also fostered meaning and morale, thereby reducing strain. Positive aspects of deployment and the personal meaning assumed to be derived from these experiences were also found to bolster morale significantly during deployment. In Chapter Six, the stressors specific to the postdeployment transition phase, rather than stressors encountered during deployment, had the strongest impact on postdeployment adjustment. Social support and a positive psychological climate in the unit (particularly evidenced by cohesiveness and caring behaviour by proximal leaders) moderated the impact of homecoming stressors. A concluding chapter summarised the dissertation and discussed its practical significance and avenues for the dissemination of its findings. Broadly, the outcomes demonstrated that an understanding of the human factors in military units within the context of the stressors-strain relationship can provide potentially useful information to commanders who want to enhance the well-being, performance, and commitment of Service members deployed on peace support operations.
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Thesis (Ph.D.) -- School of Psychology, 2008

Tropical forests represent major uncertainties in climate models and have the potential to act as both net carbon sources and sinks in the future. Projections that hurricanes will be an increasingly powerful disturbance in many tropical forests further complicate our ability to predict how these ecosystems will respond to climate change. By understanding how environmental variation at small spatial scales affects ecosystem processes shaping present-day forests, it may be possible to improve our predictions for how these forests will change in the future. This dissertation consists of three chapters examining the spatial patterns of tree species and soil greenhouse gas fluxes in a tropical forest in the Luquillo Experimental Forest, Puerto Rico. Disentangling the forces that drive the spatial distribution of tree species has been a foundational question in ecology and determining the relative importance of these forces is central to understanding spatial variation in soil biogeochemistry. In chapter 1, I use percolation threshold analysis to examine the clustering patterns of simulated and real tree spatial point patterns to understand the role that environmental filtering and density dependent processes play in shaping tree species distributions. I demonstrate that percolation threshold analysis successfully distinguishes thinning by random, environmental filtering, and density dependent processes. Additionally, the relative importance of these thinning processes varies by species’ traits; fast growing species with low LMA and shade intolerance have stronger evidence of density dependent processes compared to species with high LMA and shade tolerance. In chapter 2, I examine the spatial relationships between soil greenhouse gas fluxes and two proximal drivers of soil environmental variation: tree species and topography. I also examine how incorporating small-scale variation in greenhouse fluxes affects our scaled-up estimates of ecosystem greenhouse gas emissions. I show that including species effects improves estimates of soil CO2 fluxes, and including measures of topography improve estimates of CH4 and N2O fluxes. Incorporating spatial variation in GHG fluxes related to tree species and topography into our estimates of ecosystem GHG emissions decreased estimates of the total CO2-equivalent emissions in this forest by 5%. Finally, in chapter 3 I examine how the GHG fluxes in this forest change after an intense hurricane. I demonstrate that GHG emissions shift following a hurricane; this shift is primarily driven by a 176% increase in N2O emissions that represent a significant net loss of gaseous nitrogen from this forest. N2O fluxes accounted for 4.2% of the post-hurricane GHG-induced radiative forcing (compared to 1.8% pre-hurricane) and the combined increase in CO2, CH4, and N2O emissions observed translates to a 25% increase in CO2-equivalent emissions compared to pre-hurricane conditions. This dissertation focuses on the role of small-scale environmental variation in shaping forest communities and spatial patterns of GHG fluxes and aims to highlight how this variation can help us to better understand the role tropical forests play in the biosphere.

In arid and semi-arid deserts, soils are commonly covered with biological soil crusts. The study of arid biocrusts and their ecological function has become increasingly common in the literature over the last several decades. Interestingly, no mention is made of biological soil crusts in forested ecosystems, raising the question as to whether they exist in these areas and if they do, why they have yet to be recognized as such? Through the use a parallel logic, this study finds that biocrusts do indeed exist in forests, a novel relationship in forest ecology and seeks to determine if there exist ecophysical explanations for the abundance and distribution throughout the forest landscape. This study examined the effects of climate variables and substrate types on the abundance, distribution and overall cover of forest soil biocrust at fifty-two sites in southern Oregon, U.S.A. Sites were randomly selected within established buffer zones in the Siuslaw, Rogue-Sisikyou, Umpqua, and Fremont-Winema National Forests. The methods of Belnap et al 2001 were tested and then modified for application in forested ecosystems. Data were collected on the relative abundance and distribution of biocrust morphological groups across available substrates, community biocrust morphology, aspect, elevation and soil texture, pH and organic matter content. Site-specific data on average annual precipitation and minimum/maximum temperatures was collected using the PRISM Climate Model. This study found substrate colonization by specific morphological groups mixed across the study; though dominant communities were observed for each substrate present, substrate availability appears to be confounded by a number of variables (climate, stand age and structure and litter layer) not controlled for in this study. Biocrust community morphologies varied across sites, primarily influenced by the surface texture of the substrate and morphology of the individual. Relatively smooth surfaces (rock, bare soil) often resulted in smooth biocrust morphologies, whereas rough surfaces (dead wood, bare soil) tended to result in a rolling morphology. Litter layer directly influenced the relative proportion of substrates colonized, notably affecting dead wood and mineral soil biocrusts. Total biocrust cover increased as precipitation increased as did biocrust preference for dead wood substrates while mineral soil remained unchanged and rock surfaces were negatively represented. Aspect generally followed the anticipated distribution of total biocrust cover with the highest cover on N and NW aspects and lowest on the W aspect. Increases in elevation were negatively related to overall biocrust cover. Soil texture was not found to be directly related to overall biocrust cover, attributed in part to the highly adaptive nature of the biocrust community. Soil organic matter (SOM) influenced total biocrust cover with positive correlations between total cover and increasing SOM content. Soil pH increased as expected across the precipitation range (17 to 159 in/yr) of the transect. Total biocrust cover was found to trend with soil pH, but is believed to be attributed to the parallel relationship between precipitation and pH, rather than pH alone given the relative moderate pH range (4.39 to 6.54) of the study. The distribution and abundance of forest soil biocrusts is strongly influenced by precipitation. The confounding influence of precipitation to litter layer depth and organic matter content (through gradients of vegetative productivity) and soil pH further are concluded to influence substrate preference by morphological groups. Across the variables examined, similarities between the two communities (arid and forest) in response to climate and soil chemistry show parallel relations, justifying the formal establishment of biological soil crust community in forested regions. The differences between communities related to the presence of trees validate the establishment of forest soil biocrusts as distinct community in both form and ecological function with the forests.
Graduation date: 2013

Lichens are an important part of the biota in western Oregon forests, where they perform valuable ecological roles and contribute significantly to biodiversity. Lichens in western Oregon are threatened by a number of factors including air pollution and land use practices. If we wish to maintain the persistence of lichens in future landscapes it is critical that we understand the responses of lichen communities and individual lichen species to the environment and forest structure. This dissertation explores factors that are related to differences in lichen community composition and the distributions of individual lichen species in the western Cascades of Oregon, using a large landscape scale data set. I sought to relate major gradients in lichen community composition to environmental factors, and describe differences in lichen communities with respect to forest age (Chapter 2). I found three major gradients in lichen communities at a landscape scale in the western Oregon Cascades. These gradients were related to climate as expressed by elevation and annual temperature, air quality, north-south position, the richness of epiphytic macrolichens, and forest age. I developed a rarity score, which can be used to identify hotspots of rare species diversity at a landscape scale (Chapter 3). I then built descriptive models of this rarity score to identify abiotic and biotic factors associated with the occurrence of rarity hotspots. I found that models of rarity score that used explanatory variables based on lichen community composition performed better than models that used explanatory variables based solely on environmental factors. I narrowed my focus to the level of individual species responses to the environment and forest structure by developing habitat models for 11 lichen species in the western Cascades (Chapter 4). We selected these species because they performed important ecological roles, were rare across the landscape and associated with old growth forests, or because their distributions were poorly understood. These models can be used to increase the efficiency of landscape level surveys for rare species, predict the response of these species to forest management practices, and understand factors associated with the distributions of these lichens.
Graduation date: 2006

Atmospheric carbon dioxide levels have been steadily increasing from anthropogenic energy production, development and use. Carbon cycling in the terrestrial biosphere, particularly forest ecosystems, has an important role in regulating atmospheric concentrations of carbon dioxide. US West coast forest management policies are being developed to implement forest bioenergy production while reducing risk of catastrophic wildfire. Modeling and understanding the response of terrestrial ecosystems to changing environmental conditions associated with energy production and use are primary goals of global change science. Coupled carbon-nitrogen ecosystem process models identify and predict important factors that govern long term changes in terrestrial carbon stores or net ecosystem production (NEP). By quantifying and reducing uncertainty in model estimates using existing datasets, this research provides a solid scientific foundation for evaluating carbon dynamics under conditions of future climate change and land management practices at local and regional scales. Through the combined use of field observations, remote sensing data products, and the NCAR CESM/CLM4-CN coupled carbon-climate model, the objectives of this project were to 1) determine the interactive effects of changing environmental factors (i.e. increased CO���, nitrogen deposition, warming) on net carbon uptake in temperate forest ecosystems and 2) predict the net carbon emissions of West Coast forests under future climate scenarios and implementation of bioenergy programs. West Coast forests were found to be a current strong carbon sink after accounting for removals from harvest and fire. Net biome production (NBP) was 26 �� 3 Tg C yr�����, an amount equal to 18% of Washington, Oregon, and California fossil fuel emissions combined. Modeling of future conditions showed increased net primary production (NPP) because of climate and CO��� fertilization, but was eventually limited by nitrogen availability, while heterotrophic respiration (R[subscript h]) continued to increase, leading to little change in net ecosystem production (NEP). After accounting for harvest removals, management strategies which increased harvest compared to business-as-usual (BAU) resulted in decreased NBP. Increased harvest activity for bioenergy did not reduce short- or long-term emissions to the atmosphere regardless of the treatment intensity or product use. By the end of the 21st century, the carbon accumulated in forest regrowth and wood product sinks combined with avoided emissions from fossil fuels and fire were insufficient to offset the carbon lost from harvest removals, decomposition of wood products, associated harvest/transport/manufacturing emissions, and bioenergy combustion emissions. The only scenario that reduced carbon emissions compared to BAU over the 90 year period was a 'No Harvest' scenario where NBP was significantly higher than BAU for most of the simulation period. Current and future changes to baseline conditions that weaken the forest carbon sink may result in no change to emissions in some forest types.
Graduation date: 2013

Many studies have reported changes in the infiltration properties of soils after deforestation, whereas studies on the effects of reforestation or afforestation are scarce. On a watershed scale, it is often assumed that planting trees will increase infiltration, reduce flooding, increase dry season river flows and decrease erosion. In China, despite massive government-promoted land conversion programs occurring over the last 11 years, there is insufficient research on changes in fundamental soil infiltration properties which underpin the premise that afforestation will improve important hydrologic functions. This research, located in a poor upland farming region in Yunnan Province, southwest China, aimed to investigate the effects of monoculture plantation-style afforestation on key soil infiltration properties. This was primarily achieved by measuring hydraulic conductivity (with a tension infiltrometer) and bulk density at two depths across a mix of land uses -plantations of three different age classes, cultivated land and semi-natural 'primary' forest. Topsoil organic matter was also measured, as were plantation structural characteristics. Despite measurement uncertainties caused by heavy clay soil, soil water repellency and probable variable disturbance (past and present) of the soil's A-horizon, the results show that recovery of hydrological functions via improved infiltration properties cannot be assumed through plantation-style afforestation with Pinus species. Previous topsoil degradation was probably considerable, significantly inhibiting recovery potential especially in poorly managed and over-utilised plantations. It appears recovery is highly dependent on management-induced plantation structural characteristics. Intensely utilised thirty year old plantations with very sparse understories had inferior hydraulic characteristics and higher compaction then the prior land use of fallow-cultivation. Conversely, less-utilised and less-thinned 18-20 year old plantations with dense shrub understories and thick diverse leaf litter layers had enhanced infiltration characteristics compared to cultivated land uses and other plantation age classes. The 'primary' forest had significantly superior hydraulic properties than any other land cover, though topsoil measurements were also confounded by water repellency. The flat shape of the hydraulic conductivity curves and the relatively low saturated conductivities suggests that the heavy clay soil is poorly aggregated and that soil macropores are few in number and/or are poorly connected. In general it would appear that runoff is potentially generated quite readily even under moderate rainfall intensities and durations across most land uses. However, interception of rainfall by vegetation was not accounted for in this research. Hydraulic conditions may improve after initial wetting during rainfall events as the effects of water repellency decreases. A second component of the research explored the farming community's experiences and perceptions of afforestation, and the motivation for converting large areas of cultivated land to plantation without government support. On average, each household has converted 43 per cent of their cultivated lands to plantation in the last 10 years. The sole purpose for afforesting, from the farmer's perspective, is to increase future cash income by selling timber. However, there are numerous other important secondary uses of maturing plantations, such as sources of material for organic fertiliser and firewood, and grazing for domestic livestock. While the majority of farmers perceived positive general environmental benefits from converting large areas of arable land to plantations in their village, they were more divided on whether the plantations had positive or negative local hydrological effects. Assuming off-farm work opportunities continue to exist so that farmers can maintain increased cash income to supplement reduced crop production caused by afforestation, there are likely to be long-term socio-economic benefits to villagers.

У даній роботі захоплено актуальне питання, що стосується кожного з нас і всього людства в цілому ─ зміна клімату на нашій планеті. Зміна кліматичних показників розглянута прикладі лісостепової зони України. Висвітлено різницю між кліматичною нормою та сучасними показниками. Дано прогноз на подальшу зміну кліматичних показників та як ця зміна вплине на життєдіяльність населення в міській та сільській місцевості.
Everyday work captures current issues that affect each of us and humanity as a whole ─ changing the climate on our planet. Climate change is considered on the example of the forest-steppe zone of Ukraine. The difference between the climatic norm and modern indicators is highlighted. The forecast for further change of climatic indicators and how it changes the impact on the life of the population in urban and rural areas is given.