<p>In 2016, chestnut oak (<em>Quercus prinus</em>) trees across southern Indiana began displaying symptoms of decline disease. In the years following, widespread patches of mortality appeared on slopes and along ridges, prompting the Indiana Department of Natural Resources (IDNR) to investigate. The IDNR noted the presence of <em>Phytophthora cinnamomi </em>on one diseased chestnut oak, leading to the initiation of this study. Our goals were to (1) determine if <em>P. cinnamomi </em>contributed to the widespread decline, (2) determine what site or stand variables were associated with higher rates decline, (3) examine the growth of declining trees prior to the onset of symptoms to determine if drought contributed to decline, and (4) use Forest Service Forest Inventory and Analysis (FIA) data to examine trends in regional chestnut oak mortality.</p> <p>From 2021-2022, we collected thirty fine root and soil samples from declining chestnut oak trees within Morgan-Monroe State Forest, Yellowwood State Forest, and the Hoosier National Forest. Throughout these forests, we established sampling plots within declining and healthy chestnut oak stands. In each plot we recorded site, stand, and tree level variables, then collected tree cores from two or three chestnut oak trees. Fine root samples were tested for the presence of <em>P. cinnamomi </em>at the Purdue Pathogen and Pest Diagnostic Laboratory (PPDL) in West Lafayette, Indiana.</p> <p>We used binomial linear regression to test for significant (α = 0.05) relationships between site and stand variables and decline, where a binary decline or no decline was used as the response variable. Both basal area increment (BAI) and ring width index (RWI) chronologies were built separately for healthy, declining, and dead chestnut oak trees. We used a paired t-test (α = 0.05) to test for significant differences in 10-year segments of BAI between the three chronologies. Finally, we used linear regression to test for significant (α = 0.05) effects of the standardized precipitation-evapotranspiration index (SPEI) in current and previous year growing seasons on RWI. Chestnut oak mortality volume across the eastern United States was calculated using the EVALIdator tool provided by USDA-FS FIA. Associations between chestnut oak mortality recorded by FIA and several climate and topographical variables were examined using a random forest classification.</p> <p>Out of thirty fine root samples, only one tested positive for the presence of <em>P. cinnamomi</em>, indicating that this decline was not associated with the pathogen. The analysis of site and stand variables revealed a greater chance of decline on east and northeastern facing slopes, with a slight increase in decline likelihood with increasing stand density. There was significantly lower BAI in dead and declining trees long before decline symptoms began, a pattern consistent with previous drought induced declines. We observed a significant relationship between RWI and SPEI in the early growing season (June and 3-month June SPEI) and throughout almost all of the prior year’s growing season (May, June, 3-month June, 3-month July, and 3-month August SPEI). Chestnut oak mortality volume across the eastern US steadily increased from 2006-2020, indicating a region-wide increase in mortality. Our random forest classification indicated the importance of increased precipitation and precipitation timing on chestnut oak mortality.</p> <p>Chestnut oak decline observed in southern Indiana was induced by a series of droughts in 2005, 2007, and 2012. The greater early life BAI of chestnut oak which were impacted by decline revealed that individuals which likely prioritized stem growth over root growth were predisposed to decline and mortality from these droughts. This prioritization could be brought on by genetic differences, favoring rapid height growth in developing even-aged stands, or by an abundance of moisture availability. Our FIA analysis of mortality revealed increased mortality volume across many states from 2006-2020, and that chestnut oak mortality may be related to greater precipitation compared to historic levels. Considering these results, we suspect that chestnut oak which have recently died or are currently declining are likely individuals which lack the root system to endure repeated drought.</p>

No description available.

No description available.

Tjädern (Tetrao urogallus) är en av arterna skogshöns med sitt utbredningsområde Europa och Ryssland. Den är väl anpassad till ett liv i det norra barrskogsbältet. Beståndet av tjäder har minskat kraftigt under efterkrigstiden över hela sitt utbredningsområde utanför Ryssland, där den dock har ökat i antal. Tack vare den ökningen anger BirdLife International beståndet som stabilt. Anledningarna till nedgången i norra delen av Europa består troligen av flera orsaker varav de förändrade skogsbruksmetoderna under andra halvan av 1900-talet kan vara en av de viktigaste. Klimatfaktorer och förändrat predationstryck kan vara andra orsaker. För att försöka se effekterna av genomförda skogsbruksåtgärder inom upptagningsområdet för tjäderns lekplatser, har 12 lekplatser i norra Skaraborg som var inventerade under 1990-1995 återinventerats under våren 2005. Antalet tuppar idag på dessa lekplatser har jämförts med tidigare situation. Ingen lekplats uppvisar någon ökning av tuppar på leken och på 5 ställen har leken övergivits helt. Arealer för de olika markslagen har uppmätts inom de 300 ha som utgör en lekplats. Analyser av korrelationen mellan de olika markanvändningarna och antalet tuppar har inte gett några signifikanta resultat (p &gt; 0,05). Det finns en signifikant korrelation mellan förlorat antal tuppar och förändrad andel plantering (p&lt;0,05), det har betydelse från vilken nivå förändringen sker. Anledningarna till att tupparna försvunnit på en del ställen och minskat på andra skulle kunna vara resultatet av den samlade effekten av dels skogbruksåtgärder dels övriga faktorer. Det verkar vara betydelsefullt hur stort hygget är och var det ligger i förhållande till lekcentrum om det ska påverka tjädern. Ska hänsyn kunna tas när skogsbruksåtgärder planeras är det en förutsättning att lekplatsen är känd av berörda parter. Tjäderns höga krav på sin miljö med flera olika biotoper inom reviret och dess preferens för äldre skogar med lång kontinuitet gynnar många andra arter, vilket i sin tur även gör tjädern användbar som paraplyart inom naturvården. / The capercaillie (Tetrao urogallus) is one of the species of wood fowls with distribution in Europe and Russia. It is well adapted to a life in the northern coniferous forest area. The population of capercaillies has diminished considerably during the postwar period in the whole distribution area outside Russia, where it on the contrary has increased in number. Because of this increase the BirdLife International states the population as stable. The reasons for the decrease in the northern part of Europe are believed to emanate from different sources of which the changing methods in forestry during the second half of the 20th century seem to be one of the most important ones. Climate conditions and changed predacious pressure are other possible causes. In an attempt to observe the effects of the measures in forestry taken within the distribution areas of the mating grounds of the capercailzies, twelve sites in the northern county of Skaraborg, registered during the years 1990-1995, were again registered in spring 2005. The number of male birds today on these grounds has been compared to the number of earlier registrations. No mating ground shows an increase in the number of male birds and in five places the mating ground has been totally abandoned. Within the mating ground consisting of 300 hectares the acreage of different kinds of land has been measured. The analysis of the correlation between the use of the different kinds of land and the number of male birds has not given any significant results (p&gt; 0,05). There is one significant correlation between lost numbers of male birds and the alter of the share of plantation (p&lt;0,05). The reason why the male birds have disappeared and in other places have diminished in number could be the result of the increased effect of both the forestry measures taken and other factors. The size of the cutting area as well as the location in relation to the centre of the mating ground seems to be of importance in influencing the capercaillie. The knowledge of the mating grounds is therefore essential to the concerned parties in planning forestry measures in a considerate way. The capercaillie has high demands upon its environment with several different biotopes within its territory; its preference for old forests with a long continuity favors several other species, which thereby makes the capercaillie useful as a general covering species in the nature conservation work.

No description available.

No description available.

Arthropod parasites and micropredators, such as ticks and mosquitoes, influence terrestrial ecosystems and harm their hosts directly and indirectly by vectoring micro-organisms. Whether micropredators similarly affect marine ecosystems and hosts is not well understood. In coral reef fish communities, the most abundant micropredators are isopods, in particular, gnathiids. Our understanding of how isopods affect fishes has been restricted by a lack of information regarding basic isopod biology including; patterns of abundance, parasite identity, host specificity and host pathology. Also it is unknown if small juvenile fish are parasitised by isopods, and if this affects their survival. Sequentially, the aims of my PhD thesis were to understand the ecology of several lesser known parasites in sufficient detail to perform manipulative experiments that could test the effects of micropredation on small juvenile reef fish. All field studies took place at Lizard Island, Great Barrier Reef My first study aimed to describe temporal and spatial patterns of isopod abundance by measuring emergence rates. Gnathiid isopod juveniles emerge from the benthos into the water column to find hosts or change locations. Although diel patterns have been demonstrated, the relationship between substrate and emergence on coral reefs is not clear. I measured emergence rates of parasitic isopods (Gnathiidea and Flabellifera) in 6 “habitats” at 2 very different sites at Lizard Island. Isopods were collected from the periphery and centres of 3 sizes of reef, and from the substrate between these reefs (sand or rubble). At both sites, the most abundant gnathiid species (Gnathia falcipenis and Gnathia sp C), was exclusive to that site. Although strong diel patterns in emergence were observed, gnathiid abundance could not be predicted by habitat. However, gnathiids were larger and more often fed over reef borders than in the centres of reefs. To explain these patterns, I suggested that first stage larvae had the largest influence on total abundance and were patchily distributed in accordance with adults from which they had recently hatched. As later stage larvae also depend on fish, more successful (fed and older larvae) are found on the edges of reefs where appropriate hosts may be more abundant. Gnathiids were over-dispersed in all habitats investigated, including apparently homogeneous beds of coral rubble and sand. This indicated that gnathiid distribution may be better predicted by very fine scale differences in substrate, or that larvae are simply gregarious, and that abundance may be difficult to predict on the basis of substrate. Without reliable differences in parasite abundance among habitats at Lizard Island, subsequent studies would rely on manipulating parasite abundance via excluding wild parasites in the field (which proved very difficult) or by controlling abundance in laboratory simulations. I then investigated host specificity in the 2 most abundant gnathiid species from the previous study. Discrete species distributions between the two sites suggested that the 2 parasites may have had different diets. Host-specificity data for gnathiid isopods are scarce because the parasitic juvenile stages are difficult to identify and host-parasite contact is often brief. Engorged third stage gnathiids were photographed and permitted to moult into adults to allow identification. I compared mtDNA sequences from their blood meals to host sequences available on GenBank. The host frequency distributions used by each species were significantly different; only four host families were shared. I concluded that G. falcipenis and Gnathia sp C operate as preferential feeders. Importantly, this work showed that G. falcipenis was indeed a natural parasite of several species of damselfish (Pomacentridae) that could be collected as young recruits and used in manipulative experiments. I then used G. falcipenis as a model parasite to investigate the effects of isopods on recently recruited Dischistodus perspicillatus and small juvenile Acanthochromis polyacanthus damselfishes. Working with honours student Ms Rose Penfold, we determined that A. polyacanthus was infected by gnathiids in the wild at sizes as small as 4.2 mm SL. Laboratory infections revealed that larger A. polyacanthus were much better at eating gnathiids, a behaviour which prevented infection, and that smaller fish were more likely to die post-infection. Infection prevalence was > 3 % during the day, but we could not sample fish for nocturnal infection prevalence. A caging experiment suggested that most micropredation on damselfish took place at night. For D. perspicillatus, I found that exposure to 2 parasites each evening for 7 nights after settlement halved the growth of these fish. Lastly, numerous free-swimming cymothoid isopods were found associated with larval fish in light traps. Cymothoids have a multi-morphic life cycle composed of micropredatory stages that eventually become females, which are permanently attached to fishes. Because cymothoid taxonomy is based around female morphology, natatory-stage cymothoids can not be identified. I sequenced mtDNA from natatory and adult female life history stages and matched 4 of 11 natatory cymothoid morphotypes. Molecular data were also used to produce a phylogeny exploring the evolution of different forms of host attachment within the Cymothoidae. This phylogeny suggests that external attachment, formerly thought to be plesiomorphic, is a derived condition and has evolved several times independently. I suggest that attachment to the buccal cavity or gills is a primitive form of attachment. This research has provided information on emergence patterns and hostspecificity which is necessary for the future study of isopod vector biology. It also provides a platform for future taxonomic and phylogenetic studies on cymothoids. I demonstrate that gnathiids infect juvenile coral reef fish and suggest that they may influence survival both directly and indirectly by reducing growth and predisposing infected fish to size-selective mortality. Thus, interactions between isopod micropredators and recruiting fishes may determine the survivorship of individual fish and influence the subsequent community structure.

Arthropod parasites and micropredators, such as ticks and mosquitoes, influence terrestrial ecosystems and harm their hosts directly and indirectly by vectoring micro-organisms. Whether micropredators similarly affect marine ecosystems and hosts is not well understood. In coral reef fish communities, the most abundant micropredators are isopods, in particular, gnathiids. Our understanding of how isopods affect fishes has been restricted by a lack of information regarding basic isopod biology including; patterns of abundance, parasite identity, host specificity and host pathology. Also it is unknown if small juvenile fish are parasitised by isopods, and if this affects their survival. Sequentially, the aims of my PhD thesis were to understand the ecology of several lesser known parasites in sufficient detail to perform manipulative experiments that could test the effects of micropredation on small juvenile reef fish. All field studies took place at Lizard Island, Great Barrier Reef My first study aimed to describe temporal and spatial patterns of isopod abundance by measuring emergence rates. Gnathiid isopod juveniles emerge from the benthos into the water column to find hosts or change locations. Although diel patterns have been demonstrated, the relationship between substrate and emergence on coral reefs is not clear. I measured emergence rates of parasitic isopods (Gnathiidea and Flabellifera) in 6 “habitats” at 2 very different sites at Lizard Island. Isopods were collected from the periphery and centres of 3 sizes of reef, and from the substrate between these reefs (sand or rubble). At both sites, the most abundant gnathiid species (Gnathia falcipenis and Gnathia sp C), was exclusive to that site. Although strong diel patterns in emergence were observed, gnathiid abundance could not be predicted by habitat. However, gnathiids were larger and more often fed over reef borders than in the centres of reefs. To explain these patterns, I suggested that first stage larvae had the largest influence on total abundance and were patchily distributed in accordance with adults from which they had recently hatched. As later stage larvae also depend on fish, more successful (fed and older larvae) are found on the edges of reefs where appropriate hosts may be more abundant. Gnathiids were over-dispersed in all habitats investigated, including apparently homogeneous beds of coral rubble and sand. This indicated that gnathiid distribution may be better predicted by very fine scale differences in substrate, or that larvae are simply gregarious, and that abundance may be difficult to predict on the basis of substrate. Without reliable differences in parasite abundance among habitats at Lizard Island, subsequent studies would rely on manipulating parasite abundance via excluding wild parasites in the field (which proved very difficult) or by controlling abundance in laboratory simulations. I then investigated host specificity in the 2 most abundant gnathiid species from the previous study. Discrete species distributions between the two sites suggested that the 2 parasites may have had different diets. Host-specificity data for gnathiid isopods are scarce because the parasitic juvenile stages are difficult to identify and host-parasite contact is often brief. Engorged third stage gnathiids were photographed and permitted to moult into adults to allow identification. I compared mtDNA sequences from their blood meals to host sequences available on GenBank. The host frequency distributions used by each species were significantly different; only four host families were shared. I concluded that G. falcipenis and Gnathia sp C operate as preferential feeders. Importantly, this work showed that G. falcipenis was indeed a natural parasite of several species of damselfish (Pomacentridae) that could be collected as young recruits and used in manipulative experiments. I then used G. falcipenis as a model parasite to investigate the effects of isopods on recently recruited Dischistodus perspicillatus and small juvenile Acanthochromis polyacanthus damselfishes. Working with honours student Ms Rose Penfold, we determined that A. polyacanthus was infected by gnathiids in the wild at sizes as small as 4.2 mm SL. Laboratory infections revealed that larger A. polyacanthus were much better at eating gnathiids, a behaviour which prevented infection, and that smaller fish were more likely to die post-infection. Infection prevalence was > 3 % during the day, but we could not sample fish for nocturnal infection prevalence. A caging experiment suggested that most micropredation on damselfish took place at night. For D. perspicillatus, I found that exposure to 2 parasites each evening for 7 nights after settlement halved the growth of these fish. Lastly, numerous free-swimming cymothoid isopods were found associated with larval fish in light traps. Cymothoids have a multi-morphic life cycle composed of micropredatory stages that eventually become females, which are permanently attached to fishes. Because cymothoid taxonomy is based around female morphology, natatory-stage cymothoids can not be identified. I sequenced mtDNA from natatory and adult female life history stages and matched 4 of 11 natatory cymothoid morphotypes. Molecular data were also used to produce a phylogeny exploring the evolution of different forms of host attachment within the Cymothoidae. This phylogeny suggests that external attachment, formerly thought to be plesiomorphic, is a derived condition and has evolved several times independently. I suggest that attachment to the buccal cavity or gills is a primitive form of attachment. This research has provided information on emergence patterns and hostspecificity which is necessary for the future study of isopod vector biology. It also provides a platform for future taxonomic and phylogenetic studies on cymothoids. I demonstrate that gnathiids infect juvenile coral reef fish and suggest that they may influence survival both directly and indirectly by reducing growth and predisposing infected fish to size-selective mortality. Thus, interactions between isopod micropredators and recruiting fishes may determine the survivorship of individual fish and influence the subsequent community structure.

<p>Tjädern (Tetrao urogallus) är en av arterna skogshöns med sitt utbredningsområde Europa och Ryssland. Den är väl anpassad till ett liv i det norra barrskogsbältet. Beståndet av tjäder har minskat kraftigt under efterkrigstiden över hela sitt utbredningsområde utanför Ryssland, där den dock har ökat i antal. Tack vare den ökningen anger BirdLife International beståndet som stabilt. Anledningarna till nedgången i norra delen av Europa består troligen av flera orsaker varav de förändrade skogsbruksmetoderna under andra halvan av 1900-talet kan vara en av de viktigaste. Klimatfaktorer och förändrat predationstryck kan vara andra orsaker.</p><p>För att försöka se effekterna av genomförda skogsbruksåtgärder inom upptagningsområdet för tjäderns lekplatser, har 12 lekplatser i norra Skaraborg som var inventerade under 1990-1995 återinventerats under våren 2005. Antalet tuppar idag på dessa lekplatser har jämförts med tidigare situation. Ingen lekplats uppvisar någon ökning av tuppar på leken och på 5 ställen har leken övergivits helt. Arealer för de olika markslagen har uppmätts inom de 300 ha som utgör en lekplats. Analyser av korrelationen mellan de olika markanvändningarna och antalet tuppar har inte gett några signifikanta resultat (p > 0,05). Det finns en signifikant korrelation mellan förlorat antal tuppar och förändrad andel plantering (p<0,05), det har betydelse från vilken nivå förändringen sker. Anledningarna till att tupparna försvunnit på en del ställen och minskat på andra skulle kunna vara resultatet av den samlade effekten av dels skogbruksåtgärder dels övriga faktorer. Det verkar vara betydelsefullt hur stort hygget är och var det ligger i förhållande till lekcentrum om det ska påverka tjädern. Ska hänsyn kunna tas när skogsbruksåtgärder planeras är det en förutsättning att lekplatsen är känd av berörda parter. Tjäderns höga krav på sin miljö med flera olika biotoper inom reviret och dess preferens för äldre skogar med lång kontinuitet gynnar många andra arter, vilket i sin tur även gör tjädern användbar som paraplyart inom naturvården.</p> / <p>The capercaillie (Tetrao urogallus) is one of the species of wood fowls with distribution in Europe and Russia. It is well adapted to a life in the northern coniferous forest area. The population of capercaillies has diminished considerably during the postwar period in the whole distribution area outside Russia, where it on the contrary has increased in number. Because of this increase the BirdLife International states the population as stable. The reasons for the decrease in the northern part of Europe are believed to emanate from different sources of which the changing methods in forestry during the second half of the 20th century seem to be one of the most important ones. Climate conditions and changed predacious pressure are other possible causes.</p><p>In an attempt to observe the effects of the measures in forestry taken within the distribution areas of the mating grounds of the capercailzies, twelve sites in the northern county of Skaraborg, registered during the years 1990-1995, were again registered in spring 2005. The number of male birds today on these grounds has been compared to the number of earlier registrations. No mating ground shows an increase in the number of male birds and in five places the mating ground has been totally abandoned. Within the mating ground consisting of 300 hectares the acreage of different kinds of land has been measured. The analysis of the correlation between the use of the different kinds of land and the number of male birds has not given any significant results (p> 0,05). There is one significant correlation between lost numbers of male birds and the alter of the share of plantation (p<0,05). The reason why the male birds have disappeared and in other places have diminished in number could be the result of the increased effect of both the forestry measures taken and other factors. The size of the cutting area as well as the location in relation to the centre of the mating ground seems to be of importance in influencing the capercaillie. The knowledge of the mating grounds is therefore essential to the concerned parties in planning forestry measures in a considerate way. The capercaillie has high demands upon its environment with several different biotopes within its territory; its preference for old forests with a long continuity favors several other species, which thereby makes the capercaillie useful as a general covering species in the nature conservation work.</p>

Arctic tundra vegetation communities are rapidly responding to climate warming with increases in aboveground biomass, particularly in deciduous shrubs. This increased shrub density has the potential to dramatically alter the functioning of tundra ecosystems through its effects on permafrost degradation and nutrient cycling, and to cause positive feedbacks to global climate change through its impacts on carbon balance and albedo. Experimental evidence indicates that tundra plant growth is most strongly limited by soil nutrient availability, which is projected to increase with warming. Therefore research to date into the mechanisms driving tundra 'shrub expansion' has taken a 'bottom-up' perspective, overlooking the potential role of herbivory in mediating plant-soil interactions. In this thesis, I integrate the impacts of climate warming and caribou browsing on tundra vegetation community structure, and specifically investigate if increases in soil fertility with warming might lead to changes in vegetation biomass and chemistry that could fundamentally alter herbivore-nutrient cycling feedbacks, shifting the role of caribou browsing from restricting shrub growth to facilitating it. Using experimental greenhouses, nutrient addition plots, and caribou exclosures at Daring Lake Research Station in the central Canadian low Arctic, I showed that warming increased soil nutrient availability and plant biomass, and that caribou browsing restricted tundra shrub growth under present conditions. Plant and soil nutrient pool responses to warming demonstrated that increased growing season temperatures enhanced tundra plant growth both by increasing soil nutrient availability and by inferred increases in the rate of photosynthesis, however that the former process was comparatively more limiting. Species- and plant part-specific changes in biomass and chemistry with warming and fertilization clearly indicated the rate and magnitude of change in soil fertility substantially alters plant community structure. Nonetheless, since plant nutrient concentrations decreased with warming and plant responses to browsing were independent of soil fertility, I did not find evidence for a shift from caribou decelerating to accelerating nutrient cycling with warming. Altogether this research indicates effective conservation and management of Rangifer populations is critical to understanding how climate change will affect tundra vegetation trajectories and ultimately tundra ecosystem carbon balances. / Thesis (Ph.D, Biology) -- Queen's University, 2013-06-07 15:13:21.698