Microhabitat Associations for the Threatened Cheat Mountain Salamander in Relation to Early-stage Red Spruce Restoration Areas

The Central Appalachian Spruce Restoration Initiative was formed to promote restoration of red spruce Picea rubens forests in Central Appalachia. One goal of the initiative is to increase availability and enhance quality of habitat for wildlife, including the threatened Cheat Mountain salamander Plethodon nettingi. The purpose of this research was to compare microhabitat characteristics between an occupied Cheat Mountain salamander site and early-stage spruce restoration sites, and between four occupied sites and proximal non-detection sites. We found that soil pH was higher and soil moisture was lower at spruce restoration sites compared to the occupied site, and that light intensity, sub-canopy air temperature, and ground-level air temperature were higher in spruce restoration prescriptions with reduced canopy cover. We found that soil moisture was higher at occupied sites compared to proximal non-detection sites, but soil pH was not significantly different. Our study suggests that Cheat Mountain salamanders are associated with low soil pH and high soil moisture, and thus spruce restoration could enhance habitat quality for this species in the long-term.

Complex Drivers of Riparian Soil Oxygen Variability Revealed Using Self-Organizing Maps

Oxygen (O2) is a key regulator of soil reduction-oxidation processes and therefore modulates biogeochemical cycles. The difficulties associated with accurately characterizing soil O2 variability have prompted the use of soil moisture as a proxy for soil O2, based on the low solubility of O2 in water. Due to seasonal shifts in soil O2 depletion mechanisms, the use of soil moisture alone as a proxy measurement could result in inaccurate O2 estimations. For example, soil O2 may remain high during cool months when soil respiration rates are low. We analyzed high-frequency sensor data (e.g., soil moisture, temperature, CO2, O2) with a machine learning technique, the Self-Organizing Map, to pinpoint suites of soil conditions that are associated with contrasting O2 regimes. At two low-lying riparian sites in contrasting land use and topographic settings of northern Vermont, we found that soil O2 levels varied seasonally, and with soil moisture. For example, forty-seven percent of low O2 levels were associated with cool and wet soil conditions, whereas 32% were associated with warm and dry conditions. Contrastingly, the majority (62%) of high O2 conditions occurred under warm and dry conditions. High soil moisture levels did not always lead to low O2, however, as 38% of high O2 values occurred under cool and wet conditions. Our results highlight challenges associated with predicting soil O2 solely based on soil moisture, as variable combinations of soil and site-specific hydrologic conditions can complicate the relationship between soil water content and O2. This indicates that process-based ecosystem and denitrification models that rely solely on soil moisture to estimate O2 availability will, in some cases, need to incorporate other site and climate-specific drivers to accurately predict soil O2.

Ecological Restoration of the Wairio Wetland, Lake Wairarapa: Water Table Relationships and Cost-Benefit Analysis of Restoration Strategies

<p>The world’s wetlands are known for being highly productive environments and supporting significant numbers of fauna and flora species that rely on the wetland’s primary productions for survival. However, they were historically used by humans for hunting and fishing, wetlands were considered wastelands, best used when drained and filled for agricultural, industrial and residential development. Despite now having a greater understanding of wetlands and their ecological importance, degradation of wetlands continues, mainly due to anthropogenic activities. Wetland restoration involves reconstructing natural sites that have been degraded or completely lost and re-establishing their functions and values as vital ecosystems. Important restoration components include control of invasive weeds, emphasis on the presence of locally native species and restoration of the hydrological component. The Wairio wetland is part of the largest wetland complex in the southern North Island and supports a number of native flora and fauna, of national and international importance. Wairio wetland has been destroyed by the effects of partial draining, unnatural hydrological control, clearing of native forest, construction of Parera Road separating once joined wetlands and the establishment of invasive willow trees and agricultural grasses. The co-management by the Department of Conservation and Ducks Unlimited, commenced in 2005, has begun a positive shift for the wetland. However, issues still remain due to the majority of the wetland still being used for farming, so there is no continuity between the three fenced restoration stages; artificial hydrological flow and water storage; and established willow trees along the wetland boundary. Most ephemeral wetland vegetation displays a strong pattern of zonation, through a sequence from open water to dry land, which is correlated in some way with the duration and periodicity of water inundation. This hydrosere reflects differences in the degree of adaptation to aquatic life of different plant species. Two studies are reported here, conducted in two areas at the Wairio wetland over two desiccation periods. The first study conducted during 2010/2011 at stage one, focused on determining the environmental conditions of peak abundance and limits to distribution of key native and exotic plant species along an environmental (hydrological) gradient. The second study, conducted in 2012 at stage three, further investigated the effect of topsoil removal on the plant community and was a comparison study with the initial study at stage one. Results indicated that the Wairio wetland plant communities display strong zonation patterns progressing from aquatic species, to turf communities, to exotic grass species. Over the two desiccation periods studied it was found that the introduced species most abundant in low soil moisture were common pasture grasses, especially yorkshire fog (Holcus lanatus), brown top (Agrostis capillaris) and tall fescue (Schedonorus arundinaceus) as well as purple clover (Trifolium pratense) and the high soil moisture invasive competitor was water plantain (Alisma spp.). We also found that topsoil excavation impacts the plant community; topsoil scraping in the high soil moisture areas leads to a more native dominated plant community, with the dominant species being water plantain (Alisma spp.) and Isolepis prolifera, but scraping in relatively low soil moisture areas encourages the exotic grass weed species to grow. Wairio wetland on the Eastern shore of Lake Wairarapa has been adversely affected by anthropogenic activities since the 1960s. In 2005, Ducks Unlimited and the Department of Conservation signed a Land Management Agreement where Ducks Unlimited would commence the restoration of the wetland. Survival of trees planted during the first few years was variable. Here, I report on the design and monitoring of a large scale field experiment involving the planting of around 2,500 trees of eight native wetland tree species Dacrycarpus dacrydioides, Podocarpus totara, Cordyline australis, Olearia virgata, Pittosporum tenuifolium, Coprosma robusta, Coprosma propinqua and Leptospermum scoparium. The trees were subjected to different methods of site preparation and aftercare to determine the best combination of treatments for successful establishment of tree saplings. Treatments included the use or non-use of topsoil excavation, release spraying, weedmats, nurse trees (with two combinations of species) and different spacing between the nurse species. Survival and growth over the first six months was monitored. Preliminarily results showed survival of O. virgata and P. totara was influenced by surface water, but few immediate effects of treatments upon growth rates. Olearia virgata, however, grew best in wet areas that had been scraped free of topsoil or drier areas that had not been scraped. Monitoring over the next 18 months will give us a better understanding of which is the most costeffective combination of treatments. Early indications suggest high level survival under all treatments.</p>

Ecological Restoration of the Wairio Wetland, Lake Wairarapa: Water Table Relationships and Cost-Benefit Analysis of Restoration Strategies

<p>The world’s wetlands are known for being highly productive environments and supporting significant numbers of fauna and flora species that rely on the wetland’s primary productions for survival. However, they were historically used by humans for hunting and fishing, wetlands were considered wastelands, best used when drained and filled for agricultural, industrial and residential development. Despite now having a greater understanding of wetlands and their ecological importance, degradation of wetlands continues, mainly due to anthropogenic activities. Wetland restoration involves reconstructing natural sites that have been degraded or completely lost and re-establishing their functions and values as vital ecosystems. Important restoration components include control of invasive weeds, emphasis on the presence of locally native species and restoration of the hydrological component. The Wairio wetland is part of the largest wetland complex in the southern North Island and supports a number of native flora and fauna, of national and international importance. Wairio wetland has been destroyed by the effects of partial draining, unnatural hydrological control, clearing of native forest, construction of Parera Road separating once joined wetlands and the establishment of invasive willow trees and agricultural grasses. The co-management by the Department of Conservation and Ducks Unlimited, commenced in 2005, has begun a positive shift for the wetland. However, issues still remain due to the majority of the wetland still being used for farming, so there is no continuity between the three fenced restoration stages; artificial hydrological flow and water storage; and established willow trees along the wetland boundary. Most ephemeral wetland vegetation displays a strong pattern of zonation, through a sequence from open water to dry land, which is correlated in some way with the duration and periodicity of water inundation. This hydrosere reflects differences in the degree of adaptation to aquatic life of different plant species. Two studies are reported here, conducted in two areas at the Wairio wetland over two desiccation periods. The first study conducted during 2010/2011 at stage one, focused on determining the environmental conditions of peak abundance and limits to distribution of key native and exotic plant species along an environmental (hydrological) gradient. The second study, conducted in 2012 at stage three, further investigated the effect of topsoil removal on the plant community and was a comparison study with the initial study at stage one. Results indicated that the Wairio wetland plant communities display strong zonation patterns progressing from aquatic species, to turf communities, to exotic grass species. Over the two desiccation periods studied it was found that the introduced species most abundant in low soil moisture were common pasture grasses, especially yorkshire fog (Holcus lanatus), brown top (Agrostis capillaris) and tall fescue (Schedonorus arundinaceus) as well as purple clover (Trifolium pratense) and the high soil moisture invasive competitor was water plantain (Alisma spp.). We also found that topsoil excavation impacts the plant community; topsoil scraping in the high soil moisture areas leads to a more native dominated plant community, with the dominant species being water plantain (Alisma spp.) and Isolepis prolifera, but scraping in relatively low soil moisture areas encourages the exotic grass weed species to grow. Wairio wetland on the Eastern shore of Lake Wairarapa has been adversely affected by anthropogenic activities since the 1960s. In 2005, Ducks Unlimited and the Department of Conservation signed a Land Management Agreement where Ducks Unlimited would commence the restoration of the wetland. Survival of trees planted during the first few years was variable. Here, I report on the design and monitoring of a large scale field experiment involving the planting of around 2,500 trees of eight native wetland tree species Dacrycarpus dacrydioides, Podocarpus totara, Cordyline australis, Olearia virgata, Pittosporum tenuifolium, Coprosma robusta, Coprosma propinqua and Leptospermum scoparium. The trees were subjected to different methods of site preparation and aftercare to determine the best combination of treatments for successful establishment of tree saplings. Treatments included the use or non-use of topsoil excavation, release spraying, weedmats, nurse trees (with two combinations of species) and different spacing between the nurse species. Survival and growth over the first six months was monitored. Preliminarily results showed survival of O. virgata and P. totara was influenced by surface water, but few immediate effects of treatments upon growth rates. Olearia virgata, however, grew best in wet areas that had been scraped free of topsoil or drier areas that had not been scraped. Monitoring over the next 18 months will give us a better understanding of which is the most costeffective combination of treatments. Early indications suggest high level survival under all treatments.</p>

Effects of Shade and Planting Methods on the Growth of Heracleum moellendorffii and Adenophora divaricata in Different Soil Moisture and Nutrient Conditions

In this study, the interacting effects of shade and planting methods on the growth and competitive ability of two understory plants Heracleum moellendorffii Hance and Adenophora divaricata Franch. & Sav. were investigated under different soil moisture and nutrient conditions. One-year-old seedlings were subjected to different light levels (0%, 35%, and 55% shade) and planting methods (monoculture and mixed) under contrasting soil moisture (1.2 L/m2 and 2.3 L/m2 of water) and soil nutrient conditions (unfertilized and fertilized). Here, shading significantly improved the height growth of H. moellendorffii (10–20 cm increase) in unfertilized and fertilized plots and at high soil moisture conditions. Contrarily, A. divaricata seedlings planted singly at full sunlight yielded a higher aboveground biomass growth (8–17 g plant−1), compared with those shaded and intercropped seedlings (0.9–3.9 g plant−1). The increased competitiveness of H. moellendorffii suppressed the growth of A. divaricata across different light conditions when planted together. The amount of light, soil moisture, and nutrients and their interactions significantly affected the growth of the seedlings, resulting in asymmetric interspecific competition between the two species. Results provide us with a better understanding of the environmental factors affecting plant growth for forest farming in the understory.

Regeneration of black ash (Fraxinus nigra Marsh.) in hardwood swamps of the Great Lakes – St. Lawrence Forest Region

An inductive, ordination-based approach was used to explore patterns in the microenvironment and natural regeneration of black ash across a range of representative stands in the central Ontario portion of the Great Lakes -St. Lawrence Forest Region (GLSL) near Lake Nipissing, Ontario, Canada. The objective of this study was to describe patterns of regeneration of black ash and determine the associations between multiple indicators of black ash regeneration success and biotic and abiotic factors. Using a randomized sampling design with specific selection criteria, 12 black ash stands were sampled, each with three 400 m2 circular sample plots that contained three 4 m2 sub-plots. A suite of environmental variables such as elevation, topographic wetness index, slope, and soil characteristics (percent moisture, pH, total nitrogen, exchangeable phosphorus, potassium, magnesium) were determined for each stand. Variables capturing regeneration potential, including density, diameter, and height of all germinants, seedlings, saplings and sprouts were also collected. A sample of 15 dominant or co-dominant trees in each stand, as well as numerous black ash seedlings, saplings and sprouts were examined using dendrochronological methods to estimate ages. Principal component analysis ordinations were performed exploring the variation in environment and black ash regeneration variables among the stands. High soil moisture and the presence of canopy gaps, (as indicated by high standard deviation of canopy closure), were key variables associated with greater abundance of regeneration. Black ash was the dominant species in all stands, which were also generally characterized by a common reverse-J diameter distribution. It was observed that black ash in the sapling layer reached substantial ages (up to 60 years), indicating they are capable of withstanding long periods of suppression below the canopy. Collectively, these findings suggest that black ash-dominated stands in the study area are regenerating in multiple cohorts. Based on these patterns, it appears that regeneration in these stands is occurring through gap-phase mechanisms, suggesting single tree selection as the best management option for black ash in the GLSL.

Production, stability and degradation of Trichoderma gliotoxin in growth medium, irrigation water and agricultural soil

Gliotoxin produced by Trichoderma virens is inhibitory against various phytopathogenic fungi and bacteria. However, its stability in soil-ecosystem has not yet been well-defined. This study aimed to decipher its persistence and behaviour in growth media, irrigation water and soil ecosystems. Gliotoxin production was noticed at logarithmic growth phase and converted into bis-thiomethyl gliotoxin at late stationary growth phase of T. virens in acidic growth medium. But, no gliotoxin production was observed in neutral and alkaline growth medium. Gliotoxin was stable for several days in acidic water but degraded in alkaline water. Degradation of gliotoxin was more in unsterile soil than sterile soil and also that was higher under wet soil than dry soil. Degradation of gliotoxin was hastened by alkaline pH in wet soil but not in dry soil. Under unsterile soil conditions, high soil moisture increased the degradation of gliotoxin and the degradation of gliotoxin occurred quickly in alkaline soil (in 5 days) compared to acidic soil (in 10 days). Under sterile soil conditions, high soil moisture also enhanced the degradation of gliotoxin but level of degradation was less compared to unsterile conditions. Thus, gliotoxin stability is influenced mainly by the soil wetness, soil microbial community and pH conditions.

Investigating the drivers of the unprecedented Chernobyl Power Plant Wildfire in April 2020 and its effects on 137Cs dispersal

In this study, we explore the conditions that led to the unprecedented wildfire that occurred in the Chernobyl Exclusion Zone in April 2020 and the effect of this fire on 137Cs dispersal, as wildfires are important drivers of 137Cs resuspension, with potentially harmful consequences for the receiving ecosystems. We characterised the historical wildfire record between 2000 and 2020 using the MCD64A1.006 MODIS Burned Area Monthly Global 500 m dataset and assessed the climatic conditions associated with these wildfire events using ERA5-Land reanalysis data. We also examined fire danger indices at the time of these wildfires. We then explored the widespread effects of the April 2020 wildfire on 137Cs resuspension and subsequent deposition using the NOAA-HYSPLIT model, concluding that the impacts of such resuspension on areas further afield were minimal. Results show that climatic conditions leading to severe wildfires are increasing, especially during March and April. High soil moisture, relative humidity and extreme temperature anomalies are associated with the largest wildfires on record, and fire risk indices at the time of the April 2020 fire were higher than for other large fires on record. We have estimated that 3854 GBq of 137Cs resuspended during the CPPF, with atmospheric transport dominant over Russia, Ukraine, Moldova and Kazakhstan. The observed increase in large wildfires will have implications for wildfire-driven soil erosion processes, which will further exacerbate the effects of atmospheric-driven 137Cs redistribution.

CROSSKILL AND STAR-WHEELED ROLLERS. FUNCTIONAL AND DYNAMIC TESTS

Experimental field research of crosskill and star-wheeled rollers similar by design provides their developers and users with information on understanding their design and functional features. The purpose of the research is to compare the functional features of crosskill and star-wheeled rollers according to the criteria of clods breaking effect, compacting action, resistance to sticking in the range of pre-sowing and surface tillage depth. Methods and materials. Dynamic tests involved the study of three types of rollers. The research hypothesis assumed that the selected criteria for evaluating the work of rollers (intensity of breaking of clods, compacting action of rollers, intensity of bottom compaction and performance of rollers at high soil moisture) depend on roller pressure and different speed regimes, as they are derived from the shape of work surfaces. Sub-criteria studies were supposed to be carried out on the same type of soil: clods breaking characteristics on dry W = (10… 12) %, compacting effect on physically mature soil W = (15… 20) %, efficiency at high humidity - W = (25… 27) %. Evaluation of soil characteristics was performed by thermostatic-weight method according to the generally accepted method of "cutting ring" [Kaczynski NA, 1947], according to the volume of the cylinder 100 cm3. To determine the intensity of bottom compaction used the methodology and technical means of L. Pogorilyy UkrNDIPVT development. Statistical analysis of experimental data was performed by the method of analysis of variance according to [Dospekhov, 1985] and interpreted by standard computer programs Excel in the form of graphs. Results. The intensity of clods breaking with a classic roller is the lowest and depends on the speed of movement. The intensity of breaking by the modernized roller is approximately 1.1 times higher and with increasing speed is almost stable. The intensity of clods breaking by a specialized roller is the highest and almost (10...20) %, respectively, exceeds the previous two rollers and does not significantly depend on the increase in speed. The greatest compaction of the soil (the height of the layer to which the pre-prepared soil asked after the passage of the roller) is characteristic of a specialized roller, which is almost (1.5…1.7) times higher than the classic and modernized, respectively. Depending on the depth of pre-tillage (5…10) cm, compaction by rollers varies approximately twice. The greatest intensity of compaction of a bottom is provided by the specialized roller, and modernized and classical condense accordingly in (1,2…1,4) times below. The specialized roller sticks the fastest, which is facilitated by the 4-tier arrangement of working surfaces and their maximum in comparison with others contact with the ground. Sticking of the modernized roller surface is as that of the specialized. The classic roller surface remains clean for the longest time. Conclusions. The classic roller compacts both the upper and lower horizons of the soil well enough, brings little moisture to the surface, has a medium clods breaking effect, can be recommended for a wide range of works, but its primary purpose is cultivating after sowing; as a compromise it can be used for pre-sowing tillage with good quality indicators. The upgraded roller compacts the top layer of the soil well, carries away little moisture, mulches the surface, distributes the effort well at different depths of cultivation and can be recommended primarily for pre-sowing tillage; as a compromise solution can be used after sowing with good quality indicators. Specialized roller – star-wheeled, has good penetrating ability, works most actively, providing the best clods breaking effect, slightly carries away wet horizons on the surface; can be recommended for leveling and use on the soil after its main cultivation. Each of the studied rollers can be used to some extent in all these technological operations, but the best result will be achieved taking into account their characteristics, type and period of execution.