Differences In Decomposition Rates Research Articles

Effects of environmental and biological characteristics on leaf decomposition under wetland restoration conditions

The implementation of ecological restoration projects, such as wetland rehabilitation, is essential for achieving sustainable development. However, current research on monitoring recovery status primarily focuses on evaluating water quality and aquatic community structure, with limited understanding of macroinvertebrate and microbial networks, as well as the functions of restored ecosystems. To address this gap, we compared the leaf decomposition rates of reed (Phragmites australis) and sedge (Carex appendiculata) in short-term (1, 2, and 3 years) and long-term (17 years) restoration wetlands, using natural wetlands as controls to assess ecosystem function. Our results indicate that the leaf decomposition rate in restored wetlands is significantly lower than in natural wetlands. No significant difference in decomposition rates was detected between the two types of leaves (P>0.05). All evaluation categories, including biological network structure, influenced leaf decomposition in different wetlands, with distinct effects observed on reed and sedge leaves. Compared to sedges, the decomposition of reed leaves exhibited a stronger correlation with macroinvertebrates while showing a weaker association with microorganisms and co-occurring network topological parameters. Overall, the execution of wetland restoration projects positively influences the recovery of biodiversity co-occurrence networks and ecosystem functions. These findings provide valuable insights for environmental and sustainability assessments.

Tree species selection for optimizing soil carbon storage: Insights from litter decomposition and bacterial community analysis in coastal ecosystems

Coastal wetland ecosystems are critical sinks for atmospheric carbon dioxide, playing a vital role in global carbon cycling and climate regulation. The decomposition of leaf litter plays a crucial role in the formation and stability of soil organic carbon (SOC) in these environments. This study investigated the impact of leaf litter decomposition from five tree species (Populus deltoids, Ligustrum lucidum, Taxodium 'Zhongshanshan', Hibiscus hamabo, and Nerium oleander) on SOC dynamics, humus composition, and soil bacterial community structure in a tidal flat. Litterbags were used to monitor the mass loss and changes in litter chemical composition over 270 days. The results revealed significant differences in decomposition rates among the tree species, with Nerium oleander exhibiting the fastest decomposition and Populus deltoids the slowest. Surprisingly, initial litter chemistry did not correlate with decomposition rates; however, changes in lignin and hemicellulose content during decomposition were significantly related to mass loss. Despite its rapid decomposition, Nerium oleander litter resulted in the highest accumulation of SOC, total humus, and humin compared to the other species, challenging the conventional view that slower decomposition leads to greater SOC storage. The soil microbial community structure was significantly influenced by SOC, humus, and litter components, with distinct microbial assemblages associated with each tree species. A random forest model identified key bacterial taxa, predominantly Proteobacteria, as important predictors of SOC content, highlighting the role of bacterial diversity in regulating SOC dynamics. These findings underscore the importance of considering litter quality, decomposition dynamics, and bacterial community composition in strategies aimed at enhancing soil carbon sequestration. This study suggests that selecting tree species with rapidly decomposing litter, such as Nerium oleander, in coastal plantations can be an effective management tool for optimizing soil carbon storage, offering valuable insights for mitigating climate change impacts.

Patterns of decomposition and functional traits for flower and leaf litter in tropical woody species.

The variation within and across species has afterlife effects on carbon and nutrient cycling through the alteration of litter decomposability. However, the focus on leaves may not reflect a whole-plant economic spectrum of strategies. Here, we assessed the patterns and predictors of flower and leaf-litter decomposition at the intra- (i.e., flowers and leaves of the same species) and inter-specific (i.e., flowers and leaves from different species) levels for 29 tropical woody species in northeast Brazil. We evaluated nine functional litter traits, including structural and chemical traits. Flower litter decomposed, on average, three times faster than leaf litter (11.9% and 39.4% mass remaining, respectively) and exhibited higher water-holding capacity (WHC), leaching (LEA), and N, P, and K content. Otherwise, leaf litter showed higher density (DEN) and Ca, Mg, and Na content. The average relative differences in decomposition rate and functional traits between flower and leaf litter did not differ at both intra- and inter-specific levels. The predictors of decomposition were mostly similar, explaining 39% and 37% of flower and leaf litter, respectively. Leaching, P, Ca, Mg, and Na predict both flower and leaf-litter decomposition. However, WHC exclusively predicted flower-litter decomposition, and DEN, N, and K exclusively predicted leaf-litter decomposition. The observed differences in decomposition rate and functional traits between flower and leaf litter indicate that the afterlife effects differ between these plant organs and leverage the role of flower litter and its secondary consequences to nutrient and carbon cycling on ecosystems.

Litter Decomposition of Two Kiwifruit Cultivars (‘Jinkui’ and ‘Hort-16A’) with Different Litter Qualities in the Orchard Ecosystem

The aim of this study was to reveal the decomposition differences of kiwifruit litters with different qualities and verify the “Initial Litter Quality Hypothesis”. This study took litters of ‘Jinkui’ and ‘Hort-16A’ kiwifruit as the research objects, and carried out in situ decomposition experiments. The decomposition rate, nutrients release process, and soil enzyme activities were analyzed. In this study, the litter of ‘Hort-16A’ kiwifruit decomposed faster than the litter of ‘Jinkui’ kiwifruit. The decomposition time was positively correlated with the initial concentration of C of the litters, but negatively correlated with the concentrations of N and P. Except for P and Mn, the dynamic trends of the nutrient concentrations were similar during the litter decomposition of ‘Jinkui’ and ‘Hort-16A’ kiwifruit. After 180 days of decomposition, about 85%~95% of the initial concentrations of the macro-elements of the ‘Hort-16A’ kiwifruit litter were released. The dynamic trends of protease activities were similar, but that of sucrase, β-1,4-glucosidase, polyphenol oxidase, and phosphatase were different. In conclusion, the litter quality of kiwifruit affects the decomposition rate, and the difference in decomposition rate in turn affects the dynamic processes of nutrient release and soil enzyme activity. This study provides evidence for the “Initial Litter Quality Hypothesis” in the orchard ecosystem.

Understanding the impact of main cell wall polysaccharides on the decomposition of ectomycorrhizal fungal necromass

AbstractThe extramatrical mycelium of ectomycorrhizal fungi (EMF) is an important source of soil carbon and nitrogen. While the importance of recalcitrant compounds in the fungal cell wall has been explored earlier, the contribution of highly abundant but labile components, like glucans, and the role of their temporal dynamics during decomposition remains unknown. For the first time, we examined how the concentration of three main fungal cell wall components (chitin, melanin, glucans) in EMF necromass are related to necromass decomposition, over a period of 6 weeks. Although the initial concentrations of the three components were not good predictors of necromass loss, we found species–specific trends of chitin and glucans loss over time. The chitin concentration during decomposition was tightly linked to the weekly necromass degradation, with trends of chitin loss being dissimilar across fungal species. Chitin concentration was positively correlated with the mass loss in the first week, but in the remaining 5 weeks, it was found to be weakly negatively correlated with mass loss. The similarity in susceptibility to the decomposition of glucans and chitin likely compensates for the impacts of interspecific differences in their initial concentration, leading to overall similar decomposition patterns. Alternatively, other, non‐measured, components (e.g., glycoproteins, N content) may contribute to explaining similar decomposition patterns. Our results indicate that ectomycorrhizal necromass decomposition processes differ from those of plant litter decomposition with, unlike in plants, differences in initial concentrations of major structural carbohydrates (e.g., glucans) being unrelated to differences in decomposition rates. These findings indicate that the decomposition of fungal material cannot be inferred from assumptions based on data provided by studies of plant decomposition.Highlights Necromass of different ectomycorrhizal species decomposes similarly Main cell wall components show different decomposition patterns The relationship between cell wall compounds and mass loss changes over time Mycorrhizal necromass decomposition differs substantially from that of plant litter.

Experimental Warming of Typically Acidic and Nutrient-Poor Boreal Soils Does Not Affect Leaf-Litter Decomposition of Temperate Deciduous Tree Species

Ongoing rapid climatic changes are expected to modify the structure, composition, and functioning of forest ecosystems. Studying the influence of such changes on biogeochemical processes is thus crucial for a fuller understanding of forest response to climate change. In a temperate forest of Quebec, Canada, we emulated climate change by warming the acidic, nutrient-poor, and dry soils of two mixedwoods by 3 to 4 °C using heating cables. Leaf-litter mass loss of the local red maple, sugar maple, large-tooth aspen, and American beech were monitored to assess the ability of these tree species to condition boreal soils in the context of their northward migration under climate change. We hypothesized that decomposition rates of all leaf-litter types would be decreased equally by warming due to a drying effect of the soil and its surface, which is detrimental to microbial biomass and activity. Our results suggest differences in decomposition rates between tree species as follows: sugar maple > red maple ≥ American beech = large-tooth aspen. There was no indication of a slower turnover in these marginal soils compared to other studies conducted on typical hardwood soils. Moreover, no difference in litter mass loss was detected between treatments, likely due to a drying effect of the soil warming treatment. Results imply that climate change has a marginal influence on leaf-litter dynamics of temperate tree species on soils that are typical of the boreal forest. However, some variables that could play an important role on litter decomposition in the context of climate change were not measured (e.g., plant phenology, understory composition and density, microbes) and thus, uncertainties remain. The soil drying effect by warming also needs to be further documented and modeled. The study year was characterized by significant periods of water stress but was not considered an exceptional year in that regard. It would be relevant to test for leaf-litter dynamics during dry and wet summers and verify again our initial hypothesis of decreased leaf-litter decomposition rates due to soil warming/drying.

Simultaneous FIA Determination of Free and Combined Chlorine Based on the Difference in Decomposition Rate Under UV Light Irradiation

世界各地で水不足と水質汚染の問題が深刻となっており，衛生的な水の確保は重要な課題である．水の消毒では，遊離塩素と結合塩素の濃度を適切に管理することが重要である．遊離塩素と結合塩素の間には光分解反応速度に差が生じるため，この性質を利用することで遊離塩素と結合塩素の分別が可能であると考えた．本研究では，光照射流路と光照射のない流路への分岐を備えたフローインジェクション分析（FIA）システムを構築し，それぞれの流路を経由して得られるシグナルを時間差で検出した．その結果，それぞれのシグナルの大きさと遊離塩素及び結合塩素濃度の関係から作成した線型方程式を用いることで，一度の試料注入での同時定量が可能となった．次亜塩素酸イオンとクロラミンTの混合溶液を用いて同時定量を試みたところ，仕込み量と同等の値を得ることができた．

Drivers of community assembly change during succession in wood-decomposing beetle communities.

The patterns of successional change of decomposer communities is unique in that resource availability predictably decreases as decomposition proceeds. Saproxylic (i.e. deadwood-dependent) beetles are a highly diverse and functionally important decomposer group, and their community composition is affected by both deadwood characteristics and other environmental factors. Understanding how communities change with faunal succession through the decomposition process is important as this process influences terrestrial carbon dynamics. Here, we evaluate how beta-diversity of saproxylic beetle communities change with succession, as well as the effects of different major drivers of beta-diversity, such as deadwood tree species, spatial distance between locations, climate and forest structure. We studied spatial beta-diversity (i.e. dissimilarity of species composition between deadwood logs in the same year) of saproxylic beetle communities over 8 years of wood decomposition. Our study included 379 experimental deadwood logs comprising 13 different tree species in 30 forest stands in Germany. We hypothesized that the effects of tree species dissimilarity, measured by phylogenetic distance, and climate on beta-diversity decrease over time, while the effects of spatial distance between logs and forest structure increase. Observed beta-diversity of saproxylic beetle communities increased over time, whereas standardized effects sizes (SES; based on null models) of beta-diversity decreased indicating higher beta-diversity than expected during early years. Beta-diversity increased with increasing phylogenetic distance between tree species and spatial distance among regions, and to a lesser extent with spatial distance within regions and differences in climate and forest structure. Whereas effects of space, climate and forest structure were constant over time, the effect of phylogenetic distance decreased. Our results show that the strength of the different drivers of saproxylic beetle community beta-diversity changes along deadwood succession. Beta-diversity of early decay communities was strongly associated with differences among tree species. Although this effect decreased over time, beta-diversity remained high throughout succession. Possible explanations for this pattern include differences in decomposition rates and fungal communities between logs or the priority effect of early successional communities. Our results suggest that saproxylic beetle diversity can be enhanced by promoting forests with diverse tree communities and structures.

Nutrient controls on carbohydrate and lignin decomposition in beech litter

Nutrient pollution has increased plant litter nutrient concentrations in many ecosystems, which may profoundly impact litter decomposition and change the chemical composition of litter inputs to soils. Here, we report on a mesocosm experiment to study how variations in the nitrogen (N) and phosphorus (P) concentrations in Fagus sylvatica (European beech) litter from four sites differing in bedrock, atmospheric deposition, and climate affect lignin and carbohydrate loss rates and residual litter chemistry. We show with pyrolysis GC/MS and elemental analysis that nutrient concentrations had a strong influence on changes in litter chemistry during early decomposition (0–181 days), when greater lignin loss rates were associated with low P concentrations, whereas carbohydrate and bulk C loss were associated with high N concentrations. Nutrient concentrations, in contrast, did not influence changes in litter chemistry in the later decomposition stage (181–475 days), where the decomposition rates of lignin, carbohydrates, and bulk C all increased with litter N concentration and no differences in decomposition rates between major compound classes were detected. Our data indicate that these differences were related to the transition from increasing to constant or declining microbial biomass, and an associated decrease in microbial dependence on the mobilization of nutrients from the insoluble litter fraction.

Grass species litter have varied trait response to the photodegradation and microbial decomposition in tropical savanna grasslands, South Africa

Purpose of the paper: This paper evaluated the effects of microbial and photodegradation on the ten grass species in a tropical grassland ecosystem in South Africa. Despite continuous necromass accumulation in tropical grasslands, the process that governs how the grass litter gets to the soil has often been ignored. In the absence of fire, abiotic factors and biotic factors are drivers of this process of nutrient cycling. Methods and approaches: A classical litterbag experiment was set up to simulate photodegradation (standing litter) versus microbial (soil surface) decomposition using 10 savanna types of grass from the start of the dry season until the beginning of spring. The rates of photodegradation versus microbial decomposition were compared for tropical savanna grasses and plant traits or predictors of decomposition were also investigated. Main results: The results showed that the grass litter decomposed more rapidly when exposed to the activity of soil microbes at the soil surface (k = 0.0028 ) than when held above ground (k = 0.0018) and subjected to photodegradation only. However, examination of the individual litter species revealed up to 4 fold variation between the slowest (0.0001) and fastest (0.006) decomposing species. Differences in decomposition rates were more pronounced for litter decomposed at the soil surface than held above the soil surface. Multiple linear regression analyses did not resolve clear differences between measures of litter quality as drivers of decomposition in the two treatments. Implications: Photodegradation appeared to be a rate-controlling step during the process of decomposition in tropical savanna grasslands. Therefore grasslands dominated by photodegradation-resistant grasses were likely to need fire to get rid of moribund litter, which may be the reason why mesic grasslands need to burn to recycle nutrients.

Examining Decomposition and Nitrogen Mineralization in Five Common Urban Habitat Types across Southern California to Inform Sustainable Landscaping

Urban landscaping conversions can alter decomposition processes and soil respiration, making it difficult to forecast regional CO2 emissions. Here we explore rates of initial mass loss and net nitrogen (N) mineralization in natural and four common urban land covers (waterwise, waterwise with mulch, shrub, and lawn) from sites across seven colleges in southern California. We found that rates of decomposition and net N mineralization were faster for high-N leaf substrates, and natural habitats exhibited slower rates of decomposition and mineralization than managed urban landcovers, especially lawns and areas with added mulch. These results were consistent across college campuses, suggesting that our findings are robust and can predict decomposition rates across southern California. While mechanisms driving differences in decomposition rates among habitats in the cool-wet spring were difficult to identify, elevated decomposition in urban habitats highlights that conversion of natural areas to urban landscapes enhances greenhouse gas emissions. While perceived as sustainable, elevated decomposition rates in areas with added mulch mean that while these transformations may reduce water inputs, they increase soil carbon (C) flux. Mimicking natural landscapes by reducing water and nutrient (mulch) inputs and planting drought-tolerant native vegetation with recalcitrant litter can slow decomposition and reduce regional C emissions.

Biomass decomposition and heavy metal release from seaweed litter, Gracilaria lemaneiformis, and secondary pollution evaluation

The seaweed Gracilaria lemaneiformis can bioremediate heavy metals and improve the environmental quality of mariculture zones. However, the seaweed litter that is produced in the growth and harvest processes becomes one of the important bottlenecks and causes secondary pollution that restricts the development of sustainable seaweed cultivation. Seaweeds exist widely in the coastal areas of the world and are cultivated on a large scale in Asia, but their decomposition process is rarely studied. Experiments that compared decaying dry (dead) and fresh (falling and dying) Gracilaria were conducted to quantify the differences in decomposition rates and heavy metal release in different physiological states. The heavy metals in the seawater and sediment were investigated. The litterbag technique under controlled laboratory conditions was used. The results indicated that the decomposition rates (k) and decay times in 50% (t50%) and 95% (t95%) values varied between dry and fresh Gracilaria. Fresh Gracilaria exhibited a weight loss rate of 15%, and the dry weight loss was 44%. The variations in MAIs (accumulation index of metals) and MR (release rate of metals) between the dry and fresh Gracilaria litters differed significantly, which provides evidence that metals are released back into the environment from Gracilaria litters. The contacted sediments could accelerate the heavy metal release from Gracilaria. Based on our estimates obtained from a 45 d experiment, at least 27.5％ of Cd, 16％ of Cu, 60.1％ of Pb, 72.3％ of Zn, 49.4％ of Fe, 38.6％ of Mn, 68.1％ of Cr, and 67.5％ of Ni present in the fresh Gracilaria and 37.4％ of Cd, 46.2％ of Cu, 77.7％ of Pb, 53.7％ of Zn, 42.7％ of Fe, 67.2％ of Mn, 75.1％ of Cr, and 73.5％ of Ni present in the dried Gracilaria were released back into the water when the biomass was left to decay. This study simulates and underscores that Gracilaria has an strong effect on the heavy metal cycles in marine environments and offers a theoretical basis for the development of sustainable seaweed industries in mariculture zones.

Contrary effects of flow intermittence and land uses on organic matter decomposition in a Mediterranean river basin

Flow interruption in intermittent rivers (IRs) generates a mosaic of terrestrial and aquatic habitats across the river network affecting ecosystem processes, as organic matter (OM) decomposition. Water use for farming in arid and semi-arid climates intensifies the dry conditions and affects local river characteristics. In that way, flow intermittence and the distribution of land uses may affect the OM processing along the river. To understand the role of IRs in global OM dynamics and how global change affecting water flow regimes determines these dynamics, it is important to estimate OM-processing rates at a basin scale. The aim of this study was to evaluate the effect of the intensity of flow intermittence on OM processing, and how this effect was modulated by local environmental factors related to land uses across a Mediterranean river basin. To do this, wood decomposition (mass loss and fungal biomass) was selected as a functional indicator. Drying duration and frequency were measured to characterize flow intermittence in different reaches along the river, as well as local environmental factors. Linear models stablished the role of factors on decomposition. The results showed that differences in decomposition rates across the river network were negatively related to the duration of flow interruption. Dissolved inorganic nitrogen associated with agriculture counteracted the negative effect of intermittence on mass loss (increasing by up to three times); but with a higher duration of dry conditions, its effect was insignificant. An increase of 20% of canopy (higher in natural areas) resulted in increases of up to 5% of mass loss. Overall, our study is relevant to understanding the interaction between flow intermittence and land uses on OM processing, especially considering the intensification of flow intermittence and its increased distribution to other regions, which is expected to be a consequence of climate warming and human activities.

Scale dependence in functional equivalence and difference in the soil microbiome

Climatic history can shape the functioning of soil microbial communities and thus rates of ecosystem processes such as organic matter decomposition. For example, broad spatial scale differences in climatic history, such as contrasting precipitation regimes, have been shown to generate unique microbial functional responses to contemporary moisture conditions. Yet it is an open question as to whether local differences in soil microclimate similarly influence the functional potential of decomposer communities. Here, we use a multi-scale approach within and among two temperate forest field sites to investigate this question. Soils from fifty-four microsites, that vary in their soil moisture climate-regimes, were used as inocula for a common leaf litter (Quercus rubra L.) in a controlled, laboratory microcosm study. Microcosms were placed under dry, mesic and wet lab-moisture conditions and the rate of carbon (C) mineralization of the litter was measured over 202 days. Our results reveal differences in decomposition rates under controlled conditions that highlight broad-scale functional differences between the soil communities at each site. Specifically, we found that C mineralization differed by as much as two-fold for soil communities when compared between the sites. Our results also show that functional differences of soil communities are observable within one site but not the other. In the site where local-scale functional legacies were apparent, the historical soil moisture microclimate-regimes generated as much as an 89% change in C mineralization rates of the leaf litter under the same contemporary, lab-imposed moisture conditions. A similar pattern was not observable in the other site; instead, laboratory moisture conditions explained almost all variation in C mineralization. Notably, for the site with pronounced local-scale functional legacies, there was much greater within-site variation in field-soil microsite moisture than at the site which did not exhibit functional legacies, suggesting that the extent of local-scale variation in microclimate may act as control on whether local-scale functional legacies are observed. Regardless of whether this mechanism does explain our findings, our observations do confirm those from prior studies where regional-scale moisture-regime differences shape microbial function, and extend this prior work by providing evidence that pronounced local-scale differences in soil moisture microclimate-regimes are associated with microbial functional legacies.

Effects of gamma irradiation on instream leaf litter decomposition

Leaf litter decomposition is a key process in stream ecosystems, the rates of which can vary with changes in litter quality or its colonization by microorganisms. Decomposition in streams is increasingly used to compare ecosystem functioning globally, often requiring the distribution of litter across countries. It is important to understand whether litter sterilization, which is required by some countries, can alter the rates of decomposition and associated processes. We examined whether litter sterilization with gamma irradiation (25 kGy) influenced decomposition rates, litter stoichiometry, and colonization by invertebrates after weeks of instream incubation within coarse-mesh and fine-mesh litterbags. We used nine plant species from three families that varied widely in litter chemistry but found mostly consistent responses, with no differences in decomposition rates or numbers of invertebrates found at the end of the incubation period. However, litter stoichiometry differed between irradiated and control litter, with greater nutrient losses (mostly phosphorus) in the former. Therefore, the effects of irradiation on litter chemistry should be taken into account in studies focused on stoichiometry but not necessarily in those focused on decomposition rates, at least within the experimental timescale considered here.

Variation in Downed Deadwood Density, Biomass, and Moisture during Decomposition in a Natural Temperate Forest

Deadwood is a resource of water, nutrients, and carbon, as well as an important driving factor of spatial pedocomplexity and hillslope processes in forested landscapes. The applicability of existing relevant studies in mountain forests in Central Europe is limited by the low number of data, absence of precise dating, and short time periods studied. Here, we aimed to assess the decomposition pathway in terms of changes and variability in the physical characteristics of deadwood (wood density, biomass, and moisture) during the decomposition process, and to describe differences in decomposition rate. The research was carried out in the Žofínský Primeval Forest, one of the oldest forest reserves in Europe. Samples were taken from sapwood of downed logs of the three main tree species: Fagus sylvatica L., Abies alba Mill., and Picea abies (L.) Karst. The time since the death of each downed log was obtained using tree censuses repeated since 1975 and dendrochronology. The maximal time since the death of a log was species-specific, and ranged from 61–76 years. The rate of change (slope) of moisture content along the time since death in a linear regression model was the highest for F. sylvatica (b = 3.94) compared to A. alba (b = 2.21) and P. abies (b = 1.93). An exponential model showing the dependence of biomass loss on time since death revealed that F. sylvatica stems with a diameter of 50–90 cm had the shortest decomposition rate—51 years—followed by P. abies (71 years) and A. alba (72 years). Our findings can be used in geochemical models of element cycles in temperate old-growth forests, the prediction of deadwood dynamics and changes in related biodiversity, and in refining management recommendations.

Low-decomposition rates of riparian litter in a North Patagonian ultraoligotrophic lake

Littoral zones of lakes are important for carbon and nutrient recycling because of the accumulation and decomposition of organic matter (OM) coming from terrestrial and aquatic plants. Here, we aimed to study OM decomposition from the most abundant riparian trees (Nothofagus dombeyi and Myrceugenia exsucca), and an emergent macrophyte (Schoenoplectus californicus), in the littoral zone of an ultraoligotrophic North-Patagonian Andean lake. We analysed the initial 2-days leaching, and litter mass loss and litter nutrient changes after one year of decomposition in a litter-bag experiment. The three studied species had very slow decay rates (k < 0.005 day−1), and initial nutrient release by leaching was not related to differences in decomposition rates. However, differences in leaf traits (lignin content) were related to interspecific variation in decomposition rates. The highest decomposition rates were observed for the macrophyte S. californicus, the species with the lower lignin content, while the opposite was observed in the Myrtaceae M. exsucca. In the three studied species, nitrogen content increased during decomposition. Our results indicated that in the shore of ultra-oligotrophic lakes, litter remains for long periods with net nutrient immobilization, thus OM of the riparian vegetation represents a carbon and nutrient sink.

Detecting bird’s eggs in the diet of raccoon dog (Nyctereutes procyonoides)

Diet studies of carnivores are often based on analysis of prey remains found in scats or stomachs. In these analyses differences in decomposition rate and the degree of digestion of the prey item must be taken into consideration. In studies of raccoon dog diets, eggshells are rarely found. This may be due to three possible scenarios, which may act in combination: 1) raccoon dogs rarely eat bird´s eggs in the wild, 2) raccoon dogs eat eggs without swallowing shell parts, 3) rapid digestion of swallowed eggshells, so that they are only present briefly in stomach contents. In this study, the feeding behaviour of raccoon dogs on eggs of different sizes was observed under semi-natural conditions in an enclosure and the dissolution time of eggshells was examined. Dissolution time of eggshells of different thicknesses was tested experimentally using different concentrations of hydrochloric acid. The study showed a negative relationship between egg size/shell thickness and the amount of shell ingested by the raccoon dog. No eggshell, independent of bird species, was degraded beyond detectability after 12 hours in hydrochloric acid at pH 3.3. A correction factor estimating the mass of eggshell (g) ingested by the raccoon dog was calculated from the dry mass of eggshell found in the stomach or scat. Also the amount of eggshell estimated to be degraded by gastric acid is given. This correction factor ranged from 14 to 282 depending on eggshell thickness and egg size. From this study, it can be concluded that raccoon dogs do ingest some eggshell and that it is possible to detect eggshells in stomachs and scats of raccoon dogs, suggesting that the lack of eggshell in diet samples probably reflects a low proportion of eggs in the diet and/or preying more heavily on large eggs that are cracked open and have their contents eaten, rather than small eggs that are eaten shell-and-all.

Detecting bird’s eggs in the diet of raccoon dog (Nyctereutes procyonoides)

&#x0D; Diet studies of carnivores are often based on analysis of prey remains found in scats or stomachs. In these analyses differences in decomposition rate and the degree of digestion of the prey item must be taken into consideration. In studies of raccoon dog diets, eggshells are rarely found. This may be due to three possible scenarios, which may act in combination: 1) raccoon dogs rarely eat bird´s eggs in the wild, 2) raccoon dogs eat eggs without swallowing shell parts, 3) rapid digestion of swallowed eggshells, so that they are only present briefly in stomach contents. In this study, the feeding behaviour of raccoon dogs on eggs of different sizes was observed under semi-natural conditions in an enclosure and the dissolution time of eggshells was examined. Dissolution time of eggshells of different thicknesses was tested experimentally using different concentrations of hydrochloric acid. The study showed a negative relationship between egg size/shell thickness and the amount of shell ingested by the raccoon dog. No eggshell, independent of bird species, was degraded beyond detectability after 12 hours in hydrochloric acid at pH 3.3. A correction factor estimating the mass of eggshell (g) ingested by the raccoon dog was calculated from the dry mass of eggshell found in the stomach or scat. Also the amount of eggshell estimated to be degraded by gastric acid is given. This correction factor ranged from 14 to 282 depending on eggshell thickness and egg size. From this study, it can be concluded that raccoon dogs do ingest some eggshell and that it is possible to detect eggshells in stomachs and scats of raccoon dogs, suggesting that the lack of eggshell in diet samples probably reflects a low proportion of eggs in the diet and/or preying more heavily on large eggs that are cracked open and have their contents eaten, rather than small eggs that are eaten shell-and-all.&#x0D;

A preliminary investigation into the decomposition rate of wild boar carcasses in forest habitats

The estimation of the postmortem interval (PMI, the time that has elapsed since the death) is a critical issue for the biosecurity enforcement officers who implement to the timely establishment of biosecurity zone for preventing susceptible animals from disease transmission given the rapid occurrence of an infectious disease. Increasing attention has been paid to PMI of wild boar (Sus scrofa) carcasses associated with African swine fever epidemics in Korea since October 2019 to explain the geographical transmission of the disease, as well as to provide potential target animals for prevention measures in terms of farm biosecurity. This study is, to the best of our knowledge, the first to describe the decomposition process of wild boars in different microhabitats in the country. In the present comparative study, we obtained field data from the decomposition process of the wild boar and domestic pig carcasses continuously exposed aboveground in natural environment settings allowing animal scavenging. This study compared the pattern of decomposition in 16 wild boar carrion and 10 domestic pig carcasses placed between August and November 2019. Quite differences in decomposition rate measured by total body score and tissue's gross morphology over time were observed between wild boars and domestic pigs. Overall, the wild boar decomposed much more slowly than the domestic pig throughout the end of the experimental period. In addition, color changes to the skin were easily seen in domestic pigs, whereas there is much variation in the wild boar, especially carcasses placed in late autumn. Moreover, some wild boar carcasses did not show any sign of bloating. These results indicate that decomposition rates derived from forensic taphonomic studies on domestic pigs may be not directly applicable to the wild boar, hence there is a need to develop regional decomposition models to be employed in different geographical situations to increase the accuracy of PMI of wild boar carcasses.