Amount Of Litter Research Articles

Dynamic Change Characteristics of Litter and Nutrient Return in Subtropical Evergreen Broad-Leaved Forest in Different Extreme Weather Disturbance Years in Ailao Mountain, Yunnan Province

By studying the dynamic change characteristics of litter production, composition, nutrient content, and return amount of different components in different extreme weather interference years of Ailao Mountain evergreen broad-leaved forest, the paper provides theoretical support for the post-disaster nutrient cycle, ecological recovery, and sustainable development of the subtropical mid-mountain humid evergreen broad-leaved forest. Square litter collectors were randomly set up to collect litter. After drying to a constant mass, we calculated the seasonal and annual litter volume and the contents of organic carbon (C), total nitrogen (N), total phosphorus (P), total potassium (k), total sulfur (S), total calcium (Ca), and total magnesium (Mg). Finally, the nutrient return amount is comprehensively calculated according to the litter amount and element content. We tracked dynamic changes in litter quantity, nutrient composition, and nutrient components across different years. The results showed that the amount of litter from 2005 to 2015 was 7704–8818 kg·hm−2, and the order of magnitude was: 2005 (normal year) > 2015 (extreme snow and ice weather interference) > 2010 (extreme drought weather interference); the composition mainly included branches, leaves, fruit (flowers), and other components (bark, moss, lichen, etc.), of which the proportion of leaves was the largest, accounting for 41.70%–61.52%; The monthly changes and total amounts in different years exhibited single or double peak changes, and the monthly litter components in different years showed significant seasonality. In this study, the nutrient content of litter was higher than that of litter branches each year. The total amount of litter and the nutrient concentration of each component are C, Ca, N, K, Mg, S, and P, from large to small. The order of nutrient return in different years was the same as that of litter, and the returns of nutrients in litter leaves were greater than that of litter branches. The ratio of nutrient returns of litter and litter branches from 2005 to 2010 was 2.03, 1.23, and 3.69, respectively. The research shows that the litter decreased correspondingly under the extreme weather disturbance, and the impact of the extreme dry weather disturbance was greater than that of the extreme ice and snow weather disturbance. However, the evergreen broad-leaved forest in the study area recovers well after being disturbed. The annual litter amount and nutrient return amount is similar to that of evergreen broad-leaved forests in the same latitude and normal years in other subtropical regions. The decomposition rate and seasonal dynamics of litter nutrients are not greatly affected by extreme weather.

Soil organic carbon primarily control the soil moisture characteristic during forest restoration in subtropical China

Soil organic carbon (SOC) is a crucial component of the soil carbon pool that regulates fundamental soil properties and water status. In the global context of restoring vegetation, the soil carbon-water coupling relationship has gained attention. In particular, the regulatory mechanism of SOC on soil moisture requires further research. In this study, three typical forests in subtropical China were chosen as restoration sequences to investigate the changes in SOC and soil moisture during subtropical forest restoration and its regulation mechanisms: broadleaf-conifer mixed forest (EF), broad-leaved forest (MF), and old-growth forest (LF). The soil water content (35.71 ± 1.52%), maximum water holding capacity (47.74 ± 1.91%), capillary water holding capacity (43.92 ± 1.43%), and field water holding capacity (41.07 ± 1.65%) in LF were significantly higher than those in EF (p < 0.01). As forest restoration progressed, the amount of litter returning to the soil increased gradually, and the SOC content (0–100 cm) increased from 9.51 ± 1.42 g/kg (EF) to 15.60 ± 2.30 g/kg (LF). The SOC storage increased from 29.49 ± 3.59 to 42.62 ± 5.78 Mg/ha. On one hand, forest restoration led to a change in SOC content, which optimizes the soil structure and enhances soil porosity (path coefficient of 0.537, p < 0.01), further leading to a change in soil water content (path coefficient of 0.940, p < 0.01). On the other hand, the increase in SOC influenced the change in soil nutrient content, i.e., total nitrogen (TN) and total phosphorus (TP) (path coefficient of 0.842, p < 0.01). Changes in SOC and soil nutrients stimulated changes in the stoichiometric ratio, i.e., C:P and N:P (path coefficients of 0.988 and –0.968, respectively, p < 0.01), and the biological activity in soil changed appropriately, which eventually led to a change in soil water content (path coefficient of –0.257, p < 0.01). These results highlight the changes in SOC and soil water content (SWC), as well as the mechanism of SOC controlling SWC as a result of vegetation restoration, which is of tremendous importance for advancing our understanding of the eco-hydrological process of subtropical forest restoration.

¿Es posible conservar la diversidad biológica y producir madera en las plantaciones de pino de la Patagonia argentina? Un estudio de caso

Forest plantations mitigate environmental problems and favor lowcarbon economies, but the growing demand for wood is driving the accelerated expansion of monocultures that are potentially harmful to biological diversity. In this research, the compatibility between taxonomic diversity of vascular plants and timber production of Pinus ponderosa was evaluated in stands with three levels of canopy cover, located in the steppe and the forest-steppe ecotone of Northwestern Patagonia from Argentina (40°5´ S - 71°12´ W). Soil moisture, diversity and site index were higher in the ecotone. The P. ponderosa cover was negatively correlated with the light intensity and diversity, and positively with the amount of litter and bare soil on the forest floor. After a 45-year rotation, the projected timber production was maximum for IDR≥800, but the diversity decreased dramatically. The best option to conserve diversity was to maintain IDR≤400 throughout the stand management cycle. However, the profitability of the production of quality wood would be negative with IDR<500, regardless the site quality, area, initial density, management scheme and distance to the market for goods and services of the plantation. The negative correlation between the environmental and productive indicators would imply that there is no a silvicultural regime that simultaneously maximizes these objectives. This spatial incompatibility does not imply a priori discouraging the productive initiatives based on tree plantations. Forestry contributes to solving deep environmental, social and economic problems, particularly in the current scenario characterized by the increase in human population, the consumption of resources and the degradation and destruction of natural forests.

Seasonal variation in the correlation between beach wrack and marine litter on a sandy beach in West Iceland.

Coastal plastic pollution is a global problem, it affects local ecosystems, and can have economic and social implications. Plastic pollution is pervasive at high latitudes but there is a lack of data on the spatial and temporal amount of marine litter entering coastal systems. In this study, a seasonal accumulation survey of anthropogenic debris and beach wrack was conducted for the first time in Iceland. One hundred data collections were performed on a coast in the Snæfellsnes peninsula throughout one year. Of all the debris retrieved, over 9000 items (0.2 to 50cm), 78.5% were plastics. Beach wrack correlated strongly with the quantities of plastic debris entering the coastal environment (R2>0.9; p<10-11), with a different slope for each season. The presence of beach wrack informed important daily and spatial fluctuations in the quantities of plastic debris, while seasonal fluctuations demonstrated higher arrival rate of plastic in autumn and winter.

A temporal assessment of anthropogenic marine debris on sandy beaches from Ecuador’s southern coast

Anthropogenic marine debris (AMD) is an environmental pollution that affects marine life, human health, wellbeing, and the economy. This marine litter can deposit in the coastlines, particularly on tidal zones and beaches. To pursue future mitigation strategies to reduce AMD is important to monitor the amount, type and frequency of litter being dumped on shores. This study presents the composition, temporal distribution, abundance and size of AMD on three sandy beaches from Guayas province, Ecuador. The field data was recollected from December 2018 to February 2020. A total of 12,362 items of AMD were collected with an abundance of 1.95 macro-litter items/m2. The composition of AMD was marked by the predominance of plastic items (91.8%), followed by wood and cloth (1.9%), while cigarettes were only present in village beaches. Our results suggest that sites with more AMD abundance are beaches nearby small coastal villages and fishing communities. Also, the AMD abundance is slightly higher at the beginning of the dry season than in the rainy season. Our findings indicate that it is necessary to implement concerted solid waste management measures and proactive environmental education programs to empower the local population, as well as investigate the anthropogenic sources and other variables influencing the AMD abundance coming onto sandy shores.

Plastic capture methods in the water bodies, a review of world experience

Over the past twenty years, the plastic pollution problem in the water bodies has reached an alarming scale. The easy-to-use, light, waterproof material has the significant drawback, it is the very long decomposition period, which has led to the 368 million tons of plastic accumulation over the past 70 years, and the accumulation continues. Plastic environmental pollution is the urgent problem for the water bodies in Ukraine too. The source of plastic entering water bodies is primarily temporary waste landfills from which plastic is washed into rivers and lakes during rains, by wind and by flood. The rivers carry plastic throughout the river floodplain, polluting riverbeds and banks during the flood. In the work, the analysis of the world experience in the area of the plastic capture devices and the possibility to use these devices for the mountain rivers conditions in Ukraine was assessed. The peculiarities of the hydrological regime of the mountain rivers are the transportation of plastic during floods, significant water levels fluctuations, the danger for people being in the riverbed during the flood, high water speeds up to the 5 m/s, the large amount of litter, which in consists of the plastic, tree trunks, branches and other large debris. It was assessed the booms, trash traps and trash racks for catching litter in water outlets and temporary streams. Plastic collecting facilities such as floating boats, catamarans, and robots were not assessed, because their use during the flood is dangerous, and the small water depths in the rivers do not allow to use them effectively during the low water period. Devices for plastic capture for the mountain rivers should be autonomous, strong, have the big litter capacity, be ecological friendly, able to work with rapid water level change and under high water speed. Analysis of the existing devices shows that these requirements will be met by expensive segment. At the same time, it is known that the plastic capture in the water bodies costs in 10 times higher than the cost of collecting and sorting plastic in the populated areas. So, to solve the problem of plastic pollution in the water bodies by the expensive devices is not right way. First of all, in order to reduce plastic pollution in water bodies, it is necessary to create conditions to prevent plastic to get into the rivers, namely: voluntary limitation of the plastic usage, manufacture responsibility for the use of recyclable plastic, active informing society about the plastic harm to the environment and the necessity to collect and sort it.

How Does Long-Term Organic Matter Treatment Affect the Biological Activity of a Centre European Forest Soil?

A significant portion of the increase in atmospheric CO2 enters the environment through a decrease in the level of organic matter (SOM) in soils. One of the reasons for this is the cutting of forests and the conversion of growing areas into arable land, thus changing land use. As a result, SOM today only has approx. 70–80% of the period before the spread of intensive farming. For the long-term study of the effect of varying amounts of SOM, we set up experimental plots for litter manipulation in 2000. In the course of our investigations, we studied how changing the amount of organic matter input the soil affects the CO2 emissions of the soil and its closely related biological activity after five or ten years, in addition to the continuous maintenance of the treatments. According to our assumption, after 10 years, the biological activity of the soil will decrease as a result of the removal treatment of organic matter, and the biological activity will increase as a result of the doubling. The pH value of the soil shifted in the acidic direction over 10 years as a result of the removal of organic matter, while it did not change as a result of the increase. In the first year, we could not detect any significant differences in the enzyme activity values. From our later results, we found that a drastic reduction in the amount of leaf litter has a greater effect on soil enzyme activity and soil respiration to a greater extent than an increase in litter production above natural levels. The pH of the soil was as expected, with litter withdrawal shifting the pH towards acidic over the years.

Effects of Fertilizers and Litter Treatment on Soil Nutrients in Korean Pine Plantation and its Natural Forest of Northeast China

Organic and inorganic soil fertilizer addition or removal pose significant effects on soil nutrients. As climate change and other anthropogenic factors are causing deprivation in soil nutrient profiles and altering its proper functioning, complete insight into fertilizer modification and its consequences is required for understanding the sustenance of forest ecosystems. In this regard, an experiment was conducted at Liangshui National Nature Reserve, northeast China, in which two forest soil types (i.e., Korean pine plantation and natural Korean pine forest) were evaluated for their response to external fertilizer applications and litter treatments. The litter treatments were litter application as Ck (undisturbed litter), RL (removed litter) and AL (Alter/double litter i.e., litter removed from RL was added in double litter plots), whereas the synthetic fertilizer treatments were Control (No added N and P), Low (5 g N m−2 a−1 + 5 g P m−2 a−1), Medium (15 g N m−2 a−1 + 10 g P m−2 a−1) and High (30 g N m−2 a−1 + 20 g P m−2 a−1). The outcome showed that soil organic carbon (SOC) was directly proportionate to forest litter amounts. Synthetic fertilizers affected soil total nitrogen (STN) and maximum amounts were recorded in plots with H: 30 g N m−2 a−1 + 20 g P m−2 a−1, as 3.03 ± 0.35 g kg−1 in AL. Similarly, altered litter/double was most effective in enhancing the quantity of soil total phosphorus (STP) (0.75 ± 0.04 g kg−1). Soil sampling carried out during the start and end of the experiment showed decreases in the sixth sampling of: SOC (4–23%), STN (7.5-10.8%) and STP (8.51–13.9%). A positive correlation was observed between SOC and total nitrogen; C:N ratio also increased with SOC. Principal component analysis (PCA) on captured a total of 62.1% variability, on the x-axis (35.1%) and on the y-axis (27%). It was concluded that combined application of N and P at the level of 30 g N m−2 a−1 + 20 g P m−2 a−1 under AL (Alter/double litter) treatment level improved soil total N and P content. The results clearly depicted that forest litter is an important source for building up of soil organic matter, however for attaining maximum sustenance capabilities in soil, the continuity of fertilizer application in either form is a prerequisite.

The Characteristics of Dissolved Organic Matter and Soil Microbial Communities in the Soils of Larix principis-rupprechtii Mayr. Plantations in the Qinling Mountains, China

Soil microorganisms and dissolved organic matter (DOM) play vital roles in nutrient cycling and maintaining plant diversity. The aim of this study was to clarify the relationship between DOM component characteristics and microbial community structure in the soil of Larix principis-rupprechtii Mayr. plantations. We quantified the responses of the soil microbial and DOM characteristics to stand age in a plantation forest ecosystem using phospholipid fatty acid (PLFA) analyses, ultraviolet-visible spectroscopy, and fluorescence spectroscopy. Three humic-like components and a fulvic-like component were identified from the soil samples, and humic-like substances were the dominant component of the soil DOM of the stands of different ages. The fluorescence index showed that the sources of soil DOM in the stands of different ages throughout the growth stages may be mostly plant residues, with very little contribution from microbial sources. Furthermore, the results demonstrated that stand age and growth season had a significant effect on the contents of the soil PLFA biomarkers of L. principis-rupprechtii Mayr. Additionally, significantly higher contents of different species of soil PLFA biomarkers were observed in the young forest (17a) than in the sapling forest (7a) and half-mature forest (27a), suggesting that stand age differences in the quality and quantity of larch litter and soil physicochemical characteristics affect the microbial community structure. Redundancy analysis (RDA) showed that changes in the soil DOM quality and components that were driven by growth season and stand age were the major drivers of variations in the soil microbial community structure in the study region. Overall, the seasonal variations in DOM quality and components may contribute to the variability of soil microorganisms, and the soil microbial responses to tree age will depend upon the provisioning of these resources.

The legacy of forest logging on organic matter inputs and storage in tropical streams

AbstractRiparian forests play an important role in stream ecosystems, as they support biodiversity, reduce water erosion, and provide litter that fuels aquatic biota. However, they are affected by great array of anthropogenic threats (e.g., fire, logging, and organic pollution), which alter species composition and their physical structure. Although forest recovery after disturbance such as logging can take decades, the legacy of forest clear‐cut logging on key processes in tropical riparian ecosystems is mostly unknown. Here, we investigated how litter inputs (leaves, twigs, and reproductive parts) and storage, key processes for carbon and nutrient recycling and for forest and stream biota, are influenced by riparian vegetation undergoing succession (after 28 years from logging) through the comparison of reference and logged forest sites in the Cerrado biome. Litterfall was overall similar between forest types, but litterfall of twigs was twofold higher at logged than reference sites. Similarly, litter inputs from the bank to the stream (i.e., lateral inputs) and streambed storage were 50–60% higher at logged than reference sites. The higher litterfall observed in logged forests could be related to higher proportion of tree species that are characteristic of primary and secondary successional stages, including fast‐growing and liana species, which often are more productive and common in anthropogenic areas. Our results showed that the legacy impact of clear‐cut logging, even if residual woody vegetation is maintained in riparian buffers, can shift the type, quantity, and seasonality of litter subsidies to tropical streams. This knowledge should be considered within the context of management and conservation of communities and ecosystem processes in the forest‐stream interfaces.Abstract in Portuguese is available with online material.

Hunger for sex: Abundant, heterogeneous resources select for sexual reproduction in the field.

Major hypotheses on sex evolution predict that resource abundance and heterogeneity should either select for or against sexual reproduction. However, seldom have these predictions been explicitly tested in the field. Here, we investigated this question using soil oribatid mites, a diverse and abundant group of soil arthropods whose local communities can be dominated by either sexual or asexual species. First, we refined theoretical predictions by addressing how the effects of resource abundance, heterogeneity and abiotic conditions could modify each other. Then, we estimated the strength of selection for sexual species in local communities while controlling for phylogeny and neutral processes (ecological drift and dispersal), and tested its relation to resource and abiotic gradients. We show that sexual species tended to be favoured with increasing litter amount, a measure of basal resource abundance. Further, there was some evidence that this response occurred mainly under higher tree species richness, a measure of basal resource heterogeneity. This response to resources is unlikely to reflect niche partitioning between reproductive modes, as sexual and asexual species overlapped in trophic niche according to a comparative analysis using literature data on stable isotope ratios. Rather, these findings are consistent with the hypothesis that sex facilitates adaptation by breaking unfavourable genetic associations, an advantage that should increase with effective population size when many loci are under selection and, thus, with resource abundance.

Responses of soil fungal communities and functional guilds to ~160 years of natural revegetation in the Loess Plateau of China.

Natural revegetation has been widely confirmed to be an effective strategy for the restoration of degraded lands, particularly in terms of rehabilitating ecosystem productivity and soil nutrients. Yet the mechanisms of how natural revegetation influences the variabilities and drivers of soil residing fungal communities, and its downstream effects on ecosystem nutrient cycling are not well understood. For this study, we investigated changes in soil fungal communities along with ~160 years of natural revegetation in the Loess Plateau of China, employing Illumina MiSeq DNA sequencing analyses. Our results revealed that the soil fungal abundance was greatly enhanced during the later stages of revegetation. As revegetation progresses, soil fungal richness appeared first to rise and then decline at the climax Quercus liaotungensis forest stage. The fungal Shannon and Simpson diversity indexes were the lowest and highest at the climax forest stage among revegetation stages, respectively. Principal component analysis, Bray–Curtis similarity indices, and FUNGuild function prediction suggested that the composition, trophic modes, and functional groups for soil fungal communities gradually shifted along with natural revegetation. Specifically, the relative abundances of Basidiomycota, Agaricomycetes, Eurotiomycetes, and ectomycorrhizal fungi progressively increased, while that of Ascomycota, Sordariomycetes, Dothideomycetes, Tremellomycetes, saprotrophic, pathotrophic, arbuscular mycorrhizal fungi, and endophyte fungi gradually decreased along with natural revegetation, respectively. The most enriched members of Basidiomycota (e.g., Agaricomycetes, Agaricales, Cortinariaceae, Cortinarius, Sebacinales, Sebacinaceae, Tricholomataceae, Tricholoma, Russulales, and Russulaceae) were found at the climax forest stage. As important carbon (C) sources, the most enriched symbiotic fungi (particularly ectomycorrhizal fungi containing more recalcitrant compounds) can promote organic C and nitrogen (N) accumulation in soils of climax forest. However, the most abundant of saprotrophic fungi in the early stages of revegetation decreased soil organic C and N accumulation by expediting the decomposition of soil organic matter. Our results suggest that natural revegetation can effectively restore soil fungal abundance, and modify soil fungal diversity, community composition, trophic modes, and functional groups by altering plant properties (e.g., plant species richness, diversity, evenness, litter quantity and quality), quantity and quality of soil nutrient substrates, soil moisture and pH. These changes in soil fungal communities, particularly their trophic modes and functional groups along with natural revegetation, impact the accumulation and decomposition of soil C and N and potentially affect ecosystem C and N cycling in the Loess Plateau of China.

SOLID WASTE AUDITING AND MANAGEMENT PLAN AND POLICY IN JHARGRAM MUNICIPALITY, WEST BENGAL, INDIA

Waste (or waste) is useless or unusable materials or components that are discarded after principal use. Sometimes, it is a defective article and of no use. In the modern outlook, waste may be a valuable substance subject to an appropriate operation or action on the waste. In the context of waste management RRR (reduce, reuse and recycle) model may be followed appropriately.Pollution from waste is aesthetically unpleasing and results in large amounts of litter in our communities which can cause health problems. Plastic bags and discarded ropes and strings can be very dangerous to birds and other animals. This indicator addresses waste production and disposal, plastic waste, paper waste, food waste, and recycling. Solid waste can be divided into two categories: general waste and hazardous waste.Jhargram Municipality is one of the fastest developing Municipalities in West Bengalwith a population of 61,682 anda population density of 2882.33 /sq km in 2011 but at the present near about 92000. This Municipality has around 19775 houses, markets, apartments and offices, colleges, hospitals, and schools which generate 79 Metric Ton of solid waste per day. The study has been carried out to select solid waste disposal sites and to find out the suitable management strategies forthe solid waste system by using Geographical Information System techniques. Manually field observation and expert opinion have been taken for disposal site selection thematic layers are prepared using Remote Sensing and GIS technique. Finally, theGeographicalInformation System technique was applied in Arc GIS Software to identify the disposal sites. The leading problem is the open dumping of solid waste without recycling, which resulted in environmental pollution for thisjhargram Municipality. The auditor diagnoses the prevailing waste disposal policies and suggests the best way to combat the problems. It is therefore essential that any environmentally responsible institution and authority examine its waste processing practices. Keeping the objective of the audit the following study will be limited to the waste generated on the residence campus and surroundings.The study has been decided with some productive management strategies which may be helpful to the local people as well as municipal authority.

Microbial carbon use efficiency of litter with distinct C/N ratios in soil at different temperatures, including microbial necromass as growth component

An incubation study was carried out to investigate the effects of litter quality, i.e. 15 N-labelled maize (C/N of 25.5) and Rhodes grass (C/N of 57.8) leaf litter on microbial carbon use efficiency (CUE) and priming effects in a moderate alkaline soil at two different temperatures (15 and 25 °C). CUE values were calculated from the isotopic composition of the particulate organic matter (POM) recovered as an index for the amount of non-decomposed litter. This approach allows the inclusion of microbial necromass growth components in the calculation of CUE values. Additionally, the soil was incubated for 10, 20, and 30 days to determine the optimum incubation period. Soil microbial CUE values of maize and Rhodes grass leaf litter, including microbial necromass C in the calculation of CUE, varied around 0.61, regardless of litter type, temperature, and incubation period. However, the optimum incubation time is between 20 and 30 days, depending on temperature. The strong priming effect on autochthonous soil organic carbon (SOC) mineralization was apparently not caused by N mining, as it was similar for both litter qualities. It most likely resulted from SOC being used by microbial co-metabolism. The litter-induced true priming effect was accompanied by a significant increase in autochthonous POM. The current approach, including microbial necromass as growth component, has been shown to be a strong tool for investigating CUE values and priming effects after application of litter and harvest residues to soil, probably under all environmental conditions.

Fine root litter traits of Chamaecyparis obtusa

The purpose of this study was to clarify the process of Chamaecyparis obtusa (Sieb. & Zucc.) Endl. fine root shedding and the morphological traits of the resulting root litter. We developed a method for direct monthly sampling of root litter from the fine root system in the field. We proposed a field incubation method using centrifuge tubes with glass beads as the medium and throughfall as the nutrient solution, in which an undamaged sample of the fine root system still connected to the tree is inserted. Using this method, we collected root litter from C. obtusa for 12 months after the installation. The monthly amounts of the root litter of from the incubated fine root systems differed significantly among the sampling months. On the other hand, the morphological traits such as the root litter length and diameter of each branch order did not differ significantly among months. The first-order root litter was shorter than the incubated living first-order roots. The first-order roots were shed both at the branching positions and in the middle of first-order roots. We concluded that fine root litter with similar morphology is shed every month. Assessment of the fine root litter traits by using the new direct sampling method and the new soil ecological indicator “initial tissue C inputs” from fine roots into forest soil will improve our understanding of forest belowground carbon cycling and its indexation.

Litter Inputs Control the Pattern of Soil Aggregate-Associated Organic Carbon and Enzyme Activities in Three Typical Subtropical Forests

Soil extracellular enzyme activities among aggregate fractions are critical to short-term microbial activity and long–term carbon dynamics in forest ecosystems, but little is known regarding the effects of forest types on the soil enzyme activities in different soil aggregate fractions. Three typical subtropical forest types (Broadleaved forest, Moso bamboo forest and Chinese fir forest) were selected, and undisturbed soil samples (0–15 cm) were collected. We investigated the effects of forest types on aggregate stability (mean weight diameter, geometric mean diameter and fractal dimension), aggregate–associated organic carbon (OC) and the functionality of five enzymes (cellobiohydrolase, β-glucosidase, β-xylosidase, N–acetylglucosaminidase, leucine aminopeptidase) of different aggregate fractions (&gt;2 mm, 0.25–2 mm, 0.053–0.25 mm and &lt;0.053 mm). The results showed that the proportion of macro-aggregates, aggregate stability and macro–aggregates associated–carbon content and storage were higher in broadleaved and Moso bamboo forests than in Chinese fir forests, indicating that forest types influence the distribution of total soil OC among aggregate fraction classes and would delay the loss of OC in broadleaved and Moso bamboo forests. We also found that the extracellular enzymes were higher in aggregates of broadleaved forests and Moso bamboo forests. SEM (structural equation model) analysis also supported significantly positive relationships between litter quantity and aggregate enzyme activity, and indirect impact of litter quantity and litter C/N ratio together with soil organic carbon (SOC) and soil aggregate organic C content (SAOCC) on aggregate enzyme activity. The results of this study indicate that forest types showed large impact on aggregate-associated OC and enzyme activities, and the litter input of different forest types is the main control on enzyme activity among different aggregate fractions, and thus may play an important role in adjusting the sink capacity and stability of SOC.

Floating marine macro litter in the Black Sea: Toward baselines for large scale assessment

The Black Sea is a semi-enclosed basin subject to major anthropogenic pressures, including marine litter and plastic pollution. Due to numerous large rivers draining into the basin and a population settled along the coast, the region could accumulate significant amounts of floating litter over time. Until now, only limited field data were available, and litter quantities and distribution remained unknown. In this study, floating marine macro litter (FMML) was assessed at the regional Black Sea scale for the first time, showing relatively high litter densities across the basin that reached a weighted mean of 81.5 items/km2. Monitoring data revealed an accumulation of floating items offshore in the eastern part of the basin, resembling on a small scale a ‘garbage patch’, where litter items were trapped, showing elevated densities in comparison to their surrounding areas. Most of these items were made of plastic materials (ca. 96%) and included large numbers of plastic and polystyrene fragments of small size ranges (2.5–10 cm). Harmonised field data collection through consistent and regular monitoring programmes across the region is essential to establish baselines and thresholds for large scale assessment at international level.

Residual Forest Biomass in Pinus Stands: Accumulation and Biogas Production Potential

Lignocellulosic biomass is an abundant resource that can be valorized for the production of bioenergy. However, studies aiming to quantify the amount of biogas production potential per km forest road are scarce in the literature. In this study, fresh pine needles, pine needle litter, pine branches, and pine bark were digested in batch reactors under mesophilic conditions after a grinding/milling pre-treatment. All samples were collected from a low-altitude Mediterranean Pinus forest (North Greece) adjacent to a category G forest road with a gentle slope. The methane yield of fresh pine needles was between 115 and 164 NmL g−1 volatile solids (VS), depending on the Pinus tree size. Pine needle litter produced a significantly lower methane yield (between 58 and 77 NmL g−1 VS), followed by pine bark (85 NmL g−1 VS) and pine branches (138 NmL g−1 VS). Considering the quantity of pine needle litter accumulated on adjacent forest roads (600 ± 200 g m−2), it was possible to calculate the biomethane production potential per km of forest road (up to 500 Nm3 km−1) if the biomass collected was disposed of at an anaerobic digestion facility. The results of the study demonstrate that residual forest biomass represents an additional resource for bioenergy production. Moreover, harvesting residual forest biomass can decrease the incidence of devastating summer forest fires and their disastrous consequences for the environment, the economy, and the local populations.

Changes in litter input exert divergent effects on the soil microbial community and function in stands of different densities

Soil microbial communities influence soil biogeochemical cycling by affecting the production of extracellular enzymes and the release of carbon dioxide. Changes in litter input or stand density due to thinning can affect soil microbial communities and their function by altering soil biochemical properties. However, it is unclear how or to what extent different amounts of litter input affect soil microbial communities and their function in forest stands with different densities. Therefore, we simulated litter removal, 50 % litter reduction, normal litter input, and double litter increase under field conditions by applying different amounts of litter to soils with different stand densities in the laboratory. We then measured soil biochemical properties, microbial communities, enzyme activity, and respiration rate.Our results revealed that the responses of soil dissolved organic carbon and total nitrogen to litter input were more pronounced in the high-density forest stand with poor soil than in the low-density forest stand with nutrient-rich soil, which was mainly reflected in that the addition of litter significantly decreased the concentration of dissolved organic carbon while increasing the content of total nitrogen in the soil of the high-density forest stand. In comparison to the soil carbon component, the nitrogen component of the soil was more affected by stand density. The responses of soil fungal and bacterial communities to leaf litter treatment varied with stand density, as reflected primarily in changes in the relative abundances of Ascomycota, unclassified_K_fungi, and Proteobacteria, and changes in the relative abundances of their functional groups (ectomycorrhizal fungi, saprophytic fungi, pathogens, parasites, and bacteria involved in the nitrogen cycle). Soil fungal community responses to changes in litter input are more sensitive in the high-density forest with nutrient-poor soil than in the low-density forest stand. Furthermore, litter input inhibited the activities of soil β-glucuronidase, N-acetyl-β-d-glucosaminidase, and acid phosphatase more strongly in the low-density forest stand. Litter manipulation primarily affected enzymatic activity in the high-density forest stand by changing the diversity and composition of the soil fungal community. However, in the low-density forest stand, litter treatment affected soil enzyme activity, primarily through changes in soil bacterial and fungal community composition, as well as soil respiration through changes in bacterial richness (Chao 1) and community composition.We conclude that how the change in litter input impacts the soil microbial community and its function, or the magnitude of the effects, is largely dependent on soil quality. Relationships among soil variables, microbial communities, and function differ between stand densities. Our study contributes to an enhanced understanding of the impact of changes in litter input due to climate change or anthropogenic activities on soil biogeochemical cycles and can also guide rationally formulating forest management approaches to improve microbial function under climate change.

How can leaf-litter from different species growing in short rotation coppice contribute to the soil nutrient pool?

Quantifying leaf-litter and the potential contribution of essential nutrients to the soil is key to guaranteeing the sustainability of forest systems, especially in plantations under short rotation coppice, insofar as it can condition crop management such as the requirement for nutritional amendments. Nutrient cycling is dependent on production as well as litter decomposition, so to compare the different strategies of the species in nutrient recycling it is important not only to determine the quality and quantity of leaf litter, but also the decomposition rate dynamics and the consequent potential incorporation of organic matter and nutrients into the soil. Therefore, this work aims to quantify and analyze the dynamics of leaf-litter as well as the retranslocation rate, to assess the decomposition rate of the foliar biomass and its nutrient concentrations, and finally, to assess the evolution of leaf-litter quality.For these purposes, eight genotypes were considered in this study: Populus deltoides (‘Baldo’), Populus × canadensis (‘Ballottino’, ‘I-214′, ‘Orion’ and ‘Oudenberg’); Platanus × hispanica (‘Girona’), Salix matsudana × Salix spp. (‘Levante’) and Robinia pseudoacacia (‘Nyirsegi’). The plantation was established in central Spain with a density of 10,000 cuttings ha−1. Three rotations of 3 years each were applied, this study being carried out during the first growing season of the second rotation.Although the leaf fall dynamics were similar among the different species, the production and quality of the leaf-litter were highly species specific. Different strategies were identified; greater retranslocation of N and P being found in poplar, plane tree or only of P in the case of black locust as a conservation strategy, although lower retranslocation of all nutrients was observed in willow, which means that the leaf litter of the latter is very rich in nutrients. While willow, black locust or even some genotypes of poplar are capable of releasing many of the nutrients to the soil during decomposition, plane tree released a smaller variety of nutrients, N, P and Mg being immobilized in the leaf-litter.From the perspective of conserving the soil fertility resulting from the decomposition of leaf-litter, the plantations of species with the highest decomposition rates, such as black locust and willow, were found to be the most recommendable. However, the immobilization of some nutrients in the leaf-litter during the decomposition process could satisfy the nutritional requirements of these species in the medium and long term, thus an advantageous strategy could be to mix species with different decomposition dynamics.