Tree Litter Research Articles

Evaluating the effects of vegetation and land management on runoff control using field plots and machine learning models.

Excess surface water after heavy rainfalls leads to soil erosion and flash floods, resulting in human and financial losses. Reducing runoff is an essential management tool to protect water and soil resources. This study aimed to evaluate the effects of vegetation and land management methods on runoff control and to provide a model to predict runoff values. Filed plot data and three machine learning (ML) methods, including artificial neural network (ANN), coactive neuro-fuzzy inference system (CANFIS), and extreme gradient boosting (EGB), were used in a test site in the north of Iran. In this regard, plots with various vegetation and land management treatments including bare soil treatment, rangeland cover treatment, forest litter treatment, rangeland litter treatment, tillage treatment in the direction of slope, tillage treatment perpendicular to the slope, and repetition of treatments under forest canopy were constructed on a hillslope. After each rainfall event, the amount of rainfall and corresponding runoff generated in each plot was recorded. Three ML models (ANN, CANFIS, and EGB) were used to establish relationships between amounts of recorded runoff and its controlling factors (rainfall, antecedent soil moisture (A.M.C), shrub canopy percentage and height, tree canopy percentage and height, soil texture (clay, silt, and sand percent), slope degree, leaf litter percentage of soil, and tillage interval). These data were normalized, randomized, and divided into training and testing subsets. Results showed that the ANN performed better than the other two models in predicting runoff in training (R2 = 0.98; MSE = 0.004) and the test stages (R2 = 0.90; MSE = 0.95). Statistical analysis and sensitivity analysis of inputs factors showed that rainfall, rangeland cover, and A.M.C are the three most important factors controlling runoff generation. The adopted method can be used to predict the effect of different vegetation and land management scenarios on runoff generation in the study area and the areas with similar settings elsewhere.

Strong Responses of Soil Greenhouse Gas Fluxes to Litter Manipulation in a Boreal Larch Forest, Northeastern China

Alterations in plant litter inputs into the soil are expected to significantly affect soil greenhouse gas (GHG) emissions. However, the influence on boreal forest soils is not clear, given the large amount of accumulated soil organic matter that may buffer the impacts from the input of fresh litter. In this study, we conducted a litter manipulation experiment to explore the effects of the litter layer on soil GHG fluxes in a Dahurian larch (Larix gmelinii) forest ecosystem in northeastern China. Three litter treatments were implemented, namely aboveground litter removal (LR), litter double (LD), and unchanged litter input (CK). The associated microclimate, litter characteristics, and soil properties were also measured. The results showed that this larch forest soil acts as a source of CO2 and N2O but acts as a sink for CH4 for all litter manipulation treatments. LD increased the soil CO2 and N2O fluxes by 15% and 34%, while LR decreased them by 8% and 21%, respectively. However, soil CH4 uptake decreased by 34% in LD treatment and increased by 22% in LR treatment, respectively. Litter manipulation treatments can not only affect soil GHG fluxes directly but also, via their effects on soil MBC, NH4+−N, and NO3−−N content, indirectly affect variations in soil CO2, CH4 and N2O fluxes, respectively. Our study highlights the importance of the plant litter layer in regulating soil GHG between the atmosphere and soil in a Dahurian larch forest ecosystem, especially for litter addition. Considering the natural increase in litter quantity over time, this important regulatory function is essential for an accurate estimation of the role of boreal forests in mitigating future climate change.

Substances released during the decomposition of Vallisneria natans and Thalia dealbata

Two types of aquatic plants commonly used for the ecological restoration of rivers and lakes, Vallisneria natans (Lour.) Hara and Thalia dealbata Fraser ex Roscoe, were selected and grouped by plant parts (root, stem and foliage), and decomposing release experiments were conducted. The influence of the released substances on the water quality was analyzed, as well as the amount of nutrients released by each part of these two plants. The calculated maximum chemical oxygen demand releases from the foliage of V. natans and the foliage of T. dealbata were approximately 5.4 g/kg and 22.65 g/kg, respectively. Through three-dimensional fluorescence spectrum and parallel factor analyses, the different material compositions of the decomposing liquids from the plants were determined, and the main dissolved organic components of the decomposing liquid of V. natans were amino-acid-like and microbially derived humics, and those T. dealbata were soluble microbial by-product-like substances. The carbon-to-nitrogen ratio and humification index of each experimental group were compared. The experimental results showed that different parts of V. natans and T. dealbata had different rates of nutrient release. The dissolved organic matter in the decomposed solution can be utilized by microorganisms, which have the potential to become additional carbon sources. This study provides a new method for the treatment of aquatic plant litter. Different plant species can be used in combination according to their characteristics to ensure that better results are achieved during water treatment processes that use plant decomposing liquids as additional carbon sources.

How do moisture content, friability, and crust development of litter influence ammonia concentrations in broiler production?

Litter is the main source of ammonia (NH3) in broiler houses. The quality thereof affects the amount of NH3 volatilized and emitted from the broiler house as well as the welfare of the birds. A trial was conducted to determine how the addition of water to broiler litter (by spraying the surface) and raking of the litter or leaving the litter undisturbed will influence NH3 concentrations at litter level, litter composition, bird welfare, and performance under experimental conditions. A total of 2160 Ross 308 male broilers were divided into the following 6 treatments, each with 6 replicates of 60 animals: NR(0) = no raking of the litter, no water added; R(0) = raking of the litter, no water added; NR(1.5) = no raking of the litter, 1.5 L of water added; R(1.5) = raking of the litter, 1.5 L of water added; NR(3.0) = no raking of the litter, 3.0 L of water added; R(3.0) = raking of the litter, 3.0 L of water added. The addition of water and raking of the litter was introduced at 10 d of age, with a frequency of 2 to 3 times per week. At 38 d of age, NH3 concentrations were higher for the raked litter treatments than the treatments which were not raked (P < 0.001). The higher NH3 concentrations of the raked litter treatments coincided with a higher litter pH (P < 0.001) and temperature (P R × W < 0.001) as well as a lower uric acid and total nitrogen (N) concentration in the litter at 37 d of age. The addition of water to the litter resulted in lower litter quality scores at 29 and 37 d of age (P < 0.001) and a higher incidence of foot lesions at 29 (P W = 0.006) and 37 (P R × W = 0.025). Regardless of raking or not raking the litter, addition of moisture to the litter lead to litter of lower quality and subsequent higher incidence of foot lesions in broilers. This study demonstrates that the development of a crust on top of the litter layer reduces the formation and concentration of NH3 volatilized from the litter. Compacted litter resulted in lower NH3 concentrations while friable litter led to more NH3 being volatilized from the litter.

Aktivitas Nitrat Reduktase (ANR) Tanaman Jagung pada Pola Tumpangsari yang Diberi Serasah Jagung-Kedelai serta Biochar di Lahan Suboptimal Sidondo Sulawesi Tengah

The aim of the study was to examine the relationship between nitrate reductase activity and N uptake, tissue N content, N uptake, and chlorophyll content of corn plants in intercropping patterns which are given corn-soybean litter and biochar. The use of plant litter and biochar derived from crop residues as a source of organic matter in different intercropping patterns affected nitrate reductase activity, tissue N content, N uptake, and chlorophyll content of maize. This experiment was carried out on sub-optimal Sidondo land, Central Sulawesi with the main limiting factors being the availability of water and alkaline soil pH (7.21) which were arranged in a divided plot design with five litter treatments as subplots and five cropping patterns as the main plot with three replicates. Parameters observed were N levels, plant tissue N uptake, chlorophyll, and nitrate reductase activity. Collected data were analyzed using Anova and Duncan's multiple random tests. The results showed that corn litter, soybean mixed corn + soybean litter and their biochar in different intercropping patterns affected nitrate reductase activity, nitrogen uptake, chlorophyll levels very significantly (P˂0.01), increased nitrate reductase activity by 9710.86 mol NO2- -1g-1hour-1 at the age of 55 DAP, while N uptake (2237 mg.kg-1), tissue N content (4.33%), and total chlorophyll content (10.61 mg.l-1) were the highest in the litter treatment, corn and soybeans as well as biochar in corn and soybean intercropping (1:2), and (2:4). Thus, the provision of corn and soybean litter and biochar in intercropping systems can increase nitrate reductase activity, N uptake, tissue N levels, and corn chlorophyll levels in the corn-soybean intercropping system.&#x0D; &#x0D; Keywords: chlorophyll, N content of corn plant tissue, nitrate reductase activity, N uptake

Frequency-dependent predation and seedling fate: Effect of forest litter on regeneration of the Quercus wutaishanica seedling

Rodents attack oak (Quercus wutaishanica) seeds based on their sizes and frequencies before germination. However, the predation of oak seeds post-germination (seedling cotyledons) is not well studied. Here, we not only tested the preference of rodents for oak seedlings from different-sized seeds, but also traced the seedling fate under different litter treatments. We transplanted seedlings with frequency of large and small seed (FLSD) ratios as 1:9, 3:7, 5:5, 7:3, and 9:1, respectively, with each set treated with the litter cleared and covered. Our results showed that small-seeded seedlings were more preferred when the FLSD was 1:9 and 3:7, whereas large-seeded seedlings had a higher preference when the FLSD was 9:1 and 7:3. Moreover, the predation and survival rates of the seedlings decreased when covered with litter, thus indicating that, although forest litter prevented the seedling predation by rodents, it was unfavorable for seedling survival. Furthermore, we found that cotyledon predation by rodents had no significant effect on seedling performance, but their growth was severely inhibited when the apical bud was bitten off, thus suggesting that the apical bud loss was the main cause of seedling recruitment failure. Our study indicates that positive frequency-dependent predation helps maintain the polymorphism of germination type of Q. wutaishanica seedlings. Additionally, in the forest, the presence of litter may change the predation behavior of rodents, which consequently affects the growth and survival of the seedlings. Moreover, future studies should focus on how the forest species’ specific predatory habits and the litter of different thicknesses affect the growth and survival of the oak seedlings, to better understand the renewal mechanism of the oak trees.

Methodological features of chromato-mass spectrometric identification of organic compounds in the air during landscape fires

Introduction. In landscape fires, the question of the nature and character of the formed organic substances remains unexplored. The method of gas chromatography with mass spectrometric detection (GC-MS) has long been used in environmental analysis to identify organic compounds in complex multicomponent mixtures. Depending on the volatility and polarity of the components of organic compounds, air sampling is carried out on a solid sorbent, liquid absorber, fiber filter. The purpose of this study is to develop a comprehensive procedure for the identification of organic compounds by gas chromatography-mass spectrometry with sampling into different absorption media. Materials and methods. The studies were carried out in laboratory conditions specially created in the smoldering plant, seed chamber, chemical-analytical equipment. Biomass consisting of forest litter was used as a fuel substrate: moss, lichen, tree litter, branches, pieces of bark. An Agilent 5975 gas chromatography-mass spectrometer was used for GC-MS identification. An aspirator, a gas pipette, a Richter absorber with distilled water, and an AFA-HP-20 fiber filter were used to select the air medium. Sample preparation of concentrated air was carried out using microfibre “85 microns Carboxen/PDMS”, thermostat, vials for vapor phase analysis, ultrasonic bath, derivatizing reagent - o-pentafluorobenzylhydroxylamine, hexane. Results. A proposed complex procedure includes sampling into different absorption media, various sample preparation options. Extraction of organic compounds from absorption media was carried out by methods of solid-phase microextraction, derivatization, and liquid extraction. Volatile organic compounds were extracted from a gas bulb by the method of solid-phase microextraction on microfibre“85 microns Carboxen/PDMS”. Aldehydes and ketones were found in distilled water due to the derivatization of o-pentafluorobenzylhydroxylamine. Semi-volatile compounds were detected on the AFA-HP-20 filter due to liquid extraction in ultrasound. Limitations. The limitations of the study are related to the need to select the products of decay of a sample of forest litter under model conditions. Conclusion. The identification results showed that the following classes of substances released into the air during the burning of forest litter are present in the maximum amount: aldehydes, phenols, terpenes. The coefficient of coincidence of mass spectra also confirmed by the coincidence of experimental and library retention indices also confirmed by the coincidence of experimental and library retention indices is more than 90%.

Качество древесного опада как информативный индикатор функциональной классификации лесов

Relevance and goals. In the context of global climate change, the climate-regulating function of forests deserves special attention. There is still no functional classification of forests according to the effectiveness of their carbon storage function. The purpose of this article is to discuss an approach to such classification based on the assessment of the quality of tree litter. Objects and methods. To test the approach to the identification of functional types of forests (FTL) based on the quality of tree litter, taking into account the position in the landscape and the mechanical composition of soil-forming rocks, data on soils and vegetation obtained at 23 sites operating in the subzone of coniferous-broadleaf forests of the European part of Russia on the territory of Bryansk Polesie and Moskvoretsko-Okskaya plain were used. For indirect (on the ecological scale of E. Landolt using the SpeDiv program) to assess differences in the soil richness of forests belonging to different FTLS, the species composition of 160 descriptions of forest vegetation of the Moscow, Bryansk, Smolensk, Kostroma regions, Krasnodar Krai and the Republic of Adygea (North-Western Caucasus) was analyzed. Results. Examples of functional forest types (FTL) for coniferous and broad-leaved forests of the European part of Russia are given. The differences in the level of soil carbon accumulation between different FTLS are shown, and a preliminary assessment of the influence of the position in the landscape and the mechanical composition of soils on the accumulation of carbon in soils within FTLS is given. Conclusion. Based on the quality of the fall of tree litter, 15 FTL were identified, which are confirmed by examples based on geobotanical descriptions of forest communities common in the zone of coniferous-deciduous forests of the European part of Russia and in the belt of coniferous-deciduous forests of the North-Western Caucasus. The validity of the allocation of FTL for the efficiency of carbon accumulation in soils based on the quality of plant litter, taking into account the influence of “external factors” (the position in the landscape and the mechanical composition of soil-forming rocks) is confirmed by data obtained at 23 sites; estimates of the carbon reserves in the soil, as well as the soil richness estimated on an ecological scale, revealed differences between the allocated FTLS. Differences in carbon stocks in forest ecosystems in the same FTL formed on loamy and sandy loam soil-forming rocks were revealed. Differences in soil carbon reserves in forests belonging to the same FTL, but formed at different positions in the landscape, have been confirmed; in transit landscapes, soil carbon reserves are higher than in autonomous ones.

Comparative characterisation of forest litter on sod-podzolic soils of Forest Experimental Dacha in RSAU–MAA named after K.A. Timiryazev

Forest litter under linden and pine forests was studied at the Forest Experimental Dacha of the RSAU–MAA named after K.A. Timiryazev. Despite significant differences in physical and chemical parameters between the litter formed under the conditions of different forest communities, the properties of sod-podzolic soils formed under both vegetation types are quite similar. The litter under linden forest has higher ash content, it is less acidic and contains almost 2 times more exchangeable bases, the content of hydrogen and nitrogen is higher by 0.82 wt% and 0.66 wt%, respectively. The litter of linden and pine forests, according to the atomic ratios H : C, C : N and the degree of oxidation, are equal to 1.82, 30.3, -0.92 and 1.64, 45.7, -0.71, respectively; the litter of linden forests differs from litter of pine forests in the higher content of aliphatic, nitrogen-rich, reduced organic compounds. In the litter of linden forests concentration coefficients of phosphorus and magnesium 1.2 times higher; of carbon, potassium and aluminium – 1.3 times higher; of calcium – 1.4 times higher; of nitrogen – 1.8 times higher, and of silicon – 3 times higher, than in the litter of pine trees. However, the concentration factor of manganese in the pine forest litter is 1.9 times higher compared to the litter of linden. According to the results of UV spectroscopy, water-soluble organic matter of pine forest litter, unlike water-soluble organic matter of linden forest litter, is more enriched by components of aromatic origin. This is evidenced by higher values of SUVA254 and lower values of coefficients E2/E3 and E4/E6.

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.

Garden structure is critical for building survival in northern forest fires – An analysis using large Swedish wildfires

Despite increasing concern over wildfires in Fennoscandia, there are essentially no studies on the survivability of buildings within the wildland-urban interface of this region. We make use of four recent large-scale fires in Sweden to elucidate which factors are important for survival, using multiple logistic regression analysis of data collected at the sites. We obtained data on 187 buildings within the fire perimeters, nearly all with wood paneling and tile- or sheet metal roofing. 35 % of the buildings were lost or badly damaged. Results indicate that most buildings were approached by relatively low-intensity fire and that ignition primarily occurred through direct flame contact. The most important factor for survivability was the presence of a maintained lawn. The second most important was that no flammable material was present close to the building façade. Further, fire intensity often decreased close to buildings due to a larger portion of deciduous trees around gardens than in the surrounding forest. These factors were more important than specific features of the building itself, reflecting that the majority of buildings have combustible wooden façades. Our results suggest that the greatest potential for increasing building safety in the Swedish WUI is to keep the area immediately surrounding the building (∼5 m) free from tree litter and other flammable material. Also, since fire intensities are generally low, buildings can in most cases be defended with simple tools without compromising personal safety.

Ammonia concentrations, litter quality, performance and some welfare parameters of broilers kept on different bedding materials

ABSTRACT 1. Litter quality has been related to broiler performance, behaviour, welfare, dust and ammonia (NH3) emissions. Drier litter leads to a reduction in NH3 emissions and reduces the formation of foot- and hock lesions. However, maintaining good litter quality is often challenging. This study investigated the effects of different bedding materials on litter quality and NH3 concentrations at litter level, broiler performance, foot- and hock lesions, plumage cleanliness and breast skin irritation. 2. A total of 2160 Ross 308 male broilers were randomly assigned to 36 floor pens. There were six replications for each of the following six litter treatments: wood shavings, flax, peat, maize silage, chopped wheat straw and flax pellets. 3. For the total period, the highest feed intake and body weight was obtained for broilers housed on peat. The NH3 concentrations measured at litter level was highest for peat and chopped wheat straw at 36 d of age and numerically the lowest for flax at 30 and 36 d of age. Maize silage remained friable, but did not result in lower NH3 concentrations compared to wood shavings. Chopped wheat straw and wood shavings gave rise to the highest incidence of foot lesions at 38 d of age, while broilers kept on flax, peat, maize silage and flax pellets had the lowest incidence of foot lesions at the end of the rearing period. 4. The results of the current study suggest a complicated relationship between the type of bedding material, litter conditions and NH3 volatilised from the litter.

Effects of herbaceous covers and mineral fertilizers on the nutrient stocks and fluxes in a Mediterranean olive grove

The preservation of nutrient capital, soil fertility, and carbon (C) sequestration capacity in Mediterranean olive groves requires evaluation of agricultural practices beyond short-term productivity. We aim to contribute with a mechanistic understanding on the effects that the preservation of herbaceous cover and the use of chemical fertilizers have on the performance of olive trees and on the biogeochemical cycles of the agroecosystem. We compared nutrient fluxes and aboveground leafy stocks in an olive grove that had been organically managed for more than 60 years, in a treatment in which the annual spontaneous herbaceous cover was maintained (H), and after two years of shift to conventional management treatments in which the growth of herbaceous vegetation was avoided by the use of herbicides (NH), and where exclusion of the herbaceous cover is also combined with the supply of mineral fertilizers (NHF). Maintenance of herbaceous vegetation in H contributed to the retention of a high aboveground capital of C and nutrients, particularly nitrogen, (N), phosphorus (P) and potassium (K) that were about 2.9, 3.9 and 7.4 times greater than in NH, respectively. The permanence of herbaceous cover stimulated olive tree leaf litter decomposition rates by about 86 % and increased nutrient release. However, the H treatment led to a 37 % decrease in olive yield and lowered olive foliar N and P content as negative short-term effects. The addition of fertilizers (N, P, K, and Mg) in mineral and solid form in NHF resulted inefficient to improve olive tree nutritional status and olive production, and decelerated olive tree litter decomposition rates by 21 % and nutrient release. The nutrient retention in organic forms in the fast-growing species of herbaceous covers and the progressive nutrient release as litter decomposes may contribute to regulate and better adapt nutrient availability to the nutrient requirements of olive trees.

Liana litter decomposes faster than tree litter in a multispecies and multisite experiment

Abstract Lianas account for a small fraction of forest biomass, but their contribution to leaf or litter biomass and thus to food webs can be substantial. Globally liana exhibit fast life‐history traits. Thus, liana litter may decompose faster than tree litter, and could enhance the decomposition of tree litter (complementarity effect). The differences in decomposition may also vary with mesofauna access or across forest communities. The contribution of these factors to nutrient biogeochemical cycling is poorly understood. We examined the decomposition of litter of 20 liana and 20 tree species of three different tropical forest communities in southern China, over 1 year. (i) We incubated the litter in bags with coarse and fine mesh to distinguish mesofaunal and microfaunal effects. (ii) We used single‐species litter bags to compare decomposition rates of lianas and trees, to test which functional traits best explained decomposition, and whether those traits differed between lianas and trees, and among forest types. (iv) We used mixed‐species litter bags to test whether liana litter enhances decomposition in litter mixtures. (v) We evaluated how leaf litter nutrients decayed in relation to litter mass. Litter decayed faster in coarse‐mesh than fine‐mesh bags, but there was no interaction effect with forest type or growth form. Liana litter decayed faster than tree litter in single‐species bags with mesofauna access and in mixed bags (liana‐only mix, tree‐only mix) without mesofauna. Lianas had higher nitrogen content and specific leaf area and lower leaf dry matter content (LDMC) and toughness than trees. Decomposition rate was significantly negatively related to LDMC. Litter of evergreen broadleaved forest decomposed slower than that of other forest types. Liana litter did not enhance the decomposition of tree litter in mixtures. Liana litter released calcium slightly faster than trees. Synthesis: Leaf litter decomposes faster for lianas than trees, despite high variability of traits and decomposition rates within each growth form and overlap between growth forms, and we found no evidence for the complementarity hypothesis. Our study sheds light on the potential role of lianas within brown food webs and their importance on terrestrial biogeochemistry.

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.

Modeling Litter Stocks in Planted Forests of Northern Mexico

Litter, LS, is the organic material in which locates in the top A soil horizon, playing key ecological roles in forests. Models, in contrast to common allocation factors, must be used in LS assessments as they are currently absent in the scientific literature. Its evaluation assess the mass, input and flux of several bio-geo-chemicals, rainfall interception as one component of the local hydrology, and wildfire regimes, among others, hence its importance in forestry. The aim of this study was to: (i) develop models to assess LS, accumulation, and loss rates; and (ii) assess rainfall interception and fire regimes in 133 northern forest plantations of Mexico. Two developed techniques: the statistical model (SMLS) and the mass balance budget model (MBMLS) tested and validated local and regional LS datasets. Models use basal area, timber, aboveground tree biomass, litter fall, accumulation, and loss sub-models. The best fitting model was used to predict rainfall interception and fire behavior in forest plantations. Results showed the SMLS model predicted and validated LS datasets (p = 0.0001; r2 = 0.82 and p = 0.0001; r2 = 0.79) better than the MBMLS model (p = 0.0001; r2 = 0.32 and p = 0.0001; r2 = 0.66) but the later followed well tendencies of Mexican and World datasets; counts for inputs, stocks, and losses from all processes and revealed decomposition loss may explain ≈40% of the total LS variance. SMLS predicted forest plantations growing in high productivity 40-year-old stands accumulate LS &gt; 30 Mg ha−1 shifting to the new high-severity wildfire regime and intercepting ≈15% of the annual rainfall. SMLS is preliminarily recommended for LS assessments and predicts the need of LS management in forest plantations (&gt;40-year-old) to reduce rainfall interception as well as the risk of high-severity wildfires. The novel, flexible, simple, contrasting and consistent modeling approaches is a piece of scientific information required in forest management.

Drivers of soil respiration and nitrogen mineralization change after litter management at a subtropical Chinese sweetgum tree plantation

AbstractLeaf litter decomposition transfers elements from litter to soils that are essential for regulating nutrient cycles in plantation ecosystems, especially carbon and nitrogen. However, soil carbon and nitrogen dynamics in response to tree litter management remains insufficiently researched. We conducted a one‐year field experiment at a fast‐growing sweetgum tree plantation to evaluate the effects of leaf litter management on soil available nutrients, respiration rate and nitrogen mineralization rate. Three leaf litter treatments were applied, which were: (1) natural input (control); (2) double input and (3) non‐input. It was found that the double input treatment increased soil inorganic nitrogen and microbial biomass nitrogen, but had little effect on microbial biomass carbon, dissolved organic carbon or dissolved organic nitrogen compared with natural input. The non‐input treatment caused dissolved organic carbon to decrease compared with natural input. The respiration rate increased in the double input treatment, with a positive priming effect observed. Soil net ammonification, nitrification and mineralization rates also increased in the double input treatment in specific seasons. Meanwhile, positive linear relationships between respiration rate and all nitrogen transformation rates were observed for all treatments. Soil temperature was found to be an important prediction factor for predicting the respiration rate and mineralization as seasonal variations, but not for litter‐induced fluctuations. Soil water content and mineral nitrogen were the primary drivers of litter‐induced change to the respiration rate, whereas mineral nitrogen and microbial biomass were primary drivers of mineralization change. These results suggest that changes in soil nitrogen mineralization rate are strongly associated with the soil respiratory process, resulting in a potentially strong plant–soil feedback mechanism.

Short Communication: Metabolites of Albizia inhibit in vitro growth of phosphate solubilizing microbial consortia isolated from tea garden soil of Darjeeling hills, India

Abstract. Saha S, Ghosh A, Acharyya S, Bhattacharya M. 2022. Short Communication: Metabolites of Albizia inhibit in vitro growth of phosphate solubilizing microbial consortia isolated from tea garden soil of Darjeeling hills, India. Biodiversitas 23: 2865-2870. Phosphate solubilizing microorganisms (PSM) play a crucial role in maintaining the nutritional status and fertility of the soil. PSMs help in solubilizing the metallic phosphate salts of soil into available phosphate anions for easy uptake by plants. However, this beneficial group of microorganisms also face different challenges for survival from its immediate surroundings. This study was carried out to assess the effect of shade tree litters on the PSM consortia isolated from different tea garden soils of Darjeeling hills, since shade trees are an integral part of tea plantations. Albizia odoratissima, Albizia chinensis and Albizia procera, widely used in tea gardens as shade trees were selected. GC-MS analysis was carried out to detect the metabolites produced by the litters. Twenty-three compounds exhibiting antimicrobial activities were detected. Major peak was found in A. odoratissima, followed by A. chinensisand least in A. procera. Compounds like 1-heptanol, 2-propyl-, neophytadiene, phytol and squalene were common in all three extracts and are considered to provided antimicrobial activity to Albizia. A proportional relation has been observed between magnitude of inhibition zones and peak area percentage in Albizia spp. PSM isolates from shade tree gardens were observed to be more tolerant toward the leaf extracts.

Smoke deposition to water surfaces drives hydrochemical changes

AbstractThis study presents a unique data set from a laboratory experiment where we explored changes in the chemical composition of deionized water samples exposed to smoke. Inside a laboratory hood, water samples placed into a chamber were exposed to smoke for up to 60 min. The pattern of variations in hydrochemistry observed over time with increasing smoke exposure was similar in response to two different smoke treatments generated from burning tree litter. To estimate the smoke dosage and assess the consistency of replicate smoke treatments, we conducted additional experiments to evaluate changes in light transmission. Smoke inputs to the deionized water samples drove changes in hydrochemistry, with increases in acidity (with decreasing pH values), the content of organic matter (with increasing concentrations of dissolved organic carbon and dissolved organic nitrogen), and the content of inorganic N species (with increasing concentrations of ammonium, nitrate, and nitrite). The study was conducted on deionized water samples, and the results may not be directly transferrable to natural waters. Stream or lake waters that are low in ionic strength, poorly buffered, or low in acid‐neutralizing capacity might respond the most similar to the results of this study. In contrast, well‐buffered surface waters having higher acid‐neutralizing capacity would be more likely to neutralize acidic inputs from the smoke without significant effects on water quality. The publicly available dataset associated with this study will contribute to further consideration of the relative importance of short‐term changes in hydrochemistry driven by in‐stream inputs (e.g., changes in water chemistry from direct smoke deposition to the water surface) in contrast to terrestrial inputs (e.g., changes in water chemistry stemming from altered flow paths and source areas of the burned watershed landscape).

Effect of mangrove leaf litter on shrimp (Penaeus monodon, Fabricius, 1798) growth and color

Color, texture and flavor are all important determinants of seafood product quality and value. For shrimp, Penaeus monodon, one of the highest-priced shrimp species of the South-East Asia shrimp industry, dark tiger-striped coloration is a key product quality criterion. We evaluated the effects of leaf litter of the mangrove species Avicennia officinalis (AO), Heritiera fomes (HF), Sonneratia apetala (SA) and S.caseolaris (SC) on length, weight and body color of shrimp (Penaeus monodon) post-larvae (PL). Fifteen-day-old PL (weight: 0.01 g) were reared in 1100-L fiber-reinforced polyethylene tanks. Five treatments having three replications were conducted for four weeks. Four treatments received leaf litter of the four mangrove species and supplemental feeds and one control treatment was provided with supplemental feed only (FO). The pH, biological oxygen demand (BOD5), chemical oxygen demand (COD) and phytoplankton and zooplankton biomass were lower, while total ammonia nitrogen (TAN) concentration were significantly higher in the FO treatment than in treatments including leaf litter. PL survival averaged 89% and only differed significantly between the SA and SC leaf litter treatments (p < 0.05). After 4 weeks of culture, larvae in the FO treatment had significantly shorter body and carapace length, lower body weight and a lower specific growth rate than larvae in the other treatments, while SA-reared larvae attained significantly greater length and weight than in the other leaf litter treatments. Shrimp body coloration and pattern with leaf litter treatments were significantly different from the FO treatment. SA-reared larvae at harvest were significantly darker in body color than larvae reared with other mangrove species. Shrimp value chain stakeholders preferred dark shrimp as an indicator of organic production and higher price. Mangrove leaf litter was found to enhance the production and color quality of black tiger shrimp and this technique can be applied in commercial shrimp aquaculture.