Litter Water Research Articles

EXPERIMENTAL STUDY ON OPTIMISED COMPOSITION OF WATER BASED NITRATE SALT SOLUTION FOR SENSIBLE HEAT STORAGE

Objective: To find out factors like specific heat, heat capacity and heat loss. Method/Analysis: Sodium nitrate (NaNO3) is mixed in water with different weight quantity like 100g, 200g, 300g last 600g and potassium nitrate (KNO3 ) is mixed in water with weight quantity 100g, 200g, 300g and 400g. Findings: Total heat holding storage is more in NaNO3 than KNO3 , but KNO3 has better energy holding capacity. But KNO3 is reached saturation point in 1 litter water while NaNO3 went up 600g without reaching saturation. Novelty/Improvement: Results shows big molecule has low heat capacity and more Total heat or energy holding storage. Keywords: Energy Holding Capacity (EHC), Potassium Nitrate (KNO3 ), Sodium Nitrate (NaNO3 ), Sustainable Development, Thermal Capacity (TC), Thermal Storage Fluid System

Litter moisture adsorption is tied to tissue structure, chemistry, and energy concentration

AbstractThe ability of plant litter to adsorb water is important for wildland fire, hydrological, and biogeochemical processes. Variation in water adsorption has largely been attributed to physical differences across species, with the role of litter chemistry in moisture dynamics receiving little attention. We hypothesized that lower specific leaf area (SLA, cm2/g) and higher concentrations of hydrophobic lignin and lipid biomolecules would be associated with decreased litter water adsorption. Because plant biochemistry is tied to litter elemental and structural traits via biophysics and leaf economics, we expected to observe a suite of linked traits that were related to water adsorption, including element concentrations, carbon oxidation state, and energy concentration (ΔHc). In litter from 22 species, we observed greater than fourfold variation in the maximum amount of liquid water adsorbed (adsorption capacity, g/g) and in the rate at which dry litter adsorbed water vapor (adsorption rate, mg g−1 min−1); there was a significant positive relationship between adsorption capacity and adsorption rate. Broadly, litter with low SLA had a low carbon oxidation state, low oxygen and ash concentrations, and high concentrations of carbon, hydrogen, lignin, and lipids. The two metrics of water adsorption had significant negative relationships with concentrations of energy, lignin, carbon, and hydrogen, and positive relationships with litter SLA and carbon oxidation state. However, water adsorption was better predicted by combinations of SLA with chemical and energy traits. Several traits associated with decreased litter water adsorption, such as concentrations of lignin and energy, also directly influence some of the same ecosystem processes affected by litter moisture (e.g., decomposition, wildland fires). In particular, because plants with the hydrophobic traits identified in this study are more abundant in dry environments, our observations suggest a mechanism that could accentuate the influence of litter traits on ecosystem processes and which merits further research. Understanding the role of these traits in water adsorption could be used to help predict shifts in ecosystem function as plant communities reassemble as result of climate change as well as provide quantitative information on how plant species influence wildland fire dynamics.

Deriving surface soil moisture from reflected GNSS signal observations from a grassland site in southwestern France

Abstract. This work assesses the estimation of surface volumetric soil moisture (VSM) using the global navigation satellite system interferometric reflectometry (GNSS-IR) technique. Year-round observations were acquired from a grassland site in southwestern France using an antenna consecutively placed at two contrasting heights above the ground surface (3.3 and 29.4 m). The VSM retrievals are compared with two independent reference datasets: in situ observations of soil moisture, and numerical simulations of soil moisture and vegetation biomass from the ISBA (Interactions between Soil, Biosphere and Atmosphere) land surface model. Scaled VSM estimates can be retrieved throughout the year removing vegetation effects by the separation of growth and senescence periods and by the filtering of the GNSS-IR observations that are most affected by vegetation. Antenna height has no significant impact on the quality of VSM estimates. Comparisons between the VSM GNSS-IR retrievals and the in situ VSM observations at a depth of 5 cm show good agreement (R2= 0.86 and RMSE = 0.04 m3 m−3). It is shown that the signal is sensitive to the grass litter water content and that this effect triggers differences between VSM retrievals and in situ VSM observations at depths of 1 and 5 cm, especially during light rainfall events.

Estuarine caridean shrimp (Palaemon debilis Dana, 1852) (Decapoda: Caridea) can differentiate olfactory cues from different mangrove species for microhabitat selection

Environmental cues in mangroves such as chemicals released from senescent leaf litter could help guide juvenile nekton to their nursery habitats. A laboratory olfactory choice experiment was conducted using a three-channel choice flume to assess the ability of juveniles of the caridean shrimp Palaemon debilisDana (1852) to distinguish between water containing leachates from the leaf litter of the mangroves Avicennia marina (Forsk.) Vierh., Rhizophora stylosa Griff. and a mixture of the two species. Senescent leaves of these species of mangroves were soaked for 14 days in artificial seawater before being exposed to juvenile P. debilis in the flume. P. debilis spent significantly more time in R. stylosa water, followed by mixed R. stylosa and A. marina water, and least time in A. marina water. The consistent preference for R. stylosa water suggests that the chemical cues from senescent leaves of this mangrove species might influence choice selection by the shrimp. The olfactory choice experiment was further investigated to assess if the preference for senescent R. stylosa leachate (water) was due to the water-borne chemicals (either from the senescent R. stylosa leaf litter water or aged R. stylosa detritus) serving as an attractant to the shrimps, by comparing it to aged R. stylosa detritus and artificial seawater. Juvenile shrimp preferred senescent R. stylosa water, therefore suggesting a role of chemical attractants in the shrimp's choice of habitat.

Litter Type and Number of Flocks Affect Sex Hormones in Broiler Litter

Broiler litter contains 17β-estradiol, estrone, and testosterone, which can contaminate surface waters when surface applied to grasslands and no-till fields. The objective of this study was to evaluate the effects of litter type (full or cake cleanout), litter treatment (none or sodium bisulfate), and number of flocks raised on the litter (1-5) on sex hormone concentrations. Our results showed that in untreated broiler litter, cake cleanout had greater concentrations of 17β-estradiol, estrone, and testosterone than full cleanout, whereas in litter treated with sodium bisulfate, only the concentration of 17β-estradiol was greater in cake than in full cleanout. The concentrations of 17β-estradiol and estrone in untreated broiler litter increased as the number of flocks increased from one to three, with the largest increase observed for estrone in cake cleanout. We also sampled three broiler houses in brooding and nonbrooding sections during the growout period. We found no differences in hormone concentrations between sections of each house, but changes in hormone concentrations during growout varied depending on broiler litter water content. Water contents corresponding to ∼60% water-filled porosity favored a decrease in hormone concentrations with time, whereas a water-filled porosity of 44% was associated with increases in hormone concentration, probably due to slow decomposition rates. Our results suggest that cake cleanout of untreated litter, as well as all cleanouts from houses that have raised several flocks on the same bedding, may be good targets for treatments that can reduce hormone concentrations before the litter is surface applied to fields.

Comparing chemistry and bioactivity of burned vs. decomposed plant litter: different pathways but same result?

Litter burning and biological decomposition are oxidative processes co-occurring in many terrestrial ecosystems, producing organic matter with different chemical properties and differently affecting plant growth and soil microbial activity. We tested the chemical convergence hypothesis, i.e., materials with different initial chemistry converge toward a common profile, with similar biological effects, as the oxidative process advances, for burning and decomposition. We compared the molecular composition, assessed by 13 C NMR, of seven plant litter types either fresh, decomposed for 30, 90, 180d in a microcosms incubation experiment, or heated at 100°C, 200°C, 300°C, 400°C, 500°C for 30 minutes. We used litter water extracts (5% dry weight) as treatments in bioassays on plant (Lepidium sativum) and fungal (Aspergillus niger) growth, and a washed quartz sand amended with litter (0.5% dw) to assess heterotrophic respiration by flux chamber (i.e., [μg of CO2 released]·[g added litter]-1 ·d-1 ). We observed different molecular variations for materials either burning (i.e., a sharp increase of aromatic C and a decrease of other fractions above 200°C) or decomposing (i.e., early increase of alkyl, methoxyl, and N-alkyl C and decrease of O-alkyl and di-O-alkyl C fractions). Soil respiration and fungal growth decreased with litter age and heating severity, down to 20% relative to fresh litter. Plants were inhibited on fresh litter (on average 13% of the control), but recovered on aged (180d) and heated (30min at 500°C) materials, up to 126% and 63% of the control, respectively. Correlation between the intensity of 13 C NMR signals in litter spectra and bioassay results showed that O-alkyl, methoxyl, and aromatic C fractions are crucial to understand organic matter effects, with plant response negatively affected by labile C but positively associated to lignification and pyrogenic C. The pattern of association of soil respiration and fungal growth to these C fractions was essentially opposite to that observed for plant root growth. Our findings suggest a functional convergence of decomposed and burned organic substrates, emerging from the balance between the bioavailability of labile C sources and the presence of recalcitrant and pyrogenic compounds, oppositely affecting different trophic levels.

Effects of Plant Growth Form and Water Substrates on the Decomposition of Submerged Litter: Evidence of Constructed Wetland Plants in a Greenhouse Experiment

Wetland plants are important components in constructed wetlands (CWs), and one of their most important functions in CWs is to purify the water. However, wetland plant litter can also increase eutrophication of water via decomposition and nutrient release, and few studies have focused on the interspecific variation in the decomposition rate and nutrient release of multiple plant species in CWs. Here a greenhouse litter-bag experiment was conducted to quantify the decomposition rates and nutrient release of 7 dominant macrophytes (2 floating plants and 5 emergent plants) in three types of water substrate. The results showed that plant litter species and growth forms significantly affected the litter mass losses. The nutrient release was significantly different among plant litter species, but not between floating and emergent plants. Litter traits, such as litter lignin, total nitrogen (TN) and total phosphorus (TP) can well predict the decomposition rates of submerged litter. These results indicated that submerging litter in water did not change the relationships between litter traits and litter decomposition rates, and leaching might play a more important role in the decomposition of submerged litter in CWs than that in other terrestrial ecosystems. These findings can provide suggestions for managers about the maintenance of constructed wetlands.

Relationships among leaf functional traits, litter traits, and mass loss during early phases of leaf litter decomposition in 12 woody plant species.

Litter 'quality' or decomposability has historically been estimated through measuring chemical attributes, such as concentrations of nitrogen or 'lignin'. More recently, foliar functional traits, which may incorporate indications of the physical structures of tissues, have been found to correlate with litter mass loss rates. However, these traits may not be adequate to predict early rates of mass loss, in which two factors are crucial: the amount of material quickly lost through leaching, and the ease of access of decomposer organisms to the more labile tissues in the interior of the litter. We investigated relationships among physical and chemical traits in foliage and litter of 12 species native to British Columbia and then observed how these traits related to mass loss during the first 3months (Phase I) and between 3 and 12months (Phase II). Novel traits measured in this study include cuticle thickness, litter leaching loss, and litter water uptake. Foliar and litter traits both co-varied along spectra, but several chemical traits, such as nitrogen concentration, changed from foliage to litter, i.e., during senescence. Phase I mass loss was best predicted by leaching loss and traits relating to leaching, such as cuticle thickness and specific leaf area. Phase II mass loss was predicted by traits that may relate to decomposer access and activity, such as leaf dry matter content and foliar nitrogen. Physical traits predicted mass loss as well or better than chemical traits, suggesting that physical characteristics of litter are important in determining early rates of decomposition.

Within-House Spatial Distribution of Fecal Indicator Bacteria in Poultry Litter.

Land application of poultry litter is often considered to be a major source of water pollutants in poultry-producing regions. However, reported levels of fecal indicator microorganisms in litter vary widely, with considerable variation possible within houses and across farms, depending on management practices. Therefore, a study was conducted to determine the levels and distribution of indicator microorganisms within 12 broiler farms representing three companies. Within each house, litter samples were collected from around the feed line, water line, north wall, cool pad end, middle, and fan end. Litter moisture content was significantly different within the houses, with the litter being driest around the feed line (19.8%) and wettest around the water line (40.7%). Mean levels of total coliforms, , enterococci, and were 3.7, 3.3, 6.4, and 4.0 log colony-forming units g dry litter, respectively. Levels of total coliforms, , and were positively correlated with litter moisture content, but enterococci levels were not. Consequently, levels of total coliforms, , and , as well as enterococci, were highest around the water line and lowest around the feed line. These results indicate that areas with higher litter water content are more likely to contain higher levels of most fecal indicator microorganisms. Approaches to reduce litter water content in these areas would not only benefit the microbial quality of litter for land application but would also likely improve in-house disease control.

Effects of phenology and meteorological disturbance on litter rainfall interception for a Pinus elliottii stand in the Southeastern United States

AbstractLitter layers develop across a diverse array of vegetated ecosystems and undergo significant temporal compositional changes due to canopy phenological phases and disturbances. Past research on temporal dynamics of litter interception has focused primarily on litter thickness and leaf fall, yet forest phenophases can change many more litter attributes (e.g., woody debris, bark shedding, and release of reproductive materials). In this study, weekly changes in litter composition over 1 year were used to estimate litter water storage dynamics and model event‐based litter interception. Litter interception substantially reduced throughfall (6–43%), and litter water storage capacity ranged from 1 to 3 mm, peaking when megastrobili release and liana leaf senescence occurred simultaneously during fall 2015. Tropical storm disturbances occurred during the sampling period, allowing evaluation of how meteorological disturbances altered litter interception. High wind speeds and intense rainfall from 2 tropical storms increased litter interception by introducing new woody debris, which, in this study, stored more water than the pre‐existing woody debris. After 2 extreme weather events, a third (Hurricane Hermine) did not increase woody debris (or litter interception), suggesting that the canopy pool of branches susceptible to breakage had been largely depleted. Needle and bark shedding had minor effects on litter interception. Results suggest that the release of reproductive materials and meteorological disturbances appear to be the major compositional drivers of litter interception beyond their obvious contribution to litter thickness.

The Impact of Water Content on Sources of Heterotrophic Soil Respiration

Heterotrophic respiration (RH) is a major flux of CO2 from forest ecosystems and represents a large source of uncertainty in estimating net ecosystem productivity (NEP) using regional soil respiration (RS) models. RH from leaf litter (RHL) may contribute greatly to annual RH estimates, but its contribution may be misrepresented due to the logistical and technical challenges associated with chamber-based field measurements of RHL. The purpose of this study was to evaluate the sensitivity of sources of RH (mineral soil-derived heterotrophic respiration [RHM] and leaf litter-derived heterotrophic respiration [RHL]) of a loblolly pine plantation (Pinus taeda L.) to varying soil and litter water content over the course of a dry down event. Additionally, we investigated whether fertilization influenced RHL and RHM to understand how forest nutrient management may impact forest soil carbon (C) dynamics. RHL was measured under dry conditions and at field capacity to evaluate water content controls on RHL, determine the duration of increased CO2 release following wetting, and evaluate the potential contribution to total RH. We also measured RHM inside collars that excluded plant roots and litter inputs, from field capacity until near-zero RHM rates were attained. We found that RHL was more sensitive to water content than RHM, and increased linearly with increasing litter water content (R2 = 0.89). The contribution of RHL to RH was greatest immediately following the wetting event, and decreased rapidly to near-zero rates between 3 and 10 days. RHM also had a strong relationship with soil water content (R2 = 0.62), but took between 200 and 233 days to attain near-zero RHM rates. Fertilization had no effect on RHM (p = 0.657), but significantly suppressed RHL rates after the wetting event (p < 0.009). These results demonstrate that there is great temporal variability in both CO2 released and the water content of differing sources of RH, and forest fertilization may largely impact forest floor C stocks. This variability may not be captured reliably using conventional weekly to monthly chamber-based field sampling efforts and could lead to over- or underestimation of RH. In the context of climate change, changes in the frequency and intensity of wetting and drying events will likely alter RHL and its contribution to RS. Separate consideration of RH sources and controls, along with increased field sampling frequency using chamber-based methodology under a broader range of specific environmental conditions, are likely needed to reduce variability in RH estimates and improve the accuracy of forest NEP predictions.

IMPACT OF GARLIC EXTRACT IN COMPARISON WITH CHLOROPYRIFOSE INSECTICIDE AGAINST CERTAIN PESTS AND ASSOCIATED PREDATORS IN COTTON FIELDS AT SHARKIA GOVERNORATE, EGYPT

Field experiments were conducted in cotton fields, Gossypium barbadense L. variety Giza 86 at Zagazig District, Sharkia Governorate, Egypt during 2014 season. Four programs were applied with three respective sprays for each using commercial formulation of garlic extract Nat-108 and varied as spray start times and interval periods towards the development of more environmentally sound technologies for management of cotton aphids (Aphis gossyppii), cotton thrips (Thrips tabaci), sweet potato whitefly (Bemesia tabaci), spider mites (Tetranychus spp.), leafhoppers (Empoasca spp.), green stink bug (Nezara viridula), pink bollworm (Pectinophora gossypiella) and cotton leafworm (Spodoptera littoralis). In addition to the side effects on several predators species found in cotton fields associated with cotton pests, such as, coccinellids, chrysopids, staphylinids, anthocorid, dipterous and true spiders were studied. Results, educed that the commercial formulation of garlic extract at the rate of 1 litter/100 litter water showed relatively high efficiency against aphids, leafhoppers and thrips, with maximum reduction percentages of 81.33, 82.51 and 84.12%, respectively; moderate efficiency against pink bollworm, whitefly, spider mites, green stink bug with maximum reduction percentages of 61.50, 78.89, 67.56 and 54.46%, respectively and low efficacy against predators except at the end season where the relatively highest reduction percentage was 62.91%, while it was less effective against the cotton leaf worm ranged 23.30-25.80% reduction in comparison with 70.56-90.00% reduction in cotton leafworm population for Dursban (chloropyrifose). So, the garlic extract cannot considered as a botanical pesticide against S. littoralis under cotton field conditions at Sharkia Governorate but needs more studies to evaluate its efficacy on different levels of S. littoralis infestation and stags. In regard to the programs results for garlic extract efficacy, it cleared that the first program tended to be the highest sustainable control of aphids, whitefly, thrips and spider mites on cotton plants, where the sprays started just after cotton plants emergence, whereas the numbers of pests were very low while the third program where the sprays started after 20 days of cotton plants emergence was tended to be the highest sustainable control of leafhoppers. In case of N. viridula, it could be decided that the organophosphorous pesticide, Dursban can be used as effective insecticide especially at the end season period. Finally, garlic extract was tended to be safe to predators especially throughout its effective activity period during the period from seedling to the end of growing season of cotton plants that confirmed by the results of the third program which ranged 2.57-21.46% reduction percentages in predators population. So, garlic extract could be recommended to be used effectively against cotton aphids, leafhoppers, cotton thrips and pink bollworm in IPM program of cotton pests in cotton fields. The organophosphorous compound, Dursban can be considered as good control pesticide against tested pests recorded reduction percentages ranged 56.99-96.99% but caused serious damage to associated predators on cotton plants at the end of season period recorded reduction percentages reached to 99.76% that disturbed the natural balance in cotton cultivation area environment.

A New Look at Climate Change

The climate of the planet depends on the circulation of water in nature. The main driving force of the process is the Biota-the main consumer of water. Millions of years of interchange of water between the sky and the earth were created a harmonious balance of the water change. Man, increasing the comfort of its existence, it takes away from the nature of the territory, uses water notonly for drinking. Critical link in the chain of the water cycle decreases the transformation of water flora and fauna. The main source is the moisture vapour respiration and waste products of living creatures and plant transpiration. Suffice it to recall that one just one evaporates birch 50-60 litters of water per day. One cow drinks about 100 litters of water for the same time. It is known that a hectare of fertile soil contains 20 tons of underground living creatures, each unit which consumes water and breathes moisture and other properties. About this herd of cows in the 40 head of 500 kg. Multiply all this by the number of birch trees, cows and acres across the planet, the flora and fauna.

Monitoring litter interception of rainfall using leaf wetness sensor under controlled and field conditions

AbstractLeaf litter interception of water is an integral component of the water budget for some vegetated ecosystems. However, loss of rainfall to litter receives considerably less attention than canopy interception due to lack of suitable sensors to measure changes in litter water content. In this study, a commercially available leaf wetness sensor was calibrated to the gravimetric water content of eastern redcedar (Juniperus virginiana) litter and used to estimate litter interception in a subhumid eastern redcedar woodland in north‐central Oklahoma. Under controlled laboratory conditions, a strong positive correlation between the leaf wetness sensor output voltage (mV) and measured gravimetric litter water content (ϴg) was determined: ϴg = (.0009 × mV2) − (0.14 × mV) − 11.41 (R2 = .94, p < .0001). This relationship was validated with field sampling and the output voltage (mV) accounted for 48% of the observed variance in the measured water content. The maximum and minimum interception storage capacity ranged between 1.16 and 12.04 and 1.12 and 9.62 mm, respectively. The maximum and minimum amount of intercepted rain was positively correlated to rainfall amount and intensity. The continuous field measurements demonstrated that eastern redcedar litter intercepted approximately 8% of the gross rainfall that fell between December 16, 2014 and May 31, 2015. Therefore, rainfall loss to litter can constitute a substantial component of the annual water budget. Long‐term in situ measurement of litter interception loss is necessary to gain a better estimate of water availability for streamflow and recharge. This is critical to manage water resources in the south‐central Great Plains, USA where grasslands are rapidly being transformed to woodland or woody dominated savanna.

Short-term response of CO2 emissions to various leaf litters: a case study from freshwater marshes of Northeast China

Soil organic carbon (SOC) mineralization is an important process of carbon (C) cycling and budgeting associated with litter decomposition in terrestrial ecosystems. Research on altered plant-derived C input on soil C stability due to climate change is controversial and there remains considerable uncertainty in predicting soil C dynamics with the techniques currently available. In this study, we conducted a laboratory incubation experiment to test the effects of single- and mixed-Deyeuxia angustifolia (DA) and Carex lasiocarpa (CL) leaf litter addition on cumulative marshland soil CO2 emission under waterlogged and non-waterlogged conditions in Sanjiang Plain, Northeast China. Results showed that the cumulative CO2 emissions were significantly increased after leaf litter addition in both water conditions, and that the effect was more pronounced for DA amendment than CL regardless of water condition. The cumulative CO2 efflux differed considerably between water conditions after DA addition, whereas no significant differences were found after CL addition. Remarkably impact of leaf litter types on cumulative CO2 evolution was observed overall, water condition and interactions between leaf litter types and water conditions had no significant effect on CO2 emissions, however. There were no non-additive effects of individual leaf litter type on total CO2 efflux of the mixed-leaf litter addition treatments. The results of this study indicate that plant litter input to the C-rich marshy soil can induce rapid changes in SOC decomposition regardless of water conditions and that plant residue effects should be taken into consideration when assessing the dynamics of wetland soil system to the future climate scenarios.

Variations of deep soil moisture under different vegetation types and influencing factors in a watershed of the Loess Plateau, China

Abstract. Soil moisture in deep soil layers is a relatively stable water resource for vegetation growth in the semi-arid Loess Plateau of China. Characterizing the variations in deep soil moisture and its influencing factors at a moderate watershed scale is important to ensure the sustainability of vegetation restoration efforts. In this study, we focus on analyzing the variations and factors that influence the deep soil moisture (DSM) in 80–500 cm soil layers based on a soil moisture survey of the Ansai watershed in Yan'an in Shanxi Province. Our results can be divided into four main findings. (1) At the watershed scale, higher variations in the DSM occurred at 120–140 and 480–500 cm in the vertical direction. At the comparable depths, the variation in the DSM under native vegetation was much lower than that in human-managed vegetation and introduced vegetation. (2) The DSM in native vegetation and human-managed vegetation was significantly higher than that in introduced vegetation, and different degrees of soil desiccation occurred under all the introduced vegetation types. Caragana korshinskii and black locust caused the most serious desiccation. (3) Taking the DSM conditions of native vegetation as a reference, the DSM in this watershed could be divided into three layers: (i) a rainfall transpiration layer (80–220 cm); (ii) a transition layer (220–400 cm); and (iii) a stable layer (400–500 cm). (4) The factors influencing DSM at the watershed scale varied with vegetation types. The main local controls of the DSM variations were the soil particle composition and mean annual rainfall; human agricultural management measures can alter the soil bulk density, which contributes to higher DSM in farmland and apple orchards. The plant growth conditions, planting density, and litter water holding capacity of introduced vegetation showed significant relationships with the DSM. The results of this study are of practical significance for vegetation restoration strategies, especially for the choice of vegetation types, planting zones, and proper human management measures.

退化柞蚕林封育对枯落物和表层土壤持水效能的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 退化柞蚕林封育对枯落物和表层土壤持水效能的影响 DOI: 10.5846/stxb201404090679 作者: 作者单位: 辽宁省林业科学研究院,辽宁省林业科学研究院,辽宁省林业科学研究院,辽宁省林业科学研究院,辽宁省林业科学研究院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家科技支撑计划(2012BAD22B04); 林业公益性行业科研专项(201204101, 201404303); 辽宁省科技计划项目(2011207001); 辽宁省农业领域青年科技创新人才培养计划(2014015) Effects of enclosure and recovery for degraded Tussah-feeding oak forests on litter and surface soil water holding capacity characteristics Author: Affiliation: Liaoning Academy of Forestry,Liaoning Academy of Forestry,Liaoning Academy of Forestry,Liaoning Academy of Forestry,Liaoning Academy of Forestry Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:柞蚕林是辽东山区退化最严重的森林类型之一,因多年反复刈割导致生长逐渐衰退、更新能力下降,局部出现空地甚至土壤开始砂化,涵养水源和保持水土等生态功能明显降低。以辽东山区的退化柞蚕林为研究对象,分析了在封育9、12、21a后森林的枯落物及表层土壤持水效能。结果表明:退化柞蚕林经过封育恢复后,封育恢复时间越长,林地枯落物累积量增加的越显著,枯落物持水能力和有效拦蓄降雨能力提高也越明显。对照(未封育)、封育9、12、21a柞蚕林枯落物储量分别为3.69、7.92、8.41 t/hm2和8.74 t/hm2;最大持水量分别为6.23、14.71、15.81 t/hm2和17.18 t/hm2,有效拦蓄量分别为4.78、10.87、11.70、12.78 t/hm2。枯落物持水量与浸水时间存在显著的相关关系(P < 0.001),自然对数模型模拟拟合效果最好(R2 > 0.9)。退化柞蚕林经过封育恢复后,表层土壤水文物理性质的改善随着封育恢复时间的增加而越来越明显,封育9、12和21年柞蚕林表层土壤容重分别比对照退化柞蚕林降低了5.51%、12.60%、17.32%,毛管持水量分别增加了7.01%、28.98%、54.83%,非毛管持水量分别增加了46.14%、126.19%、187.19%。本研究结果说明退化柞蚕林封育能够通过提高其林地枯落物和改善土壤物理性质,增加表层土壤持水效能,对恢复和改善退化柞蚕林地的生态环境、恢复森林生产力具有重要作用。 Abstract:Tussah-feeding oak forests (here after referred to as TF oak forests) are seriously degraded forests in the mountainous areas of Eastern Liaoning Province. Owing to repeated cutting every year, the trees grow slowly and their ability to regenerate is markedly decreased. When open spaces appear, the soil begins to become sandy, which causes a decline in ecosystem services such as water storage and soil conservation. In this study, the water holding capacity of the litter and surface soil were investigated in a degraded TF oak forest after 9, 12, and 21 years of enclosure to facilitate recovery. In addition, the degraded TF oak forest was studied to identify the effects of enclosure and recovery time on the water holding capacity of litter and surface soil, using the spatial sequence as opposed to the time succession sequence. Litter in degraded TF oak forests increased significantly after enclosure, with more litter accumulating with increased enclosure time. Litter accumulation after 9, 12, and 21 years of enclosure was 7.92, 8.41, and 8.74 t/hm2, respectively, which was 1.15, 1.28, and 1.37 times greater than those of the degraded TF oak forest, respectively. Longer enclosure times were associated with better litter water-holding capacity and improved rainfall retention. The maximum water holding capacity of TF oak forest after 9, 12, and 21 years of enclosure was 14.71, 15.81, and 17.18 t/hm2, respectively, which was 1.36-, 1.54-, and 1.76-fold higher than that of the degraded TF oak forest. The effective retention capacity of TF oak forest after 9, 12, and 21 years of enclosure was 10.87, 11.70, and 12.78 t/hm2, respectively, which was 1.29-, 1.46-, and 1.69-fold higher than that of the degraded TF oak forest, respectively. Litter water holding capacity and immersion time were significantly correlated (P < 0.001). The best fitting curve for this relationship took the form Hl=a + b ln t, and the coefficients of determination for all enclosures (R2) were greater than 0.9. The hydro-physical properties of surface soil of degraded TF oak forests improved following enclosure, with longer enclosure times associated with greater improvements in surface soil hydro-physical properties. Compared to the degraded TF oak forests, soil bulk density at 0-15 cm depth was reduced by 5.51%, 12.60%, and 17.32% in the TF oak forests after 9, 12, and 21 years of enclosure, while total porosity increased by 12.21%, 41.85%, and 72.35%, respectively. Longer enclosure times were associated with increased soil water storage capacity. Compared to the degraded TF oak forests, water holding capacity in soil capillary pores increased by 7.01%, 28.98%, and 54.83%, while water holding capacity in soil non-capillary pores increased by 46.14%, 126.19%, and 187.19%, respectively in the TF oak forests after 9, 12, and 21 years of enclosure. Litter and surface soil water holding capacity were improved significantly after enclosure and recovery of degraded TF oak forests. Thus, enclosure played an important role the recovery and improvement of the local ecological environment, and increased forest productivity. 参考文献 相似文献 引证文献

Potential Shift in Plant Communities with Climate Change: Outcome on Litter Decomposition and Nutrient Release in a Mediterranean Oak Forest

The ongoing decline in biodiversity has fuelled concerns about its impact on ecosystem functioning. Mediterranean oak forests may prove very sensitive to global change, which could strongly influence the species composition of plant communities and thereby affect ecosystem processes. To determine the potential outcome of shifts in species composition on litter decomposition dynamics, we conducted a full-factorial decomposition experiment over a gradient of litter species diversity in a Mediterranean Downy oak (Quercus pubescens Willd.) forest. We used litter from the three dominant tree species naturally present in the Downy oak forest and litter from Aleppo pine (Pinus halepensis Mill.) in anticipation of its possible spread in the future with global change. Litter water holding capacity and N/P ratio were the most important and positive drivers of decomposition process. In contrast to other ecosystems where synergistic non-additive effects are prevalent, we observed 54% of additive and 46% of non-additive effects on litter mass loss in our Mediterranean ecosystem. These results could indicate less complementarity among decomposers for decomposition of diverse plant material in such a stressful climate. Moreover, dominant tree species are of key importance for nutrient availability, and the arrival of Aleppo pine would strongly reduce the N release during the decomposition process. Based on calculations of an annual partial nutrient budget at the ecosystem level, we showed that a shift in plant communities could affect nutrient release, ranging from 5 to 36% for N and 63 to 83% for P depending on the co-occurring tree species in the Downy oak forest.

Decomposition of Avicennia marina (Forsk.) Vierh. Foliage under field and laboratory conditions in the backwaters of Karachi, Pakistan

The fate of leaf litter decomposition of Avicennia marina (Forsk.) Vierh. was found higher under field aerobic condition (FAC) while the fate was lowest under laboratory anaerobic condition (LAAC). The time required for the loss of half of the initial day weight (t50) was 48, 55, 98 and 110 days for aerobic condition (AC), field micro-aerobic condition (MAC), laboratory aerobic condition (LAC) and LAAC, respectively. Total nitrogen content of the decomposing litter increased by contrast, total organic carbon decreased during decomposition. Consequently, carbon to nitrogen ratios declined with time during decomposition. Repeated measure design showed that weight loss, total nitrogen and total organic carbon vary significantly under all four conditions with respect to elapsed time (p &lt; 0.001; Wilks’Lambda = 0.02, 0.003, 0.02, respectively at p &lt; 0.001). The study concludes that mangrove litter has an initial rapid phase of decomposition and the variable decay rates depend on the degree of exposure/submergence of litter in water, the pressure of detrivores, and the oxygen level in the given niche of mangrove forest. DOI: http://dx.doi.org/10.3329/bjb.v44i1.22716 Bangladesh J. Bot. 44(1): 1-7, 2015 (March)

CO&lt;sub&gt;2&lt;/sub&gt; efflux from decomposing leaf litter stacks is influenced by the vertical distribution of leaf litter water content and its temporal variation

CO&lt;sub&gt;2&lt;/sub&gt; efflux from decomposing leaf litter stacks is influenced by the vertical distribution of leaf litter water content and its temporal variation