Litter Categories Research Articles

Artificial neural networks for modeling time series of beach litter in the southern North Sea

In European marine waters, existing monitoring programs of beach litter need to be improved concerning litter items used as indicators of pollution levels, efficiency, and effectiveness. In order to ease and focus future monitoring of beach litter on few important litter items, feed-forward neural networks consisting of three layers were developed to relate single litter items to general categories of marine litter. The neural networks developed were applied to seven beaches in the southern North Sea and modeled time series of five general categories of marine litter, such as litter from fishing, shipping, and tourism. Results of regression analyses show that general categories were predicted significantly moderately to well. Measured and modeled data were in the same order of magnitude, and minima and maxima overlapped well. Neural networks were found to be eligible tools to deliver reliable predictions of marine litter with low computational effort and little input of information.

The relation of litter with bathing areas typologies, number of users and scenic value. The case study of São Miguel (Azores)

Several works on public perception of bathing area quality state that litter is one of the top concerns of users. Litter was also considered the top concern of bathing users regarding Bathing Area (BA) quality in Sao Miguel (Azores). This fact highly justifies the need to evaluate BA in this perspective. During 2009 summer 11 bathing areas, covering all the proposed BA typologies in Sao Miguel Island, were assessed and rated according to litter. The methodology was based on the EA/Protocol (Environmental Agency (UK)/National Aquatic Litter Group 2000). BA were graded from A to D (very good, good, fair and poor) on several litter categories: sewage related debris, gross litter, general litter, harmful litter, accumulations, oil or similar and faeces. Transects were sampled at 7 (o’clock) p.m. on sunny Sundays to achieve extreme situations. From the bathing areas assessed 4 were rated B (Good) and 7 rated C (Fair). During the same period the users perception regarding litter was assessed. Data obtained was related to bathing areas Scenic Evaluation Index (D) value, establishing a 5-class evaluation system. Some interactions between these factors (litter, BA typologies, public perception and scenic value) were analyzed and discussed. Scenic value doesn’t seem to affect users behavior regarding litter, however seems to affect the perception of users. Some of the bathing areas typologies seem to be more affected by litter, especially Urban and Semi-urban sandy beaches. BA cleaning processes and the relation of users with the area are the main reasons to this fact.

MICROHABITAT USE BY GREY JUNGLEFOWL ( GALLUS SONNERATII) AT THENI FOREST DIVISION, WESTERN GHATS OF TAMIL NADU, SOUTH INDIA

The overall results showed 64% of Grey Junglefowl sightings in 41% shrub cover category. Use of litter cover categories was (67%) in <40 % and the use of litter depth was in <4 cm litter category. The 67% sightings were obtained in <4 tree number category.

Placental efficiency and intrauterine resource allocation strategies in the common marmoset pregnancy

Mothers and fetuses are expected to be in some degree of conflict over the allocation of maternal resources to fetal growth in the intrauterine environment. Variation in placental structure and function may be one way a fetus can communicate need and quality to its mother, potentially manipulating maternal investment in its favor. Whereas common marmosets typically produce twin litters, they regularly give birth to triplet litters in captivity. The addition of another fetus is a potential drain on maternal resource availability and thus a source of elevated conflict over resource allocation. Marmoset littermates share a single placental mass, so that differences in the ratio of fetal to placental weight across litter categories suggest the presence of differential intrauterine strategies of resource allocation. The fetal/placental weight ratio was calculated for 26 marmoset pregnancies, representing both twin and triplet litters, to test the hypothesis that triplet fetuses respond to intrauterine conflict by soliciting placental overgrowth as a means of accessing maternal resources. In fact, relative to fetal mass, the triplet marmoset placenta is significantly undergrown, with individual triplets associated with less placental mass than their twin counterparts, suggesting that the triplet placenta is relatively more efficient in its support of fetal growth. There still may be an important role for maternal-fetal conflict in the programming of placental structure and function. Placental adaptations that solicit potential increases of maternal investment may occur at the microscopic or metabolic level, and thus may not be reflected in the size of the placenta as a whole.

Impact of a eucalyptus (Eucalyptus globulus Labill.) plantation on the nutrient content and dynamics of coarse particulate organic matter (CPOM) in a small stream

Litterfall inputs, benthic storage and the transport of coarse particulate organic matter (CPOM) were studied in two headwater streams, one flowing through a mixed deciduous forest and one through a plantation of Eucalyptus globulus. Vertical and lateral traps, transported CPOM and benthic CPOM were sampled monthly to biweekly and sorted into four categories: leaves, twigs and bark, fruits and flowers and debris. The litterfall inputs were about 20% lower at the eucalyptus site but this reduction was unevenly distributed among the litter categories. The reduction of the nitrogen and phosphorus inputs was larger (50%) than that of CPOM because of the low nutrient concentration of the CPOM at the eucalyptus site. Transported CPOM was also lower at the eucalyptus site. Although total CPOM inputs to the stream were reduced in the eucalyptus plantation, benthic storage of CPOM was 50% higher due to (1) high inputs of CPOM and low discharge during summer, (2) more twig and bark inputs, (3) eucalyptus leaves being retained more efficiently in the stream than deciduous leaves (4) a lower discharge, which may in part be attributable to eucalyptus-induced changes in the hydrological cycle. Increased retention balanced lower nitrogen and phosphorus content of CPOM, so benthic storage of nitrogen and phosphorus was similar at both sites. This work demonstrates that the timing, quality and quantity of inputs and benthic storage of CPOM in streams changes substantially because of the substitution of natural deciduous forest with eucalyptus plantation. Maintenance of buffer strips of natural vegetation may be the best way to protect ecological functioning of small, forested streams.

Litter fall, nitrogen and phosphorus reabsorption inZygophyllum album(Zygophyllaceae) in the Mediterranean Coastal Region and in Suez Desert Region

Plant litter of Zygophyllum was collected in the desert region (Suez desert region and Mediterranean coastal region). The litter was subdivided into leaves, stems, flowers and fruits. The mean total litter production was 173.3 g per shrub per year in the Mediterranean region and 138.3 g per shrub per year in the Suez region. Leaves constitute generally the largest litter category composing 70-76% of the total litter. The nitrogen and phosphorus concentration of fresh leaves was found to be twofold more than that of nitrogen and phosphorus found in the litter.

Marine litter prediction by artificial intelligence

Artificial intelligence techniques of neural network and fuzzy systems were applied as alternative methods to determine beach litter grading, based on litter surveys of the Antalya coastline (the Turkish Riviera). Litter measurements were categorized and assessed by artificial intelligence techniques, which lead to a new litter categorization system. The constructed neural network satisfactorily predicted the grading of the Antalya beaches and litter categories based on the number of litter items in the general litter category. It has been concluded that, neural networks could be used for high-speed predictions of litter items and beach grading, when the characteristics of the main litter category was determined by field studies. This can save on field effort when fast and reliable estimations of litter categories are required for management or research studies of beaches––especially those concerned with health and safety, and it has economic implications. The main advantages in using fuzzy systems are that they consider linguistic adjectival definitions, e.g. many/few, etc. As a result, additional information inherent in linguistic comments/refinements and judgments made during field studies can be incorporated in grading systems.

Decomposition of sun and shade leaves from three deciduous tree species, as affected by their chemical composition

Freshly fallen leaf litter from sweet chestnut (Castanea sativa Mill), oak (Quercus robur L.) and beech (Fagus sylvatica L.) trees were classified into sun, intermediate and shade leaf types and analysed for N, acid detergent fibre, holocellulose, and lignin. In addition, the sugar constituents of structural polysaccharides (mainly from hemicelluloses) were determined after trifluoracetic acid (TFA) hydrolysis, and the phenylpropanoid (PPD) derivatives of lignin after alkaline CuO oxidation. The litters were decomposed in laboratory microcosms for 2 years. Decomposition rates were initially rapid and then plateaued, but differences in mass losses for the leaf litter categories, and between the three species, were significant at 6, 12, 18 and 24 months. Mean mass losses after 24 months were 49.6% for chestnut, 40.4% for oak and 26.3% for beech. Mean losses for chestnut, oak and beech litter categories were 48.6%, 38.2% and 24.6%, respectively, for sun leaves, and 51.0%, 44.5% and 28.5%, respectively, for shade leaves. Initial lignin concentrations showed a negative correlation with mass losses over the first 6 months but initial acid detergent fibre was a better predictor of decomposition rates after 24 months. Within species, however, total extractable sugars and PPD concentrations reflected differences in decomposition rates between the different categories of leaf types. The analysis for specific carbohydrates and lignin derivatives improved the resolution of litter quality characterisation but did not explain the observed patterns of decomposition in long-term laboratory incubations. It is suggested that these may be affected by influence of the culture conditions on the composition of fungal communities.

Differences in litter characteristics and macroinvertebrate assemblages between litter patches in pools and riffles in a headwater stream

We compared the abundance of litter categories (coarse particulate organic matter 1–16 mm, leaves >16 mm, and small woody detritus 16–100 mm) and macroinvertebrate assemblages between natural litter patches in pools and riffles in a headwater stream. Litter patches in pools were formed under conditions of almost no current (<6 cm s−1), but in riffles they were formed under variable current velocities (13–89 cm s−1). Although the abundance of each litter category exhibited seasonal change, leaves were more abundant in riffles, and coarse particulate organic matter and small woody detritus were more abundant in pools throughout the study period. Macroinvertebrate assemblages in pools and riffles also changed seasonally but distinctly differed from each other. Shredders, collector-gatherers, and predators were the dominant functional groups in abundance in both pools and riffles, but the dominant shredders were caddisflies in pools and stoneflies in riffles. It is considered that the hydraulic conditions affected macroinvertebrate assemblages directly and indirectly through influences on the characteristics of litter retained in the patches. Our results suggest that the relative abundance of litter patches in pools and riffles largely affects the macroinvertebrate community structure of the headwater stream.

Aquatic litter, management and prevention—the role of measurement

Methodology of litter management has many forms and increasingly measurement is linked to management. By providing measured profiles of the quality of litter types, trends in the input of new items can be assessed and prevention programmes directed more effectively to sources. Developing methodologies and their application to management cover three main areas. 1. Rapid appraisal where a framework of litter categories and pollution grades is used to map litter distribution on a broad geographic scale. 2. The benefits of using the ‘species-area’ approach with transects to enable quantitative data to be collected in a cost efficient manner. 3. Linking litter to an input source, requires that the qualities of individual litter items be assessed. The species area approach is useful in this context since by the time that 300–400 litter items have been described the main composition of a sample can be characterized and input sources attributed.

Litter dynamics of recently harvested and mature bamboo savannas in a dry tropical region in India

ABSTRACTAnalysis of litterfall, nutrient return and floor mass dynamics was made in mature and recently harvested bamboo savanna sites in a dry tropical region in India. The total annual litterfall was 590 and 267 g m–2 in mature and harvested sites, respectively. Of the total litterfall, 58–77% by weight was contributed by leaf litter. Although litterfall occurred throughout the year, as much as 72–83% of the leaf litterfall was recorded during winter (December–February). Seasonal distribution of total litterfall was: rainy 12–22% of annual, winter 64–65% and summer 13–22%. Nutrient concentrations in bamboo leaf litter were low compared with the other species growing in the same region. Annual nutrient return through litterfall amounted to: 28–49 kg N ha–1, 1.32.9 kg P ha–1, 33–85 kg Ca ha–1, 12–32 kg K ha–1 and 1.4–2.8 kg Na ha–1. While maximum accumulations of fresh litter on the ground occurred in summer, the partly decayed and particulate litter categories peaked in the rainy season. Decaying litter categories showed 1.5–3 times greater nutrient concentrations than the concentrations in fresh leaf litter. Marked immobilization of N and P occurred in decomposing leaf and particulate litter. The mean annual nutrient content of the floor was (kg ha–1): N 29–40, P 1.0–1.9, Ca 13.8–23.9, K 14.6–15.3 and Na 0.85–0.99. The annual turnover in litter layer was: 63–81% for dry mass and 64–90% for different nutrients.

LITTER FALL AND NITROGEN REABSORPTION IN ZYGOPHYLLUM DUMOSUM IN THE NEGEV DESERT

ABSTRACT In 1983–1984 plant litter of Zygophyllum dumosum was collected in traps in the Negev Desert of Israel. The litter was handsorted into leaves, stems, flowers, and fruits. The mean total litter production was 433 g per shrub, about 70 kg ha−1 yr−1 of litter. Leaves were generally the largest litter category constituting 65–74% of the total. The total nitrogen content of the leaves was found to be significantly higher (p < 0.005) than the total nitrogen found in litter traps. Unexpectedly, an increase in total leaf nitrogen content was recorded in 1984 in spite of lower rainfall.

Preliminary studies of man-made litter in the Firth of Forth, Scotland

Short-term studies on man-made litter deposited on the beaches of the Edinburgh coastline of the Firth of Forth, Scotland, have demonstrated that containers of all kinds, plastic bags, plastic sheeting and clothing, comprise the main and dominant components of the nineteen categories of litter analysed. Most of the litter is of local origin either deposited in situ or washed ashore from neighbouring water's-edge tips. Very little evidence was found of litter washed ashore being of foreign origin or having been tipped overboard from ships at sea. Much of the smaller items of litter are discarded by visitors to the beach. The solution to the problem is seen as one of education at all levels rather than ineffective punitive measures.

Litterfall and Decomposition Processes in the Coastal Fynbos Vegetation, South-Western Cape, South Africa

(1) Random litterfall and litter production and decomposition of Leucospermum parile and Thamnochortus punctatus were monitored between 1981 and 1983 in a 5-7-yr-old stand of coastal fynbos, south-western Cape, South Africa. This vegetation has a characteristic physiognomy consisting of proteoid, ericoid and restioid elements. (2) Annual litter production was 84 and 72 g m-2 during 1981-82 and 1982-83 respectively with summer-autumn being the main period of litterfall; the major litter came from the ericoid elements. No differences were found in fats and waxes, soluble carbohydrates, soluble phenolics and total nitrogen between leaf litter of proteoid and ericoid elements and culm litter of the restioid elements. (3) Mean annual litter production under the canopies of L. parile was 357 and 429 g m-2 during 1981-82 and 1982-83, respectively, with 51-58% being leaf litter. Seasonal variations were found in the methanol-soluble carbohydrates (summer maximum) and lignin (winter maximum) in the leaf litter of L. parile and a withdrawal of 41% nitrogen and 25-50% phosphorus was calculated during leaf abscission. (4) Female plants of T. punctatus had an annual litter production of 23 g m-2 compared with 12 g m-2 for males. The main litter category from both sexes was inflorescence parts. Holocellulose was the main organic constituent in fertile culm litter of both sexes of T. punctatus and the restioid group generally. (5) Turnover times of dry mass were calculated to be 14-5 and 11.4 yr for leaf litter of L. parile and sterile culms of T. punctatus, respectively, but male flowerheads of T. punctatus showed no significant decay. (6) Methanol-soluble carbohydrates, phenolics and holocellulose declined at approximately similar rates in decomposing leaves of L. parile. Changes in nitrogen and phosphorus contents in decomposing leaves of L. parile were negligible but accumulations of potassium, magnesium, calcium and iron were demonstrated. (7) These results are compared with those of other mediterranean-type ecosystems. The frequent fires in the fynbos vegetation may preclude the development of a steady-state litter.

Litter Fall From Shrubs in the Northern Mojave Desert

Plant litter was collected in traps from 8 to 10 replicates each of Ambarosia dumosa. Ephedra nevadensis, Krameria parvifolia, Larrea tridentata, Lycium andersonii, and Lycium pallidum in Rock Valley, southern Nevada, USA. Collections were made at biweekly to monthly intervals from 1975 to 1977 and handsorted into leaves, stems, flowers, and fruits. Lycium pallidum produced the most litter, with annual means ranging from 52 to 173 g per shrub. Annual means per shrub for other species ranged from 39 to 89 g (Lycium andersonii), 27 to 77 g (Larrea tridentata), 20 to 29 g (E. nevadensis), 6 to 18 g (K. parvifolia), and 3 to 21 g (A. dumosa). Litter fall was generally correlated with annual rainfall, which was low in 1975 (62 mm), high in 1976 (223 mm), and close to the long—term mean in 1977 (141 mm). Leaves were generally the largest litter category, followed by stems, fruits, and flowers. Large sample variations were found, particularly for reproductive parts. Aboveground litter fall from the six species, which comprise °82% of perennial plant biomass and °81% of shrub cover in Rock Valley, was about 117 kg/ha in 1975 and 318 kg/ha in 1976. Total aboveground litter fall for Rock Valley (all perennial and annual plants) was estimated to be 194 kg/ha in 1975 and 530 kg/ha in 1976. Distinct litter fall patterns occurred for shrub species and litter categories. Most litter fell during the summer months, with individual species peaks reflecting particular phenologies. Significant amounts of live aboveground biomass were shed as litter. Amounts of litter from the six species ranged from 7 to 83% of their respective live aboveground biomass.

Seasonal transfers of assimilated 14C in grassland: Plant production and turnover, soil and plant respiration

Six areas of native grassland were labelled with 14C during a growing season. Transfers from the foliage to the roots and root respiration were measured. Plant production and turnover rates were determined by sampling the labelled material at different periods following exposure to 14CO 2. Above to beneath ground plant production ratios ranged between 1.1 and 1.9 with maximal translocation to the roots occurring during the drier summer months. The distribution of the photosynthates in the roots at different depths changed with time and soil moisture content. The upper part of the soil (0–10 cm) contained 49–77% of the labelled C found beneath the soil surface. Measurement of transfers with time of the above ground labelled C from living to dead plant and litter categories gave an insight into foliage dynamics and made it possible to estimate the seasonal shoot production at 130g Cm −2 (1300kg ha −1). Root growth represented 100g Cm −2 (1000 kg ha −1). Calculations of root and soil respiration were based on the CO 2 profiles in the soil. The fluxes of labelled and unlabelled CO 2 at the soil surface were estimated using the diffusion equation method. Respiration by roots and closely associated soil organisms accounted for 12 per cent of the net assimilation of CO 2 by the plants. This proportion was constant throughout the season and represented 19 per cent of the total CO 2 evolved at the soil surface.

Litter Fall after Wildfire in Virgin Forests of Northeastern Minnesota

The Little Sioux Fire burned virgin forests in northeastern Minnesota on 14–17 May 1971. We monitored litter fall for 3 years after the fire in mixed conifer–deciduous forests both within and outside the fire boundaries. We separated four categories of litter: conifer needles, deciduous leaves, woody material, and miscellaneous material. Significantly more litter fell in the burned area during the 3 years (575 g/m2) than in the unburned areas (340 g/m2). Major differences were related to an increased fall of needles from conifers that had been killed by the fire and an increased fall of woody material from dead trees on the burn. Needles falling from these dead trees had significantly higher concentrations of N, P, and K and lower concentrations of Ca than did needles falling in the unburned areas. No other litter components showed significant differences in concentrations of N, P, K, Ca, and Mg between the burned and unburned areas for the 3 years of the study. By the 3rd year after the fire, less litter fell on the burn than on the unburned area, and the proportion of litter in all components except needles was similar in both areas.