Seasonal occurrence and distribution of myxomycetes on different types of leaf litter in a warm temperate forest of western Japan

The seasonal occurrence and distribution of myxomycetes on different types of newly defoliated leaf litter were examined in a secondary forest in a warm temperate region of western Japan. The two types of leaf litter (deciduous trees, Prunus verecunda and Quercus variabilis, and evergreen trees, Q. glauca and Cinnamomum camphora) were incubated in trays on the forest floor. A total of 45 myxomycete species were recorded from 3021 collected samples that occurred at the July peak during the warmest and humidest season from April to November. The occurrence of species was significantly related to the changes in mean temperature and minimum temperature on both leaf types under humid conditions. Myxomycete assemblages were divided into three seasonal phases. Most of the species occurred in June–September, while a few species demonstrated characteristic distributions; i.e., Didymium melanospermum appeared in April– May and Diderma umbilicatum appeared in October– November. The respective leaf types supported the reproduction of myxomycetes with high species richness and diversity, with 34 species and H’ = 2.59 on deciduous trees and similarly 30 species and H’ = 2.49 on evergreen trees. Several species, however, exhibited a preference for either the deciduous tree or evergreen tree leaves. Thus, a mixed forest that defoliates during different two seasons yields a greater species diversity of myxomycete assemblage.     

Patterns of occurrence of myxomycetes in a spruce forest in South Sweden

A 4-yr field study was carried out on selected species of myxomycetes. Reticularia jurana, Symphytocarpus flaecidus, Amaurochaete atra , and A. tubulina occur predominantly in May–June. Ceratiomyxa fruticulosa, Stemonitis axifera, S. fusca, S. hyperopta , and Fuligo septica in June–August, and Colloderma oculatum, Trichia botrytis, T. decipiens , and Fuligo muscorum in September–October. Lycogala epidendrum may occur from May to October. Whereas several species seem to be restricted to late autumn, those appearing in spring and early summer are occasionally found also later in the season. Many species with large plasmodia are rare under arid conditions. Complex factors probably influence spore germination, and it is often impossible to explain a sudden abundance of a species merely from temperature and precipitation. Several species show clear substrate preferences. Plasmodia may develop in cavities in wood and then move out to the surface to fructify. Insects are probably important for the dispersal of several species. Invertebrates, among them snails, are predators on plasmodia as well as on fructifications.     

Community of dark-spored myxomycetes in ground litter and soil of taiga forest (Nizhne-Svirskiy Reserve,Russia) revealed by DNA metabarcoding

The diversity of dark-spored myxomycetes in forest ground litter and soil from four study plots across a fire chronosequence in Nizhne-Svirskiy Nature Reserve (northwest of Russia) was assessed by a DNA metabarcoding approach. The history of fire disturbances and the season of sampling influenced the composition of myxomycete assemblages. Several species showed substrate preferences different from what is known from fruiting body records. A high abundance of nivicolous species in the majority of the samples suggests that this ecological group constitutes a common element of soil microbial communities in lowland taiga forests. Four species are reported for the Leningrad region for the first time. Our results support the hypothesis that amoebae populations of myxomycetes may have much wider ecological niches than indicated by records of fructifications, and further environmental studies may provide valuable new insights on myxomycete ecology and distribution.     

The occurrence of myxomycetes in wood

Although the fruiting bodies of myxomycetes are commonly found associated with coarse woody debris in forest ecosystems throughout the world, there is no direct evidence that these organisms actually live within wood. In the research reported herein, surface sterilisation of pieces of wood taken from the branches of eight different tree species and the subsequent culturing of slivers of wood collected from within the interior of those branches clearly revealed the presence of the amoeboflagellates of myxomycetes. No evidence of the occurrence of plasmodia within wood was found, but amoeboflagellates emerged from 47 % of the wood slivers placed in culture.     

Abundance and community structure of forest floor spiders following litter manipulation

Summary We conducted a field manipulation of forest litter to determine effects of litter structure (flat vs curly leaves) on forest floor spiders in natural and artificial leaf litter. Artificial litter made of vinyl, was nondecomposable and non-nutritive. In this way, we separated interactions of effects of litter as a nutritional base and as a spatially heterogeneous environment on litter-dwelling spiders.Structural complexity of litter significantly affected abundances of some forest floor spiders. In particular, abundances of web-building spiders were lower in treatments of flat leaves. Litter nutritional content and structural complexity only slightly affected spider species composition and richness. Results suggest that litter depth is more influential than are litter structural complexity or nutritional content, in organizing forest floor spider communities.     

Differences in litter mass change mite assemblage structure on a deciduous forest floor

Few mechanisms that determine the assemblage structure of mites have been identified. Whilst the relative abundance of soil fauna is known to change with humus form, the degree to which the quantity of litter inputs play a part in these changes has not been investigated. We tested the response of oribatid and mesostigmatid mites in litter and soil layers to increasing levels of birch Betula pubescens litter to test whether litter mass could affect the mite assemblage. Six litter treatments (1, 2, 4, 8 and 12×natural litter mass and complete litter removal) were established in November 2004 and the soil and litter communities sampled in October 2005. Species composition of oribatids was distinct for the soil and litter. There was no apparent effect of increasing litter mass on the soil mite assemblage. In the litter layer, the number of oribatids g⁻¹ of litter showed a strong negative relationship with increasing litter mass whilst the number of mesostigmatids g⁻¹ of litter was unresponsive to litter mass. Hence, the relative abundance of these two groups altered with increasing litter mass. The response of the oribatid groups Oppiidae and Poronota followed this negative relationship with litter mass but Phthiracaridae appeared less affected. Consequently, there was a subtle shift in the relative abundance of these groups with increasing litter mass. Our results demonstrate that oribatids as a whole and within groups respond in a predictable manner to increases in litter mass whilst mesostigmatids are unresponsive. Whilst there are undoubtedly biological and physical aspects that vary with litter mass, litter mass itself, is able to explain some patterns in the assemblage of oribatid mites.     

红松林和针阔叶混交林下黏菌物种多样性研究

为探讨不同林型下黏菌物种多样性的差异,本文在凉水国家级自然保护区内红松林和针阔叶混交林两种林分中开展调查研究,共采集黏菌样本242份,基于形态特征鉴定为4目7科17属50种黏菌,其中鲜红团网菌Arcyria insignis、网格筛菌Cribraria paucidictyon和玫瑰绒泡菌Physarum roseum...     

Estimates of forest floor litter frog communities: A comparison of two methods

Estimates of forest leaf litter frog density, mass, richness and diversity given by the widely used 8 m × 8 m large plot method (LPM) were compared with estimates obtained by a newly proposed method (small 2 m × 1 m plots with leaf removal; SPLR). The study site was an undisturbed area of the Atlantic Rainforest of Ilha Grande, an island located in the south of Rio de Janeiro State, Brazil. Twenty‐four LPM (totalling 1536 m² of forest floor) and 90 SPLR (totalling 180 m² of forest floor) were performed. The estimates obtained by the two methods differed markedly, indicating that even using a much smaller sampling area (11.7% of that of LPM), SPLR gave frog density estimates six times higher, and frog mass estimates approximately 2.5 times higher than estimates provided by LPM. The species richness and diversity obtained by the two methods were similar, despite the fact that the total area sampled with SPLR was much smaller. These data suggest that LPM may underestimate the abundance and biomass of leaf litter frogs in a given area.     

Tree leaf litter composition and nonnative earthworms influence plant invasion in experimental forest floor mesocosms

Dominant tree species influence community and ecosystem components through the quantity and quality of their litter. Effects of litter may be modified by activity of ecosystem engineers such as earthworms. We examined the interacting effects of forest litter type and earthworm presence on invasibility of plants into forest floor environments using a greenhouse mesocosm experiment. We crossed five litter treatments mimicking historic and predicted changes in dominant tree composition with a treatment of either the absence or presence of nonnative earthworms. We measured mass loss of each litter type and growth of a model nonnative plant species (Festuca arundinacea, fescue) sown into each mesocosm. Mass loss was greater for litter of tree species characterized by lower C:N ratios. Earthworms enhanced litter mass loss, but only for species with lower C:N, leading to a significant litter × earthworm interaction. Fescue biomass was significantly greater in treatments with litter of low C:N and greater mass loss, suggesting that rapid decomposition of forest litter may be more favorable to understory plant invasions. Earthworms were expected to enhance invasion by increasing mass loss and removing the physical barrier of litter. However, earthworms typically reduced invasion success but not under invasive tree litter where the presence of earthworms facilitated invasion success compared to other litter treatments where earthworms were present. We conclude that past and predicted future shifts in dominant tree species may influence forest understory invasibility. The presence of nonnative earthworms may either suppress of facilitate invasibility depending on the species of dominant overstory tree species and the litter layers they produce.     

Response of dissolved organic matter in the forest floor to long-term manipulation of litter and throughfall inputs

Dissolved organic matter (DOM) contributes to organic carbon either stored in mineral soil horizons or exported to the hydrosphere. However, the main controls of DOM dynamics are still under debate. We studied fresh leaf litter and more decomposed organic material as the main sources of DOM exported from the forest floor of a mixed beech/oak forest in Germany. In the field we doubled and excluded aboveground litter input and doubled the input of throughfall. From 1999 to 2005 we measured concentrations and fluxes of dissolved organic C and N (DOC, DON) beneath the Oi and Oe/Oa horizon. DOM composition was traced by UV and fluorescence spectroscopy. In selected DOM samples we analyzed the concentrations of phenols, pentoses and hexoses, and lignin-derived phenols by CuO oxidation. DOC and DON concentrations and fluxes almost doubled instantaneously in both horizons of the forest floor by doubling the litter input and DOC concentrations averaged 82 mg C l⁻¹ in the Oe/Oa horizon. Properties of DOM did not suggest a change of the main DOM source towards fresh litter. In turn, increasing ratios of hexoses to pentoses and a larger content of lignin-derived phenols in the Oe/Oa horizon of the Double litter plots in comparison to the Control plots indicated a priming effect: Addition of fresh litter stimulated microbial activity resulting in increased microbial production of DOM from organic material already stored in Oe/Oa horizons. Exclusion of litter input resulted in an immediate decrease in DOC concentrations and fluxes in the thin Oi horizon. In the Oe/Oa horizon DOC concentrations started to decline in the third year and were significantly smaller than those in the Control after 5 years. Properties of DOM indicated an increased proportion of microbially and throughfall derived compounds after exclusion of litter inputs. Dissolved organic N did not decrease upon litter exclusion. We assume a microbial transformation of mineral N from throughfall and N mineralization to DON. Increased amounts of throughfall resulted in almost equivalently increased DOC fluxes in the Oe/Oa horizon. However, long-term additional throughfall inputs resulted in significantly declining DOC concentrations over time. We conclude that DOM leaving the forest floor derives mainly from decomposed organic material stored in Oe/Oa horizons. Leaching of organic matter from fresh litter is of less importance. Observed effects of litter manipulations strongly depend on time and the stocks of organic matter in forest floor horizons. Long-term experiments are particularly necessary in soils/horizons with large stocks of organic matter and in studies focusing on effects of declined substrate availability. The expected increased primary production upon climate change with subsequently enhanced litter input may result in an increased production of DOM from organic soil horizons.     

A quantitative study of the forest floor biomass,litter fall and nutrient return in a Pinus roxburghii forest in Kumaun Himalaya

The present paper reports on the forest floor biomass, litter fall, nutrient return and turnover of organic matter in a Pinus roxburghii forest in Kumaun Himalaya. Peak values of fresh leaf litter, partially decomposed litter and wood litter on the forest floor occurred in April, May and September, respectively. The relative contribution of partially decomposed material to total forest floor biomass remained greatest throughout the annual cycle. The biomass of herbaceous vegetation was maximal in September with a total annual net production of 151 g m^-2. The total annual litter fall was 895 g m^-2, of which tree, shrub and herb litters accounted for 82.4%, 0.6%, and 16.8%, respectively. Annual nutrient return in kg ha^-1 through litter fall amounted to 278.6 ash, 73.9 N, 5.5 P, 79.7 Ca, 15.1Mg, 20.7 K and 3.6Na. The turnover rate for tree litter was 48% and that for various nutrients on the forest floor ranged between 40–79%.     

Effects of leaf litter on the growth of boreal feather mosses: Implication for forest floor development

Question: What is the effect of leaf litter on growth and mortality of feather mosses. Three experiments were conducted to isolate the shading effect from the effect of leaching of soluble compounds from the leaf litter effect on feather moss mortality and growth. Location: Edmonton, Alberta and the northern boreal coniferous forest, west‐central Alberta, Canada. Methods: In a field experiment Populus tremuloides (aspen) leaf litter was applied to beds of feather mosses dominated by Hylocomium splendens. Treatments were one layer of leaves held in place with netting; one layer of leaves coarsely ground, sprinkled over the moss layer; a shade cloth equivalent to one layer of leaves; and a control. In two growth chamber experiments, the application of aqueous extracts of P. tremuloides and Pinus contorta leaf litter and the effect of shade and soluble carbohydrates were tested on the growth and mortality of Ptilium crista‐castrensis. Results: Mortality of Hylocomium was greatest under the intact leaves, followed by the treatments using shade cloth and ground leaves and finally the control. The application of aqueous extracts of aspen leaf litter resulted in senescence or death of nearly all Ptilium shoots compared to no effects for the control or for similar extracts of pine needle litter. Extracts from aspen litter had greater concentrations of phenolic compounds and soluble sugars than pine extracts. Addition of sugars to Ptilium allowed it to grow and accumulate carbohydrates, even in low light conditions. Conclusions: Results suggest that broad‐leaved deciduous overstory species can limit the growth of feather mosses through their leaf litter and by implication affect the humus form, nutrient cycling, and understory composition of these forests.     

Effects of water and nutrient supply on amount and on nutrient concentration of litterfall and forest floor litter in Eucalyptus globulus plantations

A field experiment was initiated in March 1986 in central Portugal to evaluate the influence of water and nutrient supply on the productivity of E. globulus. The treatments applied were, irrigation plus fertiliser, irrigation and the application of fertilisers in rainfed plots. The control received neither fertilisers nor irrigation. The annual pattern litterfall was measured over a period of 5 years and the litter layer was quantified 6 years after planting. The amount of litterfall varied with the treatments. Simultaneous water and nutrient supply increased significantly litterfall, in respect to control. In rainfed conditions the timing of the maximum of litterfall was anticipated relative to the irrigated plots. However, the time of maximum litterfall did not coincide with the dry season but rather with period of maximum growth in each treatment. The N and P concentration was higher in the litterfall of the two fertilised treatments than in the others. The lowest concentrations of N and P in the leaf litter were coincident with the summer period in all treatments. The withdrawal of N and P ranged between 32 and 65% according to treatment and season. The deliverance of nutrients through litterfall was strongly increased by simultaneous water and nutrient supply. The supply of fertilisers in rainfed conditions promoted higher deliverance of nutrients than in the plots irrigated only. The mass of the litter layer was significantly increased by simultaneous water and nutrient supply. Application of fertilisers induced an increase in N and P concentration and a decrease in C/N ratio of the litter layer. Treatments and C/N values did not influence apparently the proportion of carbon, N and P released through mineralization from the litter layer. The non-fertilized treatments showed a more efficient N cycling than the others.     

Predation on artificial ground nests in relation to forest fragmentation, agricultural land and habitat structure

The impacts of forest fragmentation agricultural land and habitat structure on depredation of artificial ground nests were studied in the cultivated area in central Finland and in the forest dominated area in Finnish Lapland The overall predation rate did not differ between the regions The overall predation rate was also independent of landscape characteristics forest patch size and the distance to patch edge However, nest predation was clearly affected by the agricultural land since the robbing rate in forest edges was higher near farmlands than further away This effect was caused by avian predators which proportional importance in predation was higher in the agricultural landscape than in the forest landscape In both regions, depredation correlated positively with high numbers of pine and spruce This can be mainly explained by the preference of predators over coniferous forest habitat as a living or hunting area     

Effect of an invasive ground cover plant on the abundance and diversity of a forest floor spider assemblage

Ground dwelling spiders are important predators in the detrital food web, which plays important roles in nutrient cycling and energy flow in forest ecosystems. The cursorial spider assemblage in a Beech-Maple forest in southwestern Michigan at sites where and invasive plant, Vinca minor, has invaded was compared to a native site within the same forest and to the forest prior to invasion by the plant. Pitfall traps were used to sample cursorial spiders over the course of a summer. Vinca minor substantially altered the forest floor spider assemblage. The invasive plant reduced the total activity-abundance of spiders by nearly 49% and depressed species diversity and evenness; in contrast, species richness was not affected. We found that V. minor changed the guild and family structure with wolf spiders being common at sites where the plant had invaded. Vinca minor reduced the abundance of vagrant web building and crab spiders. Similarity indices revealed that the spider communities between the two sites were quite dissimilar (Bray-Curtis = 0.506; Jaccard’s = 0.520). Importantly, comparison to a study conducted in the same forest 28 years earlier showed that the cursorial spider assemblage in the forest prior to Vinca invasion was very different than it was after Vinca invaded but was similar to the current native site in species and guild composition. We conclude that invasion by Vinca has caused the striking changes we observed in community organization of this important group of forest floor predators. We suggest that changes in the physical structure of the litter/soil microhabitat with the invasion of V. minor are likely the cause of the substantial impacts of the plant on the spider assemblage.     

Rapid assessment of the distribution of myxomycetes in a southwestern Amazon forest

The distribution of fruit bodies of myxomycetes under different ecological conditions at the Los Amigos Biological Station in southeastern Peru was studied. Six study areas were surveyed using a combined field-laboratory methodology under different climatic conditions. Sixty species were recorded and differences in fruit body abundance and structure of the assemblages were found among collecting periods. A diversity analysis based on fruit bodies showed that values were predominantly higher during the dry period. An analysis of microenvironmental conditions applied to a subset of data collected in the field showed that pH and substratum diameter accounted for most of the variation. In addition, the most abundant myxomycetes based on fruit body occurrence showed a multivariate arrangement that suggests the existence of functional groups.     

Nutrients in the litter on jarrah forest soils

The amount of litter and its nutrient composition have been measured at seven sites on various lateritic soils within the jarrah (Eucalyptus marginata Donn ex Sm.) forest near Dwellingup, Western Australia. The weight of litter accumulated during 6 years ranges from 9 tonnes/ha for forest growing on yellow sand to 18 tonnes/ha for forest on reddish gravels. The litter on the reddish gravels contains more than twice the amounts of N, P, K and S in litter on yellow sand and grey and yellow gravels. The proportion of fine material in the forest floor litter increases with total litter weight. Phosphorus, which is less mobile than other nutrients tends to accumulate in this fine component. There are large differences between the foliar nutrient levels of jarrah and Banksia grandis Willd. (e.g. P: 0.041%, 0.025%; K: 0.57%, 0.34%; Mg: 0.43%, 0.21%; Mn: 177 μg/g. 730 μg/g). However, these differences are not reflected in the litter from sites with and without B. grandis understorey. Soil differences and the predominant contribution of the overstorey to the litter appear to be the main factors affecting the litter composition.     

Distribution,occurrence and characterization of entomopathogenic fungi in agricultural soil in the Palestinian area

The occurrence of entomopathogenic fungi was investigated in irrigated vegetable fields and citrus orchards soils, over a nine-month period (April-December 1999), using the Galleria bait method (GBM). Entomopathogenic fungi were found to occur in 33.6% of the soil samples studied, with positive samples yielding 70 fungal isolates, belonging to 20 species from 13 genera. Conidiobolus coronatus was the most frequent and abundant entomopathogenic species recovered, comprising 31.4% of the total number of isolates. Soil pH, soil moisture content and the geographical location had minor or no effect on the isolation of entomopathogenic fungi in the fields studied. On the other hand, organic matter content of soil, and vegetation type were found to significantly affect the occurrence of entomopathogenic fungi in soil habitats, with orchard fields yielding larger numbers of isolates than vegetable fields. Using Koch's postulates the pathogenicity of fungal isolates to Galleria larvae was found to range from 16-100% (mortality rate). Isolates of C. coronatus proved to be the most virulent isolates recovered. The effect of media and temperature on mycelial growth rate, conidial production and conidial germination of six entomopathogenic fungal species (C. coronatus, Entomophaga grylli, Erynia castrans, Hirsutella jonesii, Paecilomyces farinosus and Sporodiniella umbellata) was also studied. Mycelial growth rate, spore production and spore germination were significantly affected by media, temperature and isolates. In view of the present results, C. coronatus appears to be a good candidate for pest control in agricultural soils, as it has a wide tolerance to agricultural practices, has frequently been isolated from both vegetable and orchard fields, and is characterized by high mycelial growth rate, conidial production and conidial germination.