Leaf Litter Layer Research Articles

Shifts in the diversity of an amphibian community from a premontane forest of San Ramón, Costa Rica

Biological communities are experiencing rapid shifts of composition in Neotropical ecosystems due to several factors causing population declines. However, emerging evidence has provided insights on the adaptive potential of multiple species to respond to illnesses and environmental pressures. In Costa Rica, the decline of amphibian populations is a remarkable example of these changes. Here we provide evidence of variation in the amphibian richness of a premontane forest of San Ramón (Costa Rica) across a ~30 year period. We also quantified changes in the composition and abundance of the leaf-litter frog community occurring in the same premontane forest, by comparing diversity data with a difference of ~18 years. We evaluated the similarity of species richness from 1980s to 2010s based on several sources, and the dissimilarity of species diversity in the site comparing 28 standardized surveys from 1994-1995 and 2011-2012. We compared the relative abundance of some frogs that inhabit the leaf-litter layer between these same periods. Our results show that there is more similarity in amphibian richness between 1980s and 2010s (~ 52 %) than between 1980s and 1990s (~ 40 %). The richness of leaf-litter anurans was ~ 65 % similar between 1990s and 2010s. The diversity of leaf-litter anuran was clearly different between 1994-1995 and 2011-2012, and it was clustered among those periods. We determined that the amphibian community in this premontane forest drastically changed: many species have disappeared, or gradually declined through the decades (e.g. Pristimantis ridens, P. cruentus, Craugastor bransfordii) as in other well studied localities of Costa Rica, while some few species flourished after being almost absent from the site in the 1990s (e.g. Craugastor crassidigitus, Lithobates warszewistchii). Currently dominant species such as C. crassidigitus would be using developed resistance against Bd-fungus as an advantage (apparent competition) in the premontane forest where the disease is more virulent than in lowlands. Our analysis supports the hypothesis of individualized responses of anuran populations under distinct site and elevations. We suggest to continue monitoring the amphibian communities of premontane tropical forests to understand how this ecosystem gradually resist and adapts to this catastrophic time of biodiversity loss.

Redistribution characteristics of atmospheric precipitation in different spatial levels of Guangzhou urban typical forests in southern China

The aims of the present study were to determine the pH variation and chemical feature of atmospheric precipitation during the research period. We also investigated the redistribution characteristics of rainfall while passing through the canopy layer, leaf-litter layer and soil layer, successively to quantify the acid rain buffering capacity of these spatial levels in the evergreen broadleaved forest (EBF), deciduous broadleaved forest (DBF) and coniferous forest (CF) in Guangzhou urban area, China. Results showed that the rainfall was typically acidic, and the acid rain type in Guangzhou urban area is converted from sulfuric acid type to mixed type of sulfuric acid and nitric acid. The major ions from the canopy to the forest floor differed within the three forest types. However, the enrichment phenomenon of base cations in soil leachate in EBF and DBF implied that nutrient loss was more serious in the broadleaved forest than in the coniferous forest. Variability of ionic concentration and pH in the vertical sequence of different tree species showed that the net ion concentration variation index has a significant conic relationship with ne pH change rate. We also built an acid rain buffering index, which combines the neutralization and interception effects of vegetation to acid rainfall. The present results indicated that the three forest types in urban Guangzhou all have certain buffering capacity to acid rain, and following the order: DBF > EBF > CF. In the meanwhile, the forest canopy is the biggest acid rain buffer in urban Guangzhou, following by the soil.

A new species of Clavicornaltica (Coleoptera: Chrysomelidae), discovered and described on a field course to Kuala Belalong, Brunei.

BackgroundClavicornaltica is a genus of very small flea beetles living in the leaf litter layer of Asian forests, easily sampled with Winkler extraction. The genus is presumably very rich in species, but their taxonomy is hampered by their small size and morphological uniformity.New informationOn a ‘taxon expedition’-style field course at Kuala Belalong Field Studies Centre in Brunei Darussalam (Borneo), a new species, Clavicornaltica belalongensis n. sp., was discovered and taxonomically treated by the course participants. We also present the first DNA barcodes for the genus.

Five new species of dictyostelid social amoebae (Amoebozoa) from Thailand

BackgroundDictyostelid cellular slime molds (dictyostelids) are common inhabitants of the soil and leaf litter layer of fields and forests, along with animal dung, where they feed mostly on bacteria. However, reports on the species diversity of dictyostelids in South Asia, particularly Thailand, are limited. The research reported in this paper was carried out to increase our knowledge of the species diversity of this group of organisms in northern Thailand.ResultsForty soil samples were collected at four localities in northern Thailand to assess the species richness of dictyostelids. These samples yielded five dictyostelid isolates that were not morphologically consistent with any described species. Based on molecular signatures, all five of these isolates were assigned to the family Cavenderiaceae, genus Cavenderia. All five share a number of morphological similarities with other known species from this family. The new taxa differ from previously described species primarily in the size and complexity of their fruiting bodies (sorocarps). This paper describes these new species (Cavenderia aureostabilis, C. bhumiboliana, C. protodigitata, C. pseudoaureostipes, and C. subdiscoidea) based on a combination of morphological characteristics and their phylogenetic positions.ConclusionsAt least 15 taxa of dictyostelids were obtained from the four localities in northern Thailand, which indicates the high level of species diversity in this region. Five species were found to be new to science. These belong to the family Cavenderiaceae, genus Cavenderia, and were described based on both morphology and phylogeny.

Supercooling and freezing as eco-physiological alternatives rather than mutually exclusive strategies: A case study in Pyrrhocoris apterus

Overwintering insects are categorized either as freeze tolerant or freeze avoiding (supercooling) based on their ability or inability, respectively, to tolerate the formation of ice in their body. The freeze tolerant insects set their supercooling point (SCP) higher for winter to stimulate freezing at higher temperatures, while freeze avoiding insects survive winter in a supercooled state by depressing their SCP. Some supercooling insects, however, were found to survive in frozen state when freezing occurred through inoculation by external ice at mild subzero temperatures. Here, we assessed the potential relevance of inoculative freezing and freeze tolerance strategy in an insect that was so far considered as a classical example of a ‘supercooler’, the linden bug (Pyrrhocoris apterus). Microclimatic conditions of the overwintering microhabitat of P. apterus (leaf litter layer with buffered temperature fluctuations, mild sub-zero extremes, high humidity, and presence of ice) present a potentially high risk of inoculative freezing. We found that P. apterus is highly susceptible to inoculation by external ice. The temperature at which inoculative freezing occurred (above −3°C) was much higher compared to SCP (−16 °C to −20 °C in winter). The insects were inoculated through body openings and across cuticle and were able to survive after freezing. There was, however, a distinct critical ice fraction, corresponding to 38.7–42.8% of total body water, beyond which survival rapidly decreased to zero. We found that P. apterus adaptively reduces the actual ice fraction below critical ice fraction for winter season. Since many insect species overwinter in habitats similar to that of P. apterus, the ability to tolerate freezing after inoculation by external ice crystals could be much more common among ‘supercooling’ insects than it is currently appreciated.

Searching for the Immature Stages of Ixodes scapularis (Acari: Ixodidae) in Leaf Litter and Soil in Texas.

The standard tick collection methods of flagging and dragging are successful for collecting all stages of the blacklegged tick, Ixodes scapularis (Say) (Acari: Ixodidae), in the northern United States. However, for unknown reasons, these methods are unsuccessful for collecting the immature stages of I. scapularis in the southern United States. Thus, a different collection strategy was employed to search for the immature stages of I. scapularis in the southern state of Texas. Monthly sampling of three types of microhabitats potentially harboring ticks was conducted for 17 mo at the Big Thicket National Preserve. Samples of leaf litter, topsoil, and subsoil were placed within Berlese funnels to determine if the immature stages of I. scapularis are residing in these layers. No ticks were found in any of the 600 substrate samples examined. Along nearby trail edges in the same area, 656 adult I. scapularis (an average of 22.6 per 1,000 m2), as well as 268 immatures of other species (i.e., Amblyomma americanum (Linnaeaus) (Acari: Ixodidae) and Dermacentor variabilis (Say) (Acari: Ixodidae)) were collected using flagging and dragging. These results suggest that unlike speculations from previous studies in the southern United States, the immature stages of I. scapularis may not be residing in the leaf litter and soil layers in Texas. We hypothesize that they may be residing in their host's nests and burrows. Perhaps I. scapularis in the south is exhibiting a stage specific mixed host-seeking strategy by residing in nests and burrows as immatures, contributing to the geographical difference in Lyme disease prevalence between the northern and southern United States.

Forest Floor Leaf Cover as a Barrier for Dust Accumulation in Tai National Park: Implications for Primate Dental Wear Studies

Mastication causes distinct use wear scars on teeth that can aid in dietary reconstructions of fossils. However, the role played by exogenous grit in dental wear complicates the association between wear and diet. Dental wear analyses often assume that foods closer to the soil contain more exogenous grit than those in the forest canopy. Yet, a layer of leaf litter covering many forest floors may trap grit from the soil, keeping it from settling on surrounding vegetation or becoming part of atmospheric dust. Cercocebus atys is frequently referenced in dental wear studies because of its dependence on hard Sacoglottis gabonensis seeds collected from the forest floor. Here we examine quantities of dust deposition at different forest levels and assess its potential role in wear patterns observed in C. atys. We collected grit from S. gabonensis seeds (N = 64) found under the leaf litter and compared them to grit samples taken from the surface of leaves at different forest strata (N = 450) in Ivory Coast’s Tai National Park. Seeds underneath the leaf litter were coated with significantly more grit than leaves above the leaf material and we conclude that leaf litter is a significant barrier to grit particles originating from the soil. Given that evidence points to a significant difference in grit amount between foodstuffs on the ground and foods near the ground, the findings lead to a prediction of differences in dental wear patterns between purely arboreal foragers and those incorporating terrestrial food sources.

A new species of Phrynopus from the northeastern Andes of Peru, its phylogenetic position, and notes on the relationships of Holoadeninae (Anura: Craugastoridae).

We report the discovery of a geographically disjunct and morphologically distinctive species of direct-developing frog of the genus Phrynopus (Phrynopus mariellaleo sp. nov.) that changes considerably our understanding of the distribution of species in this Andean genus. The type locality lies on a subcordillera (Cerro de Campanario area) of the extreme northeastern portion of the Cordillera Central of Peru, on the headwaters of the Mayo River, Amazonas department, at 2575 m asl (6°6'42.9''S, 77°26'24''W). This area is situated 170 km to the NE from the northernmost record of Phrynopus known so far. Molecular phylogenetic analyses of a supermatrix (13269 aligned positions of gene sequences of four mitochondrial and ten nuclear genes) of 105 terminals (representing 93 named and 9 unnamed species of Holoadeninae) recover this new species as the sister to Phrynopus auriculatus, a species occurring more than 500 km south of the type locality of the new species. Both Phrynopus auriculatus and the new species occur at moderate elevations on the easternmost stretches of the Andean subcordilleras; their sister relationship point to a potentially broader distribution of species of Phrynopus along the poorly sampled intervening areas of the eastern hills of the Andes. The new species has a conspicuous and visibly large tympanic membrane (a trait rare in the clade), outlined by a marked bold black supratympanic fold and a black facial mask, and exhibits conspicuous dorsolateral, scapular, and middorsal Y-shaped folds. Specimens were found on the forest floor-a rocky substrate covered by a thick layer of leaf litter, moss and roots-of a primary humid montane forest (Yungas ecoregion) with scattered patches of bamboo (Chusquea spp.). Our phylogenetic analyses corroborate the monophyly of all Holoadeninae genera, including Euparkerella and Psychrophrynella, genera for which tests of monophyly were pending, and corroborates Hypodactylus nigrovittatus as part of Hypodactylus and sister to a clade that includes H. brunneus, H. elassodiscus and H. peraccai.

A method for extracting the leaf litter distribution area in forest using chip feature

ABSTRACTThe leaf litter layer is an important surface coverage in the forest ecosystem, which imposes an important influence on soil and water conservation and affects the soil physical and chemical characteristics as well as the ecological environment. It is also a significant factor in estimating vegetation coverage. Currently, most remote-sensing methods to obtain leaf litter target are based on the analysis of the spectral features. However, the leaf litter and the soil background are easily confused. The traditional image processing method based on the pixel spectral information alone fails to make full use of the texture and shape information of the target and diminishes the extraction effect. With the research object focused on the continuous distribution area of leaf litter, whose features are intra-class complicated and inter-class boundary blurred, this article proposes a method to extract the leaf litter distribution area in forest by using the Convolutional Neural Network (CNN) to automatically retrieve the image block (which is also called image chip) features. The ResNet50, VGG16, and VGG19 models based on CNN are, respectively, used to extract and to learn the features of the image chips so that they can automatically obtain the deeper, more abstractive and representative features. The accuracy of this method in leaf litter target extraction has reached 95.1% which demonstrated that this new method has higher classification accuracy and better generalization ability than the traditional method of manually selecting image features. Moreover, the use of pretraining models can solve the problem in deep learning with small sample size. Through the study of scale effects, we also found the appropriate segmentation scale for the chips.

A new hypogean species of the genus Chaetomargoreicheia Magrini Bulirsch, 2005 (Carabidae: Scaritinae: Clivinini) from Croatia.

Chaetomargoreicheia Magrini Bulirsch, 2005 is a recently established genus of scaritine ground beetles (Bulirsch Guéorguiev, 2008) (treated by certain authors as a subgenus of the genus Reicheadella Reitter, 1913) (Magrini Bulirsch, 2005; Balkenohl, 2017) which currently contains two endogean species inhabiting the Balkan Peninsula: Chaetomargoreicheia zoufali (Reitter, 1913) and C. lakotai (Magrini Bulirsch, 2005) (Balkenohl, 2003, 2017; Magrini Bulirsch, 2005; Bulirsch Guéorguiev, 2008). The aforementioned species are montane and inhabit confined geographic areas (Jeannel, 1957; Magrini Bulirsch, 2005). C. zoufali was found only in the surroundings of the village of Ravno (collected beneath a deep layer of leaf-litter), Mt. Bjelasnica, near Trebinje, E Herzegovina (Bosnia and Herzegovina), while C. lakotai was found at the entrance of a cave nearby a road (collected under a huge stone), in Mt. Lovćen, near Kotor, S Montenegro (Reitter, 1913; Holdhaus, 1924; Jeannel, 1957; Magrini Bulirsch, 2005). Chaetomargoreicheia species represent quite rare, stenoendemic taxa, for each of the up-to-now known species only one specimen has been collected by hand so far (Reitter, 1913; Jeannel, 1957; Magrini Bulirsch, 2005). The fourth author of the current study investigated numerous underground and endogean high-altitude habitats in Dalmatia (Croatia) in the last few years. As a result of the exploration, he has recently collected a small sample of scaritine ground beetles from a cave in S Croatia. After thorough analysis of the sample, we have identified a new Chaetomargoreicheia species.

Distinct edge effects and reproductive periods of sympatric litter-dwelling scorpions (Arachnida: Scorpiones) in a Brazilian Atlantic forest

Edge effects have drastically affected species living in tropical forests. However, understanding how species respond to edge effects remains a challenge, owing to the many factors involved and different responses of each species thereto. Here, we analyzed how the abundance of two sympatric scorpion species (Tityus pusillus and Ananteris mauryi) and their potential prey varied as a function of microhabitat changes (litter depth, dry mass, and leaf shape) from edge to interior forest habitats. We further analyzed the contribution of potential prey to scorpion abundance and reproductive periods. Data were collected monthly at three 300-m² transects/site at distances of 10, 100, and 200m from the forest edge in a fragment of the Atlantic forest in northeastern Brazil, between April 2016 and March 2017. Scorpions responded differentially to edge effects, with A. mauryi abundance being similar along the edge-interior gradient, whereas T. pusillus had a higher abundance in the interior. As T. pusillus inhabit the top layer of the leaf litter, this species will possibly be more influenced by edge effects. In contrast, being a humicolous scorpion and inhabiting the bottom layers of leaf litter, A. mauryi would not be influenced by edge effects as much as T. pusillus. The reproductive period also was distinct between the two species, with T. pusillus reproducing in the dry season and A. mauryi in the rainy season. The oscillation in the abundance of different groups of prey at different periods maintained the overall prey abundance at a relatively constant level throughout the year, mitigating the effects of prey availability on the abundance and reproductive period of the scorpions. These results suggest that microhabitat exploitation is a key factor to sustain litter-dwelling scorpions in disturbed forest remnants and that T. pusillus can be an ecological indicator of edge effects.

Biodiversity benefits of vegetation restoration are undermined by livestock grazing

Extensive areas of the Earth's terrestrial surface have been subject to restoration, but how best to manage such restored areas has received relatively limited attention. Here, we quantify the effects of livestock grazing on bird and reptile biota within 61 restoration plantings in south‐eastern Australia. Using path analysis, we identified some of the mechanisms giving rise to differences in patterns of species richness and individual species occurrence between grazed and ungrazed plantings. Specifically, we found evidence of both: (1) indirect effects of grazing on various elements of biodiversity mediated through changes in vegetation condition (primarily the leaf litter layer), and (2) direct effects of grazing on biodiversity (irrespective of modification in vegetation cover attributes), possibly as a result of trampling by livestock. We also uncovered evidence of direct effects on bird and reptile biota of other planting attributes such as planting width and planting age. The results of our study suggest that the biodiversity benefits of restoration programs can be undermined by grazing, especially by uncontrolled grazing. We suggest that where the objective of vegetation restoration is to enhance biodiversity conservation, grazing within plantings should be limited or excluded.

Laccase Activity and Azo Dye Decolorization Potential of Podoscypha elegans

Azo dyes containing effluents from different industries pose threats to the environment. Though there are physico-chemical methods to treat such effluents, bioremediation is considered to be the best eco-compatible technique. In this communication, we discuss the decolorization potentiality of five azo dyes by Podoscypha elegans (G. Mey.) Pat., a macro-fungus, found growing on the leaf-litter layer of Bethuadahari Wildlife Sanctuary in West Bengal, India. The fungus exhibited high laccase and very low manganese peroxidase activities under different culture conditions. Decolorization of five high-molecular weight azo dyes, viz., Orange G, Congo Red, Direct Blue 15, Rose Bengal and Direct Yellow 27 by the fungus was found to be positive in all cases. Maximum and minimum mean decolorization percentages were recorded in Rose Bengal (70.41%) and Direct Blue 15 (24.8%), respectively. This is the first record of lignolytic study and dye decolorization by P. elegans.

Influence of Temperature, Moisture, and Light Conditions on the Germination of Seeds of <i>Erythronium japonicum</i> Decne

Erythronium japonicum is a representative species of spring ephemeral, forest floor plants in substitution forests in Japan. Seed germination tests were conducted to observe the effects of temperature, light, and moisture content on the germination of E. japonicum. E. japonicum seeds did not germinate at constant temperatures of 5&#176C, 10&#176C, 15&#176C, 20&#176C, or 25&#176C. Seeds germinated at 5&#176C and 10&#176C after storage at 20&#176C for 1 or 2 months. Seed germinability was affected by desiccation to only 40% moisture content. Seeds germinated well in both light and dark conditions. Conditions under the leaf litter layer showed unique characteristics of temperature, light, and moisture content. The temperature was around 20&#176C under the leaf litter layer, even though it was 30&#176C above. The moisture content under the leaf litter layer was higher than that above. The leaf litter blocked out the sunlight. The temperature of 20&#176C necessary for E. japonicum germination occurred below, but not above, the leaf litter layer. The avoidance of decreasing in germinability from reduced seed moisture content in a short time is consistent with the high moisture conditions under the leaf litter layer. The leaf litter layer plays an important role in providing optimal conditions of temperature, light, and moisture content for the germination of E. japonicum seeds.

Co-invasion of three Asian earthworms, Metaphire hilgendorfi, Amynthas agrestis and Amynthas tokioensis in the USA

Earthworm invasions are one of the most serious causes of ecological deterioration in the temperate deciduous forests of North America. Non-native earthworms impact understory vegetation, leaf litter layer, carbon dynamics, nutrient availability, and the associated food webs. Here we report a significant status change and confirm expansion of known range of Amynthas agrestis, one of the most serious invasive species in North America, and two of its close relatives, A. tokioensis and Metaphire hilgendorfi. The three species have never been confirmed to co-occur in North American ecosystems. We examined 1760 earthworms collected from 30 sites across northeastern USA, and identified them using a new morphological key. Our data show that sympatric occurrence of at least two, and often all three, species is more common than having only one species. In addition, A. tokioensis was dominant in many of these earthworm communities. The status change in species composition from only one species to two or three and the shift in dominance are most likely caused by previous incorrect species identification. Our results support expansion of known range of A. tokioensis and M. hilgendorfi northward and westward into states with colder winters. This range expansion may have taken place alongside that of A. agrestis in the last 10–20 years, but has long been overlooked. Altogether, results highlight an urgent need for correct species identification. The recognition of an expanding multi-species system represents a unique opportunity to further evaluate complex interactions among co-invading and resident species, and to investigate whether interspecific interactions have unexpected non-additive impacts on ecological processes.

Stoichiometric plasticity of microbial communities is similar between litter and soil in a tropical rainforest

Heterotrophic microorganisms are commonly thought to be stoichiometrically homeostatic but their stoichiometric plasticity has rarely been examined, particularly in terrestrial ecosystems. Using a fertilization experiment in a tropical rainforest, we evaluated how variable substrate stoichiometry may influence the stoichiometry of microbial communities in the leaf litter layer and in the underlying soil. C:N:P ratios of the microbial biomass were higher in the organic litter layer than in the underlying mineral soil. Regardless of higher ratios for litter microbial communities, C, N, and P fertilization effects on microbial stoichiometry were strong in both litter and soil, without any fundamental difference in plasticity between these two communities. Overall, N:P ratios were more constrained than C:nutrient ratios for both litter and soil microbial communities, suggesting that stoichiometric plasticity arises because of a decoupling between C and nutrients. Contrary to the simplifying premise of strict homeostasis in microbial decomposers, we conclude that both litter and soil communities can adapt their C:N:P stoichiometry in response to the stoichiometric imbalance of available resources.

Interactions between soil‐dwelling arthropod predators and Ixodes scapularis under laboratory and field conditions

AbstractThe primary vector for Lyme disease and several other medically significant tick‐borne diseases, Ixodes scapularis (blacklegged tick), spends over 95% of its two‐year life cycle exposed to the soil environment. However, the effect of soil‐dwelling arthropod predator populations on I. scapularis survival either in the laboratory or under field conditions is unclear. We collected soil‐dwelling obligate arthropod predators from the field, representing 13 taxonomic families, and investigated whether they would target two I. scapularis life stages (nymph/engorged larva) under laboratory conditions. After 48 h, 30.6% of the predator species targeted I. scapularis nymphs, while 41.3% targeted engorged larvae. One spider species, Schizocosa ocreata, targeted both I. scapularis life stages reliably under laboratory conditions. We used this species to test whether an arthropod predator would affect I. scapularis survival in field microcosms which contained alternative prey items and a complex soil environment. We also investigated the direct and indirect effects of surface litter on I. scapularis survival by removing the leaf litter layer from half of the microcosms. Predator addition reduced the number of nymphs recovered from the microcosms after 21 d by 32.9%. Litter removal also had a negative effect on tick survival, and interacted weakly with the addition of a predator further decreasing tick survival. Additionally, we found that when leaf litter was removed, I. scapularis survival was positively correlated with the organic matter content of the soil within the microcosms. Naturally occurring arthropod predators may play an important role in regulating population dynamics of I. scapularis and show potential as biological control agents for use in integrated pest management protocols.

The effect of litter layer on controlling surface runoff and erosion in rubber plantations on tropical mountain slopes, SW China

In order to investigate the influence of the litter layer and undergrowth intercrops on surface runoff and soil erosion, experimental field plots were monitored over one rainy season in a rubber monoculture and a rubber/tea agroforestry system. Results indicated that the cumulative runoff from plots with bare soil was 1.7 and 2.3 times higher than plots with a litter layer, and with a litter layer plus undergrowth, respectively. Overall, soil erosion from plots with bare soil, plots with a litter layer, and plots with a litter layer plus undergrowth was 4.73, 1.92 and 0.91tha−1, respectively. This suggests that rubber/tea agroforestry was more effective in runoff and erosion control than rubber monoculture. In contrast to runoff, soil erosion was found to be highly correlated with rainfall intensity, but weakly correlated with rainfall volumes. In the early rainy season when litterfall was considerably abundant (litter coverage >70%), runoff and soil erosion in both the litter plots and litter plus undergrowth plots were significantly lower compared to the bare soil plots, or plots with only undergrowth. In the late rainy season when litter coverage <40%, runoff and soil erosion in plots with litter layer or litter plus undergrowth were no longer significantly lower than those in the bare soil or undergrowth plots. These imply that the thick, intact leaf litter layer is an important soil protection agent. In addition, the results demonstrate that the direct influence of precipitation on surface erosion becomes less important as the number of protective layers increase. Solely from the point of view of erosion control, particular attention in practical soil conservation activities should be given to the capacity of tree litter to maintaining soil cover in a rubber plantation.

Beech cupules as keystone structures for soil fauna.

Facilitative or positive interactions are ubiquitous in nature and play a fundamental role in the configuration of ecological communities. In particular, habitat modification and niche construction, in which one organism locally modifies abiotic conditions and favours other organisms by buffering the effects of adverse environmental factors, are among the most relevant facilitative interactions. In line with this, ‘keystone structures’, which provide resources, refuge, or advantageous services decisive for other species, may allow the coexistence of various species and thus considerably contribute to diversity maintenance. Beech cupules are woody husks harbouring beech fruits that remain in the forest soil for relatively long periods of time. In this study, we explored the potential role of these cupules in the distribution and maintenance of the soil fauna inhabiting the leaf litter layer. We experimentally manipulated cupule availability and soil moisture in the field to determine if such structures are limiting and can provide moist shelter to soil animals during drought periods, contributing to minimize desiccation risks. We measured invertebrate abundances inside relative to outside the cupules, total abundances in the leaf litter and animal body sizes, in both dry and wet experimental plots. We found that these structures are preferentially used by the most abundant groups of smaller soil animals—springtails, mites and enchytraeids—during droughts. Moreover, beech cupules can be limiting, as an increase in use was found with higher cupule densities, and are important resources for many small soil invertebrates, driving the spatial structure of the soil community and promoting higher densities in the leaf litter, probably through an increase in habitat heterogeneity. We propose that fruit woody structures should be considered ‘keystone structures’ that contribute to soil community maintenance. Therefore, beech trees may indirectly facilitate soil fauna activities through their decaying fruit husks, hence acting as ecosystem engineers.

Impact assessment of intense sport climbing on limestone cliffs: Response of rock-dwelling land snails

Exposed limestone cliffs in the Swiss Jura Mountains harbour a diverse gastropod community with some rare species. Sport climbing has recently increased in popularity on these cliffs. We examined the effects of sport climbing and microtopographical features of rock faces on terrestrial gastropods by assessing species diversity and abundance on climbing routes and in unclimbed areas of seven isolated cliffs in the Northern Swiss Jura Mountains. We considered exclusively living individuals resting attached to rock faces. In total, 19 gastropod species were recorded. Six of them were specialized rock-dwelling species, whose individuals spend their entire life on rock faces, feeding on algae and lichens. Plots along climbing routes harboured fewer species of rock-dwelling snails as well as other gastropod species (usually living in the leaf litter layer at the cliffs’ base) than plots in unclimbed control areas. Similarly, both the density of individuals and frequency of occurrence in plots were reduced in both groups of snails on climbing routes. The complexity of the rock surface had little influence on the species richness and abundance of gastropods. Pyramidula pusilla, the species with the smallest shell and a preference to rest underneath overhangs, was less affected by sport climbing than snail species with larger shells and a preference to rest on exposed smooth rock surface. Our findings indicate land snail diversity and abundance are suitable indicators for impact assessment in rocky habitats. Future management plans and actions should therefore not only rely on plants; they ought to consider also gastropods and other invertebrates. Any management plan should include a comprehensive information campaign to show the potential impact of intensive sport climbing on the specialized flora and fauna with the aim of educating the climbers and increasing their compliance with such measures.