Small-scale Diversity Research Articles

A novel multiproxy approach to detect the impact of charcoal production on the natural environment in NW Poland – project concept and preliminary results

Agriculture has been the major driver of deforestation in Europe in the last 1000 years. In the past, forests were also exploited for charcoal production; however, the spatial scale/extent of this activity and its impact are unknown. LIDAR data can be used as a noninvasive tool to investigate the small-scale diversity of the land relief, including forested areas. These data can reveal the extent anthropogenic modifications of topography present-day as well as in the past. One of the activities that can be analyzed based on LIDAR data is spatial distribution of charcoal production. A preliminary LIDAR data analysis indicated the intensity of this practice and its potential impact on the natural environment. This prompted us to analyze the environmental impact of charcoal hearths in northern Poland. As it turned out, this topic exceeded the scope of earth sciences and became a transdisciplinary one. In this work, we will use the research methods typical of biogeography, dendroecology, paleoecology, soil science, biology, botany, history, onomastics, as well as art history, in order to thoroughly understand not only the natural consequences but also the social and economic consequences of charcoal production. This paper presents the assumptions of our project, the research methodology, and the preliminary results. We have identified using LIDAR data more than 73 thousand relief forms which can be remnants of charcoal hearths. Our preliminary results confirmed large scale impact of past human activity related to charcoal production and suitability of the methods used for detecting and reconstructing charcoal hearths as well as determining the distribution and magnitude of past forest use for charcoal production in NW Poland.

Persistent land-use legacies increase small-scale diversity and strengthen vegetation–soil relationships on an unmanaged heathland

Land-use legacies are recognized determinants of vegetation dynamics and plant community assembly. The duration of these legacies and how they influence the structure of vegetation communities developing naturally in nutrient-poor ecosystems is not well understood. Here, we focus on the effects of increased nutrient availability from previous agricultural practices on multiple vegetation properties in a heathland where agriculture and domestic grazing ceased near 1870 and 1895, respectively. We compared diversity, compositional and functional properties of the vegetation responses to land-use legacies in the soil between areas with different agricultural histories (previously cultivated vs. uncultivated). Diversity measures were found to be higher in the previously cultivated soils. β-diversity was mainly driven by changes in species relative cover and increased with increasing nutrient availability in the cultivated area. Furthermore, functional traits related to nutrient acquisition (SLA and Leaf Nitrogen content) and the changes in vegetation composition were directly linked to soil properties only in the previously cultivated part of the heathland. Together these results revealed a shift to a deterministic control of the plant community, where increased nutrient availability leads to stronger associations between soil and vegetation properties. This suggests that as nutrients become available, niche differentiation and competitive interactions become the predominant underlying mechanisms structuring the community. Our study shows that land-use legacies of moderate intensity can alter the assembly mechanisms and diversity patterns in unmanaged vegetation that can be maintained after more than a century since cessation of agricultural practice. Identifying land-use legacies and understanding how they structure heathland communities can thus lead to management decisions adapted to the specific assembly mechanisms and result in a more effective management.

Modified kelp seasonality and invertebrate diversity where an invasive kelp co-occurs with native mussels

Non-native species have invaded coastal systems worldwide, altering community structures and ecosystem functioning. One of the most widely distributed marine invaders is the kelp Undaria pinnatifida. In Australasia, Undaria is a large annual kelp that typically has a unimodal growth pattern characterized by high cover during late-winter and spring. It is possible that Undaria co-occurs with mussels and impacts the biodiversity of mussel assemblages on rocky reefs, especially given its presence on mussel farms. Here, we tested whether Undaria and mussels co-occurred on rocky reefs at different temporal and spatial scales, and whether Undaria affects the diversity of mussel-associated small mobile invertebrates. Analyses of survey data showed that individuals of Undaria are often attached to, or interspersed around, mussel aggregations in the low intertidal zone where Undaria was found at similar abundances in its typical winter growth and summer senescence seasons. We hypothesize that this unexpected pattern is caused by overlapping generations coupled with longer growing seasons, potentially triggered by localized higher wave action, rather than individual plants persisting for an entire year. Analyses of Undaria holdfasts and non-living mimics of Undaria holdfasts, showed that live and large holdfasts, in particular, alter and increase small-scale diversity of mobile invertebrates where Undaria co-occurs with mussels. We conclude that Undaria has a longer temporal presence where it co-occurs with mussels and that Undaria alter mussel-associated communities of small mobile invertebrates.

Maximizing the monitoring of diversity for management activities: Additive partitioning of plant species diversity across a frequently burned ecosystem

Monitoring understory plant diversity is important, allowing managers to track current diversity status and trends both spatially and temporally at a landscape-scale. Improving precision in quantifying patterns in understory plant diversity improves efficiency in monitoring design and more accurate measures of success of management intervention over time. Patterns of species diversity are dependent upon the scale in which they are examined – an increase in small-scale diversity across a gradient can convert to a decrease in large-scale diversity across that same gradient. Using two extensive datasets including both mined historical data and supplemental experimental data, we performed an additive partitioning of plant diversity to elucidate the hierarchical spatial patterns of understory plant species richness, and independent measures of alpha and beta diversity in the species-rich longleaf pine ecosystem at Eglin Air Force Base in northwestern FL, USA. This analysis allowed us to identify the spatial scale that most effectively captures plant diversity to inform monitoring efforts by using measures of species turnover, specifically beta diversity. We found that while species richness and alpha diversity increased with spatial scale, beta diversity began to reach an asymptote at smaller (1 m2) scales. Furthermore, we found the sampling effort at this 1 m2 scale required as few as 60 plots to effectively estimate plant diversity within management blocks. While our results are attributable to Eglin AFB specifically, these scaling analyses can help to streamline monitoring efforts in other ecosystems that seek to elucidate the individual contributions of diversity components.

The intersection of diversity metrics and spatial mapping: a case study of regional vegetation patterns for a complex community

We evaluate the contribution of small-scale floristic diversity to regional vegetation patterns, if current vegetation classification methods adequately account for small-scale floristic diversity and the potential role of diversity metrics in contributing to improved classification and mapping of plant community patterns. Upland swamps in the Greater Blue Mountains World Heritage Area, Australia, were used as a case study for this evaluation. Eight hundred and eleven survey plots using two contrasting survey designs were used to generate diversity metrics (; ; ?; ; multivariate dispersion) and these were intersected with spatial mapping across 69 swamps. A novel classification informed by small-scale floristic diversity was also implemented. Diversity patterns at the regional scale were significantly affected by survey design (both and overestimated by a survey design using large plots, but , ? and multivariate dispersion not significantly different among plot designs). Secondly, the novel classification revealed that the majority of assemblages present were previously unreported. Thirdly, floristic assemblages previously mapped only in discrete parts of the region were found to be widespread. A poor correlation exists between current standard classification approaches and a classification informed by small-scale floristic diversity. Thus, recommended and implemented standards for survey and classification in many jurisdictions globally are inadequate for revealing diversity patterns and mapping communities with complex small-scale diversity patterns. Communities of this type are widespread globally. Our study demonstrates that the intersection of advanced diversity metrics and spatial mapping, using small-scale survey data, provides critical insights into regional vegetation patterns that may otherwise remain obscure.

LC-MS/MS Detection of Karlotoxins Reveals New Variants in Strains of the Marine Dinoflagellate Karlodinium veneficum from the Ebro Delta (NW Mediterranean).

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the detection and quantitation of karlotoxins in the selected reaction monitoring (SRM) mode. This novel method was based upon the analysis of purified karlotoxins (KcTx-1, KmTx-2, 44-oxo-KmTx-2, KmTx-5), one amphidinol (AM-18), and unpurified extracts of bulk cultures of the marine dinoflagellate Karlodinium veneficum strain CCMP2936 from Delaware (Eastern USA), which produces KmTx-1 and KmTx-3. The limit of detection of the SRM method for KmTx-2 was determined as 2.5 ng on-column. Collision induced dissociation (CID) spectra of all putative karlotoxins were recorded to present fragmentation patterns of each compound for their unambiguous identification. Bulk cultures of K. veneficum strain K10 isolated from an embayment of the Ebro Delta, NW Mediterranean, yielded five previously unreported putative karlotoxins with molecular masses 1280, 1298, 1332, 1356, and 1400 Da, and similar fragments to KmTx-5. Analysis of several isolates of K. veneficum from the Ebro Delta revealed small-scale diversity in the karlotoxin spectrum in that one isolate from Fangar Bay produced KmTx-5, whereas the five putative novel karlotoxins were found among several isolates from nearby, but hydrographically distinct Alfacs Bay. Application of this LC-MS/MS method represents an incremental advance in the determination of putative karlotoxins, particularly in the absence of a complete spectrum of purified analytical standards of known specific potency.

Space Codes for MIMO Optical Wireless Communications: Error Performance Criterion and Code Construction

In this paper, we consider a multiple-input-multiple-output optical wireless communication (MIMO-OWC) system in the presence of log-normal fading. In this scenario, a general criterion for the design of full-diversity space code (FDSC) with the maximum likelihood detector is developed. This criterion reveals that in a high signal-to-noise ratio regime, MIMO-OWC offers both large-scale diversity gain, governing the exponential decay of the error curve, and small-scale diversity gain, producing traditional power-law decay. Particularly for a two by two MIMO-OWC system with unipolar pulse amplitude modulation, a closed-form solution to the design problem of a linear FDSC optimizing both diversity gains is attained by taking advantage of the available properties on the successive terms of Farey sequences in number theory as well as by developing new properties on the disjoint intervals formed by the Farey sequence terms to attack the continuous and discrete variables mixed max–min design problem. In fact, this specific design not only proves that a repetition code is the optimal linear FDSC optimizing both the diversity gains but also uncovers a significant difference between MIMO radio frequency communications and MIMO-OWC that space dimension alone is sufficient for a full large-scale diversity achievement. Computer simulations demonstrate that FDSC substantially outperforms uncoded spatial multiplexing with the same total optical power and spectral efficiency, and the latter provides only the small-scale diversity gain.

Land managers\u2019 behaviours modulate pathways to visions of future land systems

Attempts to influence the development of land systems are often based on detailed scenarios that constrain relevant factors, describe a range of divergent but plausible futures and identify potential pathways to visions of desirable conditions. However, a number of assumptions are usually made during this process, and one of the most substantial is that land managers display homogeneous, economically rational behaviour across space, time and scenarios. This assumption precludes the consideration of important behavioural effects and limits understanding of the feasibility of scenario-based pathways towards visions. We use an agent-based land use model to examine broad forms of behavioural variation within defined scenarios in theoretical contexts. We relate model results to stakeholder-developed visions of desired future land systems in Europe and so assess the scope for behavioural pathways towards these normative futures. We find that the achievability of visions is determined by internal inconsistencies, scenario conditions and the multifunctional potential of land uses, with a fundamental tension between large-scale land use productivity and small-scale diversity (i.e. land sparing and land sharing). Trading conditions affect this balance most strongly and represent an obvious target for governance strategies concerned with achieving multifunctional land use. However, within specific circumstances behavioural effects are strong and diverse, and can accelerate, counteract or mitigate the impacts of other drivers. This suggests that visions for the land system should focus on trade-offs, identifying those that are least strong, most acceptable and most susceptible to adjustment through behavioural or other influences.

On the Optimality of Spatial Repetition Coding for MIMO Optical Wireless Communications

As a spatial diversity transmission scheme, repetition code (RC) is conjectured to be optimal in the sense of error performance for an intensity modulated direct detection multi-input-multi-output optical wireless communication (IM/DD MIMO-OWC) over log-normal fading channels. Despite the fact that all the experimental evidences thus far have strongly demonstrated that this hypothesis is indeed true, its mathematical proof remains a long-standing open problem mainly due to the lack of an explicit signal design criterion like MIMO radio frequency communications. In this letter, subject to two commonly used power constraints, we prove the optimality of RC under a much weaker condition in the sense of maximizing both large-scale and small-scale diversity gains for any space signalling using the recently established pair-wise error probability design criterion for a maximum likelihood (ML) detector.

Diversity-optimal power loading for intensity modulated MIMO optical wireless communications.

In this paper, we consider the design of space code for an intensity modulated direct detection multi-input-multi-output optical wireless communication (IM/DD MIMO-OWC) system, in which channel coefficients are independent and non-identically log-normal distributed, with variances and means known at the transmitter and channel state information available at the receiver. Utilizing the existing space code design criterion for IM/DD MIMO-OWC with a maximum likelihood (ML) detector, we design a diversity-optimal space code (DOSC) that maximizes both large-scale diversity and small-scale diversity gains and prove that the spatial repetition code (RC) with a diversity-optimized power allocation is diversity-optimal among all the high dimensional nonnegative space code schemes under a commonly used optical power constraint. In addition, we show that one of significant advantages of the DOSC is to allow low-complexity ML detection. Simulation results indicate that in high signal-to-noise ratio (SNR) regimes, our proposed DOSC significantly outperforms RC, which is the best space code currently available for such system.

Optimal Design of Linear Space Code for MIMO Optical Wireless Communications

In this paper, the design of linear full-diversity space code (FDSC) is considered for an intensity-modulated direct-detection multiple-input–multiple-output optical wireless communication (IM/DD MIMO-OWC) system, in which the channel suffers from log-normal fading and different links have different variances. Utilizing our recently established error performance criterion for the design of FDSC with a maximum-likelihood detector, we formulate the design problem of optimizing both large-scale diversity gain and small-scale diversity into a max–min optimization problem with continuous–discrete mixed design variables. We propose the use of the Farey sequence in number theory as a powerful tool to solve this kind of optimization problem. By taking advantage of some available properties and by developing some new interesting properties on the Farey sequence, a closed-form solution is attained for IM/DD MIMO-OWC equipped with two transmitters and multiple receivers. This optimal design shows that a repetition code with an optimal power allocation is optimal.

Contrasting patterns in lichen diversity in the continental and maritime Antarctic

Systematic surveys of the lichen floras of Schirmacher Oasis (Queen Maud Land, continental Antarctic), Victoria Land (Ross Sector, continental Antarctic) and Admiralty Bay (South Shetland Islands, maritime Antarctic) were compared to help infer the major factors influencing patterns of diversity and biogeography in the three areas. Biogeographic patterns were determined using a variety of multivariate statistical tools. A total of 54 lichen species were documented from Schirmacher Oasis (SO), 48 from Victoria Land (VL) and 244 from Admiralty Bay (AB). Of these, 21 species were common to all areas. Most lichens from the SO and VL areas were microlichens, the dominant genus being Buellia. In AB, in contrast, many macrolichens were also present and the dominant genus was Caloplaca. In SO and VL large areas lacked any visible lichen cover, even where the ground was snow-free in summer. Small-scale diversity patterns were present in AB, where the number of species and genera was greater close to the coast. Most species recorded were rare in the study areas in which they were present and endemic to Antarctica.

The importance of species replacement and richness differences in small-scale diversity patterns of aquatic macroinvertebrates in spring fens

This study provides new information on beta diversity (variation in species composition across space) of three invertebrate groups (Clitellata, Plecoptera, and Chironomidae) on a small, within-site spatial scale. It was conducted at small-sized spring fens where two contrasting mesohabitats, a flowing-water and a standing-water, can be clearly distinguished. Besides flow conditions, these habitats differed in the amounts of inorganic substratum and dissolved oxygen. Factors related to flow conditions (dissolved oxygen and water temperature) influenced the composition of the studied assemblages at both mesohabitats, while substratum features were important at the standing-water habitat. The water chemistry was important for Clitellata at both mesohabitats and for Chironomidae at the flowing-water. Using a new approach of disentangling beta diversity into two components (species replacement and species richness differences), clear difference in beta diversity patterns among the three assemblages were found, despite their roughly equal total beta diversities. Variation in species composition of those assemblages strongly limited by flow conditions (Plecoptera and partly Clitellata) was induced by differences in species richness, while replacement governed the variation in species rich assemblages that were able to utilise a wide range of conditions (Chironomidae and partly Clitellata). These results indicate that the size of species pool and the level of environmental filtering play an important role in forming beta diversity patterns, and caution that the same amount of beta diversity can be promoted by essentially different mechanisms, even at a very fine spatial scale with no involvement of dispersal limitations. (C) 2014 Elsevier GmbH. All rights reserved.

Small-scale diversity of plant communities and distribution of species niches on a copper rock outcrop in Upper Katanga, D.R.Congo

Background and aims – In Katanga (D. R. Congo), outcrops of bedrocks naturally enriched in Cu and Co ("copper hills"), host unique plant communities. The spatial variation of vegetation has long been attributed almost exclusively to variation in Cu concentration in the soil, but this assumption has not been experimentally tested. We analysed the variation in plant communities and the niches of selected species in relation to edaphic factors within a copper hill. Methods – Forty-eight 1 m 2 plots were sampled for plant community and soil mineral element composition, and classified with Unweighted Pair Group Method with Arithmetic mean (UPGMA) using the Bray-Curtis distance. Plant-edaphic relationships were examined using a Canonical Correspondence Analysis (CCA). Species niches were modelled with Generalized Additive Model (GAM). Mean edaphic factors between the soil of plant communities were compared with one-way Kruskal-Wallis non-parametric ANOVA. Key results – The diversity of communities at the site scale was higher than observed in previous studies at a larger scale. Cu was the most discriminating edaphic factor of plant communities. However, detailed comparisons of mean edaphic factors among communities revealed individual combinations of edaphic parameters for each community, as well as differences in soil Cu content. High covariation appears to be an essential trait of the edaphic factor variation of Katangan Cu-rich soils. This makes it difficult to examine separately the effect of these factors on plant community structures. A bimodal pattern of niche distribution was found for Cu and pH. For physical parameters, niche optima were normally distributed. Conclusions – Global variation in edaphic factors associated with variation in combinations of edaphic parameters generates a highly heterogeneous environment favourable to a high diversity of plant communities over limited areas. Conservation strategies or restoration actions to limit the impact of mining activities on Cu-enriched ecosystems should pay special attention to recreate heterogeneity, taking into account the covariation of edaphic factors.

Rock walls: small-scale diversity hotspots in the subtidal Gulf of Maine

The physical orientation of rocky substrate profoundly affects subtidal marine commu- nities of sessile organisms. Anecdotal descriptions of dramatic differences between communities on rock walls and adjacent horizontal rocky bottoms abound in the literature and are common knowl- edge among scuba divers, yet these differences have rarely been quantified by ecologists. We sam- pled rock walls and adjacent horizontal rock bottoms at 8 subtidal sites across the Gulf of Maine. Spe- cies richness and abundance, in percent cover, of sessile invertebrates on vertical walls averaged 4 times higher than that on horizontal platforms, whereas abundance of macroalgae on horizontal rock was about 3 times that on vertical walls. Both macroalgae and sessile invertebrates were less abundant, particularly on horizontal surfaces, at sites with high sea urchin densities. The consistency of sessile invertebrate domination of vertical walls versus macroalgal domination of horizontal rock, combined with previous experimental results, suggests that competition for space between autotro- phic and heterotrophic organisms drives this pattern. The partitioning of autotrophs (macroalgae) and heterotrophs (sessile invertebrates) between horizontal and vertical surfaces respectively implies that topographic heterogeneity plays an important role in the structure, composition and function of rocky subtidal ecosystems.

Small-scale Diversity and Succession of Fungi in the Detritusphere of Rye Residues

Transport of litter carbon in the detritusphere might determine fungal abundance and diversity at the small scale. Rye residues were applied to the surface of soil cores with two different water contents and incubated at 10 degrees C for 2 and 12 weeks. Fungal community structure was analysed by constructing clone libraries of 18S rDNA and subsequent sequencing. Litter addition induced fungal succession in the adjacent soil and decreased detectable fungal diversity mainly due to the huge supply of substrates. Ergosterol content and N-acetyl-glucosaminidase activity indicated fungal growth after 2 weeks. Simultaneously, the structure of the fungal community changed, with Mortierellaceae proliferating during the initial phase of litter decomposition. Ergosterol measurements were unable to detect this early fungal growth because Mortierellaceae do not produce ergosterol. In the late phase during decomposition of polymeric substrates, like cellulose and chitin, the fungal community was dominated by Trichocladium asperum. Water content influenced community composition only during the first 2 weeks due to its influence on transport processes in the detritusphere and on competition between fungal species. Our results underline the importance of species identification in understanding decomposition processes in soil.

Does species diversity limit productivity in natural grassland communities?

Theoretical analyses and experimental studies of synthesized assemblages indicate that under particular circumstances species diversity can enhance community productivity through niche complementarity. It remains unclear whether this process has important effects in mature natural ecosystems where competitive feedbacks and complex environmental influences affect diversity-productivity relationships. In this study, we evaluated diversity-productivity relationships while statistically controlling for environmental influences in 12 natural grassland ecosystems. Because diversity-productivity relationships are conspicuously nonlinear, we developed a nonlinear structural equation modeling (SEM) methodology to separate the effects of diversity on productivity from the effects of productivity on diversity. Meta-analysis was used to summarize the SEM findings across studies. While competitive effects were readily detected, enhancement of production by diversity was not. These results suggest that the influence of small-scale diversity on productivity in mature natural systems is a weak force, both in absolute terms and relative to the effects of other controls on productivity.

Deciduous trees affect small-scale floristic diversity and tree regeneration in conifer forests

There is a growing interest in the effects of deciduous trees on biodiversity, soil processes and long-term productivity in boreal, conifer-dominated forests. This study investigated whether individual birch trees allowed to grow to maturity in the coniferous forest can have a local effect on floristic richness and regeneration of tree saplings. The ground vegetation was compared in 2 m radius plots around the stem under the canopies of matched conifer–deciduous trees in a mature, conifer-dominated forest, and included in the analysis variables that could potentially mediate the tree effect (soil pH, cover of lichens, bryophytes, leaf and needle litter). The field layer vegetation was more species rich under birch (Betula pendula and B. pubescens) than under conifers (Picea abies and Pinus sylvestris), and several vascular plant species (including saplings of tree species) occurred more often under birch than under conifers. However, when the effect of the number of subordinate trees was taken into account the difference between birch and pine was not significant. The number of tree regenerations (saplings) was lowest under pines, but did not differ between spruce and birch. There were no effects of the canopy species on soil pH or on cover of lichens and bryophytes. The difference in diversity may be caused by the different effects of leaf and needle litter, and it is also likely that canopy structure has an influence via interception and throughfall and by affecting the light and microclimate.

Small-scale diversity of Harpacticoida (Crustacea, Copepoda) from an intertidal sandflat in the Jade Bay (German Bight, North Sea)

Harpacticoid copepod assemblages from an intertidal sandflat in the Jade Bay (German Bight, North Sea) were investigated during a snapshot study, uncovering a relatively high small-scale organismic diversity: 1952 adult Harpacticoida of 32 species were recorded, belonging to 19 genera and 13 families. With 1232 adult specimens (63.1 %), Ectinosomatidae were the most abundant family, containingPseudobradya minor (T. & A.Scott) as the dominating species (57.4 %). For five species,Dactylopusia vulgaris (Sars),Remanea arenicola Klie,Mesochra pygmaea (Claus),Arenopontia subterranea Kunz, andEnhydrosoma gariene Gurney, the distributional range along the German coast line was extended to the area west of the river Elbe. Two species,Arenosetella tenuissima (Klie) andPseudobradya beduina Monard, were recorded for the first time in the Jade region. Most species recorded in our study are typical inhabitants of interridal sandy and/or muddy environments. Taking into account different aspects of diversity (species richness: species numbers, estimated species numbers by Jack-knife 1 and 2, species richness plots; heterogeneity: Shannon index, rarefaction curves; phylogenetic/taxonomic relationship: taxonomic distinctness) we found only minor diversity differences between four investigated small spatial scales (circles from 18 cm to 20 m diameter). Hypothesis [a] stating increasing diversity with increasing scale had to be rejected. This unexpected result could be caused by the presence of a mosaic of more or less randomly arranged micropatches of species over the sampling domain. Obviously, all citcles were more or less within the range of a single ecological scale. A slight diversity change at the 20 m scale, mainly based on lower species density, may be due to changing tide, or to a beginning overlap of small-scale random micropatches by a larger-scale environmental pattern. Since we found only minor diversity changes from the smallest (centimetres) to the largest investigated scale (tens of metres), biotic and/or abiotic factors and processes acting at spatial scales of centimetres are assumed to be of special relevance for intertidal harpacricoid diversity. Hypothesis [b] of no significant harpacticoid assemblage differences between the investigated scales was tested by ANOSIM for two similarity measures, leading to different results. Cosine similarity revealed no significant difference in assemblage composition between all possible pairwise combinations of circles, whereas [b] had to rejected for Bray-Curtis dissimilarity which produced significant results for two pairs (A/D, C/D). The difference between the test results is suggested to be caused by a lower species density in circle D, since Bray-Curtis dissimilarity is separating similar monitoring units if the difference is only due to multiples in abundance (Pfeifer et al. 1998).

Seedling establishment after endozoochory in disturbed and undisturbed grasslands

Summary Local plant community composition and structure may be largely influenced by germination and seedling establishment from seeds dispersed in animal dung, through seed input, gap creation and nutrient enrichment. With an experimental approach we assessed (1) what the effect is of dung deposition on the number of seedlings in the plant community 3 months and 1 year after dung deposition, (2) what the effect is of this seedling establishment on the local plant community characteristics such as species richness and (3) if this effect interacts with large-scale soil disturbance which removes the close canopy, such as sod-cutting. Viable seeds of monocotylous species were abundantly present in the dung, and dung deposition led to a higher number of monocotylous seedlings after 3 months. However, this effect was no longer significant after 1 year. Moreover, the proportion of viable monocotylous seeds that effectively established in the field after 3 months was less than 5%. A lower number of viable seeds of the less-dominant dicotylous species was dispersed in the dung but they had a higher cover and species richness after 1 year. This resulted in an increased total small-scale species richness and diversity after dung deposition through a decreasing dominance of monocotylous species. Sod-cutting had a pronounced effect on seedling emergence: viable seeds dispersed by dung had a higher probability of successful establishment when the dung was deposited in large gaps. This indicates that an increase of safe sites associated with disturbance strengthens the effects of seed dispersal and gap creation by dung deposition.