Genetic Structure of Tree and Shrubby Species Among Anthropogenic Edges, Natural Edges, and Interior of an Atlantic Forest Fragment

Two species, Psychotria tenuinervis (shrub, Rubiaceae) and Guarea guidonia (tree, Meliaceae), were used as models to compare the genetic structure of tree and shrubby species among natural edges, anthropogenic edges, and a fragment interior. There were significant differences between two genetic markers. For isozymes, P. tenuinervis presented greater heterozygosity (expected and observed) and a higher percentage of polymorphic loci and median number of alleles than G. guidonia. For microsatellites, there was no difference in genetic variability between the species. Only P. tenuinervis, for isozymes, showed differences in genetic variability among the three habitats. There was no genetic structure (F _ST < 0.05) among habitats in both plant species for both genetic markers. Isozymes showed great endogamy for both plant species, but not microsatellites. The forest fragmentation may have negative effects on both spatial (among edges and interior) and temporal genetic variability.     

Floral Visitors and Pollination of Psychotria tenuinervis (Rubiaceae): Distance from the Anthropogenic and Natural Edges of an Atlantic Forest Fragment1

Pollinators, especially insects, could be influenced by forest fragmentation. The aim of this paper was to examine whether there were differences in 1) the communities of floral visitors; 2) the frequency of visits; and 3) the fruit and seed sets of individuals of Psychotria tenuinervis occurring at anthropogenic edges (AEs), natural edges (NEs), and in the forest interior (FI) in 2 yr of study. In 2002, the total number of flower visits was greater in NE and lower in AE, while no difference among habitats was found in 2003. There were differences among sample plots, within habitats, in both years. Bees were the most frequent visitors of P. tenuinervis flowers, and the introduced honeybee Apis mellifera was the most common species observed. There were no differences in the fruit and seed sets, or in the density of reproductive individuals of P. tenuinervis among habitats. However, in 2002, NE showed the greatest proportion of fruits per flower and AE the smallest. The similarity among the habitats was probably due to the marked variation or heterogeneity among the sample plots and among the plants within the habitats, which may have masked any interhabitat differences. The observed heterogeneity and the likely importance of other factors, such as gaps and the age of the edge, on the fragment studied, could be viewed as important issues for conservation programs.     

Seeds and seedlings of two neotropical montane understory shrubs respond differently to anthropogenic edges and treefall gaps

Edges resulting from forest clear-cutting and treefall gaps can affect plant populations and consequently the distribution of species across landscapes. These two types of disturbance might interact to exacerbate or ameliorate “edge effects”, a rarely tested possibility. We focused on the effects of distance from forest edge (0–10, 30–40, 60–70, and 190–200 m) and habitat within forest fragments (treefall gaps and intact forest) on the early stages of development of Palicourea gibbosa and Faramea affinis, two common shrubs of montane forests in southwest Colombia. Seed germination and seedling growth did not change with distance from forest edge. Within forest fragments, however, seed germination and seedling growth were higher in treefall gaps than in intact forest understory for both species. In contrast, seed predation was influenced by distance from forest edge and in P gibbosa it depended on habitat. Seed predation was highest in the forest interior (190–200 m from forest edge) and in P. gibbosa this was true only in treefall gap habitats. These results suggest that animal mediated processes such as post-dispersal seed predation are more likely than physiological processes to be affected by anthropogenic edges. Our results provide some evidence that treefall gaps may interact with “edge effects”, however, they are inconclusive as to whether they exacerbate or ameliorate them. Received: 31 August 1998 / Accepted: 18 February 1999     

Mating Systems of Psychotria tenuinervis (Rubiaceae): Distance from Anthropogenic and Natural Edges of Atlantic Forest Fragment

The aim of this study was to determine and compare the mating systems among Psychotria tenuinervis populations at anthropogenic edges, natural edges, and the forest interior using allozyme electrophoresis of naturally pollinated progeny arrays. P. tenuinervis showed low outcrossing rates, varying from 37% to 50% of the mating attributable to outcrossing and 50% to 63% attributable to self-fertilization, in the three habitats. The forest interior had the highest outcrossing rate (t _m = 0.50 and t _s = 0.43) among the three habitats. However, there were no differences in either multilocus or single-locus rates among the three habitats, indicating that the contribution of biparental inbreeding to the apparent selfing rate in these populations was very low. The multilocus (t _m) and single-locus (t _s) outcrossing rates for the P. tenuinervis in the sample plots within each habitat showed great heterogeneity. In conclusion, edge creation seems not to influence its mating systems. Additionally, although P. tenuinervis is a distylous species, the population’s inbreeding can be attributed almost entirely to self-fertilization.     

Forest edges and fire ants alter the seed shadow of an ant-dispersed plant

Exotic species invade fragmented, edge-rich habitats readily, yet the distinct impacts of habitat edges and invaders on native biota are rarely distinguished. Both appear detrimental to ant-dispersed plants such as bloodroot, Sanguinaria canadensis. Working in northeastern Georgia (USA), an area characterized by a rich ant-dispersed flora, fragmented forests, and invasions by the red imported fire ant, Solenopsis invicta , I monitored the interactions between ants and S. canadensis seeds in uninvaded forest interiors, uninvaded forest edges, invaded forest interiors, and invaded forest edges. I observed 95% of the seed dispersal events that occurred within the 60-min observation intervals. Seed collection rates were similar among all four (habitat × invasion) groups. The presence of invasive ants had a strong effect on seed dispersal distance: S. invicta collected most seeds in invaded sites, but was a poorer disperser than four of five native ant taxa. Habitat type (interior versus edge) had no effect on seed dispersal distance, but it had a strong effect on seed dispersal direction. Dispersal towards the edge was disproportionately rare in uninvaded forest edges, and ants in those habitats moved the average dispersed seed approximately 70 cm away from that edge. Dispersal direction was also skewed away from the edge in uninvaded forest interiors and invaded forest edges, albeit non-significantly. This biased dispersal may help explain the rarity of myrmecochorous plants in younger forests and edges, and their poor ability to disperse between fragments. This is the first demonstration that forest edges and S. invicta invasion influence seed dispersal destination and distance, respectively. These forces act independently.     

Seed rain of fleshy and dry propagules in different habitats in the temperate rainforests of Chiloé Island,Chile

In temperate rainforests on Chiloé Island in southern Chile (42°S), most canopy trees bear fleshy, avian‐dispersed propagules, whereas emergent tree species have dry, wind‐borne propagules. In the present study, the following hypothesis was tested: regardless of species, fleshy propagules are deposited in greater numbers in canopy gaps and in forest margins and hence have a more heterogeneous seed shadow than wind‐dispersed propagules. To test this hypothesis, the seed rains of these two types of propagules were compared in the following forest habitats: (i) tree‐fall gaps (edges and centre); (ii) forest margins with adjacent pastures; and (iii) under closed canopy (forest interior). Seed collectors (30‐cm diameter) were placed in two (15 and 100 ha) remnant forest patches (n = 60–100 seed collectors per patch) distributed in the four habitats. Seeds were retrieved monthly from each collector during two reproductive seasons (1996, 1997). In both years, the seed rain was numerically dominated by two species with dry propagules (Laureliopsis philippiana and Nothofagus nitida) and three species with fleshy fruits (Drimys winteri, Amomyrtus luma, and Amomyrtus meli). The seed shadows of the two species with dry, wind‐dispersed seeds differed markedly. Seeds of L. philippiana were deposited predominantly in canopy openings, whereas N. nitida seeds fell almost entirely in the forest interior. The fleshy‐fruited species, Drimys and Amomyrtus spp., had similar seed deposition patterns in the various habitats studied, but the between‐year differences in seed rain were greater in Drimys winteri than in Amomyrtus spp. Although no more than 10% of fleshy‐fruited propagules reached the margins of the patch, approximately 7% of these were carried there by birds. Every year, canopy gaps (pooling data from edges and centres) concentrated approximately 60% of the total seed rain of both propagule types in both forest patches. Forest margins received less than 20% of the total seed rain, which was largely dominated by fleshy‐fruited species. Seed shadows were a species‐specific attribute rather than a trait associated with propagule type and dispersal mode.     

Variation in breeding system among populations of the common woodland herbAnemone nemorosa (Ranunculaceae)

Recent studies of germination in natural habitats, of genetic variation within populations and of the relative proportion of vegetative and sexual reproduction in the clonal plant speciesAnemone nemorosa suggest that sexual recruitment by seeds from outcrossed flowers is important for the maintenance of this species' populations. Because published reports on its breeding system are controversial, pollination experiments were performed in five natural populations ofA. nemorosa. Differences in ovule number per flower were recorded among populations, but they were not related to obvious habitat differences. Seed/ovule-ratios were significantly higher after open pollination and artificial crossing than after either artificial or spontaneous selfing. Populations had no effect on seed/ovuleratios. Different breeding indices indicated thatA. nemorosa is mainly self-incompatible. Nevertheless, some seed set also occurred after selfing, and both artificial and spontaneous selfing exhibited higher variation in seed/ovule-ratios than open pollination and artificial crossing. Continuous variation in seed/ovule-ratios after selfing suggested that the expression and effectiveness of the self-incompatibility system ofA. nemorosa is influenced by both genetic variation and phenotypic plasticity.     

Genetic variation in an ephemeral mudflat species: The role of the soil seed bank and dispersal in river and secondary anthropogenic habitats

Many ephemeral mudflat species, which rely on a soil seed bank to build up the next generation, are endangered in their natural habitat due to the widespread regulation of rivers. The aim of the present study was to elucidate the role of the soil seed bank and dispersal for the maintenance of genetic diversity in populations of near‐natural river habitats and anthropogenic habitats created by traditional fish farming practices using Cyperus fuscus as a model. Using microsatellite markers, we found no difference in genetic diversity levels between soil seed bank and above‐ground population and only moderate differentiation between the two fractions. One possible interpretation is the difference in short‐term selection during germination under specific conditions (glasshouse versus field) resulting in an ecological filtering of genotypes out of the reservoir in the soil. River populations harbored significantly more genetic diversity than populations from the anthropogenic pond types. We suggest that altered levels and patterns of dispersal together with stronger selection pressures and historical bottlenecks in anthropogenic habitats are responsible for the observed reduction in genetic diversity. Dispersal is also supposed to largely prohibit genetic structure across Europe, although there is a gradient in private allelic richness from southern Europe (high values) to northern, especially north‐western, Europe (low values), which probably relates to postglacial expansion out of southern and/or eastern refugia.     

Cryptic seed heteromorphism in Packera tomentosa (Asteraceae): differences in mass and germination

Seed mass variation and heteromorphism may afford plant species differential germination behavior and ultimately seedling success, particularly in disturbed habitats. We asked whether such variation occurs in Packera tomentosa (Michx.) C. Jeffrey (Asteraceae), a clonal species of the southeastern USA. Seed mass was compared within and among genetic individuals differentiated using amplified fragment length polymorphisms. We compared central and peripheral seeds produced by disc and ray florets, respectively, for their morphology, mass, and germination behavior, including response to water availability, aging, and cold stratification. Seed mass was highly variable both within and among individuals and influenced germination behavior. We found cryptic seed heteromorphism in P. tomentosa. Central and peripheral seeds had similar morphologies but dissimilar mass and biomass allocation. We used failure time analysis to detect different germination behavior. Central seeds were heavier, contained larger embryos, and germinated faster and at a higher proportion in most germination studies. Highly variable mass and heteromorphism of seeds may allow persistence of P. tomentosa in its disturbed habitats. Based on our results, some future studies of Asteraceae species with disc and ray florets may need to account for possible differences between seed types, even when morphological differences are not apparent. Evaluation of individual seed mass and maternal differences in germination studies may assist in the detection of cryptic seed heteromorphism, a phenomenon thought to be common, yet rarely documented.     

Large forests enhance songbird nesting success in agricultural‐ dominated landscapes of the Midwestern US

We studied the effects of habitat composition and distance from edges on nesting success and brood parasitism of forest birds in the Kaskaskia River Bottoms, one of the largest remaining tracts of floodplain forest in the agricultural Midwestern United States. Our goal was to help the private landowners, who have maintained this region in forest cover, enhance the value of these forests for nesting birds. We measured nest predation rates and levels of brood parasitism of four species, the indigo bunting Passerina cyanea, Acadian flycatcher Empidonax virescens, northern cardinal Cardinalis cardinalis and prothonotary warbler Protonotaria citrea in relation to distances from natural and anthropogenic edges and proportion of natural and anthropogenic habitats within fixed radii around nests. We predicted that nesting success would increase with increasing distance from anthropogenic habitats and with increasing land cover in natural habitats. Our results showed no strong effect of any of these variables on avian nesting success, although parasitism levels increased slightly with increasing proportion of agricultural land around nests for two of the species. Nevertheless, nesting success for at least three of these species was much higher than in more fragmented forest tracts elsewhere in the agricultural Midwest where most forest tracts appear to be population sinks for most species. These results suggest that forest tracts in the Kaskaskia may be saturated with nest predators and brood parasites, but are not super‐saturated in a way that would cause these tracts to become ‘black hole’ population sinks. Our data further suggest that, as long as landowners maintain their private landholdings in forest cover, the details of how they manage their land may have little effect on songbird nesting success. These results also suggest that reforestation efforts in areas with many openings may still benefit forest birds.     

破碎化生境中粗柄独尾草种群大小对繁殖特性的影响

景观破碎化是目前存在的一种普遍现象,导致物种生存的原有生境总面积减小,产生许多大小不一的斑块种群。不同斑块生境中植物种群的大小直接反映植物对环境的响应特征和适应对策,与植物繁殖有关的开花结实特性、种子形态及萌发特性的研究将有助于深入了解植物在不同生境中的生存策略。以粗柄独尾草(Eremurus inderiensis)为研究对象,以野外调查为基础,对比研究不同斑块粗柄独尾草种群的种群大小和生殖成功,揭示不同生境中粗柄独尾草的生态适应性。结果表明:(1)不同斑块生境中,种群大小差异较大,且较小的种群幼苗比例也较小,种群大小与种群幼苗比例呈显著相关;(2)较小的种群自然座果率、结籽率较低,种群间差异显著;(3)随着生境破碎化程度增加,种子千粒重,种子长、宽等形态特征呈减小趋势,但种翅占比增大;(4)在粗柄独尾草最适萌发温度下,随着生境破碎化程度增加,种子萌发率有下降趋势。针对人类干扰程度强的衰退型粗柄独尾草种群,亟需减少人为干扰,依据不同生境中的干扰因素及种群生存现状,制定科学与切实可行的保护和恢复策略。     

Edge Structure Determines the Magnitude of Changes in Microclimate and Vegetation Structure in Tropical Forest Fragments1

Edge structure is one of the principal determinants of the extent and magnitude of edge effects in forest fragments. In central Amazonia, natural succession at forest edges typically produces a dense wall of vegetation dominated by Cecropia spp. that buffers the forest interior. Fire encroachment into forest edges, however, eliminates the soil seed bank, enhances plant mortality, and promotes succession to an open, Vismia–dominated edge that does not buffer the forest interior. Contrasting open, fire–encroached forest edges and closed, non–fire–encroached edges were examined in central Amazonia to assess the effects of edge structure on microclimate and vegetation structure in tropical forest fragments. Edge penetration distances for most microclimate and vegetation structure variables were as much as two to five times greater at open edges than at closed edges. The magnitude of these differences suggests that edge structure is one of the main determinants of microclimate and vegetation structure within tropical forest fragments. Edge effects also varied systematically with fragment area. For a given edge type, 100–ha fragments had consistently lower canopy height, higher foliage density, higher temperature, a higher rate of evaporative drying, lower leaf litter moisture content, and lower litter depth than continuous forest, at all distances from the forest edge. These differences, however, were relatively minor compared to the striking differences in edge penetration between open and closed forest edges. For organisms in small fragments, the difference between open and closed edges may be the difference between total edge encroachment on one hand and an effective nature reserve on the other, relatively independent of absolute fragment area.     

Road edge effect on the abundance of the lizard <Emphasis Type="Italic">Gallotia galloti</Emphasis> (Sauria: Lacertidae) in two Canary Islands forests

Transportation infrastructure is a main cause of environmental change in forest landscapes worldwide. In the Canary Islands, a dense road system fragment the native Canarian pine and laurel forests causing potential changes in population densities of endemic lacertid lizards (genus Gallotia). Our aim was to assess road edge effects on relative abundance patterns of the endemic Gallotia galloti in both forests. We also explored the species–habitat relationships in this road-fragmentation context. We found that lizard relative density in relation to road edges differed between forests. Lizards were more abundant along edges and leeward interior, but virtually absent from the interior of the windward laurel forest. In the pine forest, lizards were present at three distances from edge, with a net decrease in abundance from edge to interior. These patterns may be explained partly by differences in vegetation structure regarding road proximity in each forest that potentially affect the helio- and thigmothermic character of G. galloti, and thus its habitat use. A general suggestion of this study is that road margins create corridors that may be used by native lizards for dispersal through inhospitable forest matrix. The high road density in Tenerife may have negative implications for the conservation of the genetic variability of G. galloti. At the island scale, increased communication between lizard populations through road corridors might increase homogenization of the gene pool. Ecological processes in which this lizard plays important roles may also experience changes along road edges.     

木麻黄海防林种子雨的时空动态

为了解木麻黄(Casuarina equisetifolia)种子雨的时空间分布格局和萌发性能对其天然更新的影响,对海口木麻黄海防林种子雨的时空分布特征和种子雨的萌发动态进行了研究。结果表明,木麻黄种子落雨时间始于7月中旬,结束于次年4月中旬,持续长达9个月,期间种子雨年际平均密度为1 764.63 grain m~(-2)a~(-1);种子雨高峰期在12月上中旬,落种量占总散落量的43.38%;种子雨呈聚集分布,且种子雨密度与附近球果数量呈极显著正相关;种子雨萌发率较低,仅为11.31%,但由于种子雨密度较大,可萌发的种子雨密度仍然较大,为199.58grainm~(-2)a~(-1)。因此,种子数量和质量均不是制约木麻黄天然更新困难的主要障碍因子,但聚集分布特征使木麻黄种子在林内扩散能力十分有限。     

Edge Effects on Species Composition and Exotic Species Abundance in the North Carolina Piedmont

Edges between forest and non-forest habitats often have significant effects on forest microclimate and resource availability, with corresponding effects on species composition and abundance. Exotic species are often increased in abundance near forest edges. This increase in abundance could be either because of the increase in resource availability near edges, or because of increased dispersal into forest edges. We measured species composition and a set of geospatial variables on transects at 66 edges in the North Carolina Piedmont in an attempt to distinguish between these two factors. Mantel tests show that species composition is significantly different in forest edges than in the forest interior, but that this effect only penetrates about 5 m into the forest. Indicator species analysis finds several species that are indicative of edge communities, including trumpet vine (Campsis radicans), two drought-tolerant oak species (Quercus stellata and Q. falcata), a serviceberry (Amelanchier arboreum), and a common exotic species, tree-of-heaven (Ailanthus altissima). Poisson regression techniques showed that in both the seedling and tree strata of the forest, exotic species increased in abundance on flat sites with a high potential seed source. Mapping predicted exotic species abundance onto the landscape. We find that large-scale variation in exotic species abundance is due mostly to variation in potential seed sources, while small-scale variation relates more to edaphic factors. Our results stress that both dispersal and environmental filters are important for determining exotic species abundance, but potentially the filters operate at different spatial scales.     

Anthropogenic edges impact howler monkey (Alouatta palliata) feeding behaviour in a Costa Rican rainforest

Anthropogenic forest fragmentation impacts many aspects of animal behaviour, including feeding ecology. With forests increasingly fragmented in tropical regions due to human development, the proportion of forest edge (≤?100 m from clear-cut regions) is higher relative to forest interior. Forest edges differ in vegetation from interior, making it important to better understand how anthropogenic edges impact the feeding behaviour of primates such as mantled howler monkeys (Alouatta palliata). We predicted that howler monkeys would feed on higher-quality plant resources, from a larger number of tree families, and from larger trees in forest interior compared to anthropogenic forest edge. We surveyed howler monkey feeding behaviour across forest zones in a fragmented rainforest in Costa Rica, La Suerte Biological Research Station. We observed individual monkeys for 30-minute periods, collecting data on their feeding behaviour and tree use at 2-minute intervals. We measured feeding trees and recorded the plant parts and taxonomy of resources consumed. Monkeys consumed more leaves and fewer stems and fed from a smaller number of tree families in the forest interior, while they consumed fewer leaves and more stems and fed from a larger number of tree families in the forest edge. Monkeys also fed from larger, taller trees in the forest interior than the edge. The differences in howler monkey feeding behaviour between forest zones attest to the impact of human disturbance on howler monkey feeding ecology.

     

Plant–frugivore networks are less specialized and more robust at forest–farmland edges than in the interior of a tropical forest

Forest fragmentation and local disturbance are prevailing threats to tropical forest ecosystems and affect frugivore communities and animal seed dispersal in different ways. However, very little is known about the effects of anthropogenic forest edges and of local disturbance on the structure and robustness of plant–frugivore networks. We carried out focal tree observations to record the frugivore species feeding on eight canopy tree species in the forest interior and at forest–farmland edges in a little and a highly disturbed part of a Kenyan rain forest. For each frugivore species, we recorded its body mass and its forest dependence. We examined how forest edge and local disturbance affected the abundance, the richness and the composition of the frugivore community and tested whether forest edge and local disturbance affected plant frugivore networks. Abundance and species richness of frugivores were higher at edges than in the forest interior. Forest visitors and small‐bodied frugivores increased, while forest specialists decreased in abundance at forest edges. The changes in frugivore community composition resulted in plant–frugivore networks that were more connected, more nested and more robust against species extinctions at forest–farmland edges than in the forest interior. Network specialization was lower at forest edges than in the forest interior because at the edges plant specialization on frugivores was very low in small‐fruited species. In contrast, small‐fruited plants were more specialized than large‐fruited plants in the forest interior. Our findings suggest that forest‐visiting birds may stabilize seed‐dispersal services for small‐fruited plant species at rain forest margins, while seed‐dispersal services for large‐fruited plant species may be disrupted at forest edges due to the decrease of large‐bodied frugviores. To assess the ultimate consequences of bird movements from farmland to forest edges for ecosystem functioning, future studies are required to investigate the seed‐dispersal qualities provided by forest‐visiting bird species in the tropics.     

Seed survival of the tropical tree Cryptocarya aschersoniana (Lauraceae): Consequences of habitat disturbance

Seed survival in soil could be strongly influenced by habitat characteristics, but little is known about the behaviour of seeds sensitive to desiccation in seed banks installed in natural or disturbed habitats. Cryptocarya aschersoniana seeds disperse at the end of the rainy season but do not germinate immediately; thus, they may form seed banks in soil. This study evaluated the behaviour of C. aschersoniana seed banks induced in the natural environment of the species and in a disturbed area. Recently harvested C. aschersoniana germination units were characterized according to their water content, germination and viability. In 2011 and 2012, seed banks were established by burying samples of seeds in the understory of a semi‐deciduous forest. In 2012, samples were also buried in a disturbed area. The seed banks were sampled at certain time intervals, and the samples were characterized as described above. Precipitation and air temperature data were collected. As a result, seeds in the seed bank established in the natural environment form a transient seed bank and showed the same behaviour in both years studied. A germination peak was observed starting 210 days after burial (coinciding with the onset of the rainy season) and reached germination percentages higher than 80% at the end of the experiment for both years. Seed mortality did not exceeded 28% in the natural environment. However, in the disturbed environment, the seeds lost their viability more rapidly, with 90% of the seeds becoming unviable 240 days after burial. Germinated seeds in the disturbed environment (maximum 21%) were not able to establish seedlings. These results underscore the importance of maintaining a natural, undisturbed forest for the conservation of this species.     

Seed bank persistence of clonal weeds in contrasting habitats: implications for control

The ability of weeds to form a seed bank is important for their population dynamics and management because it provides a refuge enabling reinvasion after established target plants have died. However, knowledge of the differential seed behaviour of individual species over multiple years and varying environmental conditions is surprisingly rare but necessary for effective control of diverse weed populations. We established a seed burial experiment in alpine habitats differing in management regime (i.e., forest, hay meadow and pasture) to determine whether seeds of the unpalatable perennial weeds, Veratrum album (white hellebore) and Gentiana lutea (yellow gentian) were able to delay germination and remain viable over 3 years. Our study shows that both species formed a short-term persistent seed bank; in the third-year, the soil seed banks of both species were nearly depleted, having declined to <5% of their original size. Both species had strikingly different germination strategies: G. lutea seeds mainly germinated in their first-year, whilst the majority of V. album seeds germinated in their second-year. The fraction of dormant G. lutea seeds increased with seed age, indicating that seeds remained viable after forgoing germination in the previous year. Habitat-specific differences in seed germination increased with seed age, with germination fractions being lowest in moist hay meadows. This suggests that the negative effects of anoxic conditions became more pronounced as seeds aged in hay meadows. Conversely, seed dormancy was equal among habitats. The absence of a long-term persistent seed bank has important implications for the management of both nuisance and endangered-plant populations. In the case of V. album and G. lutea, re-colonization of habitats from the seed bank is unlikely after established plants have been removed.     

Edge responses are different in edges under natural versus anthropogenic influence: a meta‐analysis using ground beetles

Most edges are anthropogenic in origin, but are distinguishable by their maintaining processes (natural vs. continued anthropogenic interventions: forestry, agriculture, urbanization). We hypothesized that the dissimilar edge histories will be reflected in the diversity and assemblage composition of inhabitants. Testing this “history‐based edge effect” hypothesis, we evaluated published information on a common insect group, ground beetles (Coleoptera: Carabidae) in forest edges. A meta‐analysis showed that the diversity‐enhancing properties of edges significantly differed according to their history. Forest edges maintained by natural processes had significantly higher species richness than their interiors, while edges with continued anthropogenic influence did not. The filter function of edges was also essentially different depending on their history. For forest specialist species, edges maintained by natural processes were penetrable, allowing these species to move right through the edges, while edges still under anthropogenic interventions were impenetrable, preventing the dispersal of forest specialists out of the forest. For species inhabiting the surrounding matrix (open‐habitat and generalist species), edges created by forestry activities were penetrable, and such species also invaded the forest interior. However, natural forest edges constituted a barrier and prevented the invasion of matrix species into the forest interior. Preserving and protecting all edges maintained by natural processes, and preventing anthropogenic changes to their structure, composition, and characteristics are key factors to sustain biodiversity in forests. Moreover, the increasing presence of anthropogenic edges in a landscape is to be avoided, as they contribute to the loss of biodiversity. Simultaneously, edges under continued anthropogenic disturbance should be restored by increasing habitat heterogeneity.