Dune Communities Research Articles

Plant spectral diversity from high‐resolution multispectral imagery detects functional diversity patterns in coastal dune communities

AbstractQuestionRemote sensing is a fundamental tool to monitor biodiversity and spectral diversity may represent a proxy for different biodiversity facets such as taxonomic (TD) and functional diversity (FD). We used fine‐resolution multispectral imagery to explore spectral diversity (SD) patterns across spatial scales (i.e., plot, transect, area), and assess SD relationships with TD and FD along an environmental gradient.LocationCoastal sand dune, Viareggio, Italy (“Migliarino–San Rossore–Massaciuccoli” Regional Park, 43°83′ N, 10°25′ E).MethodsWe measured TD as species richness, while SD and FD were computed using probability density functions based on pixel and species position in multivariate spaces. We compared SD and FD patterns in space occupation, and we tested whether these patterns are coordinated along the sea–inland gradient. We also assessed univariate relationships between SD and biodiversity facets, and we tested how these facets were partitioned across scales.ResultsWe found a strong correspondence between functional and spectral patterns in space occupation and along the environmental gradient, with a lack of significance when considering TD. However, TD and SD showed higher variation at broader scale while most FD variation occurred at plot level.ConclusionBy measuring FD and SD with a common methodological framework, we demonstrate that SD approximates functional patterns in plant communities. Moreover, we show that SD retrieved using high‐resolution images can capture different aspects of FD, and that the occupation of the spectral space is analogous to the occupation of the functional space.

Impact of invasive Carex kobomugi on the native dune community in a US mid-Atlantic coastal system

Dunes provide numerous ecosystem services including habitat for flora and fauna, coastal protection through mitigation of wind and wave energy, and as a barrier to storm flooding. Dune vegetation that inhabits these systems plays a vital role in building dunes and resisting erosion. In the United States, the Virginia coast is a transitional temperature zone for several dominant dune grasses, where the northern species, Ammophila breviligulata (C3) and the southern species, Uniola paniculata and Panicum amarum (both C4) overlap. At Back Bay National Wildlife Refuge (NWR), Virginia, warming temperatures are resulting in native species range shifts altering biotic interactions. Additionally, the invasive sedge, Carex kobomugi (C3) has become more prevalent in the region with unknown effects on the landscape. To understand the impact of Carex on the native plant community, we quantified species distribution and morphological traits of three dominant native species, A. breviligulata, Panicum, and Uniola as well as invasive Carex. We found that Carex was most dominant and exhibited similar individual traits when compared to native species. The suite of plant traits was unique in Carex, with less variation than in native species allowing for rapid nutrient acquisition and growth. These traits, combined with species distribution data suggest that Carex may limit Ammophila abundance. Similarly, presence of Carex had a negative effect on Panicum growth, but no discernible effect on Uniola. Success of Carex at Back Bay NWR may be indicative of the future spread of the species due to above and belowground morphological traits, which may give the invasive an advantage with climate warming.

Above‐ and belowground traits along a stress gradient: trade‐off or not?

The role of plant traits in shaping community assembly along environmental gradients is a topic of ongoing research. It is well accepted that plant traits of aboveground organs tend to be conservative in stressful conditions. However, there is limited understanding of how belowground traits respond. Plants may have similar strategies above and belowground, but an intriguing possibility is that there is a tradeoff between above and belowground traits of communities to both ensure efficient resource‐use and limit niche overlap along the gradient. To test this, we asked whether the response of above and belowground traits of communities is coordinated or not along a stress gradient in Mediterranean sand dune communities. We analyzed 80 vegetation plots in central Italy to test for coordinated vs independent patterns in above vs belowground plant traits using community weighted mean and standardized effect size of functional richness. Our results show that plant communities close to the sea, which experience higher stress, were characterized by higher convergence towards aboveground resource conservation and conservative water‐use strategies but belowground resource acquisition, consistent with a strong effect of habitat filtering and an above–belowground tradeoff favoring adaptation to harsh and dry conditions. At the opposite end of the gradient with lower stress, plants exhibited higher trait diversity for both above and belowground traits, but overall a dominance of aboveground fast resource acquisition and generally acquisitive water‐use strategies, combined with conservative belowground strategies. This suggests that fast growth rate aboveground was compensated by more conservative fine‐root strategies, but processes such as competition limited niche overlap overall. Our findings provide new insights into the relationship between functional traits and environmental gradients in plant communities, shedding light on the tradeoffs between the above and belowground dimensions.

The effects of the decline of a keystone plant species on a dune community plant-pollinator network

Ecological communities are maintained through species interactions, and the resilience of species interactions is critical to the persistence of natural communities. Keystone species play outsized roles in maintaining species interaction networks, and within plant-pollinator communities are high priorities for conservation. The loss of a keystone plant from a plant-pollinator network is expected to cause changes to network structure and composition of pollinator species, with the potential to cause secondary losses of plants and pollinators. To understand how the unmanipulated decline of a keystone plant affects the structure and composition of its network, we studied the plant-pollinator interactions of a Lake Michigan dune plant community where the population of the keystone plant, Cirsium pitcheri, is in rapid decline. The network prior to C. pitcheri decline (2016) was compared to the network as C. pitcheri continued to decline (2021 and 2022) in response to habitat loss. We find evidence that the loss of C. pitcheri altered network structure such that the community may be more sensitive to perturbations. Furthermore, changes in the composition of pollinators were explained by species turnover to a greater extent than by interaction rewiring, including the loss of bumblebees. Short-term negative consequences based on the changes to network structure and composition might lead to long-term effects on the persistence of the dune community. Our study exemplifies that the decline of a keystone plant can have negative implications for conservation of a plant-pollinator community. Using an interaction network framework to assess plant-pollinator communities has potential to develop strategies for best conservation and restoration practices in habitats vulnerable to habitat loss and disturbance.

Effects of invasive Rosa rugosa on Baltic coastal dune communities depend on dune age

Rosa rugosa Thunb. (Japanese Rose) is one of the most invasive species in Europe. It spreads spontaneously in coastal areas of western, central and northern Europe, posing a threat to dune habitats, including those indicated in the EU Habitats Directive as particularly valuable. R. rugosa has already been reported to displace native plants and alter soil properties. However, little is known about how these effects are mediated by the habitat context or the invader condition (health, ontogenetic stage). This study addressed that gap by examining vegetation and soil in 22 R. rugosa-invaded sites, half of which were in yellow dunes and the other half in grey dunes, i.e. two habitats representing the earlier and later stages of dune succession. The study was conducted on the Hel Peninsula (Poland’s Baltic coast). R. rugosa had a significant impact on dune vegetation, but the impact was strongly dependent on the habitat type. In the yellow dune sites, R. rugosa outcompeted most resident plant species, which translated into a strong decline in their total cover and richness. The invasion was almost not accompanied by changes in soil properties, suggesting that it affected the resident vegetation directly (through space takeover and shading). In the grey dunes, R. rugosa caused a shift in species composition, from that characteristic of open communities to that typical of forests. In this habitat, a significant increase in the soil organic layer thickness under R. rugosa was also observed, which means that both direct and indirect effects of the invasion on the vegetation should be assumed. Finally, a negative relationship was found between the total chlorophyll content in R. rugosa leaves and the parameters of resident plant communities, showing that the invasion effects can vary not only across habitats, but also with the condition of the invader. The results may have practical implications for managing R. rugosa invasions in coastal sand dune systems. Since R. rugosa accelerates grey dune succession, protecting this habitat may be more urgent and, at the same time, more complicated than protecting dunes at the earlier stages of development.

Alien plant colonisation and community homogenisation: cause or consequence? A test in coastal dunes

Evidence of the effects of alien plant colonisation on plant communities is often hindered by the fact that similar patterns in community composition can arise through a variety of processes. The objective of this study is to determine whether changes in species composition in coastal dune communities depend on the colonisation of a neophyte plant, Oenothera stucchii, or on concurrent processes that favour its colonisation. We hypothesised two scenarios: 1) a direct impact of O. stucchii on colonised communities, leading to displacement of native species; or 2) no direct impact of O. stucchii, i.e. the species colonises plant communities by exploiting disturbances that lead to the rearrangement of plant communities. We used the species-habitat network approach to identify potential drivers of changes in species composition, assuming that changes in the structure of the species-habitat network depend on the nature of the driving process. We demonstrated that changes in species composition in plant communities were due to species rearrangement, with colonised communities characterised by more homogeneous composition of species. We suggest that changes in plant communities may not depend on colonisation by O. stucchii per se, but on concomitant processes that affect coastal dune communities while promoting colonisation by O. stucchii.

Growth-survival trade-offs and the restoration of non-forested open ecosystems

The growth-survival trade-off has been extensively documented for phanerophyte species, whereas there is little evidence for non-phanerophyte species. However, information on the growth-survival trade-offs in non-phanerophyte species could be of great use in non-forested open ecosystem restoration by providing insights for plant production and transplantation, thus impacting the planning of cost-effective restoration actions. In this study, we explored the relationship between growth and survival of individual plants of non-phanerophyte species used in a coastal dune restoration project, and we investigated whether plant functional traits explained patterns of trade-off between growth and survival. We monitored 355 individual plants of 13 perennial non-phanerophyte species belonging to foredune and transition dune communities every 30 days after planting and calculated relative growth and survival rates. In addition, we regressed the relationship between growth and survival on values of leaf and floral traits. We found that, besides being a widely recognised axis of life history variation in phanerophyte species, the growth-survival trade-off can also be observed in perennial non-phanerophyte species. Species of different coastal dune communities (i.e., foredune vs. transition dune communities) differed with respect to the growth-survival trade-off, with plant species of foredune communities exhibiting higher growth but lower survival rates than plant species of transition dune communities. Leaf dry matter content and mean number of floral displays explained species position on the growth-survival trade-off axis; species with relatively high growth and low survival rates exhibited an acquisitive strategy, with low values of leaf dry matter content, but also a low sexual reproductive effort, as revealed by low number of floral displays. In contrast, plant species with relatively low growth and high survival rates exhibited a conservative strategy but also high sexual reproductive effort, suggesting that trade-offs occur in resource allocation among vegetative and reproductive plant structures. The trade-off we found between growth and survival in perennial non-phanerophyte species provides useful insights for planning cost-effective ecosystem restoration actions of non-forested open ecosystems, especially when the actions are nature-based and involve planting individual plants. The results of this study suggest that individual plant production for coastal dune restoration should disproportionately target plant species of foredune communities because they have low survival rates associated with low sexual reproductive effort. Planning plant production based on ecological knowledge of plant species’ growth and survival after planting in the field could help achieve restoration goals while meeting project cost-effectiveness requirements.

Current State of Ammophila arenaria (Marram Grass) Distribution in the Eastern Cape, South Africa, and the Possible Effect of the Grass on the Dune System Dynamics.

The principal aim of this paper is to show that marram grass is not an invasive alien in South Africa although it affects the dune dynamics as a useful pioneer species in the dune successional process. The historical perspective of marram introduction as a dune stabiliser and the studies and conclusions reached from our European Union funded project, INVASS, in the 1990s and early 2000s is presented. Although these studies showed that marram was non-invasive, this was not clearly carried through to the authorities, and the use of the grass as a dune stabiliser was limited without a special permit. This prompted a survey of the current situation of marram on dune sites in the Eastern Cape. Along with earlier (1980s) data on the dunes, 69 relevés with 66 species abundance from sites along the Eastern Cape shoreline were assembled. These data were analysed with Detrended Correspondence Analysis to show the relationships of the samples (relevés) and species in a 2-dimensional scatter diagram. The survey showed that there are four dune sites where marram grass is no longer present, due to either marram being out of its climatic range, erosion of sand under storm conditions which made the habitat unsuitable, or in one case where marram simply disappeared. Marram often remains in other sites where three to five dune pioneer species were recorded. On some dunes, although marram is the most abundant dune pioneer, it is never dominant in the dune environment but has a presence of as much as 75% at any site. The eight pioneer species are widely dispersed on the DCA scatter diagram, while the shrub species characterising the Coastal Scrub are tightly clustered, showing that all the pioneer dune communities behave similarly in the dune successional series. The conclusion from these studies is that marram grass does not always persist in the dune systems. If marram does persist, it does not compete and behaves identically to the indigenous species as a dune pioneer. These studies show that marram grass is a non-invasive species that can be successfully used in dune stabilisation on Cape dunes.

Pollinator-Mediated Indirect Effects on Plant Fecundity Revealed by Network Indices.

AbstractIndirect effects arise when one species influences how another species interacts with a third. Pollinator-mediated indirect effects are widespread in many plant communities and are often not restricted to plant species pairs. An analytical framework does not exist yet that allows for the evaluation of indirect effects through shared pollinators in a community context as well as their consequences for plant fitness. We used network indices describing pollinator sharing to assess the extent to which plant species affect and are affected by others in a pollination network from a species-rich dune community. For 23 plant species, we explore how these indices relate to plant fecundity (seeds/flower) over two years. We further linked plant traits and indices to uncover functional aspects of pollinator-mediated indirect interactions. Species frequently visited by shared pollinators showed higher fecundity and exhibited traits that increase pollinator attraction and generalization. Conversely, species whose shared pollinators frequently visited other plants had lower fecundity and more specialized traits. Thus, pollinator sharing benefited some species while others suffered reproductive disadvantages, consistent with competition. The framework developed here uses network tools to advance our understanding of how pollinator-mediated indirect interactions influence a species' relative reproductive success at the community level.

Microbial Ecology of Qatar, the Arabian Gulf: Possible Roles of Microorganisms

The Arabian Gulf ranks among the world’s most arid and warm regions; the land has high salinity levels with many Sabkhas and receives little precipitation. This region holds about one-third of the world’s oil supply. Qatar is the leading gas producer worldwide, which raises many concerns about the pollution of the sea, groundwater, and soil. Thus, the Arabian Gulf area has paid particular attention to environmental studies since the environmental status of this region imposed unique biological diversity, and microbial ecology has gained special importance following the identification of promising roles of microorganisms. This review article discusses the microbial ecology at the main habitats of the State of Qatar. We discuss important principles for successful ecological restoration and future perspectives of using biological approaches to solve many problems related to health, the economy, and agriculture. There are at least five microbial communities that have been recognized at the Qatari habitats: marine environment, salt marshes and mangrove forests, the arid lands (including dune communities), wetlands (including pond communities), and Rawdahs (including the Ghaf tree communities). Although, the environmental conditions of this region are almost the same, these habitats are compared with those at other countries of the Arabian Gulf whenever necessary, as each habitat has its own peculiar characteristics. Some case studies are presented to describe the biochemical characterizations of bacterial isolates from soils and leaf surface of native plants, including halophytes and xerophytes at these habitats. These studies rarely went beyond the general identification at species levels. There is a discussion about the possible roles of microorganisms at the rhizosphere, non-rhizosphere, and phyllosphere, and using plant exudates to control microbial activity. However, modern approach (culture-independent methods) addressing these topics has opened the door for deeper investigations, and to explore the roles played by microorganisms at these habitats. These methods have already begun during the last decade as serious step to solve many environmental issues. In the future, it is very likely that microorganisms will be used to tackle many pollution issues, as well as health, agricultural, and economic problems.

Contrasting responses of different functional groups stabilize community responses to a dominant shrub under global change

Abstract Changes in precipitation regimes and nitrogen deposition levels due to global change are altering terrestrial ecosystems worldwide. Most attempts at understanding how biotic interactions affect plant species and community responses to global change have focused on biotic interactions measured at the community level. However, these approaches ignore that communities include functionally dissimilar species that might respond differently to changes in the effects of dominant neighbours along environmental gradients. We test the hypothesis that plant species with differences in functional traits may exhibit contrasting interactions with a dominant shrub species within a single community, thereby stabilizing community‐level responses to the effects of global change. We manipulated water and nitrogen applications in a semi‐arid dune community in northern China, quantified the biomass of herbaceous species occurring below the dominant shrub, Artemisia ordosica, and in adjacent open patches (without the shrub), and measured herbaceous species height and leaf dry matter content. The effects of A. ordosica were quantified at the species, group and community levels using the relative interaction index (RII). Redundancy analysis was performed on species traits and the RII values to assess the relationships between functional differences in species and plant–plant interactions. Species were then grouped using a cluster analysis and the RII values were recalculated at the group level. The redundancy analysis showed that species height and leaf dry matter content were significantly correlated to the changes in species' responses to the effect of A. ordosica along treatments. The four groups of species identified by the cluster analysis showed contrasting variations in competitive or facilitative responses depending on species traits and environmental treatments. However, the interactions measured at the group level balanced the community‐level responses, as we found no significant changes in the effects of A. ordosica along treatments for community biomass, richness and functional diversity indices. Synthesis. Our findings indicate that species with different functional strategies within a community exhibit contrasting responses to a dominant shrub along environmental gradients. These contrasting changes in plant–plant interactions of functionally different species may balance the responses of community‐level metrics. This suggests that functional differences between species groups and the balance of plant–plant interactions stabilize community responses to global change.

Effects of pine plantations on coastal gradients and vegetation zonation in SW Spain

One of the most important anthropic disturbances on Mediterranean coastal dunes is the plantation of pine trees. However, the impact of coastal pine plantations on environmental gradients and on the spatial zonation of vegetation has received little attention. I analysed the spatial pattern of vegetation along sea-inland gradients from the foredune inland in three dune systems at the Gulf of Cádiz (SW Spain) to assess the effects of pine plantations on both the environment and the plant communities. In this study, I focus on the effects of the “Wooded dunes with Pinus pinea and/or Pinus pinaster” European habitat (code 2270) on the “Coastal dunes with Juniperus spp.” European habitat (code 2250), both considered as priority habitat, and which in many cases compete for the same range of the spatial zonation of vegetation.CCA showed that the distance to the shoreline was the main factor controlling the composition of sand dune communities, even when several environmental gradients were modified by the presence of pine trees. Boundary Analysis detected several stretches with a characteristic vegetation that correspond to dune geomorphological zones. However, the plantation of pine trees on coastal dune ridges modified salt spray deposition and sand mobility landward, the main factors causing vegetation zonation in coastal dunes, making characteristic species of semifixed habitats such as Armeria pungens and Artemisia chritmifolia disappear. Pine plantations also shade and reduce wind flow producing negative effects on the growth and reproduction of the heliophilous and dioecious wind-pollinated Juniperus macrocarpa. Therefore, Pinus pinea may be considered as a physical ecosystem engineer in coastal sand dunes in spite of not being a species well adapted to salt spray and sand mobility, in contrast to J. macrocarpa. A better understanding of the ecological and geomorphological coastal processes is needed in order to promote better management and restoration actions of the coastal dune habitats to preserve the rich and specialized flora that inhabits these ecosystems, including Juniperus macrocarpa.

Spatial extent and severity of all‐terrain vehicles use on coastal sand dune vegetation

AbstractQuestionsIncreases in all‐terrain vehicle (ATV) use on dunes raises concerns about an ecosystem vital for coastal protection. We asked: with distance from trails, what are the effects of ATV use on (a) total, native, and non‐native plant species richness and (b) presence and cover of the dune‐stabilising plant Ammophila breviligulata? Specifically, how do (a) and (b) differ (1) between regions with and without ATV use; (2) with deeper ruts and increased distance from the ATV trail; and (3) between pioneer and shrub zones of dunes in each region?LocationMiscou Island and Kouchibouguac National Park, New Brunswick, Canada.MethodsWe assessed ATV effects by conducting field vegetation surveys in a region with (Miscou Island) and without (Kouchibouguac National Park) ATV use. Line transects were used to capture gradients of effects across the dune community via plots evenly placed to measure trail effects (on the trail), close‐edge effects (edge of the trail), and distant‐edge effects (every 5 m up to 25 m away from trail), in pioneer and shrub zones of dunes.ResultsAll‐terrain vehicle rut depth was associated with a decrease in total and native species on the trails and on the edge of trails, and with a slight increase in non‐native species beyond the trail edge. We also found a rut depth threshold of approximately 50 cm, beyond which was an abrupt decline across all species. Where ATV activity occurred, there was also a decrease of A. breviligulata in presence and cover, non‐native species increased in the pioneer zone, and the shrub zone had fewer native species.ConclusionsAll‐terrain vehicle use plays a major role in the vegetation changes observed on coastal dunes. A management plan that recognises the specific effects caused by ATV use on dune vegetation will help preserve dunes, enabling more cost‐effective coastal protection than engineered interventions.

Is richer always better? Consequences of invaded N-rich soils for the early growth of a native and an invasive species

Despite growing evidence that many invasive plants have impacts at soil level, it is less clear how these changes affect the recovery of invaded systems after their removal. Acacia longifolia is an invasive species in coastal areas around the world; it modifies soil properties and forms a thick layer of litter that can hinder the recovery of native dune communities and facilitate its own invasion. Ammophila arenaria is a key native species in the Portuguese foredunes but its habitat is gradually invaded by A. longifolia. Aiming to assess the influence of the soil altered by A. longifolia invasion on the germination and early growth of A. arenaria and A. longifolia, seeds of both species were sown under controlled conditions in native and invaded soils, and in the presence or absence of A. longifolia litter. Considering our main goal (to assess the development of each species in different conditions), and because study species have different growth forms, species were treated separately. Both species germinated better in the native soil, but after 12 weeks A. arenaria and A. longifolia had better performance in the invaded soil, exhibiting longer shoots, and higher biomass, leaf area, and relative growth rate. The root mass fraction was higher in the native soil. The added litter had no significant effect on germination or growth of either species. These results suggest that after the removal of A. longifolia no special measures are necessary to restore foredunes soil when promoting A. arenaria populations, although such measures could delay the growth of A. longifolia. Our results emphasize the importance of managing biological invasions at early stages as restoration is easier and prevent positive feedbacks that further promote the invasive species. However, more studies are needed to understand when management measures at soil level are required in ecological restoration projects.

The lichens of Moshchny Island (Lavansaari) – one of the remote islands in the Gulf of Finland


 
 
 We present a checklist for Moshchny Island (Leningrad Region, Russia). The documented lichen biota comprises 349 species, including 313 lichens, 30 lichenicolous fungi and 6 non-lichenized saprobic fungi. Endococcus exerrans and Lichenopeltella coppinsii are reported for the first time for Russia; Cercidospora stenotropae, Erythricium aurantiacum, Flavoplaca limonia, Lecidea haerjedalica, and Myriospora myochroa for European Russia; Flavoplaca oasis, Intralichen christiansenii, Nesolechia fusca, and Myriolecis zosterae for North-Western European Russia; and Arthrorhaphis aeruginosa, Calogaya pusilla, and Lecidea auriculata subsp. auriculata are new for Leningrad Region. The studied lichen biota is moderately rich and diverse, but a long history of human activity likely caused its transformation, especially the degradation of forest lichen biota. The most valuable habitats for lichens in Moshchny Island are seashore and dune communities which definitely deserve protection.
 
 

Exposure of coastal dune vegetation to plastic bag leachates: A neglected impact of plastic litter

The presence of plastic bags on coastal dunes worldwide is well documented. Plastic bags contain additives that during rainfall events can leach out from bags into sand dune and be absorbed by seeds and roots of plants. Dune plants play a fundamental role in dune system formation, yet the possible impact of bag leaching on their establishment and development has been neglected. We assessed in laboratory whether (i) not biodegradable bags (high-density polyethylene, PE) and new generation of compostable bags (Mater-bi®, MB) would influence via leaching water chemical/physical properties and (ii) leachates would affect germination and seedling growth using Thinopyrum junceum and Glaucium flavum as models. Leachates were obtained from different amounts of not-exposed and bags exposed to beach or marine conditions simulating various pollution degrees (none, low, intermediate and high pollution). All water variables were affected by leaching. The magnitude of these alterations depended on bag type and environmental exposure. Seeds of T. junceum treated with the high concentration of marine-exposed MB bag leachate germinated later than controls while those of G. flavum treated with the remaining leachates germinated earlier. For both species, leachates from the low concentration of PE and MB marine-exposed bags increased seed germinability. A short radicle was observed in T. junceum seedlings treated with not-exposed MB bag leachates. Glaucium flavum seedlings treated with beach- and marine-exposed PE bags and not-exposed MB bags leachates showed a greater below-aboveground length ratio and those grown with the low concentration of not-exposed PE bag leachate had a longer hypocotyl compared to controls. Leachates from the high concentration of PE and MB bag caused seedling anomalies in both species. These findings indicate that not biodegradable and compostable bags may interact with abiotic/biotic factors and affect via leaching germination phenology, seedling establishment and plant interactions with consequences on dune community structure.

Differentiating Footprints of Sympatric Rodents in Coastal Dune Communities: Implications for Imperiled Beach Mice

AbstractIdentifying techniques for conducting frequent, effective, and inexpensive monitoring of small mammals can be challenging. Traditional approaches such as livetrapping can be laborious, expensive, detrimental to animal health, and ineffective. Passive approaches such as tracking (e.g., from tracks on the ground or footprints collected at a tracking station) have been shown to lessen those burdens, but a problem with tracking, particularly for rodents, is the uncertainty in identifying species from footprints. To address the need for a more accurate method of identifying small mammal tracks, we measured footprints from live-captured rodents and developed a classification tree for distinguishing between subspecies and species using footprint widths treated as having known or unknown identification. We captured rodents within or near the coastal dunes of Florida and Alabama with a focus on areas occupied by threatened and endangered beach mice Peromyscus polionotus subspp., whose populations warrant regular monitoring but whose tracks are not easily distinguished from those of some sympatric species. We measured 6,996 front and hind footprints from 540 individuals across eight species. The overall accuracy of our classification tree was 82.6% and we achieved this using only the front footprint width. Footprint width cutoffs for species identification were < 5.5 mm for house mice Mus musculus, 5.5–6.7 mm for beach mice, and 6.7–8.3 mm for cotton mice Peromyscus gossypinus. We were most successful in confirming the identity of beach mice: we correctly classified approximately 94% of beach mice, while we misclassified fewer than 6% as house mice and fewer than 1% as cotton mice. When we input a beach mouse individual into the classification tree as of an unknown species, we correctly identified 78.1% of individuals as beach mice from their tracks, and most incorrect identifications were of house mouse tracks. Our study demonstrates that researchers can identify sympatric rodent species in coastal dune communities from tracks using quantitative classification based on footprint width. Accurate identification of beach mice or other imperiled species from tracks has important management implications. Not only can wildlife managers determine the presence of a species accurately, but they can monitor populations with considerably less effort than livetrapping requires. Although our study was specific to coastal dune communities, our methods could be adapted for the creation of a classification tree for identifying tracks from suites of species in other areas.

Pollination networks along the sea-inland gradient reveal landscape patterns of keystone plant species

Linking the functional role of plants and pollinators in pollination networks to ecosystem functioning and resistance to perturbations can represent a valuable knowledge to implement sound conservation and monitoring programs. The aim of this study was to assess the resistance of pollination networks in coastal dune systems and to test whether pollination interactions have an explicit spatial configuration and whether this affect network resistance. To this aim, we placed six permanent 10 m-wide belt transects. Within each transect we placed five plots of 2 m x 2 m, in order to catch the different plant communities along the dune sequence. We monitored pollination interactions between plants and pollinators every 15 days during the overall flowering season. The resulting networks of pollination interactions showed a relatively low degree of resistance. However, they had a clear spatial configuration, with plant species differently contributing to the resistance of pollination networks occurring non-randomly from the seashore inland. Our results evidenced that beside contributing to the creation and maintenance of dune ridges, thereby protecting inland communities from environmental disturbance, plant species of drift line and shifting dune communities have also a crucial function in conferring resistance to coastal dune pollination networks.

Back into the past: Resurveying random plots to track community changes in Italian coastal dunes

Resurveying studies are commonly appreciated as a means to monitoring temporal changes in plant diversity. However, most of them still rely on phytosociological plots, which, although representing an invaluable source of data, can lead to biased estimates of vegetation changes. At the community-level, temporal changes can be quantified by means of beta-diversity measures. However, compositional variation can be the result of two different, often contrasting, processes: turnover and nestedness. In this context we test the effectiveness of resurveying approaches based on quasi-permanent plots in revealing temporal changes in herbaceous communities of Mediterranean coastal dune systems. Indeed, due to their being highly dynamic, coastal dunes can be considered ideal habitats for implementing such tools. In particular, we quantified temporal changes in species composition occurred over 10–15 years by calculating Sørensen index of dissimilarity and, in order to determine whether the change was really driven by species turnover, we partitioned Sørensen index into its two components of turnover and nestedness. At the same time, since diagnostic species are considered to be particularly sensitive to habitat modifications and helpful in assessing changes in the ecological structure of a community, we analyzed temporal changes in the occurrence and cover of diagnostic species of the investigated habitats. Results show that coastal dune communities of our study area underwent consistent changes during the analyzed time-span. Almost 25% of the historical plots disappeared. Major transformations, mainly driven by species turnover, involved upper beach communities, embryonic and mobile dunes, as revealed by the parallel analysis of beta diversity and diagnostic species. This work shows how resurveying approaches can efficiently reveal useful insights on vegetation dynamics, therefore providing a solid basis for the implementation of effective conservation strategies, especially in endangered habitats.

Patterns of phylogenetic community structure of sand dune plant communities in the Yucatan Peninsula: the role of deterministic and stochastic processes in community assembly

ABSTRACTBackground: Tropical sand dunes are ideal systems for understanding drivers of community assembly as dunes are subject to both deterministic and stochastic processes. However, studies that evaluate the factors that mediate plant community assembly in these ecosystems are few.Aims: We evaluated phylogenetic community structure to elucidate the role of deterministic and stochastic processes in mediating the assembly of plant communities along the north of the Yucatan Peninsula, Mexico.Methods: We used plastid genetic markers to evaluate phylogenetic relationships in 16 sand-dune communities. To evaluate the role of climate in shaping plant community structure we carried out linear regressions between climatic variables and mean phylogenetic distance. We estimated the Net Relatedness Index and Nearest Taxon Index to identify ecological processes mediating community assembly.Results: Observed phylogenetic structure was not different from random, suggesting that stochastic processes are the major determinants of community assembly. Climate was slightly correlated with phylogenetic diversity suggesting that abiotic environment plays a minimal role in community assembly.Conclusions: Random assembly appears to be the primary factor structuring the studied sand dune plant communities. Environmental filters may represent a secondary factor contributing to the observed phylogenetic structure. Thus, both processes may act simultaneously to mediate the assembly of sand-dune plant communities.