Coastal Dune Scrub Research Articles

Neophyte invasions in European heathlands and scrub

Human-assisted introduction of alien plants is causing ecosystem transformations worldwide and is considered an important threat to biodiversity. We provide a European assessment of habitat levels of invasion in heathlands and scrub and identify successful alien plants and invasion trends across biogeographical regions. We analysed a geographically stratified data set of 24,220 dwarf shrub and scrub vegetation plots sampled across Europe. Among the 6547 vascular plant taxa occurring in these plots, we identified 311 neophytes (4.8%, i.e. alien species introduced in Europe or its sub-regions after 1500 AD) and compared five metrics of the level of invasion in (i) EUNIS habitats, (ii) broad habitat groups and (iii) biogeographical regions of Europe. We related habitat-specific levels of invasion to elevation and climatic variables using generalized linear models. Among neophytes, phanerophytes of non-European origin prevailed. The most frequent neophytes in the plots were Prunus serotina, Robinia pseudoacacia and Quercus rubra among phanerophytes, Impatiens parviflora among therophytes, and Erigeron canadensis and Solidago gigantea among hemicryptophytes. Levels of invasion significantly differed among habitats and biogeographical regions. The most invaded habitat was Macaronesian lowland scrub, followed by riparian scrub, Rubus scrub and forest-clearing scrub of temperate Europe, and coastal dune scrub of the Atlantic region. The levels of invasion were low in the shrublands of the Arctic and Mediterranean regions and decreased with elevation within habitats. Results suggest that insularity, low elevation, frequent disturbances, and high availability or considerable fluctuation of resources promote neophyte invasions in European shrublands.

Evaluation of environmental heterogeneity and its effect on arbuscular mycorrhizal interaction in coastal dunes

Background: Coastal dune scrub vegetation is established on a substrate that favors biodiversity, but this is currently restricted to small patches.
 Objective: To determine the status of the arbuscular mycorrhizal fungi (AMF) in this vegetation under different anthropogenic pressures and to propose actions addressing its conservation and restoration.
 Methods: Plant and fungal community was characterized through taxonomic identification of the AMF and determination of their percentage of viability, number of infective propagules (NIP) and percentage of mycorrhizal colonization. Three contrasting sites were identified in the Ría Lagartos Biosphere Reserve: C = Conserved, IPS = Intermediate perturbation by the salt industry and HPA = high perturbation of anthropogenic origin. In each site, fine roots were collected from 12 common species and compound soil samples were taken.
 Results and conclusions: Eight AMF species were identified, in IPS, the highest values were presented in terms of percentage of colonization 55.43 ± 6.5, NIP = 142.07 ± 91.2 and viability = 27.6 ± 15.21 % while, in HPA, a higher number of healthy spores were found 43.6 ± 11.5/50 g. Infective propagules are an indicator of a “healthy ecosystem” and were found at a higher proportion in the conserved site.

Analyzing vegetation cover-induced organic matter mineralization dynamics in sandy soils from tropical dry coastal ecosystems

To gain knowledge about carbon and nitrogen mineralization potentials and their interaction with sandy soil environment in tropical dry coastal ecosystems, we carried out a short-term laboratory incubation experiment. For this, soil surface (0–10 cm) samples were collected from tropical semi-deciduous forest (TSdF), secondary forest (SecF), coastal dune scrub_crest (DS_C), and coastal dune scrub_slack (DS_S). Soil samples were incubated at 25 °C with constant soil moisture (at field capacity) for 97 days, and over this time 10 and 11 sampling occasions were analyzed to determine carbon (CO2-C) and nitrogen (NH4+, NO3-) dynamics, respectively. We used a simple exponential model to estimate soil carbon and nitrogen mineralization pools. On average, soil organic carbon mineralization rates ranged between 0.017 and 0.053 mg CO2-C g−1 soil d−1 and varied in the following order: DS_S > SecF > TSdF > DS_C. Average net mineralization rates (mg N kg−1 soil d−1) ranged between 16.9 and 18.8 and varied in the following order: SecF > DS_S > TSdF, whereas in DS_C it was −0.44, indicating N immobilization. Co and No represented, on average, 1.08% and 5% of soil organic carbon and total organic nitrogen, respectively. On average, mineralization constants (k) for Co and No were 0.29 d−1 and 0.23 d−1, respectively, showing that SOM is easily mineralized. The proportion of NO3-/Nm was very high in SecF (89%) and TSdF (75%), while DS_C showed nitrate immobilization. The increase in NO3-/Nm ratio in SecF could be associated with legume species that have established in the nature restoration (SecF) on ex-grassland. Across all study sites, linear regression analyses suggested that soil physical and chemical properties may regulate SOM mineralization (p < 0.05).

Flower-mediated plant-butterfly interactions in an heterogeneous tropical coastal ecosystem.

BackgroundInterspecific interactions play an important role in determining species richness and persistence in a given locality. However at some sites, the studies, especially for interaction networks on adult butterflies are scarce. The present study aimed the following objectives: (1) determine butterfly species richness and diversity that visit flowering plants, (2) compare species richness and diversity in butterfly-plant interactions among six different vegetation types and (3) analyze the structure of butterfly-flowering plant interaction networks mediated by flowers.MethodsThe study was developed in six vegetation types within the natural reserve of La Mancha, located in Veracruz, Mexico. In each vegetation type, we recorded the frequency of flower visits by butterflies monthly in round plots (of radius 5 m) for 12 months. We calculated Shannon diversity for butterfly species and diversity of interactions per vegetation type. We determined the classic Jaccard similarity index among vegetation types and estimated parameters at network and species-level.ResultsWe found 123 species of butterflies belonging to 11 families and 87 genera. The highest number of species belonged to Hesperiidae (46 species), followed by Nymphalidae (28) and Pieridae (14). The highest butterfly diversity and interaction diversity was observed in pioneer dune vegetation (PDV), coastal dune scrub (CDS) and tropical deciduous flooding forest and wetland (TDF-W). The same order of vegetation types was found for interaction diversity. Highest species similarity was found between PDV-CDS and PDV-TDF. The butterfly-plant interaction network showed a nested structure with one module. The species Ascia monuste, Euptoieta hegesia and Leptotes cassius were the most generalist in the network, while Horama oedippus, E. hegesia, and L. cassius were the species with highest dependencies per plant species.DiscussionOur study is important because it constitutes a pioneer study of butterfly-plant interactions in this protected area, at least for adult butterflies; it shows the diversity of interactions among flowering plants and butterflies. Our research constitutes the first approach (at a community level) to explore the functional role of pollination services that butterflies provide to plant communities. We highlighted that open areas show a higher diversity and these areas shared a higher number of species that shaded sites. In the interaction networks parameters, our results highlighted the higher dependence of butterflies by the flowers on which they feed than vice versa. In conclusion, the plant species (as a feeding resource) seem to limit the presence of butterfly species. Thus, this protected area is highly relevant for Lepidoptera diversity and the interaction between these insects and flowering plants. We suggest that studying plant and butterfly diversity in tropical habitats will provide insight into their interspecific interactions and community structure.

Floristic survey of flowering plants in a tropical coastal ecosystem in Veracruz, Mexico

Mexico is a megadiverse country and Veracruz is one of the states with the highest floristic diversity. The reserve of La Mancha in central coastal Veracruz comprises several vegetation types. In this site we conducted for a year, monthly surveys of flowering or fruiting plants in six vegetation types, considering the frequency of occurrence of different species. We found a total of 147 species (131 genera and 63 families). The families most represented were Asteraceae, Fabaceae and Verbenaceae. In addition, we found nine species that had not been reported in previous floristic studies. The highest taxonomic richness was observed in the tropical deciduous flood forest with wetland (59 species), while the highest diversity was found in tropical deciduous forest (ISI = 0.9562). We also found that the most similar vegetation types based on the composition and frequency of species were, coastal dune scrub, tropical deciduous forest and pioneer dune vegetation. The dominant plant biological form in La Mancha were herbs (40.41 %) followed by shrubs (23.97 %), vines-lianas (18.49 %) and trees (17.12 %). This study is the first to consider the frequency-occurrence of flowering and fruiting plants in La Mancha, covering six vegetation types through one year. The more relevant results of this study show the diversity of plants in different environments using the frequency of each species based on reproductive events. This information could be useful in future researches that evaluate plant-animal interactions, like pollination and seed dispersal.

Drought and extreme temperature tolerance for Tillandsia dasyliriifolia , an epiphytic bromeliad from the northern coastal dune scrubland in Yucatan, Mexico

The ecophysiological investigations about epiphytic plants have focused on the establishment of mechanistic explanations of how plants respond to changes in their environment. The main objective of this work was to assess the drought and extreme temperature tolerance of Tillandsia dasyliriifolia individuals growing in two coastal dune scrub sites with different precipitation patterns and microhabitat distribution. This study was focused on the effect of plant size on tolerance parameters. Drought and extreme temperature tolerance were evaluated in small (S1, 9 cm) and large individuals (S2, 35 cm). Tolerance between sites was not different but varied between size classes. Tillandsia dasyliriifolia shows moderate tolerance to drought in comparison to more succulent plants. The 50% of the leaves in small plants died after 40 days of drought and after 60 days for large plants. T. dasyliriifolia also exhibits moderate tolerance to extreme temperatures tolerance, small plants tolerate a temperature range from 11 ºC to 40 ºC and the range for large plants is a little broader (9 °C to 43 °C).

Decline of the Endangered Morro Bay Kangaroo Rat in California

AbstractThe Morro Bay kangaroo rat Dipodomys heermanni morroensis occurs in the vicinity of Morro Bay (specifically in and near Los Osos) in western San Luis Obispo County in coastal central California. It was listed as endangered pursuant to the U.S. Endangered Species Conservation Act in 1970 and subsequently the U.S. Endangered Species Act in 1973. Field research from the late 1950s to the mid-1980s has documented a rapid population decline. Despite many efforts, researchers have not captured the Morro Bay kangaroo rat since 1986, and the last captive individual died in 1993. We review the biology and conservation status of the Morro Bay kangaroo rat, including taxonomy and genetics, soil type and burrows, history of decline, primary causes of decline, breeding in the wild and in captivity, habitat restoration, and threats. In particular, there are two primary causes of decline. First, development (urban, agricultural, and industrial) has resulted in direct loss of habitat. Second, in the absence of fire, the early seral stages of coastal dune scrub (optimal habitat) have matured to later successional stages of vegetation, which are denser and with substantially fewer annual food plants, and which negatively impact the locomotion of kangaroo rats and change the diversity of the small mammal community with a likely increase in competition. In 2016 only pockets of habitat remain, with optimal habitat comprising an estimated 1% of the historical geographic range. Although researchers have not demonstrated predation by domestic cats, it is likely a major threat and we suspect it has contributed to the decline based upon a review of the literature. In 2011 we observed potential signs of the Morro Bay kangaroo rat at two historical areas, which suggests it may be persisting at extremely low densities in a few isolated colonies. In addition, we could not obtain permission to survey on four private properties with potential habitat. In consideration of the vast loss and fragmentation of its habitat, along with the continuing and pervasive threats, the Morro Bay kangaroo rat is clearly conservation-reliant. We believe that without urgent human intervention, the Morro Bay kangaroo rat will soon become extinct if it is not already.

DINÁMICA DEL CARBONO Y NITRÓGENO DEL SUELO EN ECOSISTEMAS DE LA COSTA TROPICAL SECA, EN LA MANCHA (CICOLMA), VERACRUZ, MÉXICO

&lt;p&gt;This study was carried out at the La Mancha Coastal Research Center (CICOLMA) in tropical semi-deciduous forest, secondary forest and two locations in coastal dune scrub (crest and slack). The aim was to study the carbon and organic nitrogen dynamics of the soil to quantify organic matter mineralization and nitrogen supply. In the laboratory, soil samples were incubated at 25 °C for 97 days and over this time 10 samples were analyzed to monitor the soil’s carbon (CO&lt;sub&gt;2&lt;/sub&gt;-C) and nitrogen ( , ) dynamics. The results reveal that mean cumulative organic carbon content was: dune slack (2.70 mg g&lt;sup&gt;-1&lt;/sup&gt;) &amp;gt; secondary forest (2.0 mg g&lt;sup&gt;-1&lt;/sup&gt;) &amp;gt; semi-deciduous forest (1.9 mg g&lt;sup&gt;-1&lt;/sup&gt;) &amp;gt; dune crest (1.2 mg g&lt;sup&gt;-1&lt;/sup&gt;). A comparison of the means using Tukey’s test (α = 0.05) detected differences only between the dune slack and the crest. Mean cumulative inorganic nitrogen content was: secondary forest (1284 mg kg&lt;sup&gt;-1&lt;/sup&gt;) &amp;gt; dune slack (1140 mg kg&lt;sup&gt;-1&lt;/sup&gt;) &amp;gt; semi-deciduous forest (1021 mg kg&lt;sup&gt;-1&lt;/sup&gt;) &amp;gt; dune crest (302 mg kg&lt;sup&gt;-1&lt;/sup&gt;), with significant differences only between the dune crest and the other treatments. In general, organic matter mineralization was higher in the dune slack and nitrogen supply was higher in the secondary forest. We conclude that organic matter mineralization and nitrogen supply are depending on the type of ecosystem and soil properties.&lt;/p&gt;

COMPARISON OF COASTAL DUNE SCRUB IN ISRAEL AND CALIFORNIA: PHYSIOGNOMY, ASSOCIATION PATTERNS, SPECIES RICHNESS, PHYTOGEOGRAPHY

ABSTRACT Coastal dune scrub near Caesarea, Israel was quantitatively described from quadrats placed in 10 sites, ranging from pioneer to near-climax communities. Sampling intensity was greatest in a mixed shrub community (Artemisia monosperma, Helianthemum stipulation, Retama raetam) characteristic of stabilized dunes in the study area. Artemisia canopy had much less effect on the distribution of understory species than Retama and Helianthemum canopies. The sampled flora of 131 taxa was dominated by Leguminosae, Gramineae, and Compositae. About 45% of the flora had Mediterranean affinities, 17% coastal (mostly endemic to Israel), and 16% desert. California dune scrub from Point Reyes and Vandenberg areas was also sampled. The two sites are climatically similar to Caesarea, but both experience summer fog which lowers summer temperatures below those at Caesarea. Climax scrub was dominated by Lupinus arboreus and Haplopappus ericoides at Point Reyes, by H. ericoides associated with L. chamissonis, Core- thro...

Some aspects of frugivory by bird populations using coastal dune scrub in Lincolnshire

The fruit diets of Sylvia warblers, and some thrushes, were studied during 1989 at a coastal scrubland site, using faecal examination. Fruit feeding commenced as the earliest berries ripened in late July, but there were differences of timing between species. Amongst both warblers and thrushes, the larger species commenced earlier and ate more fruit. Almost all Blackcap and Garden Warbler faeces examined from early August contained some fruit remains, as did most Whitethroat faeces from mid-month. Mean fruit contents of faecal samples exceeded 80% infrequently, indicating that even the most frugivorous species always took other food, normally insects, to supplement their diet. Each species differed in their fruit diet: Blackcaps, and to a lesser extent Garden Warblers, ate Woody Nightshade berries in preference to Blackberries, as they are structurally adapted for feeding on the former plant. Only inexperienced juveniles of other species regularly chose the Nightshade berries. Elder berries, abundant from ...