Tropical Sand Dunes Research Articles

Arbuscular mycorrhizal fungal diversity in tropical sand dune and restinga at Peró Beach in Rio de Janeiro state, Brazil

Abstract The diversity of arbuscular mycorrhizal fungi (sub-phylum Glomeromycotina) in two contrasting coastal ecosystems (dunes and restinga) at Pero Beach, Rio de Janeiro state, Brazil was evaluated at the end of the rainy (May) and dry (November) seasons, in 2014. A total of 22 species belonging to ten genera and five families were recorded. Glomus macrocarpum and Rhizoglomus microaggregatum had large biomass and frequencies of glomerospores at both sites. Glomerospore abundance was higher in the dry season in dunes and in the rainy season in restinga. Redundancy analysis revealed significant relationships between AMF-physical and chemical soil parameters. Shannon's index and Pielou's evenness indicated greater AMF diversity in dunes than restinga, despite the lower number of glomerospores in dunes. These results highlight the importance of knowing the AMF communities in different coastal ecosystems, especially in dunes, which due to the low vegetation cover are most frequently impacted by anthropic actions.

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.

An Ethnobotanical Survey for Tropical Sand Dune Support Greenbelt International Airport Yogyakarta (NYIA) Glagah Village, District Temon, Kulon Progo, Yogyakarta Indonesia

Aim of survey research on the type of Gumuk Pasir Tropik (Tropical Sand Dunes) is intended to reveal species diversity, a system of knowledge that includes the use, knowledge and fulfilment of its various needs. The survey was conducted to document plant diversity, supporting the greenbelt construction of the NYIA airport to take its documentation and sustainable development. The location of the research was conducted at NYIA Airport in Glagah village, Temon district, Kulon Progo regency, Yogyakarta Province Indonesia. The research was conducted using structural and open ended interview, direct observation and survey. Local people have a good knowledge of the diversity of plant species. However, lack of wisdom in the management resulted in natural forest sand dune ecological damage. The survey of local people in Glagah village resulted in identification of 84 plants that are presented in the pape

Xylocopa Bees in Tropical Coastal Sand Dunes: Use of Resources and Their Floral Syndromes

Large bees such as species from Xylocopa Latreille are usually associated with pollination in tropical sand dune areas, which frequently present shrubby herbaceous vegetation adapted to conditions of high salinity, high solar radiation and strong winds. We report on the diversity of Xylocopa and the plants they visited to collect nectar and pollen, focusing on the floral syndromes they present in these plants and on the breadth of the trophic niche in a tropical sand dune fragment over the year. The field work was carried out monthly in Baixio (Bahia, Brazil; Northern Coast Environmental Protection Area) from April 2008 to March 2009, over two consecutive days, from 06:30 AM to 05:00 PM. The medium-large body sized Xylocopa (Neoxylocopa) cearensis Ducke and Xylocopa (Schonnherria) subcyanea Pérez were noticeable for their frequency, constancy on the flowers and sharing of plant species. Xylocopa spp. visited plants with flowers of different shapes, colors, inflorescence arrangement and syndromes. However, their resource collections were mainly concentrated on Cuphea brachiata, Waltheria cinerascens, Croton sellowii and Chamaecrista ramosa, which may be considered key species for Xylocopa spp. maintenance in coastal sand dune and restinga environments in Northeast Brazil.

Screening of CSDPs for AM Fungal Association from Arnala and Kalamb Beach Maharashtra

Abstrtact: Fourteen coastal sand dune plants (CSDPs) belonging to nine families were screened for AM fungal association from Arnala and Kalamb beach which are disturbed by over increased anthropogenic activities. In present work the major mat-forming creeper, Ipomoea pes-caprae has showed association of five AM fungal species. It is also confirmed that, the plant members belonging to Asteraceae and Poaceae are dominant in tropical sand dunes.

Ecologia da interação entre as pequenas flores de quilha de Stylosanthes viscosa Sw. (Faboideae) e as grandes abelhas Xylocopa (Neoxylocopa) cearensis Ducke, 1910 (Apoidea, Hymenoptera), em duna tropical

Stylosanthes viscosa é uma herbácea comum nas dunas tropicais da costa brasileira, com distribuição agregada nas dunas urbanas de Salvador, BA. Suas flores de quilha diminutas, com uma pequena quantidade de néctar escondido no tubo da corola, a abertura de uma única flor/inflorescência/dia e a baixa densidade floral, juntos, não deveriam ser atrativos para as abelhas de grande porte. Isso deve ser verdadeiro, principalmente, sob a alta demanda energética para termorregulação em dunas tropicais. Ao contrário do esperado, a grande maioria das espécies de abelhas amostradas nas flores de S. viscosa tem tamanho médio a grande e coletou néctar em visitas legítimas, acionando o mecanismo de polinização da quilha. Entretanto, a quilha sempre ficava inutilizada após as visitas das grandes e frequentes (78%) abelhas Xylocopa. Todas as flores visitadas por essas abelhas (inclusive aquelas com a quilha inutilizada) e as protegidas experimentalmente das visitas das abelhas produziram frutos regularmente (100%). O mecanismo de êmbolo das anteras assegura a autopolinização. Como há autopolinização autônoma e o sistema é autocompatível ainda não foi possível discriminar a importância relativa da autopolinização facilitada e da polinização cruzada por abelhas. Entretanto, as grandes abelhas Xylocopa não limitam a autopolinização. Xylocopa cearensis foi a abelha mais abundante (63%) e visitou várias flores (13,0 ± 4,27) em cada rota de vôo, numa mesma mancha, apesar da baixa densidade floral (5 a 20 flores.m-2). A distância de vôo entre flores sucessivas variou entre um e dois metros (49%), acima do que seria possível (15 a 70 cm) dada a densidade floral nas manchas. As rotas de vôo foram direcionais, isto é, a maioria dos ângulos de mudança de direção entre flores sucessivas foram abaixo de 90°, com alta frequência de ângulos pequenos (<30°). Este padrão geral é explicado com a otimização de forrageio, com ajuste a limiares críticos de oferta de recursos. Paradoxalmente, a biologia floral e o padrão de florescimento de S. viscosa deveriam desestimular a visita dessas grandes abelhas, mas esta estratégia funciona apenas temporariamente. Nesta espécie melitófila, a autopolinização autônoma (assegurada pelo êmbolo) pode ser melhor explicada pela hipótese de seleção automática do que pela hipótese de segurança, considerando a disponibilidade de abelhas grandes como polinizadores nas dunas tropicais.

Diversidade e sazonalidade de abelhas solitárias (Hymenoptera: Apoidea) em dunas litorâneas no nordeste do Brasil

A estrutura da comunidade das especies de abelhas que nidificam em cavidades pre-existentes foi sistematicamente investigada por um periodo de dois anos (maio/97 a abril/99), em um fragmento de dunas litorâneas na Area de Protecao Ambiental das Lagoas e Dunas de Abaete, Salvador, Bahia (12o56'S; 38o21'W). A tecnica de amostragem utilizada foi a de ninhos-armadilha, distribuidos no campo ao acaso, em blocos com 16 ninhos, com diâmetros variaveis, a altura de 1,5 m do solo. Os ninhos eram inspecionados quinzenalmente. Foram fundados 62 ninhos pertencentes a sete especies de abelhas. Duas especies predominaram na area, Centris (Hemisiella) tarsata Smith (58% do total de ninhos fundados), seguida por Euplusia musitans Fabricius (31%). Em geral, houve flutuacao sazonal nas abundâncias de abelhas e variacao nas frequencias totais de nidificacao entre os dois anos de amostragem. As duas especies predominantes apresentaram diferentes padroes sazonais. Houve sempre ninhos-armadilha disponiveis no campo para as abelhas, que usaram apenas 14% do total oferecido.

Spatial and temporal variability during primary succession on tropical coastal sand dunes

Abstract. We studied primary succession on mobile tropical coastal sand dunes over an 8‐yr period. Every six months, we monitored changes in species composition and sand movement in permanent quadrats located on the windward slopes, the arms and the crests. Our results indicate that sand movement decreased over time but was significantly higher on the slopes and crests than on the arms. In all cases, there were seasonal fluctuations in sand movement which increased during the period with strong northerly winds and decreased during the rainy season. Sand movement was significantly correlated with species distribution. Plant cover and species richness increased at all three locations. Diversity increased on the slope, decreased on the arms and remained unchanged on the crest. However, the equitability values indicated the dominance of a few species, especially at the end of the study period. Temporal trends and species turnover rates differed among locations. Species turnover occurred first on the arms (1994), then on the crests (1998) and lastly on the slopes (at the end of the study period). In all cases the tall grass, Schizachyrium scoparium var. littoralis, became dominant over the endemic legume, Chamaecrista chamaecristoides var. chamaecristoides. Similar to temperate dunes, primary succession on tropical sand dunes was spatially and temporally heterogeneous.

A comparative study of the effects of fluctuations in temperature and moisture supply on hard coat dormancy in seeds of coastal tropical legumes in Mexico

ABSTRACTThe effect of fluctuations in temperature and moisture supply on hard seeds of nine tropical coastal sand dune legumes, including herbs (Schrankia atiadrivalvis, Macropiilium atropurpureum and Canavalia rosea), and shrubs (Acacia farncsiana, A. macracantha, Mimosa chaetocarpa, Indigoftra sujjruticosa, Crolalaria incana and Chamaecrista chamaecrutoides), has been studied under laboratory and field conditions. Using a fluctuating temperature gradient bar seeds buried in sand were exposed to various amplitudes of diurnal temperature fluctuation over an extended period of time and seed germinability was examined at intervals. Germination percentage increased considerably in most species as a consequence of treatment with marked effects occurring at temperature fluctuations greater than 20°C and becoming detectable after 45 days. In several species the effect of applying wetting and drying cycles was to lower the amplitude of temperature fluctuation necessary to soften the seeds. Species can be grouped into physiological groups on the basis of differences in seed response to temperature fluctuations. It is suggested that these differences may help to explain the mechanisms distinguishing the different colonization patterns observed in tropical sand dune systems.

Survival of seedling cohorts of a tropical legume on a sand dune system along the Gulf of Mexico: influence of germination date

Chamaecrista chamaecristoides is a legume endemic to the coastal sand dunes along the coasts of Mexico. Hard-coat dormancy of seeds is broken through naturally occurring temperature fluctuations, and seedlings can emerge and establish throughout the year. In the study site, winter storms (called Nortes) are responsible for moving large quantities of sand that bury young seedlings. The objectives of the study were (i) to elucidate the timing of seedling emergence, (ii) to investigate the effect of date of emergence on seedling survival, and (iii) to evaluate different factors of mortality. Seedling survival was monitored under natural conditions, from January 1988 to April 1991. Survivorship curves were compared using the log-rank Peto and Peto test. It was found that the probability of survival or reproduction was not strictly determined by chronological age but by size. Larger sized seedlings survived better during the Nortes. Timing of germination has a great impact on C. chamaecristoides populations, since it affects seedling growth possibilities and thus survival and reproduction. In a changing environment like the sand dunes, there seems to be a selective advantage for maintaining cohorts germinating during different seasons of the year. Key words: tropical sand dunes, seedling survival, Gulf of Mexico, cohorts, seedling size.

Soil Cation Increase in a Tropical Sand Dune Ecosystem Due to a Terrestrial Bromeliad

Soil Cation Increase in a Tropical Sand Dune Ecosystem Due to a Terrestrial Bromeliad