How can an invasive grass affect fire behavior in a tropical savanna? A community and individual plant level approach

Some invasive grasses have been reported to change fire behavior in invaded plant communities. Urochloa brizantha is an aggressive invasive grass in the Brazilian Cerrado, an ecosystem where fire is a common disturbance. We investigated the effects of U. brizantha on fire behavior in an open Cerrado physiognomy in Central Brazil. Using experimental burnings we compared fire behavior at both the community and the individual plant level in invaded (UJ) and non-invaded (NJ) areas burned in July. We also assessed the effect of fire season in invaded areas by comparing July (UJ) and October (UO) burnings. We evaluated the following variables: fuel load, fuel moisture, combustion efficiency, maximum fire temperature, flame height, and fire intensity. Additionally, we evaluated the temperatures reached under invasive and native grass tussocks in both seasons. Fuel load, combustion efficiency, and fire intensity were higher in NJ than in UJ, whilst flame height showed the opposite trend. Fuel amount and fire intensity were higher in October than in July. At the individual plant level, U. brizantha moisture was higher than that of native species, however, temperatures reaching ���600 ��C at ground level were more frequent under U. brizantha tussocks than under native grasses. At the community level, the invasive grass modified fire behavior towards lower intensity, lower burning efficiency, and higher flame height. These results provide essential information for the planning of prescribed burnings in invaded Cerrado areas.

Clasificaci��n y caracterizaci��n de zonas h��medas del litoral alicantino (SE Espa��a), mediante las metodolog��as CAR/ASP y MEDWET: estudio de caso del Saladar de Aguamarga y el Fondet de La Senieta

En este estudio se pretende caracterizar las comunidades vegetales presentes en ambientes litorales en el SE de la provincia de Alicante, mediante el cartografiado de zonas homog��neas de vegetaci��n, mediante el empleo de los cat��logos propuestos por el RAC-SPA y Medwet. De este modo, se han determinado 7 unidades ambientales en cada uno de los sectores analizados en el estudio (saladar de Urbanova y el Fondet de la Senieta), pudiendo comparar las diferencias entre ambas t��cnicas. As��, se seleccionaron 10 parcelas al azar y su vegetaci��n fue muestreada seg��n la metodolog��a, basada en transectos, denominada ��quadrat technique�� y se identificaron las diferentes especies vegetales en el campo. Por otro lado, la medida de la cobertura vegetal total tambi��n fue tomada seg��n la metodolog��a de ��Braun Blanquet��. Se han empleado los programas inform��ticos CartaLinx�� y ArcView�� para el cartografiado de las unidades vegetales. As��, trabajo se pretende proporcionar herramientas t��cnicas y garantizar la gesti��n sostenible de los humedales y sus recursos naturales.

El Clot de Galvany-Balsares: clasificaci��n y caracterizaci��n de zonas h��medas del litoral alicantino (SE Espa��a) mediante las metodolog��as RAC/SPA y MEDWET

Este trabajo es el segundo de una serie de estudios que se realiz�� para caracterizar las comunidades vegetales presentes en ambientes litorales en el SE de la provincia de Alicante, mediante el cartografiado de zonas homog��neas y el empleo de los cat��logos propuestos por el RAC-SPA y Medwet. Se han determinado 11 unidades ambientales en el sector analizado que se corresponde al Clot de Galvany y Balsares, las cuales se han descrito y se han representado en 2 mapas que permite comparar las diferencias entre ambos cat��logos. De este modo, se seleccionaron 10 parcelas al azar y su vegetaci��n fue muestreada seg��n la metodolog��a, basada en transectos, denominada ��quadrat technique�� y se identificaron las diferentes especies vegetales en el campo. Por otro lado, la medida de la cobertura vegetal total tambi��n fue tomada seg��n la metodolog��a de ��Braun Blanquet��. Se han empleado los programas inform��ticos CartaLinx�� y ArcView�� para el cartografiado de las unidades vegetales. As��, la finalidad de este trabajo es proporcionar una serie de herramientas t��cnicas para poder garantizar la gesti��n sostenible de la compleja situaci��n de la zona de estudio, as�� como de sus recursos naturales.

Biodiversity of Archaea and floral of two inland saltern ecosystems in the Alto Vinalop�� Valley, Spain

Background. The extraction of salt from seawater by means of coastal solar salterns is a very well-described process. Moreover, the characterization of these environments from ecological, biochemical and microbiological perspectives has become a key focus for many research groups all over the world over the last 20 years. In countries such as Spain, there are several examples of coastal solar salterns (mainly on the Mediterranean coast) and inland solar salterns, from which sodium chloride is obtained for human consumption. However, studies focused on the characterization of inland solar salterns are scarce and both the archaeal diversity and the plant communities inhabiting these environments remain poorly described. Results. Two of the inland solar salterns (termed Redonda and Penalva), located in the Alto Vinalop�� Valley (Alicante, Spain), were characterized regarding their geological and physico-chemical characteristics and their archaeal and botanical biodiversity. A preliminary eukaryotic diversity survey was also performed using saline water. The chemical characterization of the brine has revealed that the salted groundwater extracted to fill these inland solar salterns is thalassohaline. The plant communities living in this environment are dominated by Sarcocornia fruticosa (L.) A.J. Scott, Arthrocnemum macrostachyum (Moris) K. Koch, Suaeda vera Forsk. ex Gmelin (Amaranthaceae) and several species of Limonium (Mill) and Tamarix (L). Archaeal diversity was analyzed and compared by polymerase chain reaction (PCR)-based molecular phylogenetic techniques. Most of the sequences recovered from environmental DNA samples are affiliated with haloarchaeal genera such as Haloarcula, Halorubrum, Haloquadratum and Halobacterium, and with an unclassified member of the Halobacteriaceae. The eukaryote Dunaliella was also present in the samples. Conclusions. To our knowledge, this study constitutes the first analysis centered on inland solar salterns located in the southeastern region of Spain. The results obtained revealed that the salt deposits of this region have marine origins. Plant communities typical of salt marshes are present in this ecosystem and members of the Halobacteriaceae family can be easily detected in the microbial populations of these habitats. Possible origins of the haloarchaea detected in this study are discussed.

Composici��n, riqueza y abundancia de cole��pteros (Coleoptera) asociados a bosques semideciduos y vegetaciones ruderales en la Sierra del Rosario, Cuba

En tres bosques semideciduos y en tres tipos de vegetaci��n ruderal del ��rea Protegida de Recursos Manejados Mil Cumbres (Sierra del Rosario, Pinar del R��o, Cuba), se analizan las comunidades de cole��pteros y se las compara respecto a la composici��n, riqueza, abundancia, diversidad, equitatividad, ordenaci��n y complementariedad. La composici��n de cole��pteros conocida hasta el momento es de 166 especies, incluidas en 75 g��neros y 34 familias. La vegetaci��n ruderal presenta�� mayor riqueza y abundancia que los bosques semideciduos. El bosque y la vegetaci��n ruderal de Pan de Guajaib��n exhibieron los valores m��s altos de riqueza, abundancia y n��mero de especies ��nicas. Ambas formaciones vegetales de Sierra Chiquita presentaron la mayor diversidad y equitatividad. Las comunidades de cole��pteros m��s afines estaban entre los bosques y entre la vegetaciones ruderales en Forneguera y Pan de Guajaib��n. Cada bosque y tipo de vegetaci��n ruderal presentaba especies exclusivas.

A PCR based method to detect Russula spp. in soil samples and Limodorum abortivum roots in Mediterranean environments

Aim of study. Orchidaceae has the largest number of species of any family in the plant kingdom. This family is subject to a high risk of extinction in natural environments, such as natural parks and protected areas. Recent studies have shown the prevalence of many species of orchids to be linked to fungal soil diversity, due to their myco-heterotrophic behaviour. Plant communities determine fungal soil diversity, and both generate optimal conditions for orchid development. Area of study. The work was carried out in n the two most important natural parks in Alicante (Font Roja and Sierra Mariola), in South-eastern of Spain. Material and Methods. We designed a molecular tool to monitor the presence of Russula spp. in soil and orchids roots, combined with phytosociological methods. Main results. Using a PCR-based method, we detected the presence in the soil and Limodorum abortivum orchid roots of the mycorrhizal fungi Russula spp. The species with highest coverage was Quercus rotundifolia in areas where the orchid was present. Research highlights. We present a useful tool based on PCR to detect the presence of Russula spp. in a natural environment. These results are consistent with those obtained in different studies that linked the presence of the mycorrhizal fungi Russula spp. in roots of the species Limodorum and the interaction between these fungal species and Quercus ilex trees in Mediterranean forest environments.

Efectos de la erosi��n del suelo sobre los patrones de la vegetaci��n y su composici��n flor��stica. Una revisi��n bibliogr��fica

En este art��culo se revisan los estudios realizados sobre la influencia que tienen los procesos erosivos sobre la vegetaci��n. Fundamentalmente se revisan las tendencias generales en la composici��n flor��stica de las comunidades vegetales sometidas a fuertes procesos erosivos, as�� como las tendencias de los patrones de la vegetaci��n y, en menor medida, de los atributos y tipos de plantas. Este campo de trabajo presenta pocos precedentes, siendo escasos los estudios de la influencia de la erosi��n sobre la vegetaci��n desde un punto de vista ecol��gico-bot��nico. Por otro lado, algunos de los resultados parecen a primera vista contradictorios, por lo que es dif��cil extraer tendencias generales y m��s o menos universales. Algunas de las generalidades observadas son que el incremento de la erosi��n del suelo produce un descenso muy claro y mantenido en la cobertura vegetal y en el n��mero de especies. El proceso erosivo no suele acarrear una sustituci��n de especies vegetales y comunidades, sino solamente la p��rdida paulatina de especies, al menos en los estadios m��s degradados. Por otro lado, se ha observado en ocasiones que la flora de los terrenos m��s erosionados depende muy fuertemente de las caracter��sticas de la roca madre, variando m��s entre litolog��as que la flora de terrenos menos erosionados. Los hemicript��fitos y los cam��fitos son las formas vitales de Raunkiaer m��s frecuentes en estos ambientes. Se discute el papel que pueden tener las diferencias de clima, procesos y tasas erosivas para explicar la gran diversidad de tendencias observadas.

Breaking down complex saproxylic communities: understanding sub-networks structure and implications to network robustness

Saproxylic insect communities inhabiting tree hollow microhabitats correspond with large food webs which simultaneously are constituted by multiple types of plant-animal and animal-animal interactions, according to the use of trophic resources (wood- and insect-dependent sub-networks), or to trophic habits or interaction types (xylophagous, saprophagous, xylomycetophagous, predators and commensals). We quantitatively assessed which properties of specialised networks were present in a complex networks involving different interacting types such as saproxylic community, and how they can be organised in trophic food webs. The architecture, interacting patterns and food web composition were evaluated along sub-networks, analysing their implications to network robustness from random and directed extinction simulations. A structure of large and cohesive modules with weakly connected nodes was observed throughout saproxylic sub-networks, composing the main food webs constituting this community. Insect-dependent sub-networks were more modular than wood-dependent sub-networks. Wood-dependent sub-networks presented higher species degree, connectance, links, linkage density, interaction strength, and were less specialised and more aggregated than insect-dependent sub-networks. These attributes defined high network robustness in wood-dependent sub-networks. Finally, our results emphasise the relevance of modularity, differences among interacting types and interrelations among them in modelling the structure of saproxylic communities and in determining their stability.