Efecto del fuego sobre la flora micorrícica de una formación natural de carrasca

El objetivo de este trabajo es el estudio tanto cuantitativo como cualitativo de los morfotipos de ectomicorrizas que aparecen asociados de forma natural a la carrasca, Quercus ilex L. subsp. ballota (Desf.) Samp. Este estudio se ha llevado a cabo en un carrascal de Navarra afectado en 1993 por un incendio forestal. Los muestreos se han realizado en dos zonas de dicho carrascal, una alterada por el incendio (zona quemada), y otra que no sufrió ninguna perturbación (zona control). Por una parte, se ha analizado el efecto del fuego sobre el estado micorrícico de las carrascas, comparando los porcentajes de micorrización de la zona quemada y de la zona control, y, por otra, se ha contrastado la diversidad y la abundancia de los morfotipos de ectomicorrizas que aparecen en ambas zonas, haciendo una descripción de dichos morfotipos, e identificando al hongo que los forma en la medida de lo posible. SUMMARY The aim of this study is the quantitative and qualitative analysis of the ectomycorrhizal morphotypes naturally associated with evergreen oak, Quercus ilex L. subsp. ballota (Desf.) Samp. The study has been undertaken in an evergreen oak forest located in Navarra. Part of this forest burned in 1993, but most of it remains undisturbed. Thus, samples have been taken from both the burned and the control study sites. The impact of fire on the mycorrhizal state of evergreen oaks has been analysed by comparing the percentages of mycorrhization in the burned and the control areas. On the other hand, the diversity and abundance of the ectomycorrhizal morphotypes occurring in both sites have also been studied. The ectomycorrhizal morphotypes found have been described, and the fungal partner has been identified when possible

Identificación y descripción de las Ectomicorrizas de Quercus Ilex L. Subsp. Ballota (Desf.) Samp. en una zona quemada y una zona sin alterar del carrascal de Nazar (Navarra)

Desde 1998, se ha llevado a cabo un estudio de campo en un bosque de Quercus ilex L. subsp. ballota (Desf.) Samp. situado en Nazar (Navarra, España). El objetivo de este estudio es la comparación cualitativa y cuantitativa de los tipos de ectomicorrizas que han sido descritos e identificados en una zona quemada y una zona control de este carrascal. Así, se pretende paliar la escasez de conocimiento en el tema de las ectomicorrizas asociadas con la carrasca en condiciones naturales, ya que la mayoría de los trabajos publicados están relacionados con la truficultura o la micorrización inducida en vivero

Post-fire, seasonal and annual dynamics of the ectomycorrhizal community in a Quercus ilex L. forest over a 3-year period

Two study plots, burned and control, were established in autumn 1998 in a Quercus ilex forest located in northern Spain, part of which had been affected by a low intensity fire in 1994. Soil samples for ectomycorrhizae (ECM) were taken over a 3-year period in each study plot in spring, summer, autumn and winter. ECM morphotypes were identified and the relative abundance of each morphotype in each soil sample calculated, along with species richness, Shannon diversity index and percentage of mycorrhization in each soil sample. The relative abundance of certain ECM morphotypes differed between burned and control plots, and the percentage of mycorrhizal tips was significantly lower in the burned than in the control plot. Nevertheless, there were no significant differences in the diversity, species richness or species composition of the ECM community in the burned and control plots. The dominant ECM morphotypes in both stands were Cenococcum geophilum and several thelephoroid fungi. Sphaerosporella brunnea and Pisolithus tinctorius thrived especially in the burned plot, whereas three ectomycorrhizal morphotypes assigned to the genus Hebeloma were especially abundant in the control plot. There was no significant variation in the relative abundance of the ECM morphotypes between seasons, but ECM community species richness was highest in autumn and lowest in summer. The percentage of mycorrhizal tips reached a maximum in winter, with its minimum in autumn. Collection of samples over the 3-year period also enabled us to detect a significant increase in percentage of ECM colonisation in the burned stand over time

Primeros datos sobre la reforestación de un área de carrascal quemado con plantas de Quercus ilex subsp. ballota inoculadas con Tuber melanosporum.

Se ha llevado a cabo un estudio acerca de la comunidad micorrícica de Quercus ilex L. subsp. ballota (Desf.) Samp. en un carrascal situado en Nazar (Navarra, España) afectado en parte por un incendio. En la zona quemada de este carrascal, que se encuentra dentro de la zona de distribución potencial de la trufa negra en Navarra, se ha introducido una serie de plantas de carrasca inoculadas en vivero con Tuber melanosporum Vitt. acompañadas por plantas no micorrizadas de forma artificial que actúan como control, para así analizar la permanencia del hongo inoculado y la posible competencia con otras especies ectomicorrícicas que se encuentren en el medio. A partir de los datos obtenidos en esta investigación se puede concluir que las micorrizas de Tuber melanosporum persisten al cabo de 3 años de su introducción en la zona quemada del carrascal de Nazar, aunque han de competir con otros hongos micorrícicos presentes en el ecosistema, por lo que T. melanosporum puede ser un hongo adecuado para su utilización como inóculo micorrícico de plantas de Quercus ilex subsp. ballota usadas para reforestar carrascales incendiados que se encuentren situados dentro del área de distribución potencial de la trufa negra en Navarra

Estudio de las ectomicorrizas en una trufera cultivada situada en Olóriz (Navarra).

En el presente trabajo se aportan los resultados obtenidos en el estudio de las ectomicorrizas presentes en una trufera cultivada situada en Olóriz (Navarra), plantada con árboles (encinas, robles y avellanos) micorrizados por la trufa negra Tuber melanosporum Vitt, a partir de los muéstreos realizados estacionalmente en primavera y otoño durante los años 1996 y 1997. Se han clasificado un total de 7 tipos micorrícicos, en 5 de los cuales se ha identificado el simbionte fúngico a nivel de especie. Se analiza también la evuloción de la micorriza de T. melanosporum, así como las diferencias entre los tres tipos de árboles y la influencia de los tratamientos de acolchado

A revision of the descriptions of ectomycorrhizas published since 1961

All available publications providing descriptions of ectomycorrhizas (ECM) were reviewed in order to build a database containing details on fungus forming the ECM, host tree, country where the material for description was collected, and habitat of the ECM. Other secondary data were also recorded. In all 1244 descriptions of ECM published since 1961 in 479 papers were reviewed. The number of different ECM morphotypes described was 814. Most ECM described were collected in Europe and North America. Gymnosperms were the most common tree associates, and boreal and temperate forests the most studied ecosystems. Fungal symbionts were mostly Basidiomycota, epigeous, and with mushroom-like morphology. The paper also addresses the gaps in ECM knowledge that mycorrhizologists should address in future studies

Comparison of the post-fire dynamics of the ectomycorrhizal community in two Quercus ilex stands in Northern Spain

A comparative study of the post-fire recolonization of ectomycorrhizae in two evergreen oak stands (Quercus ilex L. subsp. ballota (Desf.) Samp.) in Nazar and San Cristóbal (Navarra, Spain) has been carried out. In 1993 a stand in Nazar burnt, but it was not until 1998 that the study started. On the contrary, the study in San Cristóbal started immediately after the stand had caught fire in 2000. Therefore we have been able to compare the regeneration in both stands and the species composition five years after the fire and immediately after the fire, as well as the differences in ectomycorrhizal colonization and abundance of morphotypes between the burnt plots and areas which remained undisturbed in both forests, thus acting as control plots. In both sites the percentage of ectomycorrhizal colonization tended to be lower after the wildfire. In San Cristóbal, in the burnt site there was a lower abundance of morphotypes compared to the control site. However, in Nazar, five years after the fire, we did not find any significant change in species richness, but rather a shift in the abundance of each morphotype when comparing the burnt and the control plots. There are some species of mycorrhizal fungi which seem to be particularly adapted to fire, such as Type 1 in San Cristóbal and Cenococcum geophilum in Nazar. Sphaerosporella brunnea, a pioneer species considered to be especially suitable for the colonization of burnt substrates, was only found in Nazar