Monitoring endophyte populations in pine plantations and native oak forests in Northern Spain

Abstract

The replacement of native forest with plantations of other species may have important impacts on ecosystems. Some of these impacts have been widely studied, but very little is known about the effects on fungal communities and specifically endophytic fungi. In this study, endophyte assemblages in pine plantations (Pinus sylvestris, P. nigra and P. pinaster) and native oak forests (Quercus pyrenaica) in the north of the province of Palencia (Spain) were analyzed. For this purpose, samples of needles/leaves and twigs were collected from three trees in each of three plots sampled per host species. The samples were later processed in the laboratory to identify all of the endophytic species present. In addition, an exhaustive survey was carried out of the twelve sites to collect data on the environmental, crown condition, dendrometric and soil variables that may affect the distribution of the fungi. The endophyte assemblages isolated from P. sylvestris and P. nigra were closely related to each other, but were different from those isolated from P. pinaster. The endophytes isolated from Q. pyrenaica were less closely related to those from the other hosts, and therefore preservation of oak stands is important to prevent the loss of fungal diversity. Finally, the distribution of the endophyte communities was related to some of the environmental variables considered.Key words: endophytic fungi; environmental variables; soil properties; crown condition; dendrometric variables. Resumen Comunidades de hongos endófitos en plantaciones de pino y robledales del norte de EspañaLa sustitución de los bosques autóctonos por plantaciones de otras especies puede tener importantes consecuencias sobre el ecosistema. Algunos de esos cambios ya han sido ampliamente estudiados, pero hasta el momento hay muy poca información acerca de lo que ocurre con las comunidades fúngicas y en especial con las de los endófitos que ahí viven. En este trabajo se analizaron las agrupaciones de endófitos existentes en las plantaciones de pino (Pinus sylvestris, P. nigra y P. pinaster) y bosques nativos de rebollo (Quercus pyrenaica) en el norte de la provincia de Palencia (España). Para ello se recogieron muestras de acículas/hojas y ramillos de cada una de las especies estudiadas que fueron procesadas en laboratorio para determinar qué especies de hongos endófitos portaban. Además se realizó una exhaustiva toma de datos en las doce parcelas estudiadas para analizar las variables ambientales, del estado fitosanitario de la copa, dendrométricas y edáficas implicadas en la distribución de los hongos. Las comunidades de endófitos encontradas en P. sylvestris y P. nigra resultaron ser similares entre sí, y al mismo tiempo diferentes de las de P. pinaster. Los endófitos aparecidos sobre Q. pyrenaica resultaron estar alejados de los del resto de los hospedantes, por lo que la conservación de los robledales es importante para evitar la pérdida de la diversidad fúngica. Finalmente se encontraron algunas variables ambientales relacionadas con la distribució...

Endophytic and Epiphytic Phyllosphere Fungal Communities Are Shaped by Different Environmental Factors in a Mediterranean Ecosystem

“…All these findings suggest that seasonal shifts among phyllospheric fungi may be due to climatic conditions that favor propagule production or dispersal and/or to different abilities exhibited among fungal species. For example, spring preference of sporulation and differential capacity of fungi to adapt to climate have been described by Vacher et al [42] or Martinez-Alvarez et al [6]. Indeed, a great number of endophytic and epiphytic fungal genera were found to be positively associated with either spring or autumn.…”

“…In fact, rainfall has been previously identified as a key factor for the colonization pattern of endophytes [6]. Fungal community structure was also driven by mean temperatures at 10 (for endophytes) or 20 (for epiphytes) days before sampling date.…”

“…and Pinus spp. [4,6,7]. On the other hand, in tropical trees the endophytic fungal richness in leaves was reported to be higher [38] or lower [43] when compared to stems.…”

“…Phyllosphere fungi have been considered as determinant factors for plant health and productivity [2], but different drivers that shape these fungal communities on woody plants remain unclear, especially in the Mediterranean region [3]. Reports are only limited to Mediterranean oak forests (e.g., [3][4][5][6][7]), pine stands (e.g., [6,8]), and poplar plantations (e.g., [9]). Some of these studies tried to determine the factors that affect community composition of endophytic fungi, such as climatic variables [6,8], type of plant organs [7][8][9], and seasonality [4].…”

“…Climatic variables, such as average temperature, water availability, and solar radiation, were reported as drivers of endophytic fungal community composition inhabiting twigs and needles of Pinus halepensis [8]. In other pine plantations (P. sylvestris, P. nigra, and P. pinaster) and native oak forests (Quercus pyrenaica), the influence of climatic variables was not clearly understood [6]. Previous studies have reported that the composition of fungal endophytes was different in leaves and twigs of Q. cerris and Q. pubescens [7], while in other perennial plants, there were no obvious evidences to prove tissue/ organ specificity of fungal endophytes [9].…”