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Present status and evolution of the sessile oak forest in the Northeastern Iberian Peninsula

Goal: Thesis project

Date: 11 April 2019

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Jordi Bou
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The sessile oak forests found on the northeast of the Iberian Peninsula are ascribed to the Lathyro-Quercetum petraeae association and play a key role in understanding the ecology of this habitat, as this region represents its xeric limit. For this reason, we analysed the biodiversity patterns and current conservation status of the sessile oak forests in the region. To do so, we collected Braun-Blanquet inventories of 34 plots randomly distributed throughout the sessile oak forests. The results showed a relationship between the climatic conditions and the biodiversity variables. While the richness of the community increased with decreasing temperatures, the characteristic species found within the community decreased at these same temperatures. This result was due to the presence of most companion species in the cool zones at high elevations. Sessile oaks are found close to other communities, such as silver birches and Scot pine forests. On the other hand, in the warm areas at low elevations, the sessile oak community was more established, with plants typical of this type of forest. These slightly warmer zones with sessile oaks are very important in terms of conservation and more vulnerable to climate change and the thermophilization of the community, as has been studied. As such, protecting and managing these forests is key to conserving this community. Nevertheless, as current protection measures do not safeguard most of these forests, it is essential to define a conservation strategy to preserve them. Using the conservation status, we have established criteria to improve the conservation strategy for sessile oak forest on the NE Iberian Peninsula.
Jordi Bou
added a research item
The sessile oak (Quercus petraea) is a deciduous tree with a Euro‑Siberian distribution. It is widely spread throughout Europe and (as with other Euro‑Siberian species that constitute the Lathyro montani‑Quercetum petraeae plant community) its southern‑most distribution limit can be found on the Iberian Peninsula. Most of the sessile oak forests on the Iberian Peninsula are located on the Cantabrian Range and the Pyrenees. The NE Iberian Peninsula forests, in particualr, are of special ecological and conservation interest because they grow in a Mediterranean climate and, as such, are on the xeric limit for Quercus petraea. In Catalonia (Spain) the sessile oak forests cover 4,823 ha; the majority (85%) of which are in the Pre‑Pyrenees and the Pyrenees. This study has analyzed the species composition of the sessile oak forest found on the Catalan Pyrenees using plant community inventories that were carried out between 2016 and 2018. Furthermore, thanks to previous botanists’ work on the Catalan Pyrenees, the current state of the sessile oak forest has been able to be compared with their (historical) data. With a mean of 37 species per inventory, the results show that the sessile oak has a lot of biodiversity. The dominant species are Euro‑Siberian (68%) and the most common life form are the hemicryptophytes (51%); albeit with notable differences between the locations studied. The most relevant finding is that the composition of the sessile oak forest plant community on the Pyrenees has not, as a consequence of global change, altered a lot over recent decades. This result is the opposite of the patterns that have been observed in the rest of the sessile oak forests in Catalonia which, in turn, highlights the excellent conservation status of some of these forests in the Pyrenees and the need to continue along this path to ensure greater resistance against and resilience to climate change.
Jordi Bou
added a research item
The sessile oak forest (Lathyro montani-Quercetum petraea), in the NE Iberian Peninsula are at the south-ernmost limit of the Quercus petraea range, in Mediter-ranean-type conditions at the xeric limit. Studies of vegetation dynamics in these extreme conditions are crucial for improving our knowledge of vegetation response to climate change. Currently, sessile oak forests occupy a small area of the NE Iberian Peninsula, but they have not always presented this distribution pattern and, in the future, their range may be altered as a result of global change. Climate change has many direct effects on plants, like the thermophilization of plant communities. However, despite being a well-studied topic, there is little work on low-and medium-altitude mountains, which is precisely where these forests grow in the NE Iberian Peninsula. Also, land use change has had an important effect on forest, since woodlands have been exploited and transformed since ancient times. However, forest use has changed over time, particularly in the mid-20 th century, that has led to open spaces being replaced by scrublands and forests in both Europe in general, and the NE Iberian Peninsula. This is the context of this thesis, the main goal of which is to describe the ecological dynamics of sessile oak forests in the NE Iberian Peninsula since the mid-20 th century. To test the hypotheses on the effects of global change, we studied the modifications of sessile oak forests corresponding to their evolution over recent years. Focusing on the sessile oak forest plant community in the NE Iberian Peninsula (Chapter 1), we put special emphasis on the case study of the Montseny Massif, looking in detail at the distribution and structure of the sessile oak woodland (Chapters 2 and 3), as it is clearly a site at the xeric limit, in other words, strategically important for the management and conservation of these forests. Floral inventories of the sessile oak groves in the NE Iberian Peninsula show that the community species composition has been altered since the second half of the 20 th century, but in slightly different ways in each region; the changes are fairly significant in the Catalan Coastal Range where the Montnegre Natural Park has experienced a clear loss of biodiversity. In fact, many of the changes in the sessile oak forest species composition in the NE Iberian Peninsula can be explained by In this issue we introduce recently defended PhD theses in vegetation science provided to the bulletin. You are welcome to present your work to a broad audience of vegetation scientists throughout the world this way. Your message can be published in the forthcoming issues if you send your contribution to monika.janisova@gmail.com containing the following information: 1) Name and affiliation of the student (photo appreciated); 2) Name and affiliation of the supervisor (photo appreciated); 3) Topic of the thesis; 4) Summary of the thesis; 5) Date of defense; 6) Publications related to the thesis.
Jordi Bou
added a research item
El roble albar Quercus petraea se encuentra ampliamente presente en el centro de Europa. Las poblaciones del NE de la Península Ibérica se encuentran en su límite meridional de distribución y las de condiciones más mediterráneas en el xeric limit para esta especie. Los resultados de la tesis, muestran que la comunidad ha cambiado su composición de especies des de la segunda mitad del s. XX, pero de forma sensiblement diferente según cada región. La dinámica de los robledales de roble albar es su recuperación tras el cambio de los usos del bosque, y el Montseny es un buen ejemplo de este proceso. La situación es bien distinta en algunos robledales como los del Montnegre, donde los efectos del cambio climático suponen un futuro incierto. Por este motivo es importante aprovechar las localidades que se encuentran en refugios climáticos como reservorios y puntos donde poder conservar este hábitat.
Jordi Bou
added a research item
The sessile oak Quercus petraea is widespread in Central Europe. The populations in the NE Iberian Peninsula are at the southernmost limit of the species range, in the most Mediterranean-type conditions and at the xeric limit. The results of study show that the community species composition has been altered since the second half of the 20th century, but in slightly different ways in each region. The sessile oak forest is recovering from the change in forest use, and the Montseny Massif is the best example of this dynamic. For some oak forests, however, such as those in the Montnegre natural park, climate change poses an uncertain future. For this reason, it is important to take advantage of natural refuges of these species as reservoirs and places where the habitat can be preserved. http://hdl.handle.net/10803/667404
Jordi Bou
added a research item
While the sessile oak (Quercus petraea) may be widely distributed across Europe, it is somewhat rare on the NE Iberian Peninsula, its southern distribution and xeric limit. Understanding the relationship this forest has with not only climate factors but also with past human activity is important. This study aims to analyze the species composition and structure of sessile oak forests that form the xeric limit populations as well as examine the effect environmental factors have on them. The work was focused on the southernmost sessile oak forest, the Montseny Massif populations, which have a marked environmental Mediterranean influence. The sessile oak forest types were defined from field inventories and a cluster analysis classified the inventoried stands into five forest types. The compositional differences among the forest types were the result of past land uses and the intensity of forestry activity 50 y ago. Furthermore, the species composition is influenced by environmental factors, because more hydric stress promotes Mediterranean species. The study concludes that sessile oak are recovering from past forestry activity.
Jordi Bou
added a research item
Aims Our aims were 3-fold: (i) to determine whether global change has altered the composition and structure of the plant community found in the sessile oak forests on the NE Iberian Peninsula over the last decades, (ii) to establish whether the decline in forest exploitation activities that has taken place since the mid-20th century has had any effect on the forests and (iii) to ascertain whether there is any evidence of impact from climate warming. Methods We assess changes in the plant community by comparing a current survey of sessile oak forest with a historical data set obtained from previous regional studies dating from 1962 to 1977. We analyse the regional changes in the community in terms of biodiversity variables, species composition and plant traits. Furthermore, plants traits such as plant life forms and chorological groups are used to discern any effects from land-use changes and climate warming on the plant community. Important Findings There has been a loss of diversity in the community and, in the hottest region, there is also a loss of species richness. The composition of the community suggests that, although significant changes have taken place over recent decades, these changes differ between regions as a result of the low impact global change has had in the western regions. For instance, while the tree canopy cover in the western sessile oak forests remains stable, the eastern sessile oak forests are still recovering from the former exploitation that led to a loss of their rich and abundant herbaceous stratum. In fact, the recovery process in the Catalan Pre-Coastal Range has constituted an increase in the Euro-Siberian plants typical to this community. Moreover, in the eastern forests, there is evidence that climate warming has impacted the thermophilization of the sessile oak forests found on the Coastal Range.
Jordi Bou
added 2 research items
While the sessile oak (Quercus petraea) may be widely distributed across Europe, it is somewhat rare on the N.E. Iberian Peninsula, its southern distribution and xeric limit. Understanding the relationship this forest has with not only climate factors, but also with past human activity is important. The aim of this study is to analyse the distribution and structure of these forests and also describe the forest dynamic over the last 50 years. The work was focused on the southernmost sessile oak forest, the Montseny Massif populations, which have a marked Mediterranean influence. We produced a high resolution map (1:5000) of them in the Montseny area and performed a diachronic analysis. At same time, we inventoried sessile oak stands to assess the forest structure. The results show that Q. petraea currently covers only 64.1 ha, and forest density ranges from 382.2 to 2993.6 stems ha-1, while basal area spans 31.8 to 99.8 m2 ha-1. With regard to its recent development, 44% of what is now dense forest was, in 1956, much more dispersed while 11% of it consisted of open spaces or shrubs. The relationship of this coverage changes with the current forest structure, shows that during the last 50 years, the sessile oak forests have been recovering from previous forestry activity in the massif, which should be taken into account if we want to predict the future status of these forests in the xeric limit, because the effects of climate change can be masked by this dynamic. DOI: 10.7818/SIBECOLandAEETmeeting.2019
While the sessile oak (Quercus petraea) may be widely distributed across Europe, it is somewhat rare on the N.E. Iberian Peninsula, its southern distribution and xeric limit. Understanding the relationship this forest has with not only climate factors, but also with past human activity is important. The aim of this study is to analyse the distribution and structure of these forests and also describe the forest dynamic over the last 50 years. The work was focused on the southernmost sessile oak forest, the Montseny Massif populations, which have a marked Mediterranean influence. We produced a high resolution map (1:5000) of them in the Montseny area and performed a diachronic analysis. At same time, we inventoried sessile oak stands to assess the forest structure. The results show that Q. petraea currently covers only 64.1 ha, and forest density ranges from 382.2 to 2993.6 stems ha-1, while basal area spans 31.8 to 99.8 m2 ha-1. With regard to its recent development, 44% of what is now dense forest was, in 1956, much more dispersed while 11% of it consisted of open spaces or shrubs. The relationship of this coverage changes with the current forest structure, shows that during the last 50 years, the sessile oak forests have been recovering from previous forestry activity in the massif, which should be taken into account if we want to predict the future status of these forests in the xeric limit, because the effects of climate change can be masked by this dynamic.
Jordi Bou
added a research item
There is a distribution limit of sessile oak (Quercus petraea) in the northern half of the Iberian Peninsula, with its southernmost populations located at the xeric limit for the species. We present here the current distribution of these populations in the Montseny Massif (N.E. Catalonia) and how the surface area they cover has developed over the last 50 years. Using a new high-resolution map (1:5000) we have calculated that Q. petraea currently covers 64.1 ha, and is found between 450 and 1150 m above sea level with a predominantly southern exposure, with the north-facing slopes being dominated by beech forests. With regard to its recent development, 44% of what is now dense forest was, in 1956, much more dispersed while 11% of it consisted of open spaces or shrubs. Such changes clearly show that, in Montseny, Q. petraea is well capable of regenerating its forest canopy as well as colonising adjacent environments.
Jordi Bou
added a research item
Sessile Oak Forests in Montseny Nature Park: This paper presents the results of a study carried out with the aim of drawing up an inventory and mapping the sessile oak forest in Montseny Nature Park. On the massif, the Q. petraea forest grows in a narrow strip between holm oak and beech and occupies an area of 64.08 ha, and is therefore a unique component of the area. Sessile oak forest is found between 450 and 1,150 m above sea level with a predominantly southern exposure. The mean density is 1,215.3 trunks/ha and the mean basal area is 42.4 m2/ ha; most of the stands have an intermediate structure, with few young forests and only one case of a mature forest. The new information provided by this study should be used to conserve and improve the management of these forests which are so scarce in Montseny.
Jordi Bou
added a research item
Abstract. Study of the transition from Quercus petraea forest to Quercus ilex forest in the area of Marmolers (Montseny Natural Park) The Montseny massif is an area of great biodiversity interest, where forests can be found of sessile oak (Quercus petraea); a eurosiberian deciduous tree that grows in the montane zone. Holm oak forests (Quercus ilex) are also found growing beside the sessile oak forests at this altitudinal level. In the area of Marmolers this transition can be observed between the two forests, making it an ideal place for a study of this type. The main objective of this article is to study the ecotone between the Eurosiberian and Mediterranean vegetation in Marmolers. The main issues we address are how the Quercus petraea forest interacts with the Quercus ilex forest, how floristic diversity varies along the transition, which forest structure presents Marmolers forest, the recruitment dynamics in Marmolers, and how this transition is expected to evolve. The juvenile 1 (50 cm < h < 1.5 m) regeneration of Quercus petraea and Quercus ilex in the sessile oak forest and the mixed forest of Marmolers is the same for both species, as well as for seedlings (h < 50 cm). According to the floristic composition, the mixed forest is more similar to a sessile oak forest than to a holm oak forest. In contrast, there is no regeneration of juvenile Quercus petraea in the Marmolers holm oak forest. This study shows that the sessile oak forest of Marmolers has not yet been colonized by Quercus ilex. The holm oak forest in Marmolers will not change if there is no disruption. Moreover, the mixed forest of Marmolers is in equilibrium in terms of its co-dominant species and is likely to remain so for many years. Resum El massís del Montseny és un espai d’alt interès natural i forestal, on trobem la presència de boscos de Quercus petraea (roure de fulla gran), un arbre caducifoli eurosiberià que creix a l’estatge montà del massís. Alhora, en aquest estatge, també hi ha boscos de Quercus ilex (alzina), que creixen al costat de la roureda. Al paratge de Marmolers, s’hi pot trobar aquesta transició entre els dos boscos, motiu pel qual és un lloc idoni per fer-hi aquest tipus d’estudi. L’objectiu principal és estudiar l’ecotò de Marmolers, on hi ha una transició entre comunitats vegetals eurosiberianes i comunitats vegetals mediterrànies. Les qüestions més importants que cal resoldre són: com interacciona el bosc de Quercus petraea amb el bosc de Quercus ilex?; com varia la diversitat florística al llarg de la transició?; quina estructura forestal presenta la zona estudiada?; quina dinàmica s’observa en el reclutament?; com pot evolucionar la transició estudiada? Els resultats mostren que la regeneració de Quercus petraea i de Quercus ilex a la roureda pura i al bosc mixt de Marmolers és igual, tant per als juvenils 1 (50 cm < h < 1,5 m), com per als plançons (h < 50 cm). Segons la composició florística, el bosc mixt mantindria una similitud més gran amb una roureda que no pas amb un alzinar. En canvi, a l’alzinar de Marmolers no hi trobem juvenils de Quercus petraea. En aquest estudi, s’ha observat com, de moment, la roureda de Marmolers no es veu colonitzada per l’alzinar i que l’alzinar de Marmolers difícilment es veurà mai colonitzat per la roureda, si no es que hi apareixen pertorbacions. També s’hi ha comprovat que el bosc mixt de Marmolers està en equilibri quant a les seves espècies codominants, i és probable que es mantingui així durant molts anys. ISSN 0213-4039 (imprès), ISSN 2014-9727 (en línia)
Jordi Bou
added 3 research items
We assessed the influence of some environmental conditions (temperature and rainfall) on the litterfall and BAI (basal area increment), in three close forests in the Montseny massif (NE part of the Iberian peninsula, Spain). Two of them are composed of deciduous species Fagus sylvatica and Quercus petraea, and the other one is a Mediterranean evergreen species, Quercus ilex. We have collected monthly data about litterfall and radial growth since 2007. For each forest there are tree plots, with litterfall traps and band dendrometers. This data has been related with the meteorological parameters of meteorological station closed to the study area. Our results show that F. sylvatica recorded the biggest drop in annual litterfall (6 Mg•ha-1•year-1), followed by Q. ilex (4.34 Mg•ha-1•year-1) and Quercus petraea (4.4 Mg•ha-1•year-1) and that all the values were similar to those observed in other forests and mountains with the same state of maturity. Regarding the litterfall, the investigation found a decline in the leaves fall in deciduous trees in years with hot summers. In addition, these warm summers produce a decline in the F. sylvatica BAI, but not in Q. petraea. Concerning growth, we found that Q. petraea increases the BAI on the study period while F. sylvatica does not. In conclusion, we believe that in the future Q. petraea will be more tolerant to the warm conditions than F. sylvatica, making the former a possible replacement of the second species.
Jordi Bou
added 3 research items
We assessed the influence of some environmental conditions (temperature and rainfall) on the litterfall and BAI, in three close forests in the Montseny massif (NE part of Iberian Peninsula, Spain). Two of them are composed by deciduous species Fagus sylvatica and Quercus petraea, and the other is a Mediterranean evergreen species Quercus ilex. We collect data since 2007 of litterfall and radial growth, which have been correlated with the climate of the study area. Our results shows that Fagus sylvatica recorded the biggest drop in annual litterfall (6 Mg•ha-1•year-1), followed by Quercus ilex (4.34 Mg•ha-1•year-1) and Quercus petraea (4.4 Mg•ha-1•year-1) and all the values were similar to those observed in other forests and mountains with the same state of maturity. About the litterfall the investigation found a decline of the leaves fall in deciduous trees in years with hot summers. Also these warm summers produce a decline in the Fagus sylvatica BAI, but not in Quercus petraea. Concerning the growth, we found that Quercus petraea increase the BAI on the study period while Fagus sylvatica don’t. In conclusion we believe that Quercus petraea in a future will be more tolerant to the warm conditions than Fagus sylvatica, making the first a possible replace of second specie.
La robleda de roble albar en el Parque Natural del Montseny En la presente comunicación, se presentan los resultados de un estudio cuyo objetivo consistía en inventariar y cartografiar las robledas de roble albar del Parque Natural del Montseny. En el macizo, la robleda de Q. petraea se encuentra en una estrecha franja entre los hayedos y las encinas, ocupando tan solo una superficie de 64,08 ha, siendo así un elemento muy singular del territorio. En general se sitúan en las vertientes sur, entre 450 y 1150 m de altitud, de media con 1220 pies/ha y una AB de 42.3m2/ha, siendo la mayoría de bosques de estructuras intermedias, mientras que se hacen raras la masas jóvenes y solo existe un caso de bosque centenario. La nueva información aportada por el estudio, debería ser usada para la conservación y la mejora de la gestión de estos bosques tan escasos en el Montseny.
Jordi Bou
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Thesis project