No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Sessile oak forest plant community changes on the NE Iberian Peninsula over recent decades
Abstract
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.
Supplementary resource (1)
... The warm conditions on the NE Iberian Peninsula are increasing due to climate change (Martín Vide et al., 2016;Peñuelas et al., 2016), which, in turn, represents a dire threat to the conservation of the sessile oak forest ; for example, these conditions can change the species composition of the community (Bou & Vilar, 2019a). The preservation of these forests at their xeric limit is very important because they are better adapted than the northern forests to these dry and warm conditions (Mátyás, 2010). ...
... Moreover, these changes are ongoing because chestnut plantations are currently being replaced with stands of Douglas fir (Pseudotsuga menziessi (Mitb.) Franco) (Broncano et al., 2005;de Ribot Porta, 2016), an invasive plant that has been reported in sessile oak forests , 2019a. Although the exploitation of sessile oak forests has decreased, there are still a few cases of intensive activity that are causing a number of severe impacts . ...
... To evaluate the current conservation status of the sessile oak forests, we carried out 34 inventories of the plant community using a modified (Bou & Vilar, 2019a) Braun-Blanquet method (Braun-Blanquet, 1964) to measure only the abundance in 100 m 2 plots. Using the available habitat cartography of Catalonia (Vigo et al., 2005), we determined the distribution of the sessile oak forest in the study area, where we randomly distributed the plots. ...
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.
... A l'Alta Garrotxa aquest patró és més evident, ja que també s'ha trobat la tendència a la pèrdua de riquesa relativa d'hemicriptòfits. Aquest patró seria comú amb els resultats observats a Catalunya, fora de la regió pirenaica (Bou and Vilar, 2019). El procés s'ha d' entendre com la recuperació del bosc davant de l'activitat humana, que un cop s'ha reduit ha permès el desenvolupament de la vegetació llenyosa que es veia limitada per la constant explotació. ...
... El procés s'ha d' entendre com la recuperació del bosc davant de l'activitat humana, que un cop s'ha reduit ha permès el desenvolupament de la vegetació llenyosa que es veia limitada per la constant explotació. Tanmateix, aquest fenomen força evident a les rouredes orientals, no ho és pas a les rouredes occidentals, on no s' observen aquests canvis (Bou and Vilar, 2019 Pel que fa a espècies introduïdes han aparegut algunes novetats puntuals; així a la Vall de Ribes hi ha la novetat de Picea abies, arbre originari del nord d'Europa, utilitzat en plantacions forestals al NE de la Península Ibèrica, mentre que a la Vall d'Aran ha aparegut Buddleja davidii, llenyosa invasora (MAPAMA, 2018), i de la qual s'hauria de fer un seguiment per veure si acaba de colonitzar el bosc, ja que en el moment de l'estudi eren plantes joves que havien colonitzat des del marge de la carretera, cap a dins el bosc. ...
... En aquest sentit les rouredes del Pirineu i Prepirineu català mostren certa estabilitat en les últimes dècades, sense canvis significatius (Taula 5), fet que no succeeix a les rouredes de localitats més càlides del territori. Així, al Montnegre s'ha pogut evidenciar la termofilització de la comunitat florística de la roureda de roure de fulla gran (Bou and Vilar, 2019). Aquest fenomen s'atribueix a l'augment de temperatura a Catalunya des del 1950 (Martín Vide et al., 2016), i degut a aquest fet s' esperaria observar la termofilització de les rouredes com a resposta a aquestes dinàmiques meteorològiques (Reif et al., 2017). ...
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.
... This study analyses demographic resilience in an isolated sessile oak population located at the southernmost limit of the species distribution in the Iberian Peninsula ( Figure 1A). This forest stand is remarkable for its large extension (4 ha), maturity and conservation state, given that along rear edge Mediterranean areas well-developed stands of Q. petraea are rather uncommon due to intensive logging over the last century (Bou & Vilar, 2019 (Carnicer et al., 2014). The current forest structure is the result of a multidecadal period of rural abandonment since the 1950s and the lack of active forest management in most of the protected areas of the park. ...
Resilience of endangered rear edge populations of cold‐adapted forests in the Mediterranean basin is increasingly altered by extreme heatwave and drought pressures. It remains unknown, however, whether microclimatic variation in these isolated forests could ultimately result in large intra‐population variability in the demographic responses, allowing the coexistence of contrasting declining and resilient trends across small topographic gradients. Multiple key drivers promoting spatial variability in the resilience of rear edge forests remain largely unassessed, including amplified and buffered thermal exposure induced by heatwaves along topographic gradients, and increased herbivory pressure on tree saplings in defaunated areas lacking efficient apex predators. Here we analysed whether indicators of forest resilience to global warming are strongly modulated by local‐scale topographic, microclimatic and biotic conditions.
We studied a protected rear edge forest of sessile oak Quercus petraea, applying a suite of 20 indicators of resilience of tree secondary growth, including multidecadal and short‐term indices. We also analysed sapling recruitment success, recruit/adult ratios and sapling thermal exposure across topographic gradients. We found large within population variation in secondary growth resilience, in recruitment success and in thermal exposure of tree saplings to heatwaves, and this variability was spatially structured along small‐scale topographical gradients. Multidecadal resilience indices and curves provide useful descriptors of forest vulnerability to climate warming, complementing assessments based in the analysis of short‐term resilience indicators. Species‐specific associations of trees with microclimatic variability are reported.
Biotic factors are key in determining long‐term resilience in climatically stressed rear edge forests, with strong limitation of sapling recruitment by increased roe deer and wild boar herbivory. Our results also support non‐stationary effects of climate determining forest growth responses and resilience, showing increased negative effects of warming and drought over the last decades in declining stands.
Synthesis. Our findings do not support scenarios predicting spatially homogeneous distributional shifts and limited resilience in rear edge populations, and are more supportive of scenarios including spatially heterogeneous responses, characterised with contrasting intra‐population trends of forest resilience. We conclude that forest resilience responses to climate warming are strongly modulated by local‐scale microclimatic, topographic and biotic factors. Accurate predictions of forest responses to changes in climate would therefore largely benefit from the integration of local‐scale abiotic and biotic factors.
... Para poder comprobar si las hipótesis de los efectos de cambio global son ciertas, se estudian los cambios correspondientes a la evolución de los robledales en los últimos años. Trabajando a nivel de comunidad florística del robledal en el NE de la Península Ibérica (Bou & Vilar, 2019a), comparando inventarios históricos (Lapraz, 1962;Vigo, 1968Vigo, , 1996Bolòs, 1988;Viñas, 1993;Carreras et al., 1995Carreras et al., , 1997 con actuales y a su vez haciendo especial énfasis en el caso de estudio del Montseny donde se profundiza en la distribución y estructura forestal de los robledales (Bou & Vilar, 2018y Bou & Vilar, 2019b, ya que se trata de una localidad claramente en el xeric limit, es decir con una importancia estratégica en la gestión y conservación de estos bosques. ...
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.
Questions
The long‐term response of understorey vegetation to increasing tree mortality has rarely been addressed in resurvey studies. For two Quercus ‐dominated forest types, we asked: (a) How did overstorey alterations, induced by canopy mortality, affect understorey diversity and composition? (b) Is there a signal of global change effects on understorey communities? (c) Are these assemblages experiencing a homogenization process?
Location
Five sites in Quercus robur (QR) and four sites in Q. petraea (QP) forests, Slovenia.
Methods
We studied changes in vascular plants in the understorey layer from 1992/1993 to 2023 across 45 permanent 20 m × 20 m plots in QR and QP forests, respectively. Vegetation surveys were carried out following the standard Braun‐Blanquet method. We compared original surveys with recent resurveys using multivariate analysis, ecological indicator values (EIV), plant traits and methods that quantify changes in individual species.
Results
Since the early 1990s, tree layer cover decreased from 95% to an average of 55% in QR, whereas it remained relatively high (77%) in QP plots. This resulted in denser understorey vegetation and a significant increase in plot‐level species richness in QR forests, but a slight decrease in QP forests. The extensive loss of canopy cover and disturbance effects in QR forests caused significant changes in species composition. Species turnover in QR was driven by colonization of new disturbance‐tolerant taxa characterized by ruderal traits, whereas the compositional shift in QP was to a greater extent due to species losses. We detected a process of vegetation thermophilization (increase in EIV‐temperature), suggesting an effect of rapid climatic warming. Understorey communities are now more similar to each other than 30 years ago, indicating a decrease in beta‐diversity (floristic homogenization).
Conclusions
Despite some common trends, vegetation responses were forest type‐specific. Our study presents evidence of understorey vegetation changes triggered by increased canopy mortality (a strong local driver particularly in QR plots) and also points to the signal of global change symptoms (thermophilization, homogenization), which acted rather independently from the observed decline in tree layer cover.
This study proposes an empirical methodology for modelling and mapping the air temperature (mean maximum, mean and mean minimum) and total precipitation, all of which are monthly and annual, using geographical information systems (GIS) techniques. The method can be seen as an alternative to classical interpolation techniques when spatial information is available. The geographical area used to develop and apply this model is Catalonia (32000 km 2 , northeast Spain). We have developed a multiple regression analysis between these meteorological variables as the dependent ones, and some geographical variables (altitude (ALT), latitude (LAT), continentality (CON), solar radiation (RAD) and a cloudiness factor (CLO)) as the independent ones. Data for the dependent variables were obtained from meteorological stations, and data for the independent variables were elaborated from a 180 m resolution digital elevation model (DEM). Multiple regression coefficients (b n) were used to build final maps, using digital layers for each independent variable, and applying basic GIS techniques. The results are very satisfactory in the case of mean air temperature and mean minimum air temperature, with coefficients of determination (R 2) between 0.79 and 0.97, depending on the month; in the case of mean maximum air temperature, R 2 ranges between 0.70 and 0.89, while in the case of precipitation, it ranges between 0.60 and 0.91.
1 Main distribution patterns of vascular plants in Catalonia In this study we used the algorithm k-means to generate groups of vascular plant species , according to their distribution in Catalonia, and to relate the species of these groups with traditional chorological elements (defined by considering the whole World). We toke as optimal the partition into 11 groups, from which 10 are formed by typical species and show biogeographical sense. The areas defined by the overlapping distributions of species in each group can be considered as the main distribution patterns of vascular plants in Catalonia. For each group, we expose the spatial distribution, the most typical species and the traditional chorological element proportion of each group.
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.
https://www.tdx.cat/handle/10803/1962
En primer lloc s'ha realitzat una cartogragia de la distribució dels boscos de les valles de Hortmoier y Sant Aniol que formen part de l'espai natural protegit "Alta Garrotxa" (Girona). A partir d'aquesta cartografía s'ha desenvolupat un acurat treball de camp que ha permés analitzar les característiques ecològiques i estructurals d'aquests boscos amb la realització d'inventaris forestals. Aquesta anàlisi ha constatat que una explotació intensiva en el passat ha provocat una uniformització de la seva estructura i que el seu abandonó posterior ha significat una recuperació diferencial de les diverses tipologies de boscos, així com una progresssiva recuperació dels boscos potencials en substitució de les masses silvícoles secundàries. En segon lloc s'ha desenvolupat una proposta metodològica basada en l'integració i la valoració de tot un conjunt de factors físics, biològics i d'aprofitament. Aquesta valoració dels boscos ha permès establir una zonificació de l'espai forestal a partir del principi de multifuncionalitat de les masses forestals que pot ser el punt de partida científic per a una ordenació i una gestió correcta d'aquest terrritori.
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.
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.
An increase in drought could cause shifts in species composition and vegetation structure. In forests it limits the occurrence of drought sensitive tree species which become replaced by drought tolerant tree species and forest communities. Under temperate macroclimatic conditions, European beech (Fagus sylvatica L.) naturally dominates the forested landscape, except on extremely shallow soil in combination with high irradiation. On these sites beech reaches its drought limit, and is replaced by forests dominated by species like downy Oak (Quercus pubescens s.l.) and English Oak (Quercus petraea L). Phytosociological and ecological data were collected in the transition (ecotone) between European beach stands and stands of more drought tolerant species in order to quantify the drought intensity threshold, above which beech is replaced by drought tolerant species. It was shown that favourable topographic and soil conditions partially compensated the unsuitable climatic conditions for beech. The ecotone between these forest types was found to be characterized by shallow soils with an available soil water storage capacity of 73 l/m² or less, and an irradiation intensity of 6000 MJ/m2 or more during the growing season. This indicates that under conditions of climate change beech would naturally still remain the dominant tree species on the majority of central European forest sites.
La reciente edición del “Atlas digital de Flora vascular de los Pirineos” (www.florapyrenaea.org) permite delimitar la flora alpina para conocer su diversidad, su distribución espacial y algunas características ambientales. La flora alpina de los Pirineos está formada por 645 taxones (630 especies y 15 subespecies). Todas las regiones administrativas muestran más del 60% de las plantas y Cataluña y Aragón tienen la mayor representación (sobre el 90%). En el gradiente altitudinal la mayor diversidad se encuentra entre 2300 y 2500 m, pero un 25% supera los 3000 m. Por otra parte, sorprende el número de plantas alpinas que se encuentran en los niveles altitudinales más bajos: más de 300 plantas viven por debajo de los 1500 m. El rango medio altitudinal de la flora alpina es de 1369 m, 300 m más amplio que el del conjunto de la flora pirenaica. Las formas biológicas, distribución por hábitats y naturalidad de los hábitats de la flora alpina es diferente significativamente del conjunto de la flora. Las categorías de abundancia difieren también significativamente y muestran un menor grado de rareza entre las plantas alpinas que en el conjunto de la flora. Más de la mitad de los endemismos pirenaicos están presentes en la flora alpina. La alta diversidad y amplitud ecológica de la flora alpina debe ser considerada a la hora de evaluar su fragilidad frente al “cambio global” y de definir políticas de conservación desde una perspectiva común para toda la Cordillera.
Quercus robur L., (pedunculate oak) and Quercus petraea (Matt.) Liebl., (sessile oak) are common broadleaved tree species in Europe, found from Scandinavia to the Iberian Peninsula. The two species are quite similar in appearance and have a broadly overlapping range. Oak trees have cultural significance for people throughout Europe and the trees or leaves are frequently used in national or regional symbols. Oak trees can live for more than 1 000 years and grow to be 30 to 40 m in height. The wood from oaks is hard and durable and has been valued for centuries. It is favoured for construction and for wine and spirit barrels; historically it was a major source of ship timbers. Recently, concerns have arisen about the fate of oaks in the face of Acute Oak Decline, a little understood syndrome.
The evolution of the forest landscape (1950- 2013) in the Alt Empordà. In Catalonia in the last 50 years there has been a significant transformation of the landscape agroforestry. The region of Alt Empordà is a very interesting case, where the forest area has increased by 12%in the period from 1957 to 2009. This is a product of rural abandonment occurred during the second half of the twentieth century. During this period the forest and the scrublands invaded the agricultural areas, as a product of the lack of forest exploitation and abandonment of crops. As a result of this process the landscape have been homogenized, and has increased the risk of fires. Looking to the future, the landscape of Alt Empordà are going to changemore, because the climate change scenarios predict changes in the distribution of forest species and the increase of fires. It’s important to learn and understand these changes in order to improve forest management adapt to climate change and cope with fires, at the same time that we conserve a diverse natural forests, and themosaic patchwork landscape with pastures, farmlands, grassland, and forests, like the characteristic landscape of theMediterranean biogeographical region.
Using a relatively broad species concept, Flora Europaea describes about 11,500 native species (Tutin et al.1964, 1968-1980). The richest areas are around the Alps, Pyrenees and the Balkan Peninsula, where altitudinal zonation results in diverse habitats with many different species or subspecies within small areas (Ozenda 1983; Lahti and Lampinen 1999;Williams et al. 2000). Although there have been previous attempts to understand the relationships and hence the history of the mountain systems in Europe, a comprehensive analysis by comparing mountain ranges across Europe is difficult. The distribution data are compiled in various local floras that use administrative or political boundaries rather than natural biogeographical divisions. Moreover, workers at different times, even in similar areas, have used different species concepts, thus making comparisons difficult. As a new initiative, we examine here the richness and distribution of European alpine species using data from the first 11 volumes of Atlas Florae Europaeae (AFE). AFE (Jalas et al.1996) provides individual maps for more than 3000 vascular plant taxa from Lycopodiaceae to Brassicaceae, covering about 20% of all taxa treated in the five volumes of Flora Europaea. What makes this particular analysis possible is that these data have been digitised recently, enabling the use of the necessary diversity measures and area-selection analyses of alpine taxa using the WORLDMAP software (Humphries et al. 1999;Lahti and Lampinen 1999; Williams et al.2000).
Se ha estudiado la vegetación forestal del área prepirenaica comprendida entre los ríos Segre y Llobregat, que incluye la sierra de Cadi y los macizos de Port del Comte, El Verd, Pedraforca y Ensija. El área estudiada, de relieve muy montañoso, sobrepasa los 500 km2 de superficie, con un desnivel que va desde los 600 m a los 2600 m. Predominan en esta zona los materiales carbonatados, aunque en la parte septentrional y occidental aparecen suelos ácidos sobre diversos tipos de rocas (conglomerados, areniscas, pizarras...) . El clima es, en la mayor parte del territorio, axeromérico submediterráneo, si bien hacia las partes más altas se dan climas axéricos fríos (según la tipología de Gaussen).
Para el estudio de la vegetación del territorio se han levantado unos 850 inventarios siguiendo la metodología sigmatista, 204 de los cuales, correspondientes a comunidades forestales, son analizados en el presente trabajo. Se han reconocido 24 comunidades a nivel de asociación (32 a nivel de subasociación), de las cuales 3 corresponden a claros de bosques (Epilobietea), 6 a bosques de coniferas de los Vaccinio-Piceetea, 3 a orlas herbáceas y mantos arbustivos (Origanetalia y Prunetalia spinosae), lia bosques caducifolios y aciculifolios de los Querco-Fagetea y 1 a bosques esclerofilos de los Quercetea ilicis. Se propone el cambio de status para una comunidad (Primulo-Pinetum sylvestris) y se describen como nuevas 3 subasociaciones (Primulo-Pinetum teucrietosum catalaunici, Lonicero-Pinetum hypnetosum cupressiformis e Hylocomio-Pinetum abietetosum). Para cada una de las comunidades reconocidas se aporta una tabla de inventarios y se detallan la composición floristica, la estructura, la ecología y la corologia en el territorio estudiado. Además, se ha elaborado un resumen comparativo de los sintáxones de los Vaccinio-Piceetea (tabla 19) y otro de la clase Querco-Fagetea (tabla 20), así como tres catenas de vegetación potencial en las que se muestra la disposición espacial de las comunidades estudiadas. Todas las tablas van al final del texto. Es de destacar el reconocimiento de dos tipos de pinares montanos de P. sylvestris, incluibles en los Quercion pubescenti-petraeae, como comunidades potenciales.
Aquest és el primer volum publicat a Catalunya dedicat als boscos més notables del país, els més bells i antics: els boscos madurs. La complexitat d’aquestes forests excepcionals no té parió, motiu pel qual són les que acullen més biodiversitat i tenen més vàlua científica. No és pas per atzar que durant mil·lennis hagin estat venerades, tingudes per llocs sagrats, encisats o misteriosos. Modernament s’ha confirmat que tenen, a més, sorprenents propietats terapèutiques. Només quan se n’ha reduït el valor al preu de la seva fusta, s’han tallat. Ara ens resten pocs boscos madurs, petits, i encara els seguim perdent.
Aquesta obra aplega les ponències presentades a les II Jornades sobre Boscos Madurs a Catalunya, que es van dur a terme l’abril de 2013 a Santa Coloma de Farners, així com les conclusions que varen generar. Tracta
els valors patrimonials –naturals, culturals i espirituals– dels boscos madurs de Catalunya,el seu estat actual i les tendències, les seves funcions ecològiques, les raons de la seva tala i també de les respostes que s’han impulsat, des d’instàncies diverses, per identificar-los, estudiar-los, salvaguardar-los i posar-los en valor. Aporta bons exemples de reserves forestals establertes per preservar-los, algunes poc, altres fa més d’un segle, i mostra el perill que corren per la manca d’una protección efectiva.
Tots els qui se sentin atrets o enamorats pels magnífics boscos centenaris i els seus arbres majestuosos gaudiran d’aquest llibre acompanyat d’imatges i poesies evocadores.
ABSTRACT: Following some ongoing projects on phytocoenology and vegetation mapping in the central Pyrenees, we give phytocoenological descriptions of a number of communities. As a result we describe one new association, three new subassociations and five variants; the others, though described previously, were poorly known until now. For each one, species composition, ecology and distribution are discussed, and a relevé table is provided. The list, in decreasing order of dryness of habitat, is: – Quercetum rotundifoliae asplenietosum adiantinigri, subass. nova; holm oak forest growing on dry, rocky slopes, mainly of slate, in the basal (rarely sub montane) belt of the inner, drier part of the Pyrenees. – Pteridio Quercetum pubescentis; in its typical form this is a meso xerophilous deciduous oak forest, also found on non calcareous substrata, in the sub montane belt, preferring cooler slopes than the former association. It includes several variants and subassociations: pteridietosum (=typicum), betuletosum pendulae and pinetosum sylvestris, novae. – Lathyro linifolii Quercetum petraeae; deciduous oak or birch forest of the montane belt, growing on meso xeric, acid slopes at the heads of valleys. – Veronico Betuletum pendulae; deciduous mixed woodland typical of poor, acid soils, on moister aspects at the heads of valleys. – Roso pendulinae Aceretum platanoidis, ass. nova; mixed, very diverse thicket confined to rock deposits in moist, snowy habitats, in the upper part of the montane belt of Val d'Aran which experiences a mountain Atlantic climate.
Abstract In this paper we analyse the species richness of the entire flora and of different distributional and functional subgroups in the Catalan Pyrenees along the altitudinal gradient. We used the Pyrenean data gathered in the Biodiversity Data Bank of Catalonia, which consist on more than 300,000 citations of 2,491 species of vascular plants. The species number in each 100 m altitude band grows from sea level to 1,000 m and decreases from there upwards, more sharply beyond 1,500 m. The medio-European species form the largest biogeographical group, whereas Alpine and Boreo-Alpine taxa form the smallest group, which nevertheless becomes very dominant towards higher altitudes. As for life forms, hemicryptophytes are generally dominant, followed by therophytes —which are concentrated at lower altitudes— and chamaephytes —which increase slightly with the altitude. As in other neighboring mountain ranges, species richness in the Catalan Pyrenees follows an asymmetric unimodal distribution along altitude. Pyrenean particularities in the pattern of the entire flora and of the subgroups considered respond to regional physiography, bioclimate and biogeographic particularities.
La végétation des chaines pré-pyrénéennes située entre les fleuves Segre et Llobregat. 1.Communautés forestieres (foréts, manteaux et ourlets) RÉSUMÉ Le territoire envisagé dans ce travail concernc la chaine de Cadí et les rna!sifs plus méridionaux de Port del Comte, El Verd, Pedraforca et Ensija. Cette rone montagneuse dépasse les 500 km de superficie et les altitudes y sont comprises entre 600 et 2600 m. Le substrat est formé surtout par des matériaux calcaires, bien que dans les parties septentrionale et occidentale du tcrritoire apparaissent des sois acides, édifiés surdivers types de roches (conglomérats, gres, schistes,...). Le climat peut etre considéré, dans la plus grande partie de l'aire, comme axéromérique subméditerranéen (selon la typologie de Gaussen), mais les zones les plus hautes sont soumises ades climats axériques froids. En vuede l'étude de la végétation, nous avons réuni quelques 850 relevés (établis selon laméthode sigmatiste), dont 204 correspondent aux communautés forcstieres analysées dans ce travail. Nous avons reconnu dans le territoire 24 associations forestieres (32 groupements au niveau des sous-associations), dont 6 se rattachent ades clairieres (Epilobietea), 6 ades forets de coniferes des Vaccinio-Piceetea, 3 ades ourlets herbacés ou ades manteaux ligneux (Origanetalia et Prunetalia spinosae), 11 ades forets caducifoliées ou aciculifoliées des Querco-Fagetea et 1 ades foréts sclérophylles des Quercetea ilicis. Nous proposons un nouveau statut pour une des communautés (primulo-Pinetum sylvestris) et nous décrivons trois nouvelles sous-associations (Primulo-Pinetum teucrietosum catalaunici. Lonicero-Pinetum hypnetosum cupressiformis et FIylocomio-Pinetum abietetosum). Pour chacune des communautés reconnues nous présentons un tableau de relevés et nous indiquons leur composition floristique, leur structure, leur écologie et leur distribution dans le territoire étudié. On a dressé, en outre, deux tableaux comparatifs concernant, l'un (tableau 19) les syntaxa des Vaccinio-Piceetea et l'autre (tableau 20), ceux de la classe Querco-Fagetea ; ainsi que trois schémas correspondant ades chaines de végétation potentielle, pour
Significance
Around the globe, climate warming is increasing the dominance of warm-adapted species—a process described as “thermophilization.” However, thermophilization often lags behind warming of the climate itself, with some recent studies showing no response at all. Using a unique database of more than 1,400 resurveyed vegetation plots in forests across Europe and North America, we document significant thermophilization of understory vegetation. However, the response to macroclimate warming was attenuated in forests whose canopies have become denser. This microclimatic effect likely reflects cooler forest-floor temperatures via increased shading during the growing season in denser forests. Because standing stocks of trees have increased in many temperate forests in recent decades, microclimate may commonly buffer understory plant responses to macroclimate warming.
No-analog communities (communities that are compositionally unlike any found today) occurred frequently in the past and will develop in the greenhouse world of the future. The well documented no-analog plant communities of late-glacial North America are closely linked to "novel" climates also lacking modern analogs, characterized by high seasonality of temperature. In climate simulations for the Intergovernmental Panel on Climate Change A2 and B1 emission scenarios, novel climates arise by 2100 AD, primarily in tropical and subtropical regions. These future novel climates are wanner than any present climates globally, with spatially variable shifts in precipitation, and increase the risk of species reshuffling into future no-analog communities and other ecological surprises. Most ecological models are at least partially parameterized from modern observations and so may fail to accurately predict ecological responses to these novel climates. There is an urgent need to test the robustness of ecological models to climate conditions outside modern experience.
Changes of the ground layer vegetation between 1983 and 1993 were studied on permanent oak forest plots in Skåne and eastern Småland, two regions of South Sweden rich in oak but with different climatic conditions. 79 of the 123 more common species differed considerably in frequency between Skåne and Småland. The oak forests in Skåne contained more typical forest species, whereas the number of light-demanding grassland species was higher in Småland. Almost half of the more common species showed significant changes in frequency between 1983 and 1993. Several species of clearings and some light-demanding grassland species increased their frequency in Skåne. They were probably favoured by canopy thinning which occurred in 65 out of 95 permanent plots. Only two species decreased in frequency in Skåne, but 14 species showed a decrease in Småland. All were typical grassland species and their decline may be regarded as a long-term response to ceased grazing and tree canopy closure as almost no tree cutting occurred during the study period in Småland. Total species richness increased with management intensity in Skåne. This was due to decreasing species losses and increasing establishment of new species at intense management. A small general increase in species numbers was recorded in Småland. Species richness was more closely related to soil pH in Skåne than in Småland. The floristic variability between the oak forest plots was closely related to soil pH in both Skåne and Småland. We suggest that changes of light conditions as a result of changes in forest management are important for current secondary succession in South Swedish oak forests, whereas the general floristic pattern is to a large extent controlled by soil acidity.
Agricultural abandonment reflects a post war trend in western Europe of rural depopulation to which isolated and poorer areas are most vulnerable. The commercialisation of agriculture, through technological developments, and the influence of Common Agricultural Policy have increased productivity and focused agricultural activity on more fertile and accessible land thus transforming traditional approaches to farming. In many areas this has lead to a decline in traditional labour intensive practices and marginal agricultural land is being abandoned. The problems that these trends create are particularly marked in mountain areas. The social and economic impacts of these changes have been well documented. However, the implications for environmental policy are less well recognised. This paper reviews the literature on abandonment and gives a comparative analysis of European mountain case studies to assess the environmental impacts of land abandonment and decline in traditional farming practices. It finds abandonment is widespread and that, while the influence of environmental changes is unpredictable due to environmental, agricultural and socio-economic contextual factors, abandonment generally has an undesirable effect on the environmental parameters examined. The application of agri-environment policy measures in relation to abandonment is discussed and suggestions for future policy are proposed.
Questions
Have compositional changes occurred in thermophilous oak forests in Poland during the past two decades? What kinds of drivers might be responsible for these changes? Are the thermophilous oak woods still rich in species or have they rather lost their diversity?
Location
Sudetes Mts., SW Poland.
Methods
The vegetation of thermophilous oak forests within four distinct areas was surveyed on 92 semi‐permanent plots in the time periods from 1992 to 1994 and from 2010 to 2014. The overall pattern in vegetation changes, trends in species composition and site parameters, as well as the diversity of studied communities were analysed using ordination and permutation techniques.
Results
The species composition of thermophilous oak forests has changed significantly. We recorded a decrease in the share of oligotrophic light‐demanding species, whereas mesotrophic light‐demanding and nitrophilous species showed an upward trend. Regarding the fourth group of shade‐tolerant species, their share varied depending on the site. The analysis of habitat parameters revealed that the studied oak forest communities generally shifted from communities of moderately oligotrophic and mesic character towards forests growing on nutrient‐richer but drier habitats. Interestingly, the observed change in species composition was not accompanied by the loss of biodiversity that has generally been reported in other types of thermophilous forests in Europe.
Conclusions
Changes observed within thermophilous and previously coppiced oak forests of southwest Poland are going in a direction which has not been recognized so far in analogous communities. The transition of studied communities is probably a result of the cumulative influence of several drivers, the most crucial of which seem to be soil regeneration, after the period of intensive acidity caused by sulphur emission between 1960 and 2000, and decreasing moisture. The observed changes are independent of the type of forest management (or the lack thereof) within the study sites.
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.
1. The present study analyses overall trends of vegetation change during the second half of the 20th century in forests of the Swiss Midlands. 2. On an east-west transect across the Swiss Midlands, forest sites where the vegetation had been surveyed during the period 1940-1965 with the Braun-Blanquet method were resurveyed in 1998, excluding sites with obvious traces of forest management or other disturbance (in total 37 sites). Changes in species composition were evaluated in terms of presence or absence of species, species richness, growth forms and average ecological indicator values. 3. Species composition changed considerably between 1940-1965 and 1998, with 184 of the totally 241 species becoming less frequent and 44 species becoming more frequent. The average number of species per relevé decreased from 41 to 26 between the two periods. 4. According to average ecological indicator values, habitat conditions became moister, richer in nutrients, and generally darker. The observed trends generally point to more mesic conditions, which coincides with the natural life cycle of forests in increasingly mature stage. 5. A decreasing number of montane species, an increasing number of thermophilous species and the apparition of several evergreen broad-leaved exotic species together strongly suggest a change towards warmer conditions. This result is consistent with trends observed in other recently published studies on vegetation change within Swiss lowland forests and may reflect climate change.
Ecosystems at high latitudes and altitudes are particularly sensitive to climate change. As an effect of global warming, upward shifting of plant species in high mountain systems was predicted for the near future. In consequence the habitats of the alpine and nival vegetation could be restricted drastically, which might result in extinctions, particular of summit floras. Evidence of upward movement of vascular plants in high mountains was recently empirically determined in the European Alps. In 1992 and 1993, data on the flora of 30 high summits were collected. A comparison of the recent investigations with historical records from the same peaks indicated a distinct increase of species richness at 70% of the summits. A stagnation or a slight decrease of species richness was recorded at 9 summits, but one of them showed an increase in species abundance. The change of species richness is correlated with the geomorphological situation, whereas no significant difference could be found by comparing siliceous and carbonate summits. Approximate moving rates for common alpine plants were calculated to be between 0 and 4 meters per decade. This evidence of upward shifting of high mountain plants may already be a measurable result of global warming since the 19th century.
This paper analyses changes in plant cover in a valley of the Spanish Central Pyrenees during the second half of the 20th century. The role played by the extensification of farming activities in this process has been examined. The method used was based on evolutionary mapping of the plant cover, application of landscape indices and spatial analysis of livestock pressure. Throughout the century the stocking rate in the valley has decreased dramatically and sheep have been replaced by cattle. Most crop areas have been abandoned, and these areas have gone through a revegetation process (involving both natural vegetation and forest plantation). Nowadays the forest is the most abundant element. The study shows that both agricultural set-aside and the stocking rate decrease have led to a more natural landscape. Finally, the positive and negative effects of extensification and the changes in vegetation patterns associated with it are debated.
Recent, rapid and often underestimated landscape changes have occurred over large areas in Mediterranean Europe. They are the result of major rural depopulation. Old photographs of landscapes taken at the beginning of the twentieth century (i.e. old postcards) and present-day photographs taken at the same places were compared in a 2500-km2 area of southern France. Vegetation changes were analysed using transition matrices. During the 80-year study period, land uses and vegetation changed dramatically. Woodland cover and tree height increased; but in contrast, the extent of cropped lands and rangelands decreased. Forest spread was heterogeneous, depending on initial composition of the vegetation, and locally dominant ecological and socio-economic conditions. Our data show that a Mediterranean forest can re-establish under humid climatic conditions and spread within a century, despite severe prior exploitation over several decades. These dramatic changes are liable to have biological and ecological consequences (e.g. spread of woodland species, threat against open habitat species, fire regime modification, deterioration in water resources), some of them being already perceptible.
Since the last glacial–interglacial cycles, Mediterranean mountains in Southern Europe have constituted the southern refuge of numerous species of Eurosiberian and Boreal origin. Some vestiges of European Tertiary flora have also remained in this area. These mountains present one of the continent's highest plant diversity indices deriving from their geographic and historical circumstances throughout the Quaternary. Throughout this century, a change in the biogeographic characteristics of these mountains is to be expected as a result of climate change.
The few native evergreen broad-leaved species occurring in central Europe have attracted the interest of generations of scientists; thus, the factors limiting their northern distribution have been well studied. For investigation of climate change-driven range shifts, these climate-sensitive species are particularly well suited. We here analyse recent range shifts of some of the cold-hardiest evergreen broad-leaved species, including both native and introduced species in Europe.Based on updated field data and outputs from bioclimatic models, we show that the milder winter conditions of the last few decades are consistent with the northward expansion of potential ranges and an increase in the number of evergreen broad-leaved species. At the landscape scale, these species indicate a considerable change in the composition and structure of temperate deciduous forests in various parts of Europe.
While phenological shifts and migration of isolated species under climate change have already been observed on alpine summits, very few studies have focused on community composition changes in subalpine grasslands. Here we use permanent plots monitored since 1954 and precisely located phytosociological censuses from 1970 to study compositional changes of subalpine grasslands in two distinct regions of the Swiss Northern Alps. In both areas, warming trends during the monitoring period were associated with changes in land management (abandonment of goat and sheep pasturing or grazing replaced by mowing). Old and recent inventories were compared with correspondence analyses (CA). Ecological indicator values, community-affinities and biological traits of the species were used to infer the factors responsible for triggering the observed changes. In both regions, subalpine grasslands were stable with smaller changes than have previously been observed in alpine environments. Only a few species appeared or disappeared and changes were generally limited to increasing or decreasing frequency and cover of certain taxa. At one site, grazing abandonment favored fallow species. Some of these species were located at their upper altitudinal distribution limits and may have spread because of rising temperatures. In both areas, declining species were predominantly alpine and low-growing species; their decline was probably due to increased competition (e.g., shadow) with more vigorous subalpine taxa no longer limited by grazing. We conclude that vegetation communities can respond rapidly to warming as long as colonization is facilitated by available space or structural change. In the subalpine grasslands studies, changes were mainly driven by land management. These communities have a dense vegetation cover and newly arriving herbaceous species preferring warmer conditions may take some time to establish themselves. However, climate disturbances, such as exceptional drought, may accelerate community changes by opening gaps for new species.
Shifts in plant species and biome distribution in response to warming have been described in past climate changes. However, reported evidence of such shifts under current climate change is still scarce. By comparing current and 1945 vegetation distribution in the Montseny mountains (Catalonia, NE Spain), we report here a progressive replacement of cold-temperate ecosystems by Mediterranean ecosystems. Beech (Fagus sylvatica) forest has shifted altitudinally upwards by ca. 70 m at the highest altitudes (1600–1700 m). Both the beech forests and the heather (Calluna vulgaris) heathlands are being replaced by holm oak (Quercus ilex) forest at medium altitudes (800–1400 m). This beech replacement has been observed to occur through a progressive isolation and degradation of beech stands. In ‘isolated’ (small and surrounded by holm oaks) beech stands, beech trees are 30% more defoliated, beech recruitment is 41% lower, and holm oak recruitment is three times higher than in ‘continental’ (large and continuous) beech stands. The progressively warmer conditions, complemented by the land use changes (mainly the cessation of traditional land management) are the apparent causes, providing a paradigmatic example of global change affecting distributions of plant species and biomes.
Aim To assess the spatial patterns of forest expansion (encroachment and densification) for mountain pine (Pinus uncinata Ram.) during the last 50 years at a whole mountain range scale by the study of different topographic and socio-economic potential drivers in the current context of global change.
Location The study area includes the whole distributional area of mountain pine in the Catalan Pyrenees (north-east Spain). This represents more than 80 municipalities, covering a total area of 6018 km2.
Methods Forest cover was obtained by image reclassification of more than 200 pairs of aerial photographs taken in 1956 and 2006. Encroachment and densification were determined according to changes in forest cover, and were expressed as binary variables on a 150 × 150 m cell-size grid. We then used logistic regression to analyse the effects of several topographic and socio-economic variables on forest expansion.
Results In the period analysed, mountain pine increased its surface coverage by 8898 ha (an increase of more than 16%). Mean canopy cover rose from 31.0% in 1956 to 55.6% in 2006. Most of the expansion was found on north-facing slopes and at low altitudes. Socio-economic factors arose as major factors in mountain pine expansion, as encroachment rates were higher in municipalities with greater population losses or weaker primary sector development.
Main conclusions The spatial patterns of mountain pine expansion showed a good match with the main patterns of land-use change in the Pyrenees, suggesting that land-use changes have played a more important role than climate in driving forest dynamics at a landscape scale over the period studied. Further studies on forest expansion at a regional scale should incorporate patterns of land-use changes to correctly interpret drivers of forest encroachment and densification.
Questions
The 1990s were the warmest decade since the beginning of climate measurements. Based on almost 100 years of monitoring in the Swiss Alps, we asked (1) whether the extraordinary warm climatic conditions of the 1990s are reflected in the floristic composition of Alpine summit vegetation and, if so, (2) what the magnitude and rate of species change has been over the last few decades compared to the documented increase in species richness within the first 80 years of the 20th century.
Location
Ten high mountain summits of the Bernina area in the southeastern Swiss Alps.
Methods
Resurvey of the floristic composition of the uppermost altitudinal 10 m of these summits, applying the same methodology of former two surveys (1905 and 1985) and recording the presence of all vascular plant species.
Results
Whereas the continued increase in plant species richness of high alpine summit vegetation is confirmed, our results also suggest an acceleration of the trend in the upward shift of alpine plants.
Conclusion
Vegetation change in the southeastern Swiss Alps has accelerated since 1985, consistent with a climate change explanation.