Geobotanical Study of the Microforests of Juniperus oxycedrus subsp . badia in the Central and Southern Iberian Peninsula

We have studied Juniperus oxycedrus subsp. badia in the central and southern Iberian Peninsula. Here, the macrobioclimate ranges from Mediterranean-pluviseasonal-oceanic and Mediterranean-pluviseasonalcontinental, thermotype from thermomediterranean and supramediterranean. The relevés were taken following the Braun-Blanquet phytosociological methodology. A statistical treatment was applied to establish a separation among Juniperus communities. To understand the presence of Juniperus communities in territories dominated by species of the genus Quercus, we applied the formula of Thornthwaite to calculate potential evapotranspiration. The general cluster analysis clearly separates two groups of plant communities and separates the different associations in each group. All plant communities growing on rocky crests and in steeply extreme sloping areas are significantly influenced by the soil. The Ombroclimatic Index does not explain the presence of plant communities influenced by substrate: so, we propose a new Ombroedaphoxeric Index which explains the presence of the Juniperus communities in territories with a thermotype ranging from the thermo to the supramediterranean belt. The areas of distribution of Juniperus species are expanding due to the spread of rocky areas: this phenomenon causes a rise in edaphoxerophilous areas and a decrease in climatophilous one. Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 16 October 2018 doi:10.20944/preprints201810.0362.v1 © 2018 by the author(s). Distributed under a Creative Commons CC BY license.


Introduction
There are around 60 woody species worldwide belonging to the genus Juniperus L. (Cupressaceae, gymnosperms), which is divided into three sections: J. sect.Caryocedrus Endl., J. sect.Juniperus, and J. sect.Sabina Spach [1].The J. oxycedrus group is included within J. sect.Juniperus [2,3], and is distributed throughout the Mediterranean region, including eastern Portugal and Morocco, and extending as far as northern Iran [4].According to Amaral Franco [4], the species J. oxycedrus L. has three clearly differentiated subspecies.J. oxycedrus L. subsp.oxycedrus occurs in the CS territories of the Iberian Peninsula, extending toward the Italian Peninsula, Sardinia, Corsica, Croatia and Slovenia [4][5][6].J. oxycedrus L. subsp.macrocarpa (Sm.)Ball is widely distributed through the Mediterranean Region and W of Asia, until Syria [4,5].Juniperus oxycedrus L. subsp.badia (H.Gay) Debeaux is restricted to Spain, Portugal and N Africa [4].The J. oxycedrus group includes also J. navicularis Gand.(syn.: J. oxycedrus L. subsp.transtagana Franco) and J. deltoides R.P. Adams [syn.: J. oxycedrus L. subsp.deltoides (R.P. Adams) N. G. Passal], which was described and characterised as a new species by Adams and Tashev [7,8] for Greece, as distinct from J. oxycedrus.Adams and collaborators [3,9] recently reported the distribution of J. deltoides for Italy, Croatia, Greece, Turkey, Azerbaijan, Bulgaria, Cyprus, and Israel, and established phytochemical differences with J. oxycedrus due to its higher limonene and lower alpha-pinene contents.As specified previously by Adams et al. [10] and Salido et al. [11], there are clear phytochemical differences between the three subspecies of J. oxycedrus.Adams [12] also established major molecular differences between J. oxycedrus subsp.oxycedrus, J. oxycedrus subsp.badia, J. oxycedrus subsp.macrocarpa, and J. navicularis, and accordingly raises them to the rank of species.Adams et al. [13] subsequently showed that the differentiation of J. deltoides from J. oxycedrus at a level that is consistent with the divergence of J. navicularis and J. macrocarpa from J. oxycedrus is based on leaf essential oil composition, RAPD (Random Amplification of Polymorphic DNA) fingerprinting and ITS (Internal Transcribed Spacer) sequence data.Roma-Marzio et al. [14] recently proposed an identification key for the Juniperus oxycedrus group based on a combined phytochemical and morphometric approach.
Juniperus oxycedrus subsp.macrocarpa is typical of dunes and coastal sand flats and may occasionally occupy rocky areas.The communities of this taxon present on the Iberian Peninsula were described and included in the alliance Juniperion turbinatae by Rivas-Martínez [15], along with other communities dominated by Juniperus navicularis (J.oxycedrus L. subsp.transtagana Franco) and Juniperus phoenicea L. subsp.turbinata (Guss.)Nyman, also typical of psammophilous environments and dunes in coastal zones.
J. oxycedrus subsp.oxycedrus and J. oxycedrus subsp.badia are present on the Iberian Peninsula on both acid and basic hard substrates.The main differences between these two taxa according to Amaral Franco [4] mainly concern their physiognomy and the size of their mature fruits.Whereas the subspecies oxycedrus tends to take the form of a bush, the subspecies badia is a pyramid-shaped tree of considerable size.The mature galbuli in the first do not generally exceed 1 cm in size, while in the subspecies badia, they are over 1 cm.Coincidentally these subspecies are frequently found coexisting in similar biotopes, which has led to frequent confusion among some authors.
All this serves to highlight the complexity of this taxon, whose area of distribution is still insufficiently known.However, its presence in the central and southern Iberian Peninsula is very evident.In these territories it grows in formations with a broad extension, generally on rocky areas and in biotopes with shallow soils where Quercus ilex L. subsp.ballota (Desf.)Samp.(= Quercus rotundifolia Lam.) ceases to be dominant or simply cannot exist due to the lack of ecological and/or soil conditions necessary for these taxa to develop [19].
These are also phytocoenoses of considerable ecological interest owing to the presence of the companion endemics in these plant communities, which form small islands of vegetation; they act as species reservoirs as they are used for agriculture or livestock farming and have thus avoided destruction by human action.A similar condition may arise in forest fringe communities, as evidenced by Quinto-Canas et al. [20].In these phytocoenoses it is frequent to find endemic species with varying degrees of distribution on the peninsula, such as Echinospartum ibericum, Adenocarpus argyrophyllus, Digitalis purpurea subsp.mariana, Sideritis lacaitae, Coincya longirostra, Cytisus scoparius subsp.bourgaei, Cytisus striatus subsp.eriocarpus, Genista hirsuta, G. polyanthos, Dianthus crassipes, D. lusitanus, Digitalis thapsi, D. purpurea subsp.heywoodii, D. purpurea subsp.mariana, Securinega tinctoria, Lavandula stoechas subsp.luisieri, L. stoechas subsp.sampaiana, Thymus mastichina, T. granatensis subsp.micranthus, T. zygis subsp.gracilis, and Antirrhinum graniticum subsp.onubensis [21].These species live in sites of community interest (SCI) due to the presence of habitats such as Habitat 8220 "Siliceous rocky slopes with chasmophytic vegetation", and contain plant species including Digitali thapsi-Dianthetum lusitani Rivas-Martínez ex Fuente, Jasiono marianae-Dianthetum lusitani Rivas Goday, and Coincyo longirostraae-Dianthetum lusitani [22].However, the dominant species in these environments is J. oxycedrus subsp.badia.These areas can therefore be classified as hotspots of interest for conservation.All these associations are included in the Habitats 2000 directive, which emphasises the ecological importance of these areas, and the need to study them for their subsequent conservation [23].
The areas dominated by Juniperus species are currently undergoing a process of expansion in response to the increase in rocky areas, which extend every year due to deforestation, forest fire, and, consequently, to soil erosion [23].Fire is a widespread problem for the conservation of several plant communities in the Iberian Peninsula [24], leading to the spread of edaphoxerophilous zones and a decline in climatophilous ones.There are therefore more potential areas that could act as a refuge for endemic species [23].
The aim of this work was to study the communities of J. oxycedrus subsp.badia present in the central and southern Iberian Peninsula and included in Habitat 5210 "Arborescent matorral with Juniperus ssp.".This update on their structures and floristic compositions can be used to implement an efficient form of conservation for these communities.

Study Area
Location, Climate, Geomorphology and Soils Juniper communities are well represented in several biogeographic units, and can be found in both the more continentalised central and eastern areas and in the more oceanic Portuguese territories, in siliceous and limestone areas.This research was therefore conducted in the central and southern Iberian Peninsula (Figure 1).
We studied 100 weather stations in the central-southern Iberian Peninsula, 29 of which have an Ombrothermic Index (IO) [25] between 3.6 and 6.3, implying that this territory has a subhumid-humid ombrotype [26].The 71 remaining weather stations have an IO of between 2.02 and 3.6, with a predominance of a dry ombrotype throughout the whole territory.The continentality values range from 10.8 for Santiago Do Cacen (Portugal) to 21.7 in Vianos (Albacete, Spain).All this explains the presence of a Mediterranean-pluviseasonal-oceanic macrobioclimate in the westernmost areas of the territory in the study, and a Mediterranean-pluviseasonal-continental macrobioclimate in the easternmost territories.The thermotype ranges from thermomediterranean in the warmest territories near the Guadalquivir river valley, and supramediterranean on the crests of the Iberian plateau.However, the mean values for IO (3.89), IC (Continentality Index) [25] (18.54), and ITC (Compensated Thermicity Index) [25] (284) clearly express the territorial dominance of the dry-subhumid ombrotype, the mesomediterranean thermotype and the Mediterranean-pluviseasonal-oceanic macrobioclimate.The continental influence of the plateau is present in the easternmost areas (Jaén, Ciudad Real, and Toledo), where there is also evidence of the Mediterranean-pluviseasonal-continental macrobioclimate [23].We studied 100 weather stations in the central-southern Iberian Peninsula, 29 of which have an Ombrothermic Index (IO) [25] between 3.6 and 6.3, implying that this territory has a subhumid-humid ombrotype [26].The 71 remaining weather stations have an IO of between 2.02 and 3.6, with a predominance of a dry ombrotype throughout the whole territory.The continentality values range from 10.8 for Santiago Do Cacen (Portugal) to 21.7 in Vianos (Albacete, Spain).All this explains the presence of a Mediterranean-pluviseasonal-oceanic macrobioclimate in the westernmost areas of the territory in the study, and a Mediterranean-pluviseasonal-continental macrobioclimate in the easternmost territories.The thermotype ranges from thermomediterranean in the warmest territories near the Guadalquivir river valley, and supramediterranean on the crests of the Iberian plateau.However, the mean values for IO (3.89), IC (Continentality Index) [25] (18.54), and ITC (Compensated Thermicity Index) [25] (284) clearly express the territorial dominance of the dry-subhumid ombrotype, the mesomediterranean thermotype and the Mediterranean-pluviseasonal-oceanic macrobioclimate.The continental influence of the plateau is present in the easternmost areas (Jaén, Ciudad Real, and Toledo), where there is also evidence of the Mediterranean-pluviseasonal-continental macrobioclimate [23].
All these areas share the characteristic of being small mountain ranges formed by quartzite, granite, pre-Cambrian slate, limestone and dolomitic limestone, with altitudes ranging between 280-1500 m.
We used 134 samplings taken over a wide territory (Spain and Portugal).This was done by visiting the different territories and collecting relevés from all the communities dominated by the subspecies J. oxycedrus subsp.oxycedrus and J. oxycedrus subsp.badia.Specifically, nine plant communities were studied.Among these, five have been published previously [19,39] and four are new to science.
The relevés were taken following the Braun-Blanquet phytosociological methodology, as All these areas share the characteristic of being small mountain ranges formed by quartzite, granite, pre-Cambrian slate, limestone and dolomitic limestone, with altitudes ranging between 280-1500 m.
We used 134 samplings taken over a wide territory (Spain and Portugal).This was done by visiting the different territories and collecting relevés from all the communities dominated by the subspecies J. oxycedrus subsp.oxycedrus and J. oxycedrus subsp.badia.Specifically, nine plant communities were studied.Among these, five have been published previously [19,39] and four are new to science.
The relevés were taken following the Braun-Blanquet phytosociological methodology, as described in works such as Braun-Blanquet [40] and Géhu & Rivas-Martínez [41].A relevé is a rigorous inventory of the taxa present in a study area and their degree.After compiled this inventory, the taxa coverage is evaluated by assigning a quantitative index according to the abundance-dominance and sociability scales proposed by Braun-Blanquet [40].The abundance-dominance scale combines an estimate between the number of individuals of each existing species and the area occupied in the inventory area.The quantitative indexes (in bold) and their values are the following: +-Few individuals with very poor coverage (from 0.1% to 1%); 1-Very abundant individuals with low coverage (from 1% to 10%); 2-Individuals very abundant or covering at least 1/20 of the surface (from 10% to 25%); 3-Any number of individuals covering 1  4 to 1 2 of the surface (from 25% to 50%); 4-Any number of individuals covering 1  2 to 3 4 of the surface (from 50% to 75%); 5-Any number of individuals covering more than 3  4 of the surface (from 75% to 100%).
A statistical treatment with PAST (PAleontological STatistics) [42] and CAP © (Community Analysis Package) was applied to establish a separation between Juniperus communities.We compiled an Excel © table with 134 relevés x 294 species.A hierarchical clustering analysis has been applied, applying Ward's minimum variance method, using the Euclidean distance and a Detrended Correspondence Analysis (DCA).To understand the presence of Juniperus communities in territories dominated by species of the genus Quercus, we used Thornthwaite's formula, ETP monthly = 16(10.T/I) a , to calculate potential evapotranspiration, and Montero Burgos & González Rebollar's 0.2ETP (Potential Evapotranspiration) [43].We prepared a new Ombroedaphoxeric Index (Ioex) with these data which justifies the presence of microforests of Juniperus species in a comparative analysis with the Ombrothermic Index (IO) proposed by Rivas-Martínez & Loidi [25].

Phytosociological Classification Based on Numerical Analyses
All the communities of J. oxycedrus subsp.badia share the fact that they are permanent communities with an edaphoxerophilous character, which is imposed by the rocky substrate caused by soil loss.Although the territorial ombrotype could allow the survival of Quercus species, only Q. coccifera can do so in warmer territories.
The general cluster analysis clearly distinguishes two well-delimited groups: GI (FJ, MJ, SJ, EJ, GJ, CJ) (Figure 2a) and GII (JPB, TP, PJ) (Figure 2b), and separates the different associations in each group.The groups of relevés in the study belong to different plant communities, as these groups reveal clear floristic, bioclimatic, catenal and biogeographic differences, as described below.
The new DCA statistical treatments clearly separated the three associations in the subgroup: MJ, SJ and CJ.CJ was described by its authors as Cytiso eriocarpi-Juniperetum lagunae [19] for the southwest of the peninsula on siliceous substrates and in subhumid-humid environments, whereas SJ was described for the territories in the central peninsula as Stipo tenacissimae-Juniperetum lagunae [19], and shows significant floristic differences with CJ.The new association we propose in this work-MJ-is found in areas of the Sierra Morena on siliceous substrates and in dry-subhumid environments (Figure 3).
The subgroup of associations EJ and GJ grows in the Mariánico-Monchiquense sector on siliceous substrates (Paleozoic slate and quartzite), with an ombroclimate ranging from dry to humid; EJ was described by Cano et al. [19] for the supramediterranean belt as Echinosparto iberici-Juniperetum lagunae.The new association we propose is found in the mesomediterranean belt and is totally lacking in Echinospartum ibericum.The analysis of these two associations confirms their statistical separation.Both associations are in the Mariánica mountain range.The low frequency of E. ibericum explains the sole dominance of J. oxycedrus subsp.badia.The slight floristic differentiation between EJ and GJ is due to the fact that the main differentiating floristic elements, E. ibericum and Genista polyanthos, are infrequent in their respective plant communities; whereas E. ibericum is exclusive to the supramediterranean thermotype, G. polyanthos has its optimum in the thermo-and mesomediterranean, and may occasionally reach the supramediterranean, which explains the greater frequency of the microforests of Juniperus.
In contrast, the new association GJ contains species of interest such as G. polianthos, which acts as a differential species from the exclusively supramediterranean association of Echinosparto iberici-Juniperetum badiae.We therefore propose the new syntaxon Genisto polyanthi-Juniperetum badiae (Table 1 relevés from 1 to 11, typus relevé 1), located in the Marianico-Monchiquense sector.The juniper forest of J. oxycedrus subsp.badia in the eastern territories of the Iberian Peninsula (Portugal) is present in small mountain ranges with a quartzite character and frequent mesophytic flora, thanks to the continued prevalence of the mesomediterranean thermotype and subhumid-humid ombrotype.There is therefore a significant floristic component with an oceanic character, such as Erica arborea, Viburnum tinus and Cytisus eriocarpus, a community that has been described as Cytiso eriocarpi-Juniperetum badiae, very different from Cytiso tribracteolati-Juniperetum oxycedri which represents the edge of the cork-oak forest Teucrio baetici-Quercetum suberis, according to Pérez Latorre et al. [44].In contrast, the new association GJ contains species of interest such as G. polianthos, which acts as a differential species from the exclusively supramediterranean association of Echinosparto iberici-Juniperetum badiae.We therefore propose the new syntaxon Genisto polyanthi-Juniperetum badiae (Table 1 relevés from 1 to 11, typus relevé 1), located in the Marianico-Monchiquense sector.The juniper forest of J. oxycedrus subsp.badia in the eastern territories of the Iberian Peninsula (Portugal) is present in small mountain ranges with a quartzite character and frequent mesophytic flora, thanks to the continued prevalence of the mesomediterranean thermotype and subhumid-humid ombrotype.There is therefore a significant floristic component with an oceanic character, such as Erica arborea, Viburnum tinus and Cytisus eriocarpus, a community that has been described as Cytiso eriocarpi-Juniperetum badiae, very different from Cytiso tribracteolati-Juniperetum oxycedri which represents the edge of the cork-oak forest Teucrio baetici-Quercetum suberis, according to Pérez Latorre et al. [44].GJ1 GJ2 GJ3 GJ4 GJ5 GJ6 GJ7 GJ8 GJ9 GJ10 GJ11 Characteristics of Association and Higher Units P Juniperus oxycedrus subsp.badia

Characteristics of Association and Higher Units P
Juniperus oxycedrus subsp.badia Genista polyanthos Quercus rotundifolia
while the association we propose here is in the Mariánico-Monchiquense sector.Group GII is formed by JPB, TP and PJ.In this case, a DCA analysis highlights the separation between the three plant communities.PJ was described for the central peninsula (Toledano-Tagano sector) on siliceous substrates, and in the dry-subhumid mesomediterranean, whereas the two new associations proposed-JPB and TP-grow on basic substrates in the Subbetic biogeographic sector, with sufficient floristic differences for the three associations to be clearly defined in the ordination analysis (Figure 4).The subgroup GII JPB , Juniperetum phoeniceae-badiae nova, represents the juniper forest with Phoenicean juniper (Juniperus phoenicea), a highly abundant plant formation in the Subbético sector, growing in subhumid mesomediterranean environments on calcareous and dolomitic limestone substrates.This is an edaphoxerophilous community with a predominance of J. oxycedrus subsp.badia, J. oxycedrus subsp.oxycedrus and J. phoenicea (Table 3 rel. 1 to 21 typus rel.17).
Group GII includes GII PJ Pistacio terebinthi-Juniperetum badiae for Toledan territories and in the north of the province of Ciudad Real.Particularly significant are the communities of Pistacia terebinthus in the Subbético mountain ranges that grow in the subhumid-humid meso-and supramediterranean belt in rocky areas or debris fields on mountainsides.This community is physiognomically dominated by Pistacia terebintus, with other floristic elements such as J. oxycedrus subsp.badia, J. phoenicea and Teline patens.We propose the association Teline patentis-Pistacietum terebinthi nova (Table 4 relevés From 1 to 11 typus relevé 2).This association is differentiated from Phillyreo latifoliae-Pistacietum terebinthi, by Pavón Núñez et al. [45], for the absence of the thermophilous elements Clematis cirrhosa, Aristolochia baetica, Rhamnus oleoides, and R. velutinus, which are present in the typus of the association.The authors of Phillyreo latifoliae-Pistacietum terebinthi used relevés from the thermo-and mesomediterranean for their description.For this reason, relevés 3, 4 and 5 in Table 1 from the Subbético territories do not correspond to the association described.We must differentiate the thermomediterranean forest of Pistacia terebinthus from the meso-and supramediterranean forests in the Bétic biogeographic province.Quercus rotundifolia Phillyrea angustifolia Asparagus aphyllus

Catenal Analysis of the Landscape Evolution
Territories behave differently in response to the general climate, the type of substrate and the topography of the terrain.For this reason, areas on rocky crests-even though they may be in rainy environments and surrounded by climactic forests-behave differently from the territories around them.In these circumstances, islands evolve which may contain edaphoseries, minoriseries, and permaseries [46][47][48].All the plant communities growing on rocky crests and in steeply sloping areas are very significantly influenced by the soil, which allows their existence.All territories have a substrate and an orography which determines whether they have a greater or lesser capacity to retain water.There are special substrates such as ultramafic rocks (serpentines) that are rich in heavy cations and have a high content of ferromagnesium minerals [49].The Betic mountains (southern Spain) comprise marble limestone, gypsum, and serpentines [50].The rainfall values for the serpentine territories (Sierra Bermeja) indicate a wet ombrotype, very like the precipitations for the mountains in northwestern Serbia [51].The xericity of serpentines often gives rise to forests and scrublands that do not correspond to the ombrotype in the territory: plants living here develop ecophysiological and morpho-anatomical adaptations to withstand the limitations [52].In ideal situations with good soil texture and structure and without slopes, we can assume that the water retention (WR) is maximum (100%).Otherwise there are losses due to run-off and drainage, and the WR may therefore vary.Water is also lost through potential evapotranspiration (ETP).However, as plants have the capacity to self-regulate their losses, it can be assumed that the residual evapotranspiration e = 0.2ETP.So two parameters (i.e., e and WR) are implicated in the development of a vegetation that is essentially conditioned by rainfall.The Ombroclimatic Index (IO) does not therefore explain the presence of plant communities that are influenced by the substrate, and we propose the new Ombroedaphoxeric Index (Ioex) to explain the presence of communities of Juniperus in territories with a thermo-to supramediterranean thermotype.Ioex = P p − e/T p * WR, P p = mean annual precipitation; T p = Positive precipitation of the year [25]; e = residual evapotranspiration whose value is 0.2 ETP [43]; WR = water retention in parts per unit, whose values may be 0.25, 0.50, 0.75, and 1.
Table 5 shows the values for PP, TP, and IO according to the criterion established by Reference [52].The value of ETP is obtained by applying Thornthwaite's formula, ETP monthly = 16(10.T/I) a , where "T" is the mean monthly temperature, "I" is the annual heat index, and "a" is a parameter that depends on the values taken by "I".If we apply the formula Ioex for the assumptions that WR is 0.25, 0.50 and 0.75, we obtain three values, of which the most representative is Ioex2.Table 5 establishes the equivalence values in such a way that although the territorial bioclimate allows the existence of climactic forests, in wild areas with WR = 50% the humid ombrotype becomes dry or subhumid depending on whether the value of WR = 25% or 50%.The subhumid becomes dry and the dry becomes semiarid or arid.Therefore, areas with IO > 8 have Ioex2 values of 3.86 and 4.94, which is equivalent to subhumid.This allows the presence of an edaphoxerophilous community of Quercus faginea s.l. or Abies pinsapo in rocky areas, as occurs in Grazalema (Cadiz), and a value of Ioex1 = 2.47 in the case that WR = 25%.There is an edaphoxerophilous community of Quercus ilex subsp.ballota in this situation in Cazorla (Jaén) and in Grazalema (Cadiz).When the underlying ombrotype is subhumid, the equivalence value of Ioex2 is dry; an underlying dry IO gives semiarid and even arid values of Ioex2 if the underlying horizon is less than dry.This does not allow the development of Quercus tree species, but does allow the genus Juniperus.The value of Ioex is affected by climate change, as evidenced by Del Río et al. [53].According to these authors, this change in annual rainfall redistribution is taking place heterogeneously, and decreasing in most of the mountainous areas of Grazalema, Ronda, Cazorla, Segura, Sierra Nevada and a large part of the Sierra Morena.However, they have detected an increase in rainfall on the Andalusian coast and particularly in Almería.This affects forest stands, and-together with human activity [23]-favours a redistribution of the current forests due to a decline in the forests of Quercus and an increase in the microforests of Juniperus.
The following figures show the catenal contacts and reveal the coexistence of plant communities with different ombroclimatic demands.In the catenas in Figures 5 and 6 (Sierra Morena) with opposing orientations and on a siliceous substrate, there is an ombroclimatic gradient from dry to humid from the base of the mountain to the summit.In this case the presence of microforests of Juniperus is only possible due to the influence of the substrate; this is repeated in the catenas in Figures 7 and 8 (Cazorla and Mágina), which have calcareous substrates and a northern orientation, implying higher rainfall than in Sierra Morena.We therefore find edaphoxerophilous copses of Quercus ilex subsp.ballota and juniper ("sabinares"), and holm oak forests ("enebrales") of Juniperetum phoeniceae-badiae, along with forests of Portuguese oak ("quejigares") and "acerales" of Viburno tini-Quercetum alpestris, Berberido hispanicae-Quercetum alpestris and Daphno latifoliae-Aceretum granatensis.

Conclusions
The different groups of communities proposed for the Luso-Extremaduran province occupy areas whose dominant ecological factor is the xericity of the substrate.These are edaphoxerophilous formations with a permanent character that occupy restricted areas, but are currently in expansion,

Conclusions
The different groups of communities proposed for the Luso-Extremaduran province occupy areas whose dominant ecological factor is the xericity of the substrate.These are edaphoxerophilous formations with a permanent character that occupy restricted areas, but are currently in expansion,

Conclusions
The different groups of communities proposed for the Luso-Extremaduran province occupy areas whose dominant ecological factor is the xericity of the substrate.These are edaphoxerophilous formations with a permanent character that occupy restricted areas, but are currently in expansion, as frequent fires and the deforestation and clearing of the scrub layer have led to an extension of eroded areas due to soil loss: indeed, the absence or presence of fire is the main agent of vegetation change in areas with low anthropic influence [55].These biotopes do not tend to be occupied by Fagaceae, and the forests of Quercus ilex subsp.ballota are relegated to less inhospitable territories.If the factors that condition this dynamic persist, we will continue to see an exponential rise in the area occupied by species from the genus Juniperus.We can therefore predict a change in the landscape in the future, with a strong predominance of gymnosperms over angiosperms, as the former are better adapted to extreme conditions.These areas in expansion do not present a serious threat unless there is excessive pressure from livestock farming, which could lead to an alteration in these habitats that are rich in endemic species; endemics have a rate of 12 and account for 60% of their flora.As a result of the study of these wild areas we have detected a total of ten plant associations, of which we propose four as new.In all cases, these are Sites of Community Interest (SCI), as they include habitats with a high richness in endemic species.The recommendation is thus to implement conservation measures by applying a protection status to allow control over the management of the territory, for example by establishing micro-reserves for the conservation of flora and habitats, according to Spampinato et al. [56].
Soil water in semiarid areas plays an important role in evapotranspiration [57].The significance of evapotranspiration is confirmed as a tool for improving our understanding of environmental changes, and according to Liu et al. [58], has a direct connection with society.Another important aspect is that the phytosociological approach and statistical analysis are fundamental for the study and greater knowledge of plant communities; several authors consider all these data (plus others such as phytotoponims) to be crucial to their conservation and/or restoration [20,56,[59][60][61][62][63].It is worth noting that vegetation is a key element for society in general and for communities that share neighbouring geographical territories.The increase in pollution, and particularly in CO 2 emissions, can be mitigated by the absorption of this greenhouse gas by plants that convert it into organic matter [64].In many cases.this organic matter can be used in a variety of forms for building the cities of the future, i.e., the cork of Quercus suber L. [65][66][67][68][69]. Forest management is known to be a good tool for removing atmospheric CO 2 [70].In particular, this study highlights the importance of planning actions for the efficient management of Habitat 5210 "Arborescent matorral with Juniperus ssp." present in Portugal and Spain.In fact, this kind of habitat-among others-could also sequester a substantial amount of CO 2 , as in the case of the juniper forest in Central Spain, which is characterised by other species of Juniperus such as J. thurifera L. and J. communis L. [71].It is today essential to develop a modern forest management system in protected areas, and to promote the importance of forests and their extensions as a means of protecting and improving the natural environment, according to Rădulescu et al. [72].In view of this, and since vegetation knows no political borders, it is desirable to plan actions involving cross-border-cooperation projects based on other experiences in this field to ensure sustainable development and territorial cohesion between Spain and Portugal [73,74].

Sustainability 2018 ,Figure 2 .
Figure 2. (a) General cluster of the six associations in group GI with Ward's method; (b) general cluster of the three associations in group GII with Ward's method.

Figure 2 .
Figure 2. (a) General cluster of the six associations in group GI with Ward's method; (b) general cluster of the three associations in group GII with Ward's method.

Table 5 .
Comparative value of indices IO and Ioex in some localities in the Southern Iberian Peninsula.