Dataset of Phenology of Mediterranean high-mountain meadows flora (Sierra Nevada, Spain)

Abstract Sierra Nevada mountain range (southern Spain) hosts a high number of endemic plant species, being one of the most important biodiversity hotspots in the Mediterranean basin. The high-mountain meadow ecosystems (borreguiles) harbour a large number of endemic and threatened plant species. In this data paper, we describe a dataset of the flora inhabiting this threatened ecosystem in this Mediterranean mountain. The dataset includes occurrence data for flora collected in those ecosystems in two periods: 1988–1990 and 2009–2013. A total of 11002 records of occurrences belonging to 19 orders, 28 families 52 genera were collected. 73 taxa were recorded with 29 threatened taxa. We also included data of cover-abundance and phenology attributes for the records. The dataset is included in the Sierra Nevada Global-Change Observatory (OBSNEV), a long-term research project designed to compile socio-ecological information on the major ecosystem types in order to identify the impacts of global change in this area.


Project title
Sierra Nevada Global-Change Observatory (OBSNEV)

Personnel
Regino Jesús Zamora Rodríguez (Scientifi c Coordinator, Principal Investigator, University of Granada); Francisco Javier Sánchez Gutiérrez (Director of the Sierra Nevada National Park and Natural Park).

Funding
Sierra Nevada Global Change Observatory is funded by Andalusian Regional Government (via Environmental Protection Agency) and by the Spanish Government (via "Fundación Biodiversidad", which is a Public Foundation).

Study area descriptions/descriptor
Sierra Nevada (Andalusia, SE Spain), a mountainous region with an altitudinal range between 860 m and 3482 m a.s.l., covers more than 2000 km 2 (Figure 1a, b). Th e climate is Mediterranean, characterized by cold winters and hot summers, with pronounced summer droughts (July-August). Th e annual average temperature decreases in altitude from 12-16 °C below 1500 m to 0 °C above 3000 m a.s.l., and the annual average precipitation is approximately 600 mm. Additionally, the complex orography of the mountains causes strong climatic contrasts between the sunny, dry south-facing slopes and the shaded, wetter north-facing slopes. Annual precipitation ranges from less than 250 mm in the lowest parts of the mountain range to more than 700 mm in the summit areas. Winter precipitation is mainly in the form of snow above 2000 m of altitude. Th e Sierra Nevada mountain range hosts a high number of endemic plant species (ca. 80; Lorite et al. 2007) for a total of 2100 species of vascular plants (25% and 20% of Spanish and European fl ora, respectively). Th is mountain area comprises 27 habitat types from the habitat directive. It contains 31 animal species (20 birds, 5 mammals, 4 invertebrates, 2 amphibians and reptiles) and 20 plant species listed in the Annex I and II of habitat and bird directives. It is thus considered one of the most important biodiversity hotspots in the Mediterranean region (Blanca 1996, Blanca et al. 1998, Cañadas et al. 2014. Th is mountain range has several types of legal protection: Biosphere Reserve MAB Committee UNESCO; Special Protection Area and Site of Community Importance (Natura 2000 network); and National Park. Th e area includes 61 municipalities with more than 90000 inhabitants. Th e main economic activities are agriculture, tourism, cattle raising, beekeeping, mining, and skiing .

Design description
Sierra Nevada Global Change Observatory (OBSNEV) ) is a longterm research project which is being undertaken at Sierra Nevada Biosphere Reserve (SE Spain). It is intended to compile the information necessary for identifying as early as possible the impacts of global change, in order to design management mechanisms to minimize these impacts and adapt the system to new scenarios (Aspizua et al. 2010. Th e general objectives are to: • Evaluate the functioning of ecosystems in the Sierra Nevada Nature Reserve, their natural processes and dynamics on a medium-term time scale. • Identify population dynamics, phenological changes, and conservation issues regarding key species that could be considered indicators of ecological processes. • Identify the impact of global change on monitored species, ecosystems, and natural resources, providing an overview of trends of change that could help bolster ecosystem resilience. • Design mechanisms to assess the eff ectiveness and effi ciency of management activities performed in the Sierra Nevada in order to implement an adaptive management framework. • Help to disseminate information of general interest concerning the values and importance of Sierra Nevada.
Th e Sierra Nevada Global-Change Observatory has four cornerstones: 1 A monitoring program with 40 methodologies that collect information on ecosystem functioning (Aspizua et al. 2012(Aspizua et al. , 2014. Th is Observatory is also involved in several European projects like MS-MONINA (FP7 project, www.ms-monina.eu) or EU BON (Hoff mann et al. 2014) In addition to monitoring the ecosystems of this mountain range (i.e. collection of recent data from biotic and abiotic variables) the Sierra Nevada Global-Change Observatory is incorporating historical information of biodiversity into its information system and some historical experiments and studies are being revisited to detect potential changes due to global change. Th e dataset described here is a good example of this idea: a singular ecosystem was revisited and resampled 30 years after its inception to check whether the phenology of its fl ora community had undergone changes.

Taxonomic coverage
Th is dataset includes records of the phylum Magnoliophyta (10939 records, 99.43%) and marginally Pteridophyta (63 records, below 1% of total records). Most of the records included in this dataset belong to both the class Magnoliopsida (6057 records; 55.04%) and Liliopsida (4883 records; 44.37%). Th e class Psilotopsida is represented by 63 records. Th ere are 19 orders represented in the dataset, Poales (44.25%) and Lamiales (12.52%) being the most important order from classes Liliopsida and Magnoliopsida, respectively ( Figure 2). Th e class Psilotopsida is represented only by order Ophioglossales. In this collection, 28 families are represented, with Cyperaceae, Poaceae and Fabaceae being the families with highest number of records ( Figure 3). Th e dataset contains 72 taxa belonging to 51 genera. Carex, Nardus, and Scorzoneroides are the most represented genera in the database. Th ere are 29 threatened taxa (Table 1).

General spatial coverage
Th e present dataset covers the Mediterranean high-mountain meadows ecosystems (known locally as borreguiles), which is considered a singular ecosystem of the Sierra Nevada ) (for a description of Sierra Nevada see study area of the Project section). Borreguiles are conditioned by the snow dynamics and are potentially sensitive to changes in water availability and temperature (Martínez-Parras et al. 1987, Fernández-Casas 1974. Th is ecosystem occupies an altitudinal range between 2200 and 3000 m a.s.l. and its distribution is determined by accumulation of the meltwater (Fernández-Casas 1974). Although it represents only 1.4% of this mountain range (1125 ha), it has a high rate of plant endemicity (Table 1) , APMM 2013. Th e borreguiles are included in the Annex I of the Habitats Directive (EU habitat code 6230) (Bartolomé et al. 2005, Rigueiro et al. 2009). Th is ecosystem lies over hydromorphic soils that develop around mountain lakes, streams, depressions and glacial valleys. Th e overall appearance of borreguiles in summer is intense green, contrasting with the yellowish colour of the surrounding psychroxerophilic grasslands (Figure 4). Th is ecosystem contains several plant communities arranged as parallel bands in relation to natural water courses (Molero-Mesa 1999, Lorite et al. 2003, Sánchez-Gutiérrez and Pino 2004 (Figure 4). Th e fl oristic composition of these communities depends on moisture content of the substrate. First, on some moist soil, as a transition from dry grasslands to the borreguiles themselves, there is a medium coverage grassland called dry borreguil (Armerio-Agrostietum nevadensis). It hosts species such Agrostis nevadensis, Plantago nivalis, Ranunculus acetosellifolius, Th ymus serpylloides or Arenaria tetraquetra subsp. amabilis (among others) (Losa- Quintana et al. 1986. Th en dense grassland appears, located in areas with constant moisture throughout the summer and deep soils. As typical species of this community (Nardo-Festucetum ibericae) include Nardus stricta, Festuca iberica, Scorzoneroides microcephala, Lotus corniculatus subsp. glacialis, Luzula spicata, Ranunculus demissus, and Campanula herminii. Moreover, in the promontory areas appears a variation of the borreguil (Ranunculo-Vaccinietum uliginosi) enriched with the presence of Vaccinium uliginosum subsp. nanum. In places under constant fl ooding and still waters until fall, the optimum conditions of oxygen deprivation exist for incipient peat formations. Th ese communities (Ranunculo-Caricetum intrincatae) are characterized by the presence of species such as Carex nigra, Eleocharis quinquefl ora, C. echinata, C. nevadensis, Juncus articulatus, Ranunculus angustifolius, Pinguicula nevadensis or Festuca frigida.
In addition to its high ecological value, this ecosystem plays an important role in transhumance livestock systems (Robles et al. 2009). Th ese are pastures with a high nutritive value and with the greatest forage production of the Sierra Nevada ecosystems (Boza et al. 2007, González-Rebollar 2006, Robles et al. 2009, APMM 2013. Th is is important because they act as a trophic reserve for livestock in summer (Fernández-Casas 1974, Robles 2008. However, the abandonment of uses linked to this practice has tended to reduce the surface area of these ecosystems and consequent overloading of neighbouring areas (González-Rebollar 2006, Robles 2008.

Study extent description
We selected one of the most representative borreguiles of Sierra Nevada (for more info about borreguiles ecosystems see "General spatial coverage" section), located at San Juan river basin (Guejar-Sierra; Granada, Spain) (Figure 1c). Th e catchment area is nearly 1325 ha. and the basin was formed by glacial erosion of the bedrock (mica schists) and presents a valley with U-shaped (Martín-Martín et al. 2010). Th is meadow, which originated about 2000 years ago (Esteban 1996), occupies an area of approximately 100 ha.

Sampling description
We sampled at three localities along an altitudinal gradient ( Figure 5a): one at Prado de la Mojonera (Low Altitude; around 2200 m a.s.l.) and two at Hoya del Moro (middle and high altitude; 2430-2550 m a.s.l. and around 2775 m a.s.l., respectively). For each locality, the sampling was performed every 15 days during the free-snow period once a year from 1988-1990 and from 2009 to 2013. For the middle altitude locality, we have data from two periods: 1988-1990 and 2009-2013. For low-and high-altitude locations, we have data from 2009-2013 period.
At each locality, permanent plots of 1 × 1 m were distributed to cover the diff erent types of borreguiles. In each plot, a fl oristic inventory was made. Th e presence/absence and an estimation of abundance-coverage using the Braun-Blanquet cover-abundance scale (Braun-Blanquet 1964) were recorded for each taxa (Figure 5b). We also counted the number of individuals belonging to the three main phenological phases (phenophase) established: vegetative phenophase, reproductive phenophase (fl owering) and seed phenophase. Th e plots were divided into quadrats of 25 × 25 cm to facilitate counting ( Figure 5c) (Sánchez-Rojas 2012).

Method step description
All data were stored in a normalized database and incorporated into the Information System of Sierra Nevada Global-Change Observatory. Taxonomic and spatial validations were made on this database (see Quality-control description). A custom-made SQL view of the database was performed to gather occurrence data and other variables associated with some occurrence data, specifi cally: • Flowering abundance: number of fl owering individuals per square meter • Fruit abundance: number of individuals in fruiting period per square meter • Cover: the percentage of cover per taxon. Th e value represents a transformation of Braun-Blanquet cover-abundance scale (van der Maarel 1979(van der Maarel , 2007 Th e occurrence and measurement data were accommodated to fulfi l the Darwin Core Standard (Wieczorek et al. 2009(Wieczorek et al. , 2012. We used Darwin Core Archive Validator tool (http://tools.gbif.org/dwca-validator/) to check whether the dataset meets Darwin Core specifi cations. Th e Integrated Publishing Toolkit (IPT v2.0.5) (Robertson et al. 2014) of the Spanish node of the Global Biodiversity Information Facility (GBIF) (http://www.gbif.es:8080/ipt) was used both to upload the Darwin Core Archive and to fi ll out the metadata.

Quality control description
Th e sampling plots were georeferenced using a Garmin eTrex Legend GPS (ED1950 Datum) with an accuracy of ±5 m. We also used colour digital orthophotographs provided by the Andalusian Cartography Institute and GIS (ArcGIS 9.2; ESRI, Redlands, California, USA) to verify that the geographical coordinates of each sampling plot were correct (Chapman and Wieczorek 2006).

Object name
Darwin Core Archive Phenology of Mediterranean high-mountain meadows fl ora (Sierra Nevada, Spain).