Joan Pino

Extinction debt: a challenge for biodiversity conservation

Local extinction of species can occur with a substantial delay following habitat loss or degradation. Accumulating evidence suggests that such extinction debts pose a significant but often unrecognized challenge for biodiversity conservation across a wide range of taxa and ecosystems. Species with long generation times and populations near their extinction threshold are most likely to have an extinction debt. However, as long as a species that is predicted to become extinct still persists, there is time for conservation measures such as habitat restoration and landscape management. Standardized long-term monitoring, more high-quality empirical studies on different taxa and ecosystems and further development of analytical methods will help to better quantify extinction debt and protect biodiversity.

Habitat fragmentation causes immediate and time‐delayed biodiversity loss at different trophic levels

Intensification or abandonment of agricultural land use has led to a severe decline of semi-natural habitats across Europe. This can cause immediate loss of species but also time-delayed extinctions, known as the extinction debt. In a pan-European study of 147 fragmented grassland remnants, we found differences in the extinction debt of species from different trophic levels. Present-day species richness of long-lived vascular plant specialists was better explained by past than current landscape patterns, indicating an extinction debt. In contrast, short-lived butterfly specialists showed no evidence for an extinction debt at a time scale of c. 40 years. Our results indicate that management strategies maintaining the status quo of fragmented habitats are insufficient, as time-delayed extinctions and associated co-extinctions will lead to further biodiversity loss in the future.

Landscape structure and bird species richness: implications for conservation in rural areas between natural parks

Regional planning is bound to play an increasing role in nature conservation policies because much biodiversity is located outside natural parks and other protected areas. Differences in landscape structure between natural parks and surrounding areas may affect their respective species richness and may provide seasonal habitats that enhance total biodiversity. To test these ideas, we analyzed patterns of bird species richness, and its associated conservation value in a largely forested rural area that lies between the natural parks of Sant Llorenc del Munt and Montseny (Catalonia, NE Spain). Relationships of species richness with spatial gradients (X and Y Universal Transversal of Mercator (UTM) coordinates) and with altitude and landscape variables were tested by stepwise multiple regression analysis. Regressions were performed separately for both breeding and wintering species, and considering both all species and only several dominant ecological groups (forest, forest-cropland and cropland species). Bird species richness and its associated conservation value were higher in the study area than in the surrounding borders of natural parks. Cropland and forest-cropland species concentrated outside the natural parks, whereas forest species were uniformly distributed. Total bird species richness was mainly related to landscape diversity and to abundance of open habitats like croplands and shrublands. Cropland species were the most dependent on the abundance of crops and on landscape diversity, whereas forest and forest-cropland species exhibited weak correlations with landscape variables. Most forest species were year-round residents, whereas forest-cropland and cropland species exhibited seasonal shifts in the number of species, mainly because of interchanges with other areas. Results indicate that rural areas play a role complementary to the surrounding natural protected areas in the conservation of bird species richness at different scales. Implications for the design and optimization of ecological networks in the perimetropolitan area of Barcelona are discussed.

Land cover change in Europe between 1950 and 2000 determined employing aerial photography.

BIOPRESS (‘Linking Pan-European Land Cover Change to Pressures on Biodiversity’), a European Commission funded ‘Global Monitoring for Environment and Security’ project, produced land cover change information (1950—2000) for Europe from aerial photographs and tested the suitability of this for monitoring habitats and biodiversity. The methods and results related to the land cover change work are summarized. Changes in land cover were established through 73 window and 59 transect samples distributed across Europe. Although the sample size was too small and biased to fully represent the spatial variability observed in Europe, the work highlighted the importance of method consistency, the choice of nomenclature and spatial scale. The results suggest different processes are taking place in different parts of Europe: the Boreal and Alpine regions are dominated by forest management; abandonment and intensification are mainly encountered in the Mediterranean; urbanization and drainage are more characteristic of the Continental and Atlantic regions.

Alien Vascular Plants of Europe

In terms of invasion biology, vascular plants are the most intensively researched taxonomic group; at least 395 plant invaders have been addressed in detailed case studies globally, accounting for 44% of all invasive taxa studied; after North America, Europe is the continent enjoying the most intensive study with at least 80 invasive plant species having been addressed (Pysek et al. 2008). However, although there is a considerable body of information on major plant invaders in Europe (see also Weber 2003), the situation is much less satisfactory as far as complete national inventories of alien plants are concerned. Prior to the DAISIE project (www.europe-aliens.org), only few countries had a sound information on the composition of their alien floras, available in specialised checklists, notably Austria (Essl and Rabitsch 2002), the Czech Republic (Pysek et al. 2002), Germany (Klotz et al. 2002; Kuhn and Klotz 2003), Ireland (Reynolds 2002) and the UK (Clement and Foster 1994; Preston et al. 2002, 2004). This situation directly translated into poor knowledge across the European continent. The only available continental analysis of plant invasion patterns in Europe (Weber 1997) was based on data from Flora Europaea (Tutin et al. 1964–1980), the only syn-thetic source of information on floras of particular countries, including alien spe-cies. This source is, however, nowadays outdated and contains numerous inaccuracies in data for individual countries (Pysek 2003). In general, information on the presence and distribution of alien plant species for most European countries was scattered in a variety of published and unpublished accounts and databases; this is the case in other continents too (Meyerson and Mooney 2007). On the plant side, DAISIE was thus a major challenge of collating and assessing existing data on the most numerous group of European aliens and concentrating this informa-tion in an authoritative continental inventory.The European area covered (Fig. 4.1) by the plant team of DAISIE was partly determined by the geographical coverage of source floras, but it was broadly attempted to use the limits set by Flora Europaea (Tutin et al. 1964–1980) for the north and central continental boundaries (i.e., as far east as the Urals, to the bor-der of the Black Sea but excluding the Caucasus). In the south-east, Cyprus was

Widespread plant species: natives versus aliens in our changing world

Estimates of the level of invasion for a region are traditionally based on relative numbers of native and alien species. However, alien species differ dramatically in the size of their invasive ranges. Here we present the first study to quantify the level of invasion for several regions of the world in terms of the most widely distributed plant species (natives vs. aliens). Aliens accounted for 51.3% of the 120 most widely distributed plant species in North America, 43.3% in New South Wales (Australia), 34.2% in Chile, 29.7% in Argentina, and 22.5% in the Republic of South Africa. However, Europe had only 1% of alien species among the most widespread species of the flora. Across regions, alien species relative to native species were either as well-distributed (10 comparisons) or more widely distributed (5 comparisons). These striking patterns highlight the profound contribution that widespread invasive alien plants make to floristic dominance patterns across different regions. Many of the most widespread species are alien plants, and, in particular, Europe and Asia appear as major contributors to the homogenization of the floras in the Americas. We recommend that spatial extent of invasion should be explicitly incorporated in assessments of invasibility, globalization, and risk assessments.

Linking Plant Invasions to Global Environmental Change

Biotic invasions have been recognized as an important element of global change (Vitousek 1994). Introductions of alien species into novel habitats have increased in tandem with travel and international trade (McNeely 2001). Many species have been introduced accidentally (e.g., in water ballast, in soil, or as crop seed “contaminants”), but some have been intentionally introduced as ornamentals, food, or fiber products. The introduction of alien species can have many ecological impacts, and contribute to the homogenization of biological systems worldwide (Lockwood and McKinney 2001). Biotic invasions, along with alterations in land-use patterns and disturbance regimes, are among the major causes of biodiversity loss worldwide (Soulé 1991). In cases where alien species have quantitative or qualitative trait differences from native species, invasions can also alter ecosystem processes such as nutrient cycling dynamics and disturbance regimes (Vitousek et al. 1987; D’Antonio and Vitousek 1992; D’Antonio and Corbin 2003; Levine et al. 2003). There are some well known cases of devastating effects of invasive plants on ecosystems such as the invasion of annual grasses in western U.S. (Mack 1981) or the invasion of pines in South-African shrublands (Le Maitre et al. 1996). These dramatic invasions emphasize that invaders often parallel environmental changes that are taking place at the regional scale. Therefore, research on the links between invasions and environmental changes is urgent and timely. Biotic invasions are capable of interacting with other anthropogenic changes in the environment to alter biodiversity and ecosystem processes in invaded habitats. For example, there is evidence from a variety of ecosystems that N inputs favor alien plant species (Huenneke et al. 1990; Vinton and Burke 1995; Maron and Connors 1996). Furthermore, land-use changes such as clearing for agriculture, road building (Gelbard and Belnap 2003), or alteration of disturbance regimes (Mack and D’Antonio 1998; D’Antonio et al. 1999) have been shown to facilitate plant invasions. The aim of this chapter is to present evidence of the interactions between several components of global environmental change and plant invasions. We focus on the effects of increasing atmospheric CO2 concentrations ([CO2]), climate change, terrestrial eutrophication, and changes in land-use/cover on the distribution and performance of plant invasions. We focus on plant invasions because in terrestrial ecosystems plants interact most dramatically with environmental and landscape changes, often reverberating to higher tropic levels. We do not consider the interactions between changes in disturbance regimes “per se”, such as wildfires and invasions, because they have been extensively reviewed elsewhere (Mack and D’Antonio 1998; D’Antonio et al. 1999).

Direct and indirect landscape effects on Quercus ilex regeneration in heterogeneous environments.

Understanding how plant–animal interactions shape plant regeneration is traditionally examined at local scales. In contrast, landscape ecologists working at regional scales often have to infer the mechanisms underlying vegetation patterns. In this study, we empirically explored how landscape attributes (patch connectivity, size, shape, irradiance, slope, and elevation) influence biotic interactions in 1- and 2-year seedlings and saplings of Quercus ilex. We combined field data and GIS-based information under a set of five connectivity scenarios, presuming low, intermediate, and long-distance seed dispersal. Our study emphasizes that landscape, apart from its direct effects on plants, plays a key, albeit indirect, role in plant demography through its effects on seed dispersers and predators. Moreover, the effects of landscape on recruitment differed between plant life stages. One-year seedlings and saplings appear to depend more on plant–animal interactions, while 2-year seedlings depend more on irradiance. Differences in patch connectivity resulted in direct and indirect effects on biotic interactions, which, in turn, produced contrasting positive and negative effects on regeneration at different stages of the life cycle. While jays and wild boars seem crucial to all life stages and most of the connectivity scenarios, rodents and herbivores affected only 1-year seedlings and saplings, respectively, and only a few of the connectivity scenarios. By simultaneously including an ensemble of explanatory factors, our study emphasizes that regeneration depends on a set of key drivers, both abiotic (i.e. irradiance) and biotic (i.e. jays and wild boars), whose effects are greatly modulated by landscape traits.

Invasibility of four plant communities in the Llobregat delta (Catalonia, NE of Spain) in relation to their historical stability

Presence and cover of alien plants were analysed in relation to recent naturalness changes (1956–1999) in the Llobregat delta by means of GIS techniques and field surveys. Two land cover maps of 1956 and 1999 were generated by photo-interpretation of orthoimages and they were then reclassified into naturalness classes, defined as the degree of preservation of the pristine state. The resulting naturalness maps were combined in order to obtain a naturalness change map, which was used to design field sampling in four pristine communities: reedbeds, rushbeds, halophilous scrubs and fixed dune communities. Two study areas were selected for each community and three stability regimes (stable, semi-stable and non-stable) obtained from the naturalness change map. Five vegetation inventories were performed on average in each of these areas using the classical sigmatist method. Results showed a negative relationship between stability and invasibility, with several variations between communities. No alien species were found in stable areas of all communities. Alien species number, species percentage and relative cover increased from semi-stable to non-stable regimes in reedbeds and dune communities, indicating that reversion towards the climax reduces opportunities for alien establishment in these communities. In contrast, halophilous habitats such as rushbeds and scrubs did not exhibit significant differences between semi-stable and non-stable plots, probably because saline stress makes their invasion by alien plants difficult, even under disturbance.

Learning and the transformative potential of citizen science.

The number of collaborative initiatives between scientists and volunteers (i.e., citizen science) is increasing across many research fields. The promise of societal transformation together with scientific breakthroughs contributes to the current popularity of citizen science (CS) in the policy domain. We examined the transformative capacity of citizen science in particular learning through environmental CS as conservation tool. We reviewed the CS and social-learning literature and examined 14 conservation projects across Europe that involved collaborative CS. We also developed a template that can be used to explore learning arrangements (i.e., learning events and materials) in CS projects and to explain how the desired outcomes can be achieved through CS learning. We found that recent studies aiming to define CS for analytical purposes often fail to improve the conceptual clarity of CS; CS programs may have transformative potential, especially for the development of individual skills, but such transformation is not necessarily occurring at the organizational and institutional levels; empirical evidence on simple learning outcomes, but the assertion of transformative effects of CS learning is often based on assumptions rather than empirical observation; and it is unanimous that learning in CS is considered important, but in practice it often goes unreported or unevaluated. In conclusion, we point to the need for reliable and transparent measurement of transformative effects for democratization of knowledge production.