Assessing coexisting plant extinction debt and colonization credit in a grassland–forest change gradient

Bagaria G., Helm A., Rodà F., Pino J. (2015) Assessing coexisting plant extinction debt and colonization credit in a grassland–forest change gradient. Oecologia. 179: 823-834.
Link
Doi: 10.1007/s00442-015-3377-4

Abstract:

Changes in species richness along the ecological succession gradient may be strongly determined by coexisting extinction debts of species from the original habitats and colonization credits of those from the replacing habitats. The magnitude of these processes and their causes remain largely unknown. We explored the extinction debt and colonization credit for grassland and forest specialist plants, respectively, and the local and landscape factors associated to the richness of these species groups in a 50-year process of forest encroachment into semi-natural Mediterranean grasslands. A set of sampling plots of persistent grasslands and forests and their transitional habitat (wooded grasslands) was selected within fixed-area sites distributed across the landscape. Our results confirm the extinction debt and suggest colonization credit (according to observed trends and model predictions) in wooded grasslands when compared to persistent forests, despite wooded grasslands and persistent forests having similar tree cover. Grassland connectivity and solar radiation had opposing effects on the richness of both grassland and forest specialists, and it is possible that the availability of seed sources from old forests may have accelerate the payment of colonization credit in the wooded grasslands. These results suggest that extinction debt and colonization credit have driven species turnover during the 50 years of forest encroachment, but at different rates, and that local and landscape factors have opposing effects on these two phenomena. They also highlight the importance of documenting biodiversity time lags following habitat change when they are still in progress in order to timely and adequately manage habitats of high conservation value such as the grasslands studied here. © 2015, Springer-Verlag Berlin Heidelberg.

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Examining the role of landscape structure and dynamics in alien plant invasion from urban Mediterranean coastal habitats

Basnou C., Iguzquiza J., Pino J. (2015) Examining the role of landscape structure and dynamics in alien plant invasion from urban Mediterranean coastal habitats. Landscape and Urban Planning. 136: 156-164.
Link
Doi: 10.1016/j.landurbplan.2014.12.001

Abstract:

This paper aims to disentangle the effects of both current landscape structure and recent land use-change on alien plant invasion in urban Mediterranean coastal habitats. Patches of four habitat types (rock outcrops, sand dunes, scrublands and forests) of different sizes and surrounding landscape compositions were selected along the coast of the Metropolitan Region of Barcelona (NE Spain). Attributes of habitat patches, historical (1956) and current landscape composition around them, land-cover changes (1956-2005) and other environmental and geographic factors within these patches were obtained. The association of these attributes with alien plant richness, abundance and composition was investigated using GLM and CCA. Alien species richness was mostly explained by patch size and shape and built-up area proportion from 1956 and 2005 in a 50. m buffer around patches. Alien species abundance was mostly related to patch shape, temperature, rainfall, land-cover changes within patches and cropland cover of 1956 in a 50. m buffer around patches. Alien species composition was primary related to habitat type, temperature, land-cover changes within patches and the composition of the surrounding landscape. Results suggest that landscape factors affect alien species richness and abundance differently, which are indicative of species colonization and spread, respectively. Landscape history positively affects both colonization and spread, with evidence for a colonization credit related with past urban cover, and the association between recent patch dynamics and present aliens spread. Results highlight the importance of including landscape structure and dynamics in the management of plant invasions in coastal Mediterranean habitats, especially in metropolitan regions. © 2014 Elsevier B.V.

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Of niche differentiation, dispersal ability and historical legacies: What drives woody community assembly in recent Mediterranean forests?

Basnou C., Vicente P., Espelta J.M., Pino J. (2015) Of niche differentiation, dispersal ability and historical legacies: What drives woody community assembly in recent Mediterranean forests?. Oikos. : 0-0.
Link
Doi: 10.1111/oik.02534

Abstract:

Community assembly rules have been extensively studied, but its association with regional environmental variation and land use history remains largely unexplored. Land use history might be especially important in Mediterranean forests, considering their historical deforestation and recent afforestation. Using forest inventories and historical (1956) and recent (2000) land cover maps, we explored the following hypotheses: 1) woody species assembly is driven by environmental factors, but also by historical landscape attributes; 2) recent forests exhibit lower woody species richness than pre-existing due to the existence of colonization credits; 3) these credits are modulated by species' life-forms and dispersal mechanisms. We examined the association of forest historical type (pre-existing versus recent) with total species richness and that of diverse life-forms and dispersal groups, also considering the effects of current environment and past landscape factors. When accounting for these effects, no significant differences in woody species richness were found between forest historical types except for vertebrate-dispersed species. Species richness of this group was affected by the interaction of forest historical type with distance to coast and rainfall: vertebrate-dispersed species richness increased with rainfall and distance to the coast in recent forests, while it was higher in dryer sites in pre-existing forests. In addition, forest historical types showed differences in woody species composition associated to diverse environmental and past landscape factors. In view of these results we can conclude that: 1) community assembly in terms of species richness is fast enough to exhaust most colonization credit in recent Mediterranean forests except for vertebrate-dispersed species; 2) for these species, colonization credit is affected by the interplay of forest history and a set of proxies of niche and landscape constraints of species dispersal and establishment; 3) woody species assemblage is mostly shaped by the species' ecological niches in these forests. © 2015 The Authors.

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Filtering of plant functional traits is determined by environmental gradients and by past land use in a mediterranean coastal marsh

Batriu E., Ninot J.M., Pino J. (2015) Filtering of plant functional traits is determined by environmental gradients and by past land use in a mediterranean coastal marsh. Journal of Vegetation Science. 26: 492-500.
Link
Doi: 10.1111/jvs.12251

Abstract:

Question: What is the effect of past land use and environmental gradients on plant functional traits within coastal marsh plant communities? Location: Mediterranean microtidal marshes in the Llobregat Delta, NE Spain. Methods: We used a data set collected previously comprising 45 vegetation plots with associated soil parameters, water table conditions and past land use. For each species we obtained the values or states for a set of plant functional traits: plant height, leaf dry matter content, specific leaf area, seed production, seed weight, life form and lateral expansion. To account for the effect of phylogeny, we evaluated trait diversity skewness by means of an ultrametric phylogenetic tree specifically constructed for the species studied. The association between both environmental gradients and past disturbance, and plant functional traits was tested by means of RLQ analysis. Results: Of all the traits, only seed weight showed a phylogenetic signal; consequently, phylogeny was not included in the RLQ analysis. Conductivity was negatively correlated with seed weight, whereas water table conditions and soil ionic balance were negatively correlated with specific leaf area. Past disturbance was negatively correlated with leaf dry matter content and with lateral expansion. Conclusions: Plant traits of Llobregat Delta coastal marsh communities are conditioned by environmental gradients and by past land use. Soil ionic balance and water table conditions determine key plant functional traits such as specific leaf area. This finding also corroborates the importance of soil ionic balance as a plant life driver in microtidal Mediterranean marshes. The effect of past land use on species traits might, however, be partially indirect and mediated by associated environmental changes. © 2014 International Association for Vegetation Science.

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Interactions between transplants of Phragmites australis and Juncus acutus in Mediterranean coastal marshes: The modulating role of environmental gradients

Batriu E., Ninot J.M., Pino J. (2015) Interactions between transplants of Phragmites australis and Juncus acutus in Mediterranean coastal marshes: The modulating role of environmental gradients. Aquatic Botany. 124: 29-38.
Link
Doi: 10.1016/j.aquabot.2015.03.003

Abstract:

Interactions between two coastal marsh plants (Phragmites australis and Juncus acutus) were investigated along three natural gradients of salinity, water table and soil texture, variously combined in a microtidal Mediterranean coastal marsh. Our aim was to clarify to what extent plant interactions explain the occurrence of stands of both species, since they are not solely due to their tolerance to environmental conditions. We used a replacement series design of field transplants. Mortality and relative yield index of aerial biomass were analyzed to assess the outcome of interactions using Generalized Linear Mixed Models. Results show that mortality was entirely driven by natural gradients. Specifically, higher salinity and soil clay contents increased mortality in both species, whereas high water table increased survival only in P. australis. Growth was controlled by plant interactions and by natural gradients. According to these results P. australis can suppress J. acutus in waterlogged and non-saline conditions. Where water table is deeper, J. acutus can suppress P. australis along a wide range of saline conditions. In the driest situations both species exhibited mutual interference and, in some cases, P. australis can again suppress J. acutus. Facilitation occurred along the salinity gradient in situations that correspond to low, medium or high stress for the beneficiary species, pointing that exceptions to the stress gradient hypothesis may occur in systems including multiple stress gradients. Our results suggest that competitive interactions and environmental gradients are not fully responsible for plant distribution in microtidal coastal marshes. © 2015 Elsevier B.V.

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Exploring changes in the invasion pattern of alien flora in Catalonia (NE of Spain) from large datasets

Girado-Beltran P., Andreu J., Pino J. (2015) Exploring changes in the invasion pattern of alien flora in Catalonia (NE of Spain) from large datasets. Biological Invasions. 17: 3015-3028.
Link
Doi: 10.1007/s10530-015-0930-3

Abstract:

Plant invasions are characterized by their dynamism, but they are generally described at a precise time step due to the dearth of datasets on species distribution across time. In this paper we employed specific alien plant databases to assess the factors associated with recent changes in plant invasion patterns in Catalonia from two perspectives, site and species. We gathered records of neophyte plant species per 10-km UTM cell from two spatially coincident large-scale datasets collected in 1989 and 2012. We estimated the richness increase of species per UTM cell and the range size increase of each species (i.e. the number of occupied UTM cells) between these dates. We then evaluated the association of richness increase with geographic, climatic and landscape factors, and that of range size increase with species traits and the characteristics of the introduction event. We found 401 species, 291 recorded up to 1989 and 110 afterwards. Richness increase was concentrated in new hotspots compared to those observed in 1989, suggesting that patterns of susceptibility to plant invasion have changed in recent decades. Climatic factors were the most important in determining the large-scale pattern of alien species, with the highest values of species richness increase in warmest and rainiest areas. Range size increase of each alien species was mostly explained by the historical range size, the introduction pathway, namely unintentional introductions and the interaction between habitat and the minimum residence time. These factors were more influential than species traits in the recent spread of alien plant species across the region. © 2015, Springer International Publishing Switzerland.

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Shifts in indigenous culture relate to forest tree diversity: A case study from the Tsimane', Bolivian Amazon

Gueze M., Luz A.C., Paneque-Galvez J., Macia M.J., Orta-Martinez M., Pino J., Reyes-Garcia V. (2015) Shifts in indigenous culture relate to forest tree diversity: A case study from the Tsimane', Bolivian Amazon. Biological Conservation. 186: 251-259.
Link
Doi: 10.1016/j.biocon.2015.03.026

Abstract:

Understanding how indigenous peoples' management practices relate to biological diversity requires addressing contemporary changes in indigenous peoples' way of life. This study explores the association between cultural change among a Bolivian Amazonian indigenous group, the Tsimane', and tree diversity in forests surrounding their villages. We interviewed 86 informants in six villages about their level of attachment to traditional Tsimane' values, our proxy for cultural change. We estimated tree diversity (Fisher's Alpha index) by inventorying trees in 48 0.1-ha plots in old-growth forests distributed in the territory of the same villages. We used multivariate models to assess the relation between cultural change and alpha tree diversity. Cultural change was associated with alpha tree diversity and the relation showed an inverted U-shape, thus suggesting that tree alpha diversity peaked in villages undergoing intermediate cultural change. Although the results do not allow for testing the direction of the relation, we propose that cultural change relates to tree diversity through the changes in practices and behaviors that affect the traditional ecological knowledge of Tsimane' communities; further research is needed to determine the causality. Our results also find support in the intermediate disturbance hypothesis, and suggest that indigenous management can be seen as an intermediate form of anthropogenic disturbance affecting forest communities in a subtle, non-destructive way. © 2015 Elsevier Ltd.

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How Does Cultural Change Affect Indigenous Peoples' Hunting Activity? An Empirical Study among the Tsimane' in the Bolivian Amazon

Luz A., Guèze M., Paneque-Gálvez J., Pino J., MacIá M., Orta-Martínez M., Reyes-Garciá V. (2015) How Does Cultural Change Affect Indigenous Peoples' Hunting Activity? An Empirical Study among the Tsimane' in the Bolivian Amazon. Conservation and Society. 13: 382-394.
Link
Doi: 10.4103/0972-4923.179879

Abstract:

Wildlife hunting is an important economic activity that contributes to the subsistence of indigenous peoples and the maintenance of their cultural identity. Changes in indigenous peoples' ways of life affect the way they manage the ecosystems and resources around them, including wildlife populations. This paper explores the relationship between cultural change, or detachment from traditional culture, and hunting behaviour among the Tsimane', an indigenous group in the Bolivian Amazon. We interviewed 344 hunters in 39 villages to estimate their hunting activity and the degree of cultural change among them. We used multilevel analyses to assess the relationships between three different proxies for cultural change at the individual level (schooling, visits to a market town, and detachment from tradition), and the following two independent variables: 1) probability of engaging in hunting (i.e., hunting activity) and 2) hunting efficiency with catch per unit effort (CPUE). We found a statistically significant negative association between schooling and hunting activity. Hunting efficiency (CPUE biomass/km) was positively associated with visits to a market town, when holding other co-variates in the model constant. Other than biophysical factors, such as game abundance, hunting is also conditioned by social factors (e.g., schooling) that shape the hunters' cultural system and impel them to engage in hunting or deter them from doing so. © 2015 Luz et al.

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A multivariate fractional regression approach to modeling land use and cover dynamics in a Mediterranean landscape

Molowny-Horas R., Basnou C., Pino J. (2015) A multivariate fractional regression approach to modeling land use and cover dynamics in a Mediterranean landscape. Computers, Environment and Urban Systems. 54: 47-55.
Link
Doi: 10.1016/j.compenvurbsys.2015.06.001

Abstract:

The way landscapes change in time reveal a great deal of information about the interplay between the forces of nature and the impact of human-driven changes in a Mediterranean landscape. To understand the dynamics behind the process of polygon fragmentation in land use and cover vector maps we illustrate the potential of a novel regression methodology to cope with multivariate fractional data.An overlay of two vector-based land cover maps separated by a time interval of several years (1956 and 1993) show polygons that have become fragmented. Those fragments thus form a multivariate fractional bounded data set. An extension of the Papke and Wooldridge (1996) fractional regression estimation to the case of multivariate response variables has been subsequently developed to study the processes of polygon fragmentation between the two land use and cover maps.The methodology has been applied to a representative set of vector maps from the Barcelona province, Spain. Several explanatory variables have been used, among them the land cover type of the most important adjacent 1956 polygon. The results of our study indicate that the dynamics of fragmentation are determined not only by geographical and environmental variables but also by the neighboring landscape. We discuss its potential use when employed with techniques of landscape modeling. © 2015 Elsevier Ltd.

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