Journals
Authors:
Conti, L. (Autor de correspondencia); Valencia, E.; Galland, T.; et al.
Journal:
PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
ISSN:
0962-8452
Year:
2023
Vol.:
290
N°:
2001
pp.
20230344
Ecological theory posits that temporal stability patterns in plant populations are associated with differences in species' ecological strategies. However, empirical evidence is lacking about which traits, or trade-offs, underlie species stability, especially across different biomes. We compiled a worldwide collection of long-term permanent vegetation records (greater than 7000 plots from 78 datasets) from a large range of habitats which we combined with existing trait databases. We tested whether the observed inter-annual variability in species abundance (coefficient of variation) was related to multiple individual traits. We found that populations with greater leaf dry matter content and seed mass were more stable over time. Despite the variability explained by these traits being low, their effect was consistent across different datasets. Other traits played a significant, albeit weaker, role in species stability, and the inclusion of multi-variate axes or phylogeny did not substantially modify nor improve predictions. These results provide empirical evidence and highlight the relevance of specific ecological trade-offs, i.e. in different resource-use and dispersal strategies, for plant populations stability across multiple biomes. Further research is, however, necessary to integrate and evaluate the role of other specific traits, often not available in databases, and intraspecific trait variability in modulating species stability.
Authors:
Valeriano, C.; Gutiérrez, E.; Colangelo, M.; et al.
Journal:
DENDROCHRONOLOGIA
ISSN:
1125-7865
Year:
2023
Vol.:
78
pp.
126057
Tree phenology is sensitive to climate warming and changes in seasonal precipitation. Long xylogenesis records are scarce, thus limiting our ability to analyse how radial growth responds to climate variability. Alternatively, process-based growth models can be used to simulate intra-annual growth dynamics and to better understand why growth bimodality varies along temperature and precipitation gradients. We used the Vaganov-Shashkin (VS) growth model to analyse the main climatic drivers of growth bimodality in eight trees and shrubs conifers (four pines and four junipers) across Spain. We selected eleven sites with different continentality degree and spring/autumn precipitation ratios since we expected to find pronounced bimodal growth in less continental sites with spring and autumn precipitation peaks. The VS model successfully simulated annual growth rates at all sites as a function of daily temperature and soil moisture data. Bimodal growth patterns clustered into less continental sites showing low spring/autumn precipitation ratios. This finding agrees with observed climate-growth associations showing that growth was enhanced by wet-cool winter-to-spring conditions, but also by wet autumn conditions in the most bimodal sites. We observed a stronger growth bimodality in pines compared to junipers.
Journal:
FORESTS
ISSN:
1999-4907
Year:
2022
Vol.:
13
N°:
5
pp.
791
Journal:
FORESTS
ISSN:
1999-4907
Year:
2022
Vol.:
13
N°:
9
pp.
1434
The efficient conservation of vulnerable ecosystems in the face of global change requires a complete understanding of how plant communities respond to various environmental factors. We aim to demonstrate that a combined use of different approaches, traits, and indices representing each of the taxonomic and functional characteristics of plant communities will give complementary information on the factors driving vegetation assembly patterns. We analyzed variation across an environmental gradient in taxonomic and functional composition, richness, and diversity of the herb-layer of a temperate beech-oak forest that was located in northern Spain. We measured species cover and four functional traits: leaf dry matter content (LDMC), specific leaf area (SLA), leaf size, and plant height. We found that light is the most limiting resource influencing herb-layer vegetation. Taxonomic changes in richness are followed by equivalent functional changes in the diversity of leaf size but by opposite responses in the richness of SLA. Each functional index is related to different environmental factors even within a single trait (particularly for LDMC and leaf size). To conclude, each characteristic of a plant community is influenced by different and even contrasting factors or processes. Combining different approaches, traits, and indices simultaneously will help us understand how plant communities work.
Journal:
PLANT ECOLOGY AND DIVERSITY
ISSN:
1755-0874
Year:
2022
Vol.:
15
N°:
3 - 4
pp.
137 - 151
Background Climate and land-use changes, which include the application of various types of organic and inorganic fertilisers, have been reducing the species diversity of Mediterranean grasslands and threatening its conservation. Annual plants are one of the most diverse functional groups of species in these grasslands, despite suffering competitive pressure from perennial herbaceous and woody species, and they are essential for ecosystem functioning and stability. Aims To quantify how fertilisation modulates the impact of plant-to-plant interactions and climate fluctuations on the dynamics of annuals in Mediterranean grasslands. We hypothesised that the application of sewage sludge would increase competition between functional groups, reducing the abundance of annuals in the long-term, but would buffer the negative impacts of drought on the year-to-year fluctuation of the diversity of annuals. Methods In a semi-natural species-rich Mediterranean grassland in northern Spain, we analysed the changes in the taxonomical and functional composition and diversity of annuals over 14 years in response to variations in the abundance of perennial herbaceous and woody species, climate fluctuations and fertilisation with sewage sludge. We quantified separately the patterns of year-to-year fluctuations and long-term trends. Results The frequency and diversity of annuals decreased with higher abundance of perennial herbaceous species, drought in June and cold winters. The addition of sewage
Authors:
Sperandii, M. G. (Autor de correspondencia); de Bello, F.; Valencia, E.; et al.
Journal:
JOURNAL OF VEGETATION SCIENCE
ISSN:
1100-9233
Year:
2022
Vol.:
33
N°:
2
pp.
e13115
Analysing temporal patterns in plant communities is extremely important to quantify the extent and the consequences of ecological changes, especially considering the current biodiversity crisis. Long-term data collected through the regular sampling of permanent plots represent the most accurate resource to study ecological succession, analyse the stability of a community over time and understand the mechanisms driving vegetation change. We hereby present the LOng-Term Vegetation Sampling (LOTVS) initiative, a global collection of vegetation time-series derived from the regular monitoring of plant species in permanent plots. With 79 data sets from five continents and 7,789 vegetation time-series monitored for at least 6 years and mostly on an annual basis, LOTVS possibly represents the largest collection of temporally fine-grained vegetation time-series derived from permanent plots and made accessible to the research community. As such, it has an outstanding potential to support innovative research in the fields of vegetation science, plant ecology and temporal ecology.
Journal:
JOURNAL OF ECOLOGY
ISSN:
0022-0477
Year:
2022
Vol.:
110
N°:
5
pp.
1174 - 1188
Understanding the mechanisms underlying community stability has become an urgent need to protect ecosystems from global change and resulting biodiversity loss. While community stability can be influenced by species richness, synchrony in annual fluctuations of species, species stability and functional traits, the relative contributions of these drivers to stability are still unclear. In semi-natural grasslands, land-use changes such as fertilization might affect stability by decreasing richness and influencing year-to-year fluctuations. In addition, they can promote long-term directional trends, shifting community composition and influencing grassland maintenance. Thus, it is important to consider how species and community stability vary year-to-year but also in the long term. Using a 14-year vegetation time series of a species-rich semi-natural Mediterranean grassland, we studied the relative importance of richness, synchrony, species stability and functional traits on community stability. To assess land-use change effects on stability, we applied a fertilization treatment. To distinguish stability patterns produced by year-to-year fluctuations from those caused by long-term trends, we compared the results obtained using a detrending approach from those without detrending. Independently of the treatment and approach applied, the most stable communities were those composed of asynchronous species with low specific leaf area. Fertilization decreased year-to-year and long-term community stability by increasing community-weighted mean of specific leaf area, decreasing species stability or also reducing richness in the case of year-to-year stability. Additionally, traits such as seed mass had an indirect effect on stability through synchrony. Long-term trends appeared in control and fertilized plots (due to fertilization), decreasing community and species stability and leading to differences in the relationships found between community stability and some of its drivers. This reflects the importance of accounting for the effect of temporal trends on community and species stability using both a long-term and a year-to-year approach. Synthesis. Stability is influenced by richness, synchrony and functional traits. Fertilization decreases species and community stability by promoting long-term trends in species composition, favouring competitive species and decreasing richness. Studying stability at the community level and species level, and accounting for the effect of trends is essential to understand stability and its drivers more comprehensively.
Journal:
FORESTS
ISSN:
1999-4907
Year:
2021
Vol.:
12
N°:
7
pp.
938
The understory of temperate forests harbour most of the plant species diversity present in these ecosystems. The maintenance of this diversity is strongly dependent on canopy gap formation, a disturbance naturally happening in non-managed forests, which promotes spatiotemporal heterogeneity in understory conditions. This, in turn, favours regeneration dynamics, functioning and structural complexity by allowing changes in light, moisture and nutrient availability. Our aim is to study how gap dynamics influence the stability of understory plant communities over a decade, particularly in their structure and function. The study was carried out in 102 permanent plots (sampled in 2006 and revisited in 2016) distributed throughout a 132 ha basin located in a non-managed temperate beech-oak forest (Bertiz Natural Park, Spain). We related changes in the taxonomical and functional composition and diversity of the understory vegetation to changes in canopy coverage. We found that gap dynamics influenced the species composition and richness of the understory through changes in light availability and leaf litter cover. Species with different strategies related to shade tolerance and dispersion established in the understory following the temporal evolution of gaps. However, changes in understory species composition in response to canopy dynamics occur at a slow speed in old-growth temperate forests, needing more than a decade to really be significant.
Authors:
Valencia, E. (Autor de correspondencia); De Bello, F.; Leps, J.; et al.
Journal:
JOURNAL OF VEGETATION SCIENCE
ISSN:
1100-9233
Year:
2020
Vol.:
31
N°:
5
pp.
792 - 802
Questions: Compensatory dynamics are described as one of the main mechanisms that increase community stability, e.g., where decreases of some species on a year-to-year basis are offset by an increase in others. Deviations from perfect synchrony between species (asynchrony) have therefore been advocated as an important mechanism underlying biodiversity effects on stability. However, it is unclear to what extent existing measures of synchrony actually capture the signal of year-to-year species fluctuations in the presence of long-term directional trends in both species abundance and composition (species directional trends hereafter). Such directional trends may lead to a misinterpretation of indices commonly used to reflect year-to-year synchrony. Methods: An approach based on three-term local quadrat variance (T3) which assesses population variability in a three-year moving window, was used to overcome species directional trend effects. This "detrending" approach was applied to common indices of synchrony across a worldwide collection of 77 temporal plant community datasets comprising almost 7,800 individual plots sampled for at least six years. Plots included were either maintained under constant "control" conditions over time or were subjected to different management or disturbance treatments. Results: Accounting for directional trends increased the detection of year-to-year synchronous patterns in all synchrony indices considered.
Authors:
Valencia, E. (Autor de correspondencia); de Bello, F. ; Galland, T. ; et al.
Journal:
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
ISSN:
0027-8424
Year:
2020
Vol.:
117
N°:
39
pp.
24345 - 24351
The stability of ecological communities is critical for the stable provisioning of ecosystem services, such as food and forage production, carbon sequestration, and soil fertility. Greater biodiversity is expected to enhance stability across years by decreasing synchrony among species, but the drivers of stability in nature remain poorly resolved. Our analysis of time series from 79 datasets across the world showed that stability was associated more strongly with the degree of synchrony among dominant species than with species richness. The relatively weak influence of species richness is consistent with theory predicting that the effect of richness on stability weakens when synchrony is higher than expected under random fluctuations, which was the case in most communities. Land management, nutrient addition, and climate change treatments had relatively weak and varying effects on stability, modifying how species richness, synchrony, and stability interact. Our results demonstrate the prevalence of biotic drivers on ecosystem stability, with the potential for environmental drivers to alter the intricate relationship among richness, synchrony, and stability.
Authors:
Camarero Martínez, J. J.; Gazol, Antonio; Sangüesa Barreda, G.; et al.
Journal:
FRONTIERS IN ECOLOGY AND EVOLUTION
ISSN:
2296-701X
Drought-triggered declines in forest productivity and associated die-off events have increased considerably due to climate warming in the last decades. There is an increasing interest in quantifying the resilience capacity of forests against climate warming and drought to uncover how different stands and tree species will resist and recover after more frequent and intense droughts. Trees form annual growth rings that represent an accurate record of how forest growth responded to past droughts. Here we use dendrochronology to quantify the radial growth of different forests subjected to contrasting climatic conditions in Spain during the last half century. Particularly, we considered four climatically contrasting areas where dominant forests showed clear signs of drought-induced dieback. Studied forests included wet sites dominated by silver fir (Abies alba) in the Pyrenees and beech (Fagus sylvatica) stands in northern Spain, and drought-prone sites dominated by Scots pine (Pinus sylvestris) in eastern Spain and black pine (Pinus nigra) in the semi-arid south-eastern Spain. We quantified the growth reduction caused by different droughts and assessed the short-and long-term resilience capacity of declining vs. non-declining trees in each forest. In all cases, drought induced a marked growth reduction regardless tree vigor. However, the capacity to recover after drought (resilience) at short- and long-term scales varied greatly between declining and non-declining individuals. ..
Journal:
JOURNAL OF VEGETATION SCIENCE
ISSN:
1100-9233
Year:
2016
Vol.:
27
N°:
4
pp.
728 - 738
Journal:
AMERICAN JOURNAL OF BOTANY
ISSN:
0002-9122
Year:
2014
Vol.:
101
N°:
8
pp.
1286 - 1292
Premise of the study: Plants respond to the prevailing conditions in the surrounding environment, but since they are dynamic systems this response may vary during their life. Thus, the identification of key aspects for the maintenance of plant populations requires the consideration of plant performance across environmental gradients and along life stages. This study examines how abiotic conditions and biotic interactions and processes determine the spatial distribution of two life-story stages that play a key role in the functioning of a representative population of Carex remota.
Methods: We used structural equation modeling (SEM) to test for direct and indirect influences of abiotic and biotic factors on seedlings and adults of Carex remota. The variables used in the analysis were number of seedlings, cover of adults, soil moisture, leaf litter cover, relative light, and topographic position.
Key results: Population patterns partially depend on direct and indirect effects of abiotic conditions. Whereas adult individuals were only affected by topsoil moisture, seedling emergence was largely affected by multiple environmental conditions. The number of seedlings increased with high topsoil moisture, low leaf-litter values, high light values as well as in low parts of the study area. The importance of adult individuals in determining seedling success is also highlighted: higher abundance provides seed rain in the surroundings and modifies the microenvironmental conditions favoring high seedling establishment.
Conclusions: As hypothesized, adults and seedlings responded to the environmental conditions differently. Seedling emergence was a critical aspect in C. remota performance, and abrupt changes in the environment during this stage may strongly influence population performance.
Journal:
ECOHYDROLOGY
ISSN:
1936-0584
Year:
2014
Vol.:
7
N°:
2
pp.
524 - 531
This work explains the effect of microtopography on the spatio-temporal gradient of topsoil moisture in a first-order stream in a forested mountainous area of northern Spain. This gradient was also related with the availability of suitable microsites for a forest riparian sedge (Carex remota).
Topsoil moisture, presence of C. remota and height and distance from the stream edges were measured in 385 points along 35 transects perpendicular to the stream. Soil moisture measurements were repeated in three different dates.
Topsoil moisture showed a sigmoid trend that defined the limits of a wet riparian zone at 125m of distance from and 055m in elevation above stream banks. Our riparian zone was narrower than other studies because of the steep slopes (25%) of the mountainous area studied. Elevation above stream banks was more influential than distance in defining the limits of the riparian zone.
In the riparian zone, values of soil moisture were high and constant even at the end of a dry period due to the continuous water flow. In the adjacent upland forest, soil moisture varied according to rainfall. These high and constant soil moisture values defined the suitable microsites for C. remota.
Journal:
BOLETÍN DE LA ASOCIACIÓN DE HERBARIOS IBERO-MACARONÉSICOS
ISSN:
1136-5048
Year:
2013
Vol.:
14 - 15
pp.
54
Journal:
STOCHASTIC ENVIRONMENTAL RESEARCH AND RISK ASSESSMENT
ISSN:
1436-3240
Year:
2013
Vol.:
27
N°:
1
pp.
59-76
This study attempts to understand the dependence on abiotic factors and on the biotic process of the population development. We used three spatial point process models (Poisson, Area-Interaction and shot-noise Cox processes) in both homogenous and inhomogeneous versions to model the distribution of three Carex remota cohorts in wet zones of a temperate forest in the north of Spain. The cohorts studied were adults and seedlings born in two consecutive years. With the use of these models we are able to simulate separately and jointly the effect on plant distribution of a homogeneous or heterogeneous habitat, and the absence or presence of some biotic processes, as seed dispersal and/or density-dependent interactions. The result of the bivariate function analysis does not reveal sufficient evidences, but suggests a weak positive relation between adults and seedlings that survived a dry period in the first summer. Models from the three cohorts show a decreasing degree of clustering from seedlings to adults. Besides, the results show that the importance of the main factors that explain the population structure changes along the development of Carex stages. Compared to seedlings, the adults pattern shows an increasing dependence on abiotic factors.
Journal:
REPORTS OF THE FINNISH ENVIRONMENT INSTITUTE
ISSN:
1796-1718
Year:
2013
Vol.:
25
pp.
47 - 50
Journal:
THE FINNISH ENVIRONMENT
ISSN:
1238-7312
Year:
2011
N°:
18
pp.
53 - 57
Journal:
Acta Oecologica
ISSN:
1146-609X
Year:
2010
Vol.:
36
N°:
6
pp.
634 - 644
Journal:
Plant Ecology (Print)
ISSN:
1385-0237
Year:
2010
Vol.:
211
N°:
1
pp.
37 - 48
Journal:
Plant Ecology (Print)
ISSN:
1385-0237
Year:
2010
Vol.:
207
N°:
1
pp.
1 - 11
Spatial patterns of vascular plant diversity were studied in an unmanaged temperate forest in northern Spain. Diversity in 102 plots of 400 m(2) was analyzed against environmental and spatial variables. The Principal Coordinates of Neighbor Matrices method was used to create spatial variables that represent spatial structures on multiple scales. Variation partitioning on multiple regression was used to discover pure environmental and spatial fractions and their joint effects on diversity. Additionally, we created maps of the response and some explanatory variables to interpret their patterns. The results show that diversity is heterogeneously distributed in the basin and is explained mainly by environmental factors. Leaf litter cover proved the most important environmental factor. The spatial variables play an important role in structuring the environment but the low amount of variance explained by these when the effect of the environment is removed points to the lesser importance of neighborhood relations to the distribution of diversity values.
