Past research projects

My research focuses on the association between environmental conditions, species life history attributes (e.g., functional traits, distribution ranges, climatic niche), evolutionary patterns/dynamics and community emerging properties (e.g., richness, diversity, and evenness); looking at the consistency and recurrence of these relations across space (from local to global) and over time (in the next century and over the last 21.000 years). For this, my work has an emphasis in on the ecological effects (namely changes in the distribution of biomes, diversity patterns, ecosystem services and function) of natural and human drivers of ecosystem change (i.e., past and future climate change and invasive species). Through this research, I hope to understand, predict, and advise on future ecosystem behavior in the face of earth’s changing biogeochemical, climatic and disturbance gradients. My work combines elements of ecosystem modeling, analysis of ecosystem function and services, with a particular interest in understanding the relationships between environmental conditions and individuals, species, populations and communities functional and distribution patterns. For this, I use local, regional continental and global datasets, to understand the effects of natural–human disturbance, climate, species reshuffling and community assembly mechanism on community attributes, ecosystem function, and processes.

MACROECOLOGICAL STUDIES OF LONG-TERM HISTORICAL CONSTRAINTS ON FUNCTIONAL DIVERSITY AND ECOSYSTEM FUNCTIONING ACROSS CONTINENTS (HISTFUNC)

Earth’s environment is ongoing massive changes in response to climate change, land-use change, pollution, and biological invasions, with substantial impacts on ecosystem functioning (structure and dynamics) and therefore on the ecosystem services on which human societies depend on. It is, therefore, a critical priority for science to improve understanding of ecosystem functioning as well as the capacity for accurately predicting its dynamics under ongoing and future changes in the environment, notably, climate change. Traditionally, ecosystem functioning is understood to be the outcome of contemporary environmental drivers and their interplay with dominant species. However, during the last two decades, there has been increasing emphasis on – and controversy over – the additional importance of species diversity for ecosystem functioning.

Vascular plants constitute a particularly relevant group for studying historical constraints on functional diversity (functional diversity and functional composition), given their critical roles in terrestrial ecosystems. Plants have received particular attention in small-scale experimental studies of biodiversity effects. Large-scale regional effects on plant species diversity have also been documented; showing that past climate change has elicited severe regional extinctions, and still strongly influence plant species diversity patterns, even penetrating to local scales.

Functional diversity of European plants for each one of the Atlas Flora Europaea grid-cell (ca. 50km2). From left to right functional A) richness, B) evenness and C) dispersion. Functional diversity values are represented in 10% intervals (from red to blue).

Functional diversity of European plants for each one of the Atlas Flora Europaea grid-cell (ca. 50km2). From left to right functional A) richness, B) evenness and C) dispersion. Functional diversity values are represented in 10% intervals (from red to blue).

The objective of HISTFUNC is to apply macroecological analyses to provide ground-breaking assessments of large-scale drivers of functional diversity and ecosystem functioning, including effects of diversity on functioning. In particular, it will assess the novel hypothesis that ecosystem functioning is subject to long-term (102-107 year) constraints mediated by biodiversity effects and driven by past climate change and other historical factors. The postdoc project will investigate the existence long-term historical constraints on global and regional patterns in functional diversity of vascular plants using macroecological approaches. The HISTFUNC project will link several very large data sets on plant species distributions across large regions to large amounts of functional trait data as well as phylogenetic data and geospatial data on current climate and other aspects of the current environment as well as on paleoclimate to assess the extent to which current patterns of plant functional diversity reflect long-term historical constraints. Reflecting data availability, the project will focus on functional diversity for vascular plants across Europe and the New World as well as for palms (2600 species; a functionally highly significant group) globally.
This unprecedented assessment of the importance of historical constraints for plant functional diversity will shed light on the central pathways by which historical factors may affect the functioning of terrestrial ecosystems, namely via effects on plant functional diversity. Its results will also be necessary for nature management, where plants are emphasized and may shed light on why ecosystems vary in their propensity to be invaded by non-natives.

QUATERNARY CLIMATE-CHANGE EFFECTS ON TREE TAXA DISTRIBUTION SHIFTS

My work on this front has focused on the idea that individuals, populations or species must produce adaptive responses to persist under changing climatic conditions. Based on this, my work aims to provide a synthetic overview of how species communities and ecosystems have responded to the past (i.e., Quaternary) and could possible deal with current rates of climatic change. For this, I developed a new method for mapping the spatial rates of change in species distributions inferred from relative pollen abundances during the last deglaciation and compared these to climate velocities during the last deglaciation. I then applied such approach to assessing how plant communities’ distributions changed since the last glacial maximum. Additionally, focusing on North American plant taxa, and combining occurrence records (derived from fossil pollen databases as NEOTOMA and the North America pollen database) and paleoclimatic reconstructions (specifically the latest SynTrace transient simulations of the CCSM3 climate model), I evaluate the temporal trajectories of climatic factors since the last glacial maximum for a group of woody plant taxa. This work is done in close collaboration the NEOTOMA Paleoecology Database and the SynTrace climatic simulation team.

Associations between observed and expected rates of movement for the northern and southern boundaries of core distributions. For each period, the hi-square test of the proportion of observed latitudinal changes of evaluated taxa that fall above and below the observed=expected line (dashed diagonals), with significance levels marked as *** for p<0.001, ** for p<0.01, * for p0.05. Points represent the mean rate of biotic (y-axis) and climate velocity (x-axis) for each taxon. Positive values indicate northwards boundary-movement while negative values indicate southward movement. Horizontal and vertical dashed lines indicate zero velocity. Percentages in the four quadrants summarize the proportion of taxa falling into the corresponding cases.

My results in this regard support the idea of climate-limited distributions, particularly for northern populations; and that climate change paced the rates of biotic velocity for phenomena related to changes in abundance within species distributions. A point that set my work apart from all others evaluating the past and future rates of range or distributional change is the evaluation of the trailing edge (southern) populations.  Thanks to this I have been able to show that leading and trail edge of the taxa distributions, suggesting that rates of contraction for southern populations will be slow when compared to rates of expansion of northern populations. However, overall distributional changes of woody taxa since the last glacial maximum has shown a lagged response, due to the interaction between biological (traits), ecological (competition), evolutionary (niche conservatisms) and environmental (velocity of climate change) factors.

PROJECTED CLIMATE RESHUFFLING BASED ON CLIMATE-ANALOG AND CLIMATE-VELOCITY ANALYSES: IMPLICATIONS FOR COMMUNITY DISAGGREGATION

Using a combination of future climate scenarios I have studied the potential magnitude and velocity of climate change at different scales (from local to continental), and use these estimates as a measurement of the sensitivity of plant communities to future climate changes. I am particularly interested in using newly emerging methods such as climate analogs and climate-change velocities, and develop new multidimensional approaches, to complement more traditional species-based approaches (e.g., species distributional models) that assume only limited changes in climate. I work in close collaboration with the Wisconsin Initiative on Climate Change (WICCI), and the University of Wisconsin Nelson Institute Centre for Climatic Research (CCR). These partnerships have also allowed me to establish relationships with climatologists, biologists, and various stakeholders in Wisconsin and the North Eastern United States, who are working to mitigate and adapt to climate change.

Histograms of the spatial distance and directional histograms (rose plots inserts) of the bearing between each Wisconsin grid cell and the North American grid cell with the closest late-20th-century (1961-2000) climatic analog to the late-21st-century climates projected for the target Wisconsin grid cell. Bearings are oriented from the contemporary analog towards the Wisconsin grid cell, i.e. along the direction of climate change. Future climates are based on the ensemble of 15 GCM WICCI-downscaled grids for the late 21st century for the IPCC (a) A1B, (b) A2, and (c) B1 scenario. Late-20th-century climatic surfaces were obtained from Maurer et al., (2002).

HOW FUNCTIONAL DIFFERENTIATION COULD BE USED TO PREDICT CHANGES IN COMMUNITY COMPOSITION OVER TIME: AND INVASIVE SPECIES CASE STUDY

My research on this subject addresses two fundamental questions about invasive species: “Which species are invasive?” and “Which habitats are most likely to be invaded?“. For this, I have used state-of-the-art statistical tools to analyze performance, survival, reproduction and use of resources by introduced exotics, and the role of environmental conditions (i.e., soil, climate and human disturbance) on shaping these patterns. For this, I first compared native and alien plant attributes using statistical dissimilarity analyses, and then I evaluated the ecological setup (i.e., evolutionary relations, scale, and resource availability) into which “aliens” were introduced. Then, I tested whether evolutionary dynamics could explain the observed patterns of dissimilarity between natives and invasive. Lastly, I assess how these patterns change along worldwide resource availability gradients. The result of my work on this matter has shown that aliens are different when compared to their native counterparts regarding their performance, competitive and reproductive attributes and phylogenetic proximity to the native community; this is regardless of changing climatic, edaphic (e.g., soils) and human disturbance gradients. The differences between natives and invasive plants are strongly dependent on their evolutionary (phylogenetic) relations, which determine the possible rapid adaptation of aliens to the new environments. In particular, three attributes establish the success of an introduction: (1) the evolutionary similarity between natives and aliens; (2) the resources available to the invasive; and (3) the disturbance regime of the target community. Preventing the introduction and spread of invasive plants is an enormous challenge, especially under climatic change conditions; my research helps us know what to look for so we can try to prevent disasters before they occur. This work has been done in collaboration with members of the ARC-NZ Research Network for Vegetation Function, the Comparative Ecology Group (Macquarie University), the NCEAS-NEOTROPICS working group; and the cooperation of both GOBNET and LEDA trait databases.

 Conceptualization of the '''alien introduction continuum'' and the 'alien introduction continuum and the barriers any introduced plant must overcome to establish viable communities in a new area.

Conceptualization of the ”alien introduction continuum” and the ‘alien introduction continuum and the barriers any introduced plant must overcome to establish viable communities in a new area.

 MEASURING EXPOSURE TO ENVIRONMENTAL CHANGE.

In my research in this field has two focuses. First, developing a new methodology that combines estimates of climate and land use rates of change that builds on recently developed measures of climate velocity. Second, I have used such metrics to assess the exposure to past changes in climate and expected changes in environmental (climate and land use) conditions in the near future. The new direction I plan to take in this field is evaluating for Europe and then globally, the observed historical changes (over the last 50 to 100 years) in climate and land use, as well as those expected by 2100. While doing this, I plan to evaluate the extent to which metrics of climatic divergence and displacement of environmental isoclines can be used to characterize the opening up of new portions of climate space and the formation of novel ecosystems. This work would focus on determining the most useful one-dimensional and multidimensional velocity indices for the prediction of biological responses to future climate change. It will also identify mismatches between management and planning strategies.

NCC-CCandLUC

Combined exposure of US ecosystems to high speeds of climate speeds and local land use. a–c, Land-use contrast represent changes across all land-use types (a), forests (b) and rangelands (c). Colour ramp for land-use change shows the color of all possible multivariate climate and land-use speed combinations. Kernel density plots show the proportion of cells within the continental US with a particular combination of speeds of climatic and land-use, forest and rangeland change