Manuel del Jesus

Hydroperiod regime controls the organization of plant species in wetlands

With urban, agricultural, and industrial needs growing throughout the past decades, wetland ecosystems have experienced profound changes. Most critically, the biodiversity of wetlands is intimately linked to its hydrologic dynamics, which in turn are being drastically altered by ongoing climate changes. Hydroperiod regimes, e.g., percentage of time a site is inundated, exert critical control in the creation of niches for different plant species in wetlands. However, the spatial signatures of the organization of plant species in wetlands and how the different drivers interact to yield such signatures are unknown. Focusing on Everglades National Park (ENP) in Florida, we show here that cluster sizes of each species follow a power law probability distribution and that such clusters have well-defined fractal characteristics. Moreover, we individuate and model those signatures via the interplay between global forcings arising from the hydroperiod regime and local controls exerted by neighboring vegetation. With power law clustering often associated with systems near critical transitions, our findings are highly relevant for the management of wetland ecosystems. In addition, our results show that changes in climate and land management have a quantifiable predictable impact on the type of vegetation and its spatial organization in wetlands.

Maximum entropy production, carbon assimilation, and the spatial organization of vegetation in river basins.

The spatial organization of functional vegetation types in river basins is a major determinant of their runoff production, biodiversity, and ecosystem services. The optimization of different objective functions has been suggested to control the adaptive behavior of plants and ecosystems, often without a compelling justification. Maximum entropy production (MEP), rooted in thermodynamics principles, provides a tool to justify the choice of the objective function controlling vegetation organization. The application of MEP at the ecosystem scale results in maximum productivity (i.e., maximum canopy photosynthesis) as the thermodynamic limit toward which the organization of vegetation appears to evolve. Maximum productivity, which incorporates complex hydrologic feedbacks, allows us to reproduce the spatial macroscopic organization of functional types of vegetation in a thoroughly monitored river basin, without the need for a reductionist description of the underlying microscopic dynamics. The methodology incorporates the stochastic characteristics of precipitation and the associated soil moisture on a spatially disaggregated framework. Our results suggest that the spatial organization of functional vegetation types in river basins naturally evolves toward configurations corresponding to dynamically accessible local maxima of the maximum productivity of the ecosystem.

Signs of critical transition in the Everglades wetlands in response to climate and anthropogenic changes

The increasing pressure of climatic change and anthropogenic activities is predicted to have major effects on ecosystems around the world. With their fragility and sensitivity to hydrologic shifts and land-use changes, wetlands are among the most vulnerable of such ecosystems. Focusing on the Everglades National Park, we here assess the impact of changes in the hydrologic regime, as well as habitat loss, on the spatial configuration of vegetation species. Because the current structuring of vegetation clusters in the Everglades exhibits power-law behavior and such behavior is often associated with self-organization and dynamics occurring near critical transition points, the quantification and prediction of the impact of those changes on the ecosystem is deemed of paramount importance. We implement a robust model able to identify the main hydrologic and local drivers of the vegetation species spatial structuring and apply it for quantitative assessment. We find that shifts in the hydropatterns will mostly affect the relative abundance of species that currently colonize specific hydroperiod niches. Habitat loss or disruption, however, would have a massive impact on all plant communities, which are found to exhibit clear threshold behaviors when a given percentage of habitable habitat is lost.

Modeling the Interaction of Water Waves with Porous Coastal Structures

AbstractThe mathematical modeling of the interaction of water waves with porous coastal structures has continuously been among the most relevant challenges in coastal engineering research and practice. Finding a tool to better predict essential processes, relevant to the functionality and stability of breakwaters and jetties, and how they are affected by permeability, has been hampered by computational limitations that are being overcome. Over the last 60 years, the Journal of Waterway, Port, Coast, and Ocean Engineering has witnessed gradual developments leading from linearized solutions based on wave theories and constant friction coefficients to very sophisticated Eulerian or Lagrangian solvers of the Navier-Stokes (NS) equations, including turbulence within porous media. Today, although not without difficulty, the first steps are being made toward addressing the simulation of a fully three-dimensional interaction of complete sea states with porous structures at prototype scale. In this paper, after po...

Point rainfall statistics for ecohydrological analyses derived from satellite integrated rainfall measurements

Satellite rainfall measurements, nowadays commonly available, provide valuable information about the spatial structure of rainfall. In areas with low-density rain gage networks, or where these networks are nonexistent, satellite rainfall measurements can also provide useful estimates to be used as virtual rain gages. However, satellite and rain gage measurements are statistically different in nature and cannot be directly compared to one another. In the present paper, we develop a methodology to downscale satellite rainfall measurements to generate rain-gage-equivalent statistics. We apply the methodology to four locations along a strong rainfall gradient in the Kalahari transect, southern Africa, to validate the methodology. We show that the method allows the estimation of point rainfall statistics where only satellite measurements exist. Point rainfall statistics are key descriptors for ecohydrologic studies linking the response of vegetation to rainfall dynamics.

The role of forest maturity in extreme hydrological events

Environmental Hydraulics Institute, Universidad de Cantabria ‐ Avda. Isabel Torres, 15, Parque Científico y Tecnológico de Cantabria, 39011 Santander, Spain Aquatic Ecosystems Program, IRTA, Carretera Poblenou, km 5.5, 43540 Sant Carles de la Ràpita, Catalonia, Spain Department of Civil Engineering, Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción, Chile Centro de Investigación en Biodiversidad y Ambientes Sustentables. “CIBAS”. Facultad de Ciencias, Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción, Chile Correspondence Oscar Belmar, Aquatic Ecosystems Program, IRTA, Carretera Poblenou, km 5.5, 43540 Sant Carles de la Ràpita, Catalonia, Spain. Email: oscar.belmar@irta.cat; oscarbd@um.es

Numerical Modeling of Tsunami Waves Interaction with Porous and Impermeable Vertical Barriers

Tsunami wave interaction with coastal regions is responsible for very important human and economic losses. In order to properly design coastal defenses against these natural catastrophes, new numerical models need to be developed that complement existing laboratory measurements and field data. The use of numerical models based on the Navier-Stokes equations appears as a reasonable approach due to their ability to evaluate complex flow patterns around coastal structures without the inherent limitations of the classical depth-averaged models. In the present study, a Navier-Stokes-based model, IH-3VOF, is applied to study the interaction of tsunami waves with porous and impermeable structures. IH-3VOF is able to simulate wave flow within the porous structures by means of the volume-averaged Reynolds-averaged Navier-Stokes (VARANS) equations. The equations solved by the model and their numerical implementation are presented here. A numerical analysis of the interaction of a tsunami wave with both an impermeable and porous vertical breakwater is carried out. The wave-induced three-dimensional wave pattern is analysed from the simulations. The role paid by the porous media is also investigated. Finally, flow around the breakwater is analyzed identifying different flow behaviors in the vicinity of the breakwater and in the far field of the structure.

La integración del conocimiento sobre la Cordillera Cantábrica: hacia un observatorio inter-autonómico del cambio global

Delgado L.A. 2018. Landscape Heterogeneity and tree species diversity in a tropical forest. Development and validation of a methodological proposal. Ecosistemas 27(1): 105-115. Doi.: 10.7818/ECOS.1475 Many landscapes exist as unstable spatial-temporal mosaics where changes in patterns of biodiversity are affected by nature processes and the dynamic interaction between social and ecological factors. It is a consequence of the natural dynamics of socio-economic systems that regulate man-made tropical forests. However, a significant proportion of studies have made generalizations about the relative values of biodiversity, without taking into account the high levels of internal heterogeneity in the biophysical properties and land uses of each site. The purpose of this study is to propose and validate a methodology to delimit the heterogeneity of the landscape based on criteria that integrate the coupling of human-ecological systems such as: space-time dynamics of deforestation and fragmentation; complexity of the landscape structure; current and historical land use and biophysical variability. For this, the use of satellite images, landscape metrics, field work, documentary review and multivariate analysis were combined. The proposed methodology is intended to help guide the empirical delimitation of landscape heterogeneity as a prerequisite for the selection of similar landscapes and forest patches in studies of the diversity of tree species, in order to provide an opportunity to control the possible difficulties caused by variability in the proportion of forests, landscape configuration and successional states, in estimating its effects on forest richness and floristic composition.

A rainfall analysis and forecasting tool

MENSEI-L is a stand-alone software tool for the automatic analysis of pluviometric networks, that also provides three-day rainfall forecasts based on weather types. The software tool, implemented in Python and R, is able to fill missing values in original daily data series and to generate synthetic pluviometers in ungauged locations, by means of kriging techniques. MENSEI-L also characterizes punctual and spatial, average and extreme distributions of precipitation for the complete pluviometric network. Tenerife (Canary Islands, Spain) is used as study site to evaluate the capabilities of MENSEI-L and the implicit rainfall analysis methodology that it implements. MENSEI-L proves to be a useful tool to extract information from dense observation networks where manual analysis is not practical. A rainfall analysis methodology is implemented around three procedures: weather types generation, point statistics and a spatio-temporal interpolation.The methodology, implemented in a software called MENSEI-L, uses of the latest Python and R libraries for the analysis.MENSEI-L can be used to reconstruct a pluviometric network by filling missing values and generating synthetic pluviometers.MENSEI-L uses the reconstructed network and the weather types to generate rainfall characterizations of average and 3-day rainfall forecast.MENSEI-L constitutes a powerful tool that simplifies the process to inform engineering design, decision-making and risk assessments.