Horacio Paz

• PhD
• National Autonomous University of Mexico

In many terrestrial habitats, plants experience temporal heterogeneity in water availability both at the intra and inter annual scales, creating dry-wet pulse scenarios. This variability imposes two concomitant challenges for plants: surviving droughts and efficiently utilizing water when it becomes available, whose responses are closely interconne...

Seasonality is one of the most important features of Tropical Dry Forests (TDFs), then water scarcity must be overcome by perennial sources dependent of groundwater flows. Groundwater recharge processes in TDFs are controlled by (i) the seasonal dynamics of the components of the water cycle through their interaction with the soil and underlying geo...

Aim Successional changes in functional diversity provide insights into community assembly by indicating how species are filtered into local communities based on their traits. Here, we assess successional changes in taxonomic and functional richness, evenness and redundancy along gradients of climate, soil pH and forest cover. Location Neotropics....

Fine roots are specialized in nutrient and water acquisition and are critical for species performance and ecosystem functioning. Recent evidence has shown a broad root economic space determined by the orthogonal collaboration and conservation gradients related to resource acquisition and resource conservation, respectively. However, whether these g...

Arid and semi-arid ecosystems are widely distributed around the world, covering about 60% of the earth’s land area. This type of ecosystem has low resilience and high fragmentation caused by human activities related to land use changes to agricultural uses. It has been seen that one of the mechanisms that can help recover the structure and function...

We characterize the taxonomic and functional diversity of waterbird communities in mangrove forests of 23 coastal lagoons in the southern Mexican Pacific coast, to evaluate the hypothesis of decline of taxonomic and functional richness of waterbird communities in the face of loss of natural habitat cover and increased fragmentation. We quantified p...

Tropical dry forests (TDF´s) are seasonal ecosystems that develop under complex hydrological systems. We analyzed the hydrological processes in three micro-basins on the southern coast of the state of Jalisco, Mexico, which sustain a TDF in a state of conservation on fractured granite. Although there is available information spanning more than 40 y...

Las islas mexicanas representan un reservorio de biodiversidad importante que se encuentra amenazado por el cambio global. En épocas recientes, la isla Socorro, archipiélago Revillagigedo ha experimentado importantes pertubaciones tales como brotes poblacionales de la langosta centroamericana (Schistocerca piceifrons). En este estudio se evaluó la...

The drought susceptibility of woody saplings may explain their low survival in arid environments. Therefore, it is critical to determine which morphological and physiological traits are more responsive to drought among young plants. This study tested whether plant responses to experimental drought differ between two plant functional groups: deciduo...

Given the outstanding global progress of research on the hydraulic pathway in plants, and its important role as an indicator of plant mortality risk, we reviewed: (1) the adaptive basis of hydraulic traits and their importance for overall plant function; (2) the number of primary scientific articles on plant hydraulics that have been produced in Me...

Premise: Although ecological differentiation driven by altitude and soil is hypothesized to promote coexistence of sympatric tree species of Damburneya (Lauraceae), the mechanistic role of leaf functional variation on ecological differentiation among co-occurring species remains unexplored. We aimed to determine whether the patterns of leaf trait...

The study of above- and below-ground organ plant coordination is crucial for understanding the biophysical constraints and trade-offs involved in species' performance under different environmental conditions. Environmental stress is expected to increase constraints on species trait combinations, resulting in stronger coordination among the organs i...

Tropical dry forests are environmentally complex ecosystems with highly heterogeneous water availability, such that distinctive plant communities are found in contrasting habitats in close proximity to each other. This leads to the question of how resource heterogeneity has led to functional heterogeneity among communities. One hypothesis is that t...

La fotografía juega un papel fundamental para enfrentar los efectos de la crisis global de biodiversidad, pues las imágenes ayudan a inspirar a la población para comprometerse con el cuidar de la naturaleza. El registro fotográfico es un valioso apoyo para divulgar los resultados de proyectos científicos encaminados a proteger la biodiversidad. Ade...

Key message Oak species displayed high interspecific functional trait variation. The resource use strategy among oaks both at the above and belowground organs was guided by the fast-slow continuum. AbstractPlant functional ecology has focused on the study of functional strategies and general patterns of trait covariation. Mostly, studies intend to...

Humans’ impacts on natural environments have become pervasive, and natural regeneration is often hampered by extreme soil degradation. This situation is exacerbated in insular habitats where introductions of non-native grazing mammals have left behind completely barren areas. Once mammals are removed, aggressive native or non-native plant species c...

Agriculture, cattle grazing, and human settlements negatively affect bird biodiversity, driving the loss of ecologically specialized species and favoring the dominance of generalists. Because ecological pressures define organisms’ success by acting on their intrinsic traits, biodiversity loss due to anthropization might cause directional trait shif...

Significance Tropical forests disappear rapidly through deforestation but also have the potential to regrow naturally through a process called secondary succession. To advance successional theory, it is essential to understand how these secondary forests and their assembly vary across broad spatial scales. We do so by synthesizing continental-scale...

Plants from arid environments display covarying traits to survive or resist drought. Plant drought resistance and ability to survive long periods of low soil water availability should involve leaf phenology coordination with leaf and stem functional traits related to water status. This study tested correlations between phenology and functional trai...

Abiotic and biotic filters may play differential roles in the plant community organization along forest succession in abandoned fields. However, little is known about how life stage-specific filters influence species replacement during succession. We approach this issue by analyzing changes in community attributes (abundance, species density, speci...

Secondary succession involves dynamic feedback among vegetation, environmental conditions and biota. Nevertheless, the recovery of tropical forests after anthropic management is often evaluated based solely on vegetation cover, which is easier to measure and requires less equipment and expertise than the assessment of soil and microclimate, but doe...

In semiarid ecosystems, many plant species are tolerant to drought. However, increased aridity as a result of climatic change could modify the capacity of germination and establishment. Under drought conditions, small-seeded species will tend to germinate in higher proportions than large-seeded species because the former have larger surface-to-volu...

Background: In semiarid ecosystems, many plant species are tolerant to drought. However, increased aridity as a result of climatic change could modify the capacity of germination and establishment. Hypothesis: Under drought conditions, small-seeded species will tend to germinate in higher proportions than large-seeded species because the former ha...

In the humid tropics, the substitution of forest cover by open pastures generates hotter and dryer conditions limiting the establishment of native plants. In this context reforestation of pastures using fast-growing tree species is commonly used to improve the environmental conditions, however, contrary to expected this strategy may lead to drier s...

The geographic distribution of species depends on their relationships with climate and on the biotic interactions of the species. Ecological Niche Models (ENMs) mainly consider climatic variables only and may tend to overestimate these distributions, especially for species strongly restricted by biotic interactions. We identified the preference of...

Predicting plant community assembly is challenging in part because the influence of environmental conditions via plant functional strategies and the relevance of mechanisms of community assembly change across habitats and these changes remain poorly studied. To assess how environmental conditions drive species sorting in a tropical dry forest, we u...

Cloud forest tree seedlings of higher leaf mass to area ratio and leaf dry matter content displayed higher survival along an elevation gradient in the forest understorey. Phenotypic plasticity in leaf functional traits was not related to seedling survival. Understanding the relationship between seedling survival and phenotypic plasticity of leaf fu...

Aims Mechanisms of plant drought resistance include both tolerance and avoidance. Xylem vulnerability to embolism and turgor loss point are considered traits that confer tolerance, while leaf abscission and deciduousness characterizes the avoidance strategy. While these mechanisms are thought to trade-off expressing a continuum among species, littl...

Tropical forests are converted at an alarming rate for agricultural use and pastureland, but also regrow naturally through secondary succession. For successful forest restoration, it is essential to understand the mechanisms of secondary succession. These mechanisms may vary across forest types, but analyses across broad spatial scales are lacking....

Cloud forest tree species are reported to be shifting and retracting their distributional ranges in response to increasing temperatures. However, there is limited information regarding the impact of increasing temperatures on the recruitment of cloud forest trees, a critical phase in population dynamics. Evaluating the establishment of introduced s...

Understanding hurricane resistance and resilience in tree species is a challenge to the management and conservation of coastal tropical forests. Tree responses to hurricanes partly depend on species attributes related to architecture and resource use strategy; however, few studies have used multiple traits to identify the role of functional trade-o...

Many developing countries harbour large numbers of species that face little‐understood, gradual changes in their environment, including chronic anthropogenic disturbance ( CAD ), a high frequency but low intensity form of disturbance. These countries also lack the resources to study each species, so conservation practices have been generalized, ass...

In seasonal plant communities, it is recognized that topography-related variation in water availability and solar radiation determine vegetation structure and community composition; however, the effects on functional structure, particularly through changes in resource use strategies of plants are still poorly understood. This study examines the eff...

Long-term human disturbance of tropical forests may favor generalist plant species leading to biotic homogenization. We aimed to a) assess if generalist species dominate across different successional ages and topographical positions in a tropical dry forest with a long history of human disturbance, b) to characterize functional traits associated wi...

The floristic composition, structure, and texture of 1 ha of mesophytic mountain forest in Omiltemi, Guerrero, is described. With 138 species of vascular plants in the plot, this forest is very rich, with epiphytes, trees and herbs comprising the most diverse growth forms. The geographic affinities of this forest are diverse; many elements are shar...

Oak species (Fagaceae: Quercus) differ in their distribution at the landscape scale, specializing to a certain portion of environmental gradients. This suggests that functional differentiation favors habitat partitioning among closely related species. To elucidate the mechanisms of species coexistence in oak forests, we explored patterns of intersp...

Functional Diversity is considered an important driver of community assembly in environmental and successional gradients. To understand tree assembly processes in a semideciduous tropical forest, we analyzed the variation of Functional Richness (FRic), Functional Divergence (FDiv), and Functional Evenness (FEve) of small vs. large trees in relation...

In seasonal plant communities where water availability changes dramatically both between and within seasons, understanding the mechanisms that enable plants to exploit water pulses and to survive drought periods is crucial. By measuring rates of physiological processes, we examined the trade-off between water exploitation and drought tolerance amon...

Aim Tropical forests store 25% of global carbon and harbour 96% of the world's tree species, but it is not clear whether this high biodiversity matters for carbon storage. Few studies have teased apart the relative importance of forest attributes and environmental drivers for ecosystem functioning, and no such study exists for the tropics. Locatio...

1.Successional gradients are ubiquitous in nature, yet few studies have systematically examined the evolutionary origins of taxa that specialize at different successional stages. Here we quantify successional habitat specialization in Neotropical forest trees and evaluate its evolutionary lability along a precipitation gradient. Theoretically, succ...

Root growth and morphology may play a core role in species-niche partitioning in highly diverse communities, especially along gradients of drought risk, such as that created along the secondary succession of tropical dry forests. We experimentally tested whether root foraging capacity, especially at depth, decreases from early successional species...

The response of plants to altitudinal gradients depends on several factors and might differ among life strategies. Understanding these responses is highly relevant for management of forest species, particularly under climate change scenarios. We explored the response to drought of different provenances of Lupinus elegans, obtained from an altitudin...

Drought stress in provenances of Lupinus elegans from different altitudesThe response of plants to altitudinal gradients depends on several factors and might differ among life strategies. Understanding these responses is highly relevant for management of forest species, particularly under climate change scenarios. We explored the response to drough...

We tested whether and how functional composition changes with succession in dry deciduous and wet evergreen forests of Mexico. We hypothesized that compositional changes during succession in dry forest were mainly determined by increasing water availability leading to community functional changes from conservative to acquisitive strategies, and in...

In tropical dry forests, spatial heterogeneity in soil water availability is thought to determine interspecific differences in key components of resource use strategies, such as leaf phenology and xylem function. To understand the environmental drivers of variation in leaf phenology and xylem function, we explored the relation of soil water potenti...

With data from 15 species in eight families of tropical dry forest trees, we provide evidence of coordination between the stem and leaf economic spectra. Species with low-density, flexible, breakable, hydraulically efficient but cavitationally vulnerable wood shed their leaves rapidly in response to drought and had low leaf mass per area and dry ma...

The mechanisms of drought resistance that allow plants to successfully establish at different stages of secondary succession in tropical dry forests are not well understood. We characterized mechanisms of drought resistance in early and late-successional species and tested whether risk of drought differs across sites at different successional stage...

As a result of an increase in the urban demand for organic horticultural products, locally available soil amendments need to be evaluated. Here, the effects on growth and reproductive output of Cucurbita pepo, were assessed for the aquatic invasive Eichornia crassipes, a commercially produced vermicompost, and chicken manure. In addition, their eff...

Presentamos una síntesis del programa de investigación de largo plazo (iniciado en 2004) denominado Manejo de Bosques Tropicales (MABOTRO), llevado a cabo por académicos de once instituciones y más de 50 estudiantes de licenciatura y posgrado. Se construyó un marco metodológico para la generación de conocimientos que coadyuve a la preservación de s...

A common observation in tropical dry forests is the habitat preference of tree species along spatial soil water gradients. This pattern of habitat partitioning might be a result of species differentiation in their strategy for using water, along with competing functions such as maximizing water exploitation and tolerating soil water stress. We test...

Plant hydraulic architecture has been studied extensively, yet we know little about how hydraulic properties relate to species' life history strategies, such as drought and shade tolerance. The prevailing theories seem contradictory. We measured the sapwood (K(s) ) and leaf (K(l) ) hydraulic conductivities of 40 coexisting tree species in a Bolivia...

Cavitation resistance is a critical determinant of drought tolerance in tropical tree species, but little is known of its association with life history strategies, particularly for seasonal dry forests, a system critically driven by variation in water availability. We analysed vulnerability curves for saplings of 13 tropical dry forest tree species...

Background/Question/Methods Precipitation patterns in the southern Sonoran Desert are highly variable from year to year. Variation in drought tolerance strategies of desert woody species is important for explaining their survival and distribution patterns. Four Parkinsonia small-tree species occurring sympatrically in the Sonoran Desert where used...

Changes in the position along the elevational gradient for plant species are a predicted consequence of global and local climate change. Within the area of influence of cities it is necessary, for conservation and ecological restoration, to understand the effect on plant communities of climate change and urban heat islands, that can increase the te...

It has been proposed that natural selection should favor distinct temporal patterns of sex allocation in selfing vs pollinator-dependent taxa. In autogamous selfers in which pollen receipt is highly reliable, selection should favor genotypes that maintain low and stable pollen to ovule (P : O) ratios throughout flowering. By contrast, in outcrosser...

A central goal of comparative plant ecology is to understand how functional traits vary among species and to what extent this variation has adaptive value. Here we evaluate relationships between four functional traits (seed volume, specific leaf area, wood density, and adult stature) and two demographic attributes (diameter growth and tree mortalit...

Several studies have proposed a group of morpho-functional traits as determinants of the ecological strategy of species. Among these, four morpho-functional traits are considered to be relevant in determining a plant's ecological strategy: specific leaf area (SLA), height at maturity (Hmax), wood density (WD), and seed mass (SM). We examined the va...

Among plants, pairs of selfing vs. outcrossing sister taxa provide interesting systems in which to test predictions concerning the magnitude and direction of temporal changes in sex allocation. Although resource availability typically declines towards the end of the growing season for annual taxa, temporal changes in mating opportunities depend on...

When ecologically important plant traits are correlated they may be said to constitute an ecological 'strategy' dimension. Through identifying these dimensions and understanding their inter-relationships we gain insight into why particular trait combinations are favoured over others and into the implications of trait differences among species. Here...

Sex allocation theory has assumed that hermaphroditic species exhibit strong genetically based trade-offs between investment in male and female function. The potential effects of mating system on the evolution of this genetic covariance, however, have not been explored. We have challenged the assumption of a ubiquitous trade-off between male and fe...

Experimental field data and interspecific comparative analyses were used to detect effects of seed mass on seedling performance within and among seven species of Psychotria sown in gaps and shaded rainforest sites. In addition we compared the effects of seed mass within and among species to detect concordance between the two ecological scales. We u...

Autogamously self-fertilizing taxa have evolved from outcrossing progenitors at least 12 times in the annual wildflower genus, Clarkia (Onagraceae). In C. xantiana, individuals of the selfing subspecies (ssp. parviflora) flower at an earlier age, produce successive flowers more rapidly, and produce flowers that complete their development more rapid...

I analyzed patterns of variation in root mass allocation and root morphology among seedlings of woody species in relation to environmental factors in four Neotropical forests. Among forests, I explored the response of root traits to sites varying in water or nutrient availability. Within each forest, I explored the plastic response of species to di...

Large seeds have been hypothesized to confer survival advantages in the shaded forest, and small seeds to confer growth advantages in open habitats. We explored these hypotheses using experimental studies in both field and controlled conditions. Our experiments examined intraspecific effects of seed mass on seedling demography in eight sympatric wo...

We examined the effects of seed mass on performance between the time of seed dispersal and emergence within seven sympatric rain forest woody species of Psychotria in two contrasting natural habitats: gaps and shaded forest. We determined the effects of seed mass on emergence (the total proportion of emerged seedlings) and on the speed of emergence...

The floristic composition, structure, and texture in a 1-ha plot of mesophytic mountain forest in Omiltemi, Guerrero, is described. With 138 species of vascular plants in the plot, this forest is very rich, with epiphytes, trees and herbs comprising the most diverse growth forms. The geographic affinities of this forest are diverse; many elements a...