Tara J Massad

• Doctor of Philosophy
• Managing Director at Gorongosa National Park

Fire and large mammal herbivores (LMH) are the principal top‐down forces maintaining savanna structure. Nonetheless, experiments designed to investigate interactions between fire and LMH are rare in savannas, and relationships between environmental variation and biodiversity in the context of fire and LMH are poorly understood. This study addresses...

Declines in biodiversity generated by anthropogenic stressors at both species and population levels can alter emergent processes instrumental to ecosystem function and resilience. As such, understanding the role of biodiversity in ecosystem function and its response to climate perturbation is increasingly important, especially in tropical systems w...

Declines in biodiversity generated by anthropogenic stressors at both species and population levels can alter emergent processes instrumental to ecosystem function and resilience. As such, understanding the role of biodiversity in ecosystem function and its response to climate perturbation is increasingly important, especially in tropical systems w...

Insect herbivory can be an important selective pressure and contribute substantially to local plant richness. As herbivory is the result of numerous ecological and evolutionary processes, such as complex insect population dynamics and evolution of plant antiherbivore defenses, it has been difficult to predict variation in herbivory across meaningfu...

Interactions between plants and herbivores are central in most ecosystems, but their strength is highly variable. The amount of variability within a system is thought to influence most aspects of plant-herbivore biology, from ecological stability to plant defense evolution. Our understanding of what influences variability, however, is limited by sp...

Top‐down and bottom‐up forces in tropical savannas have shaped the evolution of traits that enable plants to thrive in environments where soils are poor, dry seasons are long, fire is frequent, woody plants and grasses compete and herbivores range from cryptic caterpillars to elephants that topple entire trees. African savannas and the South Americ...

Declines in biodiversity generated by anthropogenic stressors at both species and population levels can alter emergent processes instrumental to ecosystem function and resilience. As such, understanding the role of biodiversity in ecosystem function and its response to climate perturbation is increasingly important, especially in tropical systems w...

Declines in biodiversity generated by anthropogenic stressors at both species and population levels can alter emergent processes instrumental to ecosystem function and resilience. As such, understanding the role of biodiversity in ecosystem function and its response to climate perturbation is increasingly important, especially in tropical systems w...

Phytochemical diversity is an effective plant defensive attribute, but much more research has focused on genetic and environmental controls of specific defensive compounds than phytochemical diversity per se. Documenting plasticity in phytochemical richness and plant chemical composition as opposed to individual compounds is important for understan...

Insect herbivory can vary from an inconsequential biotic interaction to a factor that contributes substantially to the diversity of plants and animals and overall interaction diversity. As herbivory is the result of numerous ecological and evolutionary processes, including complex population dynamics and the evolution of plant defense, it has been...

Declines in biodiversity generated by anthropogenic stressors at both species and population levels can alter emergent processes instrumental to ecosystem function and resilience. As such, understanding the role of biodiversity in ecosystem function and its response to climate perturbation is increasingly important, especially in tropical systems w...

Insect herbivory is a critical top-down force structuring plant communities, and quantifying the factors that mediate damage caused by herbivores is fundamental to understanding biodiversity. As herbivory is the result of numerous ecological and evolutionary processes, including complex population dynamics and the evolution of plant defense, it has...

Miombo is the most extensive ecosystem in southern Africa, being strongly driven by fire, climate, herbivory, and human activity. Soils are major regulating and supporting services, sequestering nearly 50% of the overall carbon and comprising a set of yet unexploited functions. In this study, we used next-generation Illumina sequencing to assess th...

Species richness in tropical forests is correlated with other dimensions of diversity, including the diversity of plant–herbivore interactions and the phytochemical diversity that influences those interactions. Understanding the complexity of plant chemistry and the importance of phytochemical diversity for plant–insect interactions and overall for...

Creating robust datasets of plant–insect interactions is important for understanding ecosystem dynamics, and data on species interactions can be used to evaluate conservation interventions. In the present work, we collected plant–herbivore–parasitoid data on an understudied but critical ecosystem—gallery forests in the Brazilian cerrado. We collect...

Natural history studies documenting spatial and temporal variation of species assemblages and their interactions are critical for understanding biodiversity and community ecology. We characterized caterpillar–parasitoid assemblages on shrubs in the genus Piper across remnants of semi‐evergreen forest in the Yucatán Península during the rainy and ra...

Plant functional traits provide a valuable tool to improve our understanding of ecological processes at a range of scales. Previous handbooks on plant functional traits have highlighted the importance of standardising measurements of traits to improve our understanding of ecological and evolutionary processes. In open ecosystems (i.e. grasslands, s...

Understanding the effects of fire and herbivory on vegetation is crucial for biodiversity conservation in miombo woodlands. Changes in fire regimes in miombo alter plant growth and functional traits, such as carbon and nitrogen content, specific leaf area (SLA), and the concentrations of polyphenols, which can also change herbivory patterns in thes...

Plant functional traits provide a valuable tool to improve our understanding of ecological processes at a range of scales. Previous handbooks on plant functional traits have highlighted the importance of standardising measurements of traits to improve our understanding of ecological and evolutionary processes. In open ecosystems (i.e. grasslands, s...

Demographic modelling predicts the critically endangered Clanwilliam cedar (Widdringtonia wallichii), an iconic conifer of South Africa, to be headed for extinction. Due to an apparent mismatch in life-history traits with the local fire regime, such as time to reproductive maturity exceeding mean fire return intervals and no clear seed dispersal ag...

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research sp...

Urban forests are critical for biodiversity conservation and offer a broad range of benefits to society, including provisioning, regulating, and cultural components of ecosystem services. Urban forests warrant more ecological attention in order to ensure the sustainability of these important natural areas, especially as they are often faced with un...

How do large-mammal communities reassemble after being pushed to the brink of extinction? Few data are available to answer this question, as it is rarely possible to document both the decline and recovery of wildlife populations. Here we present the first in-depth quantitative account of war-induced collapse and postwar recovery in a diverse assemb...

Absolute total numbers of all animals counted during aerial surveys of Gorongosa National Park. Records are limited to Rift Valley habitat within the limits of the 2014–2016 count block. Grey cells are years in which given species were not surveyed. Numbers can be converted into biomass by multiplying by the species-specific body mass estimates sho...

Illustrative metadata for the individual sightings of wildlife in Gorongosa National Park from aerial surveys spanning the period 1969–2018. The table shows five records from the dataset; the interpretation of each column heading is described below. The full dataset of 70,102 spatially referenced sighting records is available as a supplementary onl...

Converting raw count data into comparable figures. (DOCX)

Estimated numerical densities (individuals km-2) of all animals counted during aerial surveys of GNP. Rrecords are limited to Rift Valley habitat within the 2014–2016 count block. Grey cells are years in which a given species was not surveyed. These are the values used in our primary analyses in the main text. Numbers can be converted into biomass...

Absolute total numbers of all animals counted during the aerial surveys of GNP and limited areas north of the park boundary (uncorrected for area and habitat covered). Grey cells are years in which a given species was not surveyed. Hatched cells are years for which no spatial information is available. [37]. (DOCX)

Estimation of total large-herbivore carrying capacity (Ktot). Data are from [38]. Blue lines show 90th and 10th quantile regression lines, used as estimates of upper and lower plausible estimates of Ktot, respectively; red line shows ordinary least squares regression. Thin gray lines show estimates of mean annual precipitation (vertical) and biomas...

Spatial pattern of waterbuck sightings based on spatially equivalent flight lines in helicopter surveys of the Rift Valley portion of Gorongosa from 2001 to 2016. For 2014 and 2016, only data from the same sample lines as used in earlier counts are included, and all years are clipped to show only the spatial extent of the 2014/2016 ‘total counts.’...

Data set of 70,102 spatially referenced sighting records of wildlife from 15 aerial wildlife counts 1969–2018. (XLSX)

Construction of the logistic-regression model. (DOCX)

Wildlife introduction and translocations into GNP. Table includes numbers of individuals, years, and localities of origin for each of seven wildlife species introduced into the park between 2007–2018 (precise sex ratios for each group are not known). Only elephant bulls were translocated in 2008. Coutada 9 is a hunting concession located ~180 km no...

Phytochemical variation among plant species is one of the most fascinating and perplexing features of the natural world and has implications for both human health and the functioning of ecosystems. A key area of research on phytochemical variation has focused on insects that feed on plants and the enormous diversity of plant-derived compounds that...

A longstanding paradigm in ecology is that there are positive associations between herbivore diversity, specialization, and plant species diversity, with a focus on taxonomic diversity. However, phytochemical diversity is also an informative metric, as insect herbivores interact with host-plants not as taxonomic entities, but as sources of nutrient...

Climate change is predicted to manifest in more extreme droughts in large parts of Africa. Investigating how species' distributions may change in response to drought is therefore necessary for understanding ecosystem functioning, and it will also help inform land managers regarding changes in resource availability. This work can be approached at th...

The interaction between droughts and land-use fires threaten the carbon stocks, climate regulatory functions, and biodiversity of Amazon forests, particularly in the southeast, where deforestation and land-use ignitions are high. Repeated, severe, or combined fires and droughts result in tropical forest degradation via nonlinear dynamics and may le...

As researchers try to predict the effects of human modification at all trophic levels and mediate the impact of rapid environmental change, it has become clear it is no longer a matter of agreeing that both bottom-up and top-down forces play important roles in diverse ecosystems. Rather, the question is: how do these forces interact across aquatic...

Understanding tropical forest diversity is a long-standing challenge in ecology. With global change, it has become increasingly important to understand how anthropogenic and natural factors interact to determine diversity. Anthropogenic increases in fire frequency are among the global change variables affecting forest diversity and functioning, and...

Cavity-enhanced Raman multigas spectrometry is introduced as a versatile technique for monitoring of (13)CO2 isotope labeling experiments, while simultaneously quantifying the fluxes of O2 and other relevant gases across a wide range of concentrations. The multigas analysis was performed in a closed cycle; no gas was consumed, and the gas compositi...

Large amounts of carbon are required for plant growth, but young, growing tissues often also have high concentrations of defensive secondary metabolites. Plants' capacity to allocate resources to growth and defense is addressed by the growth‐differentiation balance hypothesis and the optimal defense hypothesis, which make contrasting predictions. I...

Anthropogenic understorey fires affect large areas of tropical forest, yet their effects on woody plant regeneration post-fire remain poorly understood. We examined the effects of repeated experimental fires on woody stem (less than 1 cm at base) mortality, recruitment, species diversity, community similarity and regeneration mode (seed versus spro...

The study of plant-insect interactions constitutes a large and growing branch of ecology that includes the two most diverse groups of higher organisms. This field of research addresses issues ranging from species-specific evolutionary arms races to the immense diversity of tropical plant communities to the effects of insect herbivores on reforestat...

One of the goals of chemical ecology is to assess costs of plant defenses. Intraspecific trade-offs between growth and defense are traditionally viewed in the context of the carbon-nutrient balance hypothesis (CNBH) and the growth-differentiation balance hypothesis (GDBH). Broadly, these hypotheses suggest that growth is limited by deficiencies in...

The effect of herbivory on plant performance is the subject of a large number of ecological studies, and plant responses to herbivory range from reduced reproduction to overcompensation. Because plant defenses, stored resources, and allocation demands change throughout a plant's lifetime, it can be hypothesized the effects of herbivory also vary wi...

Surface fires burn extensive areas of tropical forests each year, altering resource availability, biotic interactions, and, ultimately, plant diversity. In transitional forest between the Brazilian cerrado (savanna) and high stature Amazon forest, we took advantage of a long-term fire experiment to establish a factorial study of the interactions be...

Background/Question/Methods Fire increasingly threatens the integrity of the Amazon forest, particularly along its agricultural frontier. In addition, fire alters nutrient availability and herbivory, two factors hypothesized to affect plant diversity. Studying the diversity of regenerating vegetation as affected by fire, nutrient additions, and h...

QuestionsCan the growth of saplings be improved by limiting herbivory during reforestation? Can chemical ecology and diverse planting designs be applied to decrease herbivory in tropical reforestation? LocationReforestation plantings in Heredia, Costa Rica. Methods This study directly evaluates the effects of herbivory on seedling growth and the ro...

Instant symposiuM S ixteen years ago, a schoolteacher from New Jersey collected a caterpillar in a Costa Rican rainforest. When a parasitoid emerged several days later, it became the first data point of a long-term volunteer–mediated study on tritrophic interactions across the Americas. The teacher was an Earthwatch Institute scien-tist and the pro...

Plant traits – the morphological, anatomical, physiological, biochemical and phenological characteristics of plants and their organs – determine how primary producers respond to environmental factors, affect other trophic levels, influence ecosystem processes and services and provide a link from species richness to ecosystem functional diversity. T...

Background/Question/Methods A variety of abiotic and biotic factors are hypothesized to affect the maintenance of tropical forest diversity, and understanding these is the topic of continued study. Due to anthropogenic pressures which reduce the integrity of these forests, it is now imperative that factors influencing the recovery of diversity af...

Variation in plant secondary metabolite content can arise due to environmental and genetic variables. Because these metabolites are important in modifying a plant’s interaction with the environment, many studies have examined patterns of variation in plant secondary metabolites. Investigations of chemical defenses are often linked to questions abou...

Global environmental changes are hypothesized to affect herbivores indirectly via changes in plant defenses, and many studies have been conducted to explore effects of environmental change on plant chemistry and herbivory. We quantitatively synthesized data from these studies to produce generalities about the effects of a broad array of environment...

In this study, seedling growth and herbivory were monitored during the first 4 years of plot development in a large-scale reforestation experiment in Brazil’s Atlantic Rainforest (Mata Atlˆantica). Seedlings were planted in a factorial design testing two levels of density, three levels of diversity, and the presence or absence of pioneer species at...

In this study, seedling growth and herbivory were monitored during the first 4 years of plot development in a large-scale reforestation experiment in Brazil's Atlantic Rainforest (Mata Atlântica). Seedlings were planted in a factorial design testing two levels of density, three levels of diversity, and the presence or absence of pioneer species at...

Background/Question/Methods The goal of most tropical reforestation is to develop planting strategies for fast-growing species that will eventually produce quality timber. There are relatively few tropical reforestation studies that focus on ecosystem restoration, and as a result very little is known about community interactions in this applied se...

To examine top-down and bottom-up influences on managed terrestrial communities, we manipulated plant resources and arthropod abundance in alfalfa (Medicago sativa L.) fields. We modified arthropod communities using three nonfactorial manipulations: pitfall traps to remove selected arthropods, wooden crates to create habitat heterogeneity, and an a...