A5031682814- Ecology and Vegetation Dynamics Studies
- Fire effects on ecosystems
- Plant Water Relations and Carbon Dynamics
- Plant and animal studies
- Forest ecology and management
- Rangeland and Wildlife Management
- Conservation, Biodiversity, and Resource Management
- Tree-ring climate responses
- Plant responses to water stress
- Plant Parasitism and Resistance
- Plant Diversity and Evolution
- Forest Management and Policy
- Botany, Ecology, and Taxonomy Studies
- Agroforestry and silvopastoral systems
- Plant responses to elevated CO2
- Environmental and biological studies
- Genetic diversity and population structure
- Tree Root and Stability Studies
- Irrigation Practices and Water Management
- Soil Management and Crop Yield
- Plant nutrient uptake and metabolism
- Climate variability and models
- Ecosystem dynamics and resilience
- Remote Sensing in Agriculture
- Amazonian Archaeology and Ethnohistory
North Carolina State University
2016-2025
North Central State College
2021
Brooke Army Medical Center
2021
Universidade de Brasília
2000-2004
Duke University
1999-2002
NSF National Center for Atmospheric Research
2002
Harvard University
1998-2000
The University of Texas at Austin
2000
Ecologists have long sought to understand the factors controlling structure of savanna vegetation. Using data from 2154 sites in savannas across Africa, Australia, and South America, we found that increasing moisture availability drives increases fire tree basal area, whereas reduces area. However, among continents, magnitude these effects varied substantially, so a single model cannot adequately represent woody biomass regions. Historical environmental differences drive regional variation...
In classical growth analysis, relative rate (RGR) is calculated as RGR = (ln W2 - ln W1)/(t2 t1), where W1 and are plant dry weights at times t1 t2. Since usually using destructive harvests of several individuals, an obvious approach to substitute with sample means W2. Here we demonstrate that this yields a biased estimate whenever the variance natural logarithm-transformed weight changes through time. This bias increases increase in RGR, length interval between harvests, or size. The can be...
• We aimed to identify the limits of savanna across Africa, Australia and South America. based our investigation on rich history hypotheses previously examined: that are variously determined by rainfall, rainfall seasonality, soil fertility disturbance. categorized vegetation all continents as 'savanna' (open habitats with a C4 grass layer) or 'not-savanna' (closed no used combination statistical approaches examine how presence varied function five environmental correlates. The is...
Tropical savanna and forest are recognized to represent alternate stable states, primarily determined by feedbacks with fire. Vegetation-fire dynamics in each of these vegetation types largely the influence on fire behavior, as well effects behavior tree mortality, topkill (defined here complete death aerial biomass, regardless whether plant recovers resprouting), rate growth resprouts. We studied effect three savanna-forest boundaries central Brazil. Fire intensity was greater than forest,...
Savannas are defined based on vegetation structure, the central concept being a discontinuous tree cover in continuous grass understorey. However, at high-rainfall end of tropical savanna biome, where heavily wooded mesic savannas begin to structurally resemble forests, or forests degraded such that they open out savannas, structure alone may be inadequate distinguish from forest. Additional knowledge functional differences between these ecosystems which contrast sharply their evolutionary...
Tropical savannas have been increasingly viewed as an opportunity for carbon sequestration through fire suppression and afforestation, but insufficient attention has given to the consequences biodiversity. To evaluate biodiversity costs of increasing sequestration, we quantified changes in ecosystem stocks associated communities plants ants resulting from Brazilian Cerrado, a global hotspot. Fire resulted increased 1.2 Mg ha
Roughly 3% of the Earth's land surface burns annually, representing a critical exchange energy and matter between atmosphere via combustion. Fires range from slow smouldering peat fires, to low-intensity intense crown depending on vegetation structure, fuel moisture, prevailing climate, weather conditions. While links biogeochemistry, climate fire are widely studied within Earth system science, these relationships also mediated by fuels—namely plants their litter—that product evolutionary...
Catastrophic hydraulic failure will likely be an important mechanism contributing to large-scale tree dieback caused by increased frequency and intensity of droughts under global climate change. To compare the susceptibility 22 temperate deciduous shrub species during a record drought in southeastern USA, we quantified leaf desiccation, native embolism, wood density, stomatal conductance predawn midday water potential at four sites with varying intensities. At two driest sites, there was...
Abstract Disentangling species strategies that confer resilience to natural disturbances is key conserving and restoring savanna ecosystems. Fire a recurrent disturbance in savannas, vegetation highly adapted often dependent on fire. However, although the woody component of tropical savannas well studied, we still do not understand how ground‐layer plant communities respond fire, limiting conservation management actions. We investigated effects prescribed fire community structure...
Summary Fire is important in the dynamics of savanna–forest boundaries, often maintaining a balance between forest advance and retreat. We performed comparative ecological study to understand how savanna species differ traits related fire tolerance. compared bark thickness, root stem carbohydrates, height reproductive individuals within 10 congeneric pairs, each containing one species. Bark thickness averaged nearly three times that species, thereby reducing risk death during fire. The...
1. Burning typically occurs at intervals of 1–3‐years in the Brazilian cerrado, a rate that exceeds precolonization fire regime. To determine if woody plants cerrado successfully reproduce within short span time between burns, experimental burns were used to quantify effects on sexual and vegetative reproduction six species resprouting trees shrubs. 2. Four vegetatively by producing root suckers. For three these species, Rourea induta , Myrsine guianensis Roupala montana sucker production...
Human activity has resulted in high fire frequency many moist tropical savannas. To simulate the effects of increased on woody plants cerrado savannas Brazil, I constructed matrix population models for five species, including a subshrub, two shrubs, and trees, using four years demographic data. The projected that species will decline under frequent burning but increase abundance infrequent burning. For these four, intervals 2–9 yr are required long-term persistence, depending species. fifth...
Belowground vertical community composition and maximum rooting depth of the Edwards Plateau central Texas were determined by using DNA sequence variation to identify roots from caves 5–65 m deep. Roots identified comparing their sequences for internal transcribed spacer (ITS) region 18S–26S ribosomal repeat against a reference ITS database developed woody plants region. Sequencing provides, our knowledge, first universal method identifying plant roots. At least six tree species in system...
Tropical savannas have been heavily impacted by human activity, with large expanses transformed from a mixture of trees and grasses to open grassland agriculture. The National Center for Atmospheric Research (NCAR) CCM3 general circulation model, coupled the NCAR Land Surface Model, was used simulate effects this conversion on regional climate. Conversion savanna reduced precipitation approximately 10% in four five regions under study; only northern African showed no significant decline....
Summary 1 The savanna–forest boundary in the tropics is marked by a discontinuity not only tree density, but also species composition, with few regularly occurring both savanna and forest environments. 2 We performed comparative growth analysis for nine congeneric pairs, each containing one species, grown factorial design involving two light nutrient levels. 3 Contrary to predictions, there was no difference relative rates (RGR) between species. However, were clear differences allocation...
1 It was hypothesized that if facilitation is important for seedling establishment in savanna, then fire should reduce establishment. 2 This tested the cerrado savanna of Brazil with a factorial experiment designed to evaluate effects cover and prescribed burning on 3 Seeds 12 species trees shrubs were sown plots located sites providing three densities woody four times since last burning. 4 Seedling generally greater under crowns than open grassland, but individual responded differently...
Abstract The higher flammability of tropical savanna, compared with forest, plays a critical role in mediating vegetation‐environment feedbacks, alternate stable states, and ultimately, the distribution these two biomes. Multiple factors contribute to this difference flammability, including microclimate, fuel amount type. To understand transition we studied characteristics microclimate across eight savanna–forest boundaries south‐central Brazil. At each boundary, environment was monitored...
Summary Leaf traits are commonly associated with the life history, distribution and resource requirements of a species. To improve our understanding ecological physiological differences between tropical savanna forest trees, we compared leaf species native to gallery (riverine) forests in Cerrado region central Brazil. Congeneric pairs from 14 different taxonomic families were studied, each present at study site. Only individuals growing conditions under full sun studied. We measured foliar...
The impact of nocturnal water loss and recharge stem storage on predawn disequilibrium between leaf (ψL) soil (ψS) potentials was studied in three dominant tropical savanna woody species central Brazil (Cerrado). Sap flow continued throughout the night during dry season contributed from 13 to 28% total daily transpiration. During season, ψL substantially less negative covered transpiring leaves, day night, than exposed leaves. Before dawn, differences leaves were about 0.4 MPa. When...