Treesearch

Residential green spaces are increasingly gaining attention for their potential to contribute to ecosystem services of social and ecological value for cities. This research evaluated the potential of residential yards of San Juan, Puerto Rico, to contribute to urban sustainability through the provision of ecosystem services using a social-ecological approach. The study builds upon prior work at this site led by the San Juan Urban Long Term Research Area (ULTRA) Collaborative Network and addressed the following overarching question: Which social-ecological factors could be influencing the...

Aerosols can interact with radiation directly through scattering and absorption and indirectly by serving as cloud condensation nuclei. The uncertainty of how particles and clouds interact with radiation is still high amidst the progress made in recent years, which hinders our current understanding of how these particles affect the Earth’s radiation budget. This works aims to reduce this uncertainty by targeting the two most light-absorbing atmospheric particles, mineral dust and black carbon, and study how they interact with radiation, how they serve as cloud condensation nuclei, assessing...

Freshwater environments are highly dynamics but are subject to natural and anthropogenic influences. Although lotic ecosystems have resilience to deal with natural disturbance, the additional pressure from anthropogenic stresses can often lead to irreversible changes. Particularly, urban activities have resulted in increased anthropogenic discharge into freshwater environments with significant effects on organisms. The main objective of this thesis was to evaluate the toxicity of the freshwater shrimp Xiphocaris elongata to synthetic pyrethroid and organophosphate pesticides. Experiments...

Mountains are model systems for understanding the mechanisms that underlie patterns of biodiversity and ecosystem function. This study disentangles the effects of climatic and edaphic properties on patterns of trait variation across two mountains, tests foundational assumptions of trait-based approaches, and tests the stress dominance hypothesis of decreasing trait variation with increasing environmental stress. The results suggest that elevation as a proxy of abiotic conditions is not enough to generalize the variability of plant strategies across mountains. The ability to distinguish...

This report examines the nation’s legal, institutional, and economic capacity to promote forest conservation and sustainable resource management through a set of 10 indicators associated with criterion 7 of the Montréal Process criteria and indicators framework. Specifically, we considered (1) legislation and policies, (2) cross-sectoral coordination, (3) taxation and incentives, (4) property rights and land tenure, (5) law enforcement, (6) programs and services, (7) research and technology, (8) partnerships, (9) public participation and conflict resolution, and (10) monitoring and...

Categorization of topographical features into landform type is a long-standing method for understanding physiographic patterns in the environment. Differences in forest composition between landform types are driven primarily by concurrent differences in soil composition and moisture, but also disturbance regime. Many studies have focused on the interaction between fire disturbance, succession, and landforms, but the effects of hurricane disturbance on compositional differences between landforms are poorly understood. In the study presented here, we assess compositional and structural...

The effects of climate change on tropical forests may have global consequences due to the forests’ high biodiversity and major role in the global carbon cycle. In this study, we document the effects of experimental warming on the abundance and composition of a tropical forest floor herbaceous plant community in the Luquillo Experimental Forest, Puerto Rico. This study was conducted within Tropical Responses to Altered Climate Experiment (TRACE) plots, which use infrared heaters under free-air, openfield conditions, to warm understory vegetation and soils + 4°C above nearby control plots....

Ecologists addressed the effects of disturbances from the onset of the field by focusing on ecesis, which is the process by which organisms migrate and establish under the environmental conditions created by disturbances. Ecesis is the onset of succession, a self-organizing process whose nature, speed, and outcome depend in part on the outcomes of ecesis and the residual legacies remaining after disturbances. A by-product of succession after a disturbance is the reorganization of species dominance, or novelty. The degree of novelty in the outcome increases with the severity of the disturban...

A warming Arctic has been associated with increases in aboveground plant biomass, specifically shrubs, and changes in vegetation cover. However, the magnitude and direction of changes in NDVI have not been consistent across different tundra types. Here we examine the responsiveness of fine-scale NDVI values to experimental warming at eight sites in northern Alaska, United States. Warming in our eight sites ranged in duration from 2‑23 seasons. Dry, wet and moist tundra communities were monitored for canopy surface temperatures and NDVI in ambient and experimentally-warmed plots at near-dail...