This paper builds on the expansion of urban ecology from a biologically based discipline—ecology in the city—to an increasingly interdisciplinary field—ecology of the city—to a transdisciplinary, knowledge to action endeavor—an ecology for and with the city. We build on this “prepositional journey” by proposing a transformative shift in urban ecology, and we present a framework for how the field may continue this shift. We conceptualize that urban ecology is in a state of flux, and that this shift is needed to transform urban ecology into a more engaged and action based field, and one that includes a diversity of actors willing to participate in the future of their cities. In this transformative shift, these actors will engage, collaborate, and participate in a continuous spiral of knowledge → action → knowledge spiral and back to knowledge loop, with the goal of co producing sustainable and resilient solutions to myriad urban challenges. Our framework for this transformative shift includes three pathways: (1) a repeating knowledge → action → knowledge spiral of ideas, information, and solutions produced by a diverse community of agents of urban change working together in an “urban sandbox”; (2) incorporation of a social–ecological–technological systems framework in this spiral and expanding the spiral temporally to include the “deep future,” where future scenarios are based on a visioning of seemingly unimaginable or plausible future states of cities that are sustainable and resilient; and (3) the expansion of the spiral in space, to include rural areas and places that are not yet cities. The three interrelated pathways that define the transformative shift demonstrate the power of an urban ecology that has moved beyond urban systems science and into a realm where collaborations among diverse knowledges and voices are working together to understand cities and what is urban while producing sustainable solutions to contemporary challenges and envisioning futures of socially, ecologically, and technologically resilient cities. We present case study examples of each of the three pathways that make up this transformative shift in urban ecology and discuss both limitations and opportunities for future research and action with this transdisciplinary broadening of the field.

The world has become urban; cities increasingly shape our worldviews, relation to other species, and the large-scale, long-term decisions we make. Cities are nature, but they need to align better with other ecosystems to avoid accelerating climate change and loss of biodiversity. We need a science to guide urban development across the diverse realities of global cities. This need can be met, in part, by shifts in urban ecology and its linkages to related sciences. This perspective is a “synthesis of syntheses”, consolidating ideas from the other articles in the Special Section. It re-examines the role of urban ecology, and explores its integration with other disciplines that study cities. We conclude by summarizing the next steps in the ongoing shift in urban ecology, which is fast becoming an integral part of urban studies.

We ask how environmental justice and urban ecology have influenced one another over the past 25 years in the context of the US Long-Term Ecological Research (LTER) program and Baltimore Ecosystem Study (BES) project. BES began after environmental justice emerged through activism and scholarship in the 1980s but spans a period of increasing awareness among ecologists and environmental practitioners. The work in Baltimore provides a detailed example of how ecological research has been affected by a growing understanding of environmental justice. The shift shows how unjust environmental outcomes emerge and are reinforced over time by systemic discrimination and exclusion. We do not comprehensively review the literature on environmental justice in urban ecology but do present four brief cases from the Caribbean, Africa, and Asia, to illustrate the global relevance of the topic. The example cases demonstrate the necessity for continuous engagement with communities in addressing environmental problem solving.

Conservation is a long-term process that unfolds over time and seeks to develop harmony between human activity and ecosystems of all types. The unfolding of conservation in the Luquillo Mountains of Puerto Rico took place over a period of over 140 years, beginning in 1876. The conservation process in Puerto Rico involved the description of the biodiversity, the understanding of forest dynamics in relation to the conditions prevailing in the Luquillo Mountains, extensive research on the life history of critical species, understanding the basis of forest resilience, recognizing the social-ecological-technological context of conservation, applying advanced technological tools, and resolving the inevitable conflict that develops among the different actors involved in the conservation effort. Unfolding conservation within a country requires continuous and effective support from governmental, non-governmental, business, and scientific sectors of the social-ecological-technological systems of the country. These sectors come together at different moments in time, and the path followed is different in different countries. In Puerto Rico, the unfolding of conservation was triggered by the government in close collaboration with academic and governmental scientific sectors. Within the Luquillo Mountains, the business sector did not oppose conservation activities, and the unfolding process reached high levels of effectiveness. The rest of Puerto Rico benefited from the conservation process unfolding on the Luquillo Mountains. In contrast, conservation in the Amazon has been characterized by conflict among different actors competing for a common resource. In general, commercial activities that are based on resource exploitation lead to conflict and a slower development of conservation activities. When the business community used science to improve land productivity, as it did in Central America, conservation benefited because the science that was used stimulated conservation values. The establishment of government institutions with a focus on conservation through research and education appeared late in the mainland tropics compared to Puerto Rico, but when it happened, it accelerated the unfolding of conservation. All the countries examined here were most effective in conservation when the collaboration among the different sectors of society was high and based on objective and anticipatory scientific activity.

Search this collection of freely available full text articles on the science behind sustainable management of forests and rangelands, restoration of native plants, wildlife, fish and ecosystems, protecting against wildfires and invasive species, and improving the resilience of our lands in the face of climate change.

Over the last two decades, recognition of the important role terrestrial plants play in regulating silicon (Si) cycling has emerged. Si improves plant fitness by protecting them from abiotic (e.g., desiccation) and biotic (e.g., fungal attack) stressors. Once incorporated into plant biomass this biogenic Si is more bio-available than the lithogenic material from which it was ultimately derived. Thus plants play a key function in regulating the amount and timing of Si availability in downstream ecosystems. Recent work has highlighted the importance of salt marshes in the temperate Si cycle. However, the role of their tropical counterparts, mangroves, has largely gone unexplored. Here we report foliar concentrations of plant Si (as %Si by dry weight) for four Caribbean mangrove species: Conocarpus erectus (buttonwood), Laguncularia racemosa (white mangrove), Avicennia germinans (black mangrove), and Rhizophora mangle (red mangrove). Overall, the median Si concentration was low (0.07%) and did not vary among plant part (e.g., foliage, twig, and propagule). There was also little variation in Si among species. Using literature values of aboveground net primary production, and the concentrations reported here, we estimate an aboveground mangrove Si uptake rate of 2–10 kg Si ha –1 year –1 . These rates are on par with rates reported for temperate and boreal forests as well as low nutrient salt marshes, but lower than estimates for high nutrient salt marshes. Thus, despite the low Si concentrations observed in mangroves, their high productivity appears to make them a hot spot of Si cycling in tropical coastal systems.

The Luquillo Experimental Forest (LEF) has a long history of research on tropical forestry, ecology, and conservation, dating as far back as the early 19th Century. Scientific surveys conducted by early explorers of Puerto Rico, followed by United States institutions contributed early understanding of biogeography, species endemism, and tropical soil characteristics. Research in the second half of the 1900s established the LEF as an exemplar of forest management and restoration research in the tropics. Research conducted as part of a radiation experiment funded by the Atomic Energy Commission in the 1960s on forest metabolism established the field of ecosystem ecology in the tropics. Subsequent research has built on these early advances to develop new theories on ecosystem response to disturbance regimes and the role of the biota in ecosystem resilience. Recent and current research in the LEF has advanced understanding of resilience to hurricane disturbances, human land use, gamma irradiation, landslides, drought, and warming, showing that even following the most severe disturbances (e.g., landslides, agriculture) forests reestablish within 60 years. Work in the LEF has reversed the paradigm that tropical ecosystems are fragile, but instead exhibit remarkable resilience to many forms of disturbance present at multiple spatial and temporal scales. Current research is already advancing understanding of how climate change and attendant effects on the disturbance regime might affect the composition, structure, and function of tropical forest ecosystems.

The origins of the Luquillo Long Term Ecological Research Program are traced through four historical trends that still influence research activity in Puerto Rico’s Luquillo Mountains: (1) A history of identifying lands for protection and their designation for public uses; (2) A history of governmental and non-governmental institutions acting with the foresight to pursue scientific research for the benefit of economic development and the will to support scientific activity; (3) The uninterrupted progression of scientific activity through projects and programs that cumulatively developed a knowledge base that supported succeeding projects and programs; (4) The excellence of the individual scientific talent that participated in research in this location over the last 200 years. These historical trends took place within the context of four time intervals: (1) Discovery and colonization of Puerto Rico (1493 to 1898); (2) The negotiation of the Paris Treaty in 1898, which transferred Puerto Rico to the United States of America and led to the Scientific Survey of Puerto Rico (1913 to 1957); (3) Development of tropical forestry and ecosystem-level research through the establishment of the USDA Forest Service Tropical Forest Experiment Station in 1939 and the funding of radio-ecological and ecological research by the Atomic Energy Commission and the Department of Energy from 1963 to 1988 (1939 to 1988); (4) Funding of multiple research programs, including the Luquillo LTER, by the National Science Foundation (1989 to the present). This history demonstrates how advancing scientific understanding of tropical ecosystems benefited science, society, and the conservation of Neotropical natural resources.

Background 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 differences between landform types in the tree community of a young sub-tropical forest that is frequently subjected to hurricanes. Specifically, we ask whether the tree community (1) changed structurally over the study period, (2) experienced compositional change over the study period, (3) is compositionally different between landform types, and (4) exhibits compositional change mediated by landform type. Results The tree community experienced significant structural change over the course of our study, but compositional change was only significant for some landforms. Conclusion Despite large-scale, intense, and frequent hurricane disturbance to our study system, compositional change in the tree community was localized and only significant for some landform types.

We review literature relevant to assessing the future of tropical forests and supplement the review with new data from the lowlands of Venezuela. Compared to today, future tropical forests will have a higher level of novelty, defined as the degree of dissimilarity of a system relative to a historical baseline. Processes of succession and evolution generate novelty in forests and have done so for millennia. Under increasing human activity and climate change, the rate of generation of novelty has increased and the resulting forests are termed novel forests to distinguish them from historical forests. Historical forests are less exposed to anthropogenic disturbances and operate at slower levels of novelty generation. Acclimation, adaptation, changes in species composition and dominance, and changes in the proportions of species in communities are the responses of the biota to climate change and anthropogenic disturbances. Therefore, novelty contributes to the persistence of tropical forests in spite of increasing levels of human activity. Novel forests are similar to historical forests in terms of structure but they are younger, they have a faster turnover of mass and chemical elements, and different species composition. Historical species assemblages cannot cope with the altered environments that result from chronic anthropogenic disturbances. The dominant species in novel forests tend to be, and function as, pioneer species. High levels of species dominance in novel forests influence the proportions of chemical elements, which when coupled to species traits and attributes, help explain how novel forests cope with the conditions that result from anthropogenic activities. Novelty is more common in the tropics than in other latitudinal regions, and within the tropics, it is more common in islands where human activity is more intense than in continents. Novel tropical forests in islands have greater representation and dominance of introduced species than novel forests in continents, where native species with wide geographic distributions dominate. Regardless of geography, novel tropical forests share similar attributes and functioning. The adaptability of novel forests to extreme conditions created by human activity signals a future for tropical forests that is different from predictions of constant degradation, homogenization, and loss of biodiversity. Instead, a process of recombination of species (all taxa) into new species assemblages maintains structure, function, physiognomy, species richness, and ecological services. This remixing initially involves loss of large organisms, certain groups of species, and loss of old-growth attributes of forests. Some of these losses can be reversed through succession, assuming there is sufficient time to restore depleted stores such as soil organic matter. Continued environmental change will stimulate continued remixing of species, loss of vulnerable species, gains of less vulnerable ones, and more dissimilarity with historical forests. Novel forests are an answer to the changes induced by climate change and other anthropogenic disturbances, and as such require conservation measures, because as they mature, novel forests usually diversify and help restore lost biodiversity. We also review strategies to conserve biodiversity and optimize ecological services using novel forest succession.

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 disturbance event. Initially, ecologists focused mostly on non-anthropogenic disturbances, but as human activity intensified and became a global force, more attention was given to the effects of anthropogenic disturbances on ecosystems. Today, anthropogenic and non-anthropogenic disturbances and their interactions are increasingly affecting ecosystems, particularly those exposed to extreme disturbance events. Extreme disturbance events are complex and low probability events composed of several disturbance forces that individually and in synergy affect different sectors of ecosystems, including the conditions that drive ecesis. I review the literature on disturbance research including the effects of extreme disturbance events on social–ecological–technological systems (SETSs). A SETS is an ecosystem defined by the flow and accumulation of energy through the medium of organisms, constructed infrastructure, institutions, and their environment. Human intentions, values, and capacities are part of the functioning of SETS, and they can drive ecological processes as do non-anthropogenic forces. Moreover, human-directed activities after an extreme disturbance event affect whole landscapes. The passage of hurricane María over the Puerto Rico SETS established that extreme disturbance events are of such power and complexity that they can influence the level and kind of relationship between humans and the environment, including the structure and species composition of the ecological systems within SETS. However, extreme disturbance events such as hurricanes have not changed the successional trajectory originally impulsed by anthropogenic disturbances. Thus, the species composition and functioning of novel forests in Puerto Rico are tied to economic activity in the social and technological sectors of SETS. It is no longer possible to interpret ecosystem functioning without considering the synergy between anthropogenic and non-anthropogenic extreme disturbances.

The United States Department of Agriculture Forest Service International Institute of Tropical Forestry (the Institute) celebrates its 75th Anniversary with the publication of this Special Issue of Forests. This Issue is based on presentations delivered in a symposium held in San Juan, Puerto Rico in 2014. It augments a quarter century of scientific knowledge and capitalizes on a unique set of synergies chartered by a strategy based on shared stewardship, innovative transdisciplinary collaborations, and breakthroughs in science and technology. The manuscripts contained here present advancements in our approach to the development of policies for effective governance and stewardship, long-term focus for the understanding of ecosystem processes and functions, novelties given attention to cross-boundary collaborative approaches to science, and proposed alternative institutional visions in the Anthropocene. As the Institute continues to collaboratively explore new frontiers in science, we recognize advances in forestry, atmospheric sciences, modeling, hydrology, plant physiology, and microbial ecology as core to the understanding of tropical forests in the Anthropocene.

This book describes the immediate effects of, and response to, Hurricane María on the social, ecological, and technological systems (SETS) of Puerto Rico while also showing how aspects of human behavior, such as greed and lack of ethics, have enormous effects on how extreme events affect SETS.

When infrastructure and government service collapse in a technologically advanced society, people are first stunted but soon react to assure survival. After María, the importance of individual and community action at a time of need became a lesson that was obvious to all Puerto Ricans. This lesson was made more relevant in light of another lesson, that of the failure of governance. The conditions after María underscored the importance of governance to a society. Puerto Ricans understood and witnessed how corruption was affecting them directly by turning governance against their interests. A third lesson was that after passing through the consequences of María, which are still in progress, business as usual is not the path to a healthy, resilient, and just society.

Tropical forests are a source of controversy among international and national sectors and in almost all parts of modern society. The positions assumed by the participants in discussions of the matter are divided and antagonistic. In 1980, tropical Latin America (including Central and South America) had an area of 938 million ha of primary forests. The great Amazon forest is the largest area of tropical forest in the world. Deforestation rates varied from country to country, depending upon the climate, and social and economic conditions. Latin American tropical forests are threatened by multiple factors. Population growth is one but not the only one, nor the most important one. Population increase brings increased demands for food, materials, and energy. Forests should form an integral part of Latin American regional economies. The protection and management of the tropical forests will be successful if society recognizes its value and its contribution to human welfare.

After an extreme event there is a strong momentum to repair damages and resolve the problems created by the event. Money and resources are made available to those that are quick with fixes. Ideas and suggestions are abundant and come from all sectors of society. There is social license for action. However, each social sector acts independently from other sectors. There is little or no integration or search for a common vision of the future. It is a dangerous period for a SETS because the impetus for action can lead to business a usual and a repeat of past mistakes that led to the damages and problems that society is looking to avoid. This is happening in Puerto Rico at this time, when business as usual is preventing a course reversal with a radical new way of reacting to an extreme event. Governance and social actions need an overhaul in Puerto Rico. Resilience thinking, systems thinking, or SETS thinking provide a blueprint for expanding social dialogue towards greater inclusivity and consensus. It is not clear what direction Puerto Rico will take over the long-term.

The ecological systems appeared to have collapsed after hurricane María because the defoliation of vegetation was so extensive as to give the appearance that the vegetation was killed. In reality, the rapid re-greening of vegetation quickly reversed these visible effects. Forests continued to yield clean water from watersheds and began a process of change that would restore their structure and functioning, even if species composition might change as they matured. Extreme events such as María have positive long-term effects on Caribbean forests and contribute to adaptability of organisms to a changing world environment.