Early ecologists viewed succession as a local, progressive, and orderly process of species replacement culminating in a stable climax community in equilibrium with the local climate. Today’s ecologists hold a nonequilibrium view of succession, emphasizing the role of recurrent disturbances in shaping population and community structure. Currently, forest succession is considered a hierarchical process, incorporating effects of the surrounding landscape on the structure of local populations and communities. But ecological processes are still seen as the primary driver of successional dynamics, limiting humans to the role of external agents of disturbances that initiate succession (by, for example, harvesting plants and animals or clearing and burning vegetation) or alter successional trajectories. Species “foreign” to the original ecosystem are regarded as disturbance agents rather than as components of regenerating ecosystems. This view also holds that ecological knowledge is necessary and sufficient to understand, manage, and restore tropical forests.
Many forest scientists now challenge this perspective on environmental dynamics. We live in a complex world that does not conform to a strictly ecological paradigm of forest succession; instead, human agency must be integrated into the successional paradigm and not simply relegated as an external factor. Forest succession is a socioecological process and has been so wherever and whenever human populations have coexisted with forests.
Consider the dichotomies that have marked our understanding of forests and people: unmanaged versus managed, natural versus unnatural, intact versus fragmented, pristine versus disturbed, novel versus historical, conservation versus restoration, mitigation versus adaptation. These contrasts are increasingly blurring. Moreover, their forced distinctions impede the establishment of resilient forest landscapes, which form the foundation of Earth’s life-support system. Now, with three-quarters of the terrestrial biosphere altered by human activity, concepts of native ecosystems and native landscapes are increasingly challenged and tested. Terms such as anthromes (anthropogenic biomes) and neolandscapes (anthropogenic landscapes) have enriched our vocabulary. In many parts of the world, the forests of the future are not going to resemble the forests of the past. Let’s move on.
Expanding human populations are placing increased demands on the remaining forests, which are shrinking in extent, have lost key animal mutualists, and are impacted by multiple biotic and abiotic stressors. This unsustainable pattern can be seen across the planet. How can we expect the ecosystem functions of Brazil’s once vast and unbroken Atlantic Forest to be performed by the small, isolated, and struggling forest patches that occupy less than 12 percent of its former expanse? Something has got to give.
Add to this mix projected scenarios of novel climates and increasingly extreme climatic events, as climate change is expected to bring about new combinations of temperature and rainfall that will test the adaptive capacity of species and directly affect human populations and geographic patterns of land use. The dynamics of intact forests, forest fragments, and newly established reforests—plantations, restored forests, agroforests, and everything in between—will be directly and indirectly impacted by interacting climate and anthropogenic stressors.
We need to help new forests establish, grow, and prosper, whether through active planting and careful management or through spontaneous or assisted natural regeneration. There are too many interdependent variables to allow predictions of how all these factors will interact and affect future forest dynamics and landscape change. But some general trends can be predicted. First, successional forests will be increasingly prevalent across the world as both natural and anthropogenic disturbances increase in frequency and intensity. In the aftermath of human migration and changing land-use practices, forest ecosystems will spontaneously regenerate whenever and wherever they are afforded the chance. We can encourage and create opportunities for this process.
Second, successional forests will be increasingly humanized and homogenized within mosaic landscapes and close to urban and agricultural areas. Increasingly, their composition will likely comprise both generalist species and those species adapted to disturbed habitats that are broadly distributed and have wide ecological tolerances. Nonnative species will increasingly predominate within and along the edges of these second-growth forests, as is already the case in the eastern United States, in subtropical regions of Queensland, Australia, and on islands such as Hawaii, Puerto Rico, and Réunion. More diverse secondary forests composed largely of native species will be found in the buffer zones of protected areas in remote regions.
Third, successional forests will be increasingly important in both climate change adaptation and mitigation and will play critical roles in water regulation, soil stabilization, and nutrient conservation. They will also provide havens for biodiversity and create living corridors reestablishing landscape connectivity for wildlife, including links across different elevational zones, which will allow species to migrate to more favorable climatic conditions.
A socioecological paradigm of forest succession views human interventions as being inherent elements of disturbance regimes. Forest dynamics emerge from feedbacks from social and biophysical drivers that affect the functioning of ecological subsystems and determine the potential for sustainable management. Long-term monitoring of social and biophysical characteristics across different tropical landscapes is required to reveal the interplay of local, regional, and global drivers of successional forest change. Research conducted within an integrated socioecological framework is urgently needed to provide insight into critical issues such as the effects of global change on tropical ecosystems (including changes in climate, biodiversity, land use, and land cover), future scenarios for biodiversity conservation, sustainable provision of ecosystem goods and services, and options for sustainable forest-based livelihoods. Further, socioecological research can elucidate the drivers of tropical forest degradation and thus guide short-and long-term interventions to halt future degradation and restore forests on lands where regenerative capacity has been lost.
Restoring the world’s forests will also restore humanity. Ensuring a promising future for forests requires that we go beyond recognizing and valuing the many goods and services that forests offer us. It is time to develop a real mutual partnership between people and forests. We must provide for the needs of forests, become stewards of forests, and help guide them through hard times. We need to recognize both their resilience and their vulnerability, and we need to begin now. The life-support systems of our planet are at stake.
OCEAN 2.0
J. EMMETT DUFFY
When I was born, in 1960, the ocean was still a mysterious and often frightening world, full of watery wildernesses few had seen because only a handful of scientists and adventurers had yet breathed underwater. The deepest spot in the ocean was plumbed that very year, but most of the vast depths remained unknown, and even on the surface sailors traveled thousands of miles without seeing a trace of humanity. As the space age dawned, many still scoffed at the idea that the ocean could be depleted of fish.
Those days are gone. The high seas are still a wilderness of sorts, as we realize when supertankers are hijacked and disappear seemingly into thin air. But the revolutions in technology that the space age ushered in have filled in nearly all the blank regions on the map. Many of us now have experienced the magic of the underwater world, some by scuba diving, the rest by pressing a remote-control button from the comfort of their couch. Robots prowl the deep-sea floor in search of rare metals. And fish can no longer hide from the military-inspired technology that routinely brings fresh seafood to our tables from the far corners of the globe. Dizzying advances in many fields of science have opened the ocean’s treasure chest and revealed its riches in more detail than was imaginable in the mid-twentieth century.
Most of us—more than seven in ten people on Earth—live within one hundred miles (160 kilometers) of a coast. But even in the continental interiors of Minneapolis and Mongolia, the unseen sea is central to human life and
livelihoods. The ocean is one of Earth’s two lungs, its microscopic algae producing half the oxygen we breathe. In the process, these plants act as a biological pump, absorbing much of our combusted fossil carbon and sequestering it in the deep ocean. Similarly, we have the ocean to thank for taking the heat for us, absorbing 93 percent of the warming produced by our industrial metabolism and reducing climate change to a fraction of what it would otherwise be. Sea life is a key source of humanity’s protein, especially in the developing world—the average person on Earth eats twice as much fish as poultry and three times as much fish as beef. And the ocean connects us: sea shipping carries more than 90 percent of the trade generated by our appetites. If the ocean were a country, it would have the sixth-largest economy in the world.
But the ultimate sea change is now upon us. The signs are alarmingly familiar—declining fisheries, whirlpools of plastic debris, oxygen-starved dead zones, and more. So what are we going to do about it? Happily, there is light at the end of the tunnel, and if we can reach that source, it can guide us toward a soft landing in the brave new ocean. Finding and amplifying the bright spots will require deeper understanding both of the vast, interconnected ocean ecosystems that sustain us and of our own unique species, which now dominates their dynamics. In the past decade or so, the global community has recognized these challenges and risen to them with innovations in natural and social sciences, making progress on both fronts. Technological advances in particular have transformed environmental science and conservation in sometimes spectacular ways. One major impetus has been the satellite and geospatial technology that we now take for granted when navigating our cars to the soothing voice of Siri. Another is the flourishing of social media that allow scientists and members of the general public throughout the world to collaborate, advancing both innovation and democratic decision making. A striking example that unites these themes is the nonprofit SkyTruth’s online sharing of satellite imagery showing what’s happening in near-real time across the world’s oceans. By making this data publicly available, SkyTruth’s Global Fishing Watch program fosters crowdsourced identification of pirate fishing by illegal and disguised vessels—among the most pernicious threats to ocean life—and apprehension of the culprits. Crowdsourced satellite tracking has also shut down seismic surveys by a ship exploring for oil on the sensitive Mesoamerican Barrier Reef in violation of Belize law.
Satellites give us an unprecedented view of the ocean’s surface, but they can’t penetrate it. Many challenges still require boots on the ground—or fins in the water. Recognizing that there are too few professional marine biologists to cover the great expanses of the ocean, the Reef Life Survey program has engaged a large and enthusiastic community of recreational scuba divers, training them rigorously to census reef animals and habitats and logging surveys at more than four thousand sites worldwide to produce an unparalleled database on marine biodiversity. This coalition of scientist and citizen-scientist divers has gathered hard evidence documenting how marine ecosystems shift in response to climate change and showing that large reserves and enforced protection from fishing provide a major boost to ocean biodiversity.
The bright spots in ocean science and conservation are the result of purposeful actions, many of them necessitated by evidence of declining ecosystem services. But we can’t fix problems if we don’t see them in the first place. In our age of accelerating change, global real-time information is more important than ever to inform critical decisions. A special challenge is tracking the wildly diverse species and interactions that are the heart of functioning ecosystems. Building such a capacity requires innovations in both technology and the ways we interact with one another and the world around us. The Smithsonian’s Marine Global Earth Observatory (MarineGEO) program embodies that spirit, marshaling technological and social innovation together. It is building a networked community of scientists and volunteers around the world who combine next-generation DNA sequencing, drone-based habitat mapping, and other tools to create an open-access resource for understanding changing marine life and ecosystems.
Perhaps the brightest ray of hope for nature in the Anthropocene is that the current rapid pace of technological change is being paralleled by the rapid evolution of human attitudes in many areas—gender and race equality and animal welfare, among others. There are hints of a great acceleration in human awareness and engagement in safeguarding our planet. Environmental consciousness concerning the ocean took some time to awaken but has spread like wildfire in the age of social media. I am comforted by young people everywhere passionately wanting to change the world for the better and by the growing international agreement on climate action. Nearly one hundred countries have banned shark fishing or the sale of their fins, and many airlines now refuse to transport shark products. In 2015, more of Planet Earth was officially protected than in any other year in history, and most of that area—more than two million square miles (five million square kilometers)—was underwater.
Committing to a change in course that avoids massive disruption of human communities and economies is the central policy challenge of our era. Making that course correction will require harnessing and amplifying the passion and ingenuity already evident in current sustainability work. Although the Anthropocene ocean will be very different than the one we have known, there is still time to ensure that it will be healthy and productive. A fundamental transformation similar to that of the land surface has not yet happened in the sea, and the ocean’s big animals are mostly still with us. We need above all to transition to a carbon-neutral economy. And we must recognize that most of the ocean is no longer wilderness—it requires wise spatial planning, just like the land. That planning will depend on an intimate knowledge of how the ocean’s diverse and beautiful life-forms interact to create healthy ecosystems. We have a chance. But we don’t have time to waste.
THE EARTH IS A GARDEN
ARI NOVY, PETER H. RAVEN, AND HOLLY H. SHIMIZU
The most visible planetary evidence of the Anthropocene is the tremendous extent to which we develop land to suit our various needs. In terms of raw area impacted, our single greatest land use is for growing plants to feed ourselves and our grazing animals, the act of gardening on a worldwide scale. In the residential and aesthetic context, we often call this practice horticulture and in the extensive or rural context agriculture, although these terms are by no means mutually exclusive or clearly delineated. Regardless of terminology, we are gardening the planet at a historically unprecedented scale to provide benefits to ourselves. Agriculture, which occupies more than half of the land in the United States and over a third of land worldwide, must form a part of the sustainable whole on which our survival depends. The land modifications we make for agriculture and horticulture are primary determinants of our sense of place, and hence identity, as well as our capacity to feed, clothe, fuel, and provide other staples to a rapidly growing population on a hot and hungry planet.
Historically, clearing habitat for agriculture, while necessary for sustaining humans, has been the biggest enemy of biodiversity and the major cause of its loss. Some 12 percent of Earth’s surface is devoted to cropland and another 26 percent to grazing. The explosive growth of the human population—from about 1 million 10,000 years ago through 1 billion around 1810 to 7.4 billion today—together with an even more rapid growth in consumption, is challenging the sustainability of Earth’s resources. Over the years, we have averted widespread famine by increasing agricultural yield, through the expansion of lands devoted to agriculture, the application of new technologies, and the genetic improvement of crops. Notwithstanding these advances, some 750 million people remain malnourished, with about 100 million on the verge of starvation at any time.
Projections for feeding the world in the future are alarming. The Population Reference Bureau predicts that the world population will increase to 9.9 billion by 2050. The Global Footprint Network estimates that we are currently using about 164 percent of the sustainable productivity of our planet, whic
h makes the future look very challenging. A stable population and sustainable levels of consumption are essential to species success.
Global climate change makes meeting the challenges of the next few decades and beyond even more difficult. Following meaningful global agreements in December 2015, the overall increase in temperatures may be limited to 2°C (3.6°F), though this seems unlikely. But even an increase of just 2°C would negatively impact the world’s major agricultural zones. How, then, will we feed more people?
We must determine how much food will be needed and find ways to produce and distribute it. Critically, we must frame this issue with a sense of attainability. The current public discourse on the future of agriculture is heavily dominated by overly simplified or ideological positions that favor specific processed-based solutions, such as preferring organic, urban, hydroponic, precision, or genetically-modified-organism-based agriculture. A more pragmatic approach would circumscribe the desired outcome without favoring or eliminating any specific solution. We might frame the challenge as a set of goals, a proverbial moonshot, such as providing nutritious food for eleven billion people by 2100 on 20 percent less land than is currently used and with decreased inputs, such as fertilizer and pesticides, both per hectare and per unit of production.
Living in the Anthropocene Page 9
