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Las figuras y material suplementario que contiene el documento se localizan al final del mismo., Planted woodland islets act as sources of seed that may accelerate woodland development in extensive agricultural landscapes. We assessed a 1-ha plot that was planted with 16 100-m2 islets of holm oak Quercus ilex subsp. ballota seedlings near Toledo (Spain) in 1993. In spring 2014 we measured (1) acorn predation and (2) seedling emergence from seeded acorns at different distances from and orientations around the islets with half of the acorns protected to prevent predation, (3) survival of emerged seedlings, and (4) natural tree establishment outside of the planted islets. Most (96.9 %) unprotected acorns were removed or predated. Seedling emergence from protected acorns ranged from 42.9 % on the northern side of the islets to 13.2 % on the southern side, suggesting a less stressful microclimate on the northern side. Survival of naturally established seedlings was 28.6 % by the end of first summer; seedling mortality was chiefly due to drought (45.0 %) and herbivory (35.0 %). Density of emerged seedlings, surviving seedlings after first dry season, and established oaks >1-year old was similar at different distances from the islets. Over the 21 year time period, 58 new oak individuals >1-year old have established (an average of 3.3 established individuals per ha per year) at an average distance of 6.3 ± 5.4 m away from the closest islet. We conclude that initial oak regeneration triggered by small planted islets in Mediterranean abandoned farmland is slowed down by high acorn predation, seedling herbivory, and stressful microclimatic conditions. Regardless, these islets are a viable tool for regeneration of Mediterranean oak woodland., Projects from the Spanish Ministry of Science and Education (CGL2010-18312 and CGL2014-53308-P) and the Government of Madrid (S2013/MAE-2719, REMEDINAL-3) are currently providing financial support for this body of research. We are indebted to Aurora Mesa and Paula Meli for their help for acorn seeding and to Laura Ferna´ndez and Luis Cayuela for their input with some statistical analyses. The subject editor and two anonymous reviewers provided valuable comments on a former version of this manuscript.

Plant functional traits, in particular specific leaf area (SLA), wood density and seed mass, are often good predictors of individual tree growth rates within communities. Individuals and species with high SLA, low wood density and small seeds tend to have faster growth rates. If community-level relationships between traits and growth have general predictive value, then similar relationships should also be observed in analyses that integrate across taxa, biogeographic regions and environments. Such global consistency would imply that traits could serve as valuable proxies for the complex suite of factors that determine growth rate, and, therefore, could underpin a new generation of robust dynamic vegetation models. Alternatively, growth rates may depend more strongly on the local environment or growth-trait relationships may vary along environmental gradients. We tested these alternative hypotheses using data on 27 352 juvenile trees, representing 278 species from 27 sites on all forested continents, and extensive functional trait data, 38% of which were obtained at the same sites at which growth was assessed. Data on potential evapotranspiration (PET), which summarizes the joint ecological effects of temperature and precipitation, were obtained from a global data base. We estimated size-standardized relative height growth rates (SGR) for all species, then related them to functional traits and PET using mixed-effect models for the fastest growing species and for all species together. Both the mean and 95th percentile SGR were more strongly associated with functional traits than with PET. PET was unrelated to SGR at the global scale. SGR increased with increasing SLA and decreased with increasing wood density and seed mass, but these traits explained only 3.1% of the variation in SGR. SGR-trait relationships were consistently weak across families and biogeographic zones, and over a range of tree statures. Thus, the most widely studied functional traits in plant ecology were poor predictors of tree growth over large scales. Synthesis. We conclude that these functional traits alone may be unsuitable for predicting growth of trees over broad scales. Determining the functional traits that predict vital rates under specific environmental conditions may generate more insight than a monolithic global relationship can offer. The most widely studied functional traits in plant ecology, specific leaf area, wood density and seed mass, were only weakly associated with tree growth rates over broad scales. Assessing trait-growth relationships under specific environmental conditions may generate more insight than a global relationship can offer. © 2015 British Ecological Society.

Summary 1 While reclamation of degraded landscapes is becoming increasingly common, few studies have investigated the long-term effects of reclamation efforts on plant conservation. The goals of this study were to determine whether vegetation communities on reclaimed mines approximate those of the surrounding forest, and to evaluate how intensive reclamation practices used to address short-term erosion and water quality concerns affect long-term recovery. 2 In 1992–93 and 1999 the vegetation on 15 coal surface mines reclaimed between the years 1967–87, and five periodically logged hardwood forest reference sites in south-western Virginia, were surveyed. 3 Herbaceous species richness was similar on all sites, whereas woody species richness was higher in reference sites than in reclaimed sites. 4 Vegetation community composition on reclaimed sites continued to progress towards reference forest sites between the two sampling periods, but vegetation community composition even on the oldest sites (reclaimed > 35 years prior) still differed substantially from reference sites. 5 Herbaceous cover was higher and tree basal area was lower in reclaimed sites compared with reference sites at the first sampling period, but these differences were much less pronounced by the second sampling period. 6 The overall composition of the older reclaimed sites was similar to the reference forest sites, suggesting a high level of resilience in the forests studied. But, as with a number of previous studies of long-term recovery on highly disturbed sites, a number of less common forest species still had not colonized reclaimed sites, raising the question of their value for conservation. 7 These results concur with a common theme that goals for short-term and long-term recovery of highly disturbed sites may conflict. Planting with aggressive non-native ground cover species to minimize short-term erosion may have slowed long-term recovery on the sites studied. Widespread planting of Pinus strobus has not reduced species richness thus far, but may as the canopy closes. More emphasis should be given to long-term recovery potential in developing mine reclamation plans, and strategies to further this goal should be tested.

Summary 1 The objective of this study was to evaluate whether early successional shrubs facilitate, tolerate or inhibit different stages of tree establishment in abandoned tropical pasture. 2 Seed rain, seed predation, seed germination and seedling survival of tropical forest trees in pasture grass, below small ( 40 m 2 ) shrub patches, were compared in one abandoned pasture in Costa Rica over 2 years. 3 Seed rain of animal-dispersed trees was higher below both large and small shrub patches than below grass. Seed rain of wind-dispersed trees did not differ in the three patch types. 4 Predation of all animal-dispersed seeds combined and of three individual species was significantly higher below large and small shrub patches compared with below grass; predation of five species did not differ significantly in the three patch types. 5 Germination did not differ significantly in the three patch types for any of the species. 6 Seedling survival was highest below large shrub patches for three of four species. 7 Computer simulations of probabilities of seeds arriving in the pasture and surviving to the seedling stage suggest that early successional shrubs have a net facilitative effect on the early stages of forest tree seedling establishment compared with areas without shrubs in the pasture studied, although variance was high. Shrubs may facilitate, inhibit and tolerate different stages of tree seedling establishment.

Correspondence Energy: social fixes are on the up Already governments, environmental agencies, non- governmental organizations and businesses are on the way to meeting Benjamin Sovacool’s call for energy research to be more socially oriented (Nature 511, 529–530; 2014). The annual Behavior, Energy and Climate Change Conference, this year to be held in December, reviews their achievements and ongoing research activities. Examples of social energy practices include smartphone apps that allow remote control of domestic thermostats and can even track carbon emissions. The US Energy Star programme and the Leadership in Energy and Environmental Design rating systems ensure that buildings are energy-efficient and environmentally sound. Other energy-efficiency initiatives include Japan’s Top Runner and the UK Energy Saving Trust. The US company Opower, which serves 32 million households and businesses, enables consumers to compare their energy usage. Car manufacturers, with help from researchers at the University of California, Davis, are studying drivers’ behaviour with a view to creating a display that indicates how to cut fuel consumption. And US start-up companies such as Zipcar, Uber and Lyft are changing consumer relationships with their vehicles by enabling car sharing. Developing countries are also on the front line of new business models for clean and sustainable energy. The ‘en.lighten’ initiative, led by the Global Environment Facility, the United Nations Environment Program and industry partners, is accelerating conversion to energy-efficient lighting. In India, the think tank TERI (The Energy and Resources Institute) is leading efforts to provide solar lighting for poor communities and tackling gender issues that might prevent it from being widely accepted. And in Africa, mobile-phone payment systems are making it easier for kerosene consumers to switch to solar energy. David E. Rodgers, Dustin S. Schinn The Global Environment Facility, Washington DC, USA. dschinn@thegef.org Energy: we need all hands on deck A more interdisciplinary approach will advance our understanding of energy issues (see also B. K. Sovacool Nature In considering how to improve energy efficiency using a particular technology, for example, an engineering-only analysis would seek to optimize technical efficiency, whereas an engineering–economic analysis would aim to make it more cost- effective. But an interdisciplinary analysis would take in wider considerations. For example, convenience to consumers and the attributes of organizations promoting the technology can affect adoption rates by a factor of ten when financial incentives are comparable (P. C. Stern Energy Res. Soc. Sci. 1, 41–48; Psychologist Kurt Lewin remarked that “there is nothing so practical as a good theory” (Field Theory in Social Science Harper, 1951). I suggest that nothing advances theory better than tackling a practical problem by integrating different perspectives. Paul C. Stern National Research Council, Washington DC, USA. pstern@nas.edu Energy: humanities frame the aims Social scientists offer more than just information for producing a best fit between energy technologies and social circumstances (B. K. Sovacool Nature 511, 529–530; 2014). By eliciting different social framings of energy systems and technologies, they help to determine points of commonality and disagreement about the sort of Earth we want to inhabit. The humanities are concerned with profound questions about justice, fairness, responsibility and care. Such questions can no longer be regarded as external to the design of energy devices and systems because they are central to the entire social and technical fabric of modern society (see, for example, N. Castree et al. Nature Clim. Change 4, 763–768; 2014). Noel Castree University of Wollongong, Australia; and University of Manchester, UK. ncastree@uow.edu.au Better monitoring of fish in dam projects Inadequate ecological monitoring before and after removal of dams in the northwestern United States is hampering evaluation of the success of dozens of these projects (see Nature 511, A primary purpose of dam removal in the region has been to revive populations of endangered migrating salmonid fish by restoring natural river functions. Populations are being monitored after demolition of the 38-metre Condit dam and 64-metre and 33-metre Elwha dams, but these are exceptions. Using fish ladders, salmonids were able to ascend the Marmot and Hemlock dams you mention and move into the upper river. But to gauge the ecological impact of such dam removals, it is necessary to have baseline data on fish passage from before the structure was destroyed. In most other cases, these data are not available, thwarting future assessments. Long-term ecological evaluation and monitoring must be built into dam-removal projects. Otherwise, millions of dollars will continue to be spent with no evidence that the desired outcome is being achieved. Peter Brewitt, Karen D. Holl University of California, Santa Cruz, USA. pbrewitt@ucsc.edu Seals collect more Southern Ocean data Marine mammals equipped with recording devices can help to overcome the practical challenges of collecting year-round physical data in the Southern Ocean (see M. C. Kennicutt II et al. Nature Data collection using satellite remote sensing or surface research vessels, for instance, is limited to the short summer period for access to high latitudes or to the northerly margins of winter sea ice. By contrast, small oceanographic sensors worn by seals can provide high-resolution oceanographic profiles from Antarctica throughout the winter (see, for example, F. Roquet et al. Scientific Data, in the press). The data can be used to study and map ocean fronts and to monitor the annual formation and growth rate of sea ice (J.-B. Charrassin et al. Proc. Natl Acad. Sci. USA Data derived using seals can help us to predict rapid changes and their effects in the Southern Ocean. This would give the global community time to develop adaptation policies. Clive R. McMahon Sydney Institute of Marine Science, New South Wales, Australia. Robert Harcourt Macquarie University, Sydney, Australia. clive.mcmahon@utas.edu.au CONTRIBUTIONS Correspondence may be submitted to correspondence@nature. com after consulting the guidelines at http:// go.nature.com/cmchno. 4 S E P T E M B E R 2 0 1 4 | VO L 5 1 3 | NAT U R E | 3 3 © 2014 Macmillan Publishers Limited. All rights reserved

We investigated the hypothesis that maritime climatic factors associated with summer fog and low cloud stratus (summer marine layer) help explain the compositional diversity of chaparral in the coast range of central California. We randomly sampled chaparral species composition in 0.1-hectare plots along a coast-to-interior gradient. For each plot, climatic variables were estimated and soil samples were analyzed. We used Cluster Analysis and Principle Components Analysis to objectively categorize plots into climate zone groups. Climate variables, vegetation composition and various diversity measures were compared across climate zone groups using ANOVA and nonmetric multidimensional scaling. Differences in climatic variables that relate to summer moisture availability and winter freeze events explained the majority of variance in measured conditions and coincided with three chaparral assemblages: maritime (lowland coast where the summer marine layer was strongest), transition (upland coast with mild summer marine layer influence and greater winter precipitation), and interior sites that generally lacked late summer water availability from either source. Species turnover (β-diversity) was higher among maritime and transition sites than interior sites. Coastal chaparral differs from interior chaparral in having a higher obligate seeder to facultative seeder (resprouter) ratio and by being dominated by various Arctostaphylos species as opposed to the interior dominant, Adenostoma fasciculatum. The maritime climate influence along the California central coast is associated with patterns of woody plant composition and β-diversity among sites. Summer fog in coastal lowlands and higher winter precipitation in coastal uplands combine to lower late dry season water deficit in coastal chaparral and contribute to longer fire return intervals that are associated with obligate seeders and more local endemism. Soil nutrients are comparatively less important in explaining plant community composition, but heterogeneous azonal soils contribute to local endemism and promote isolated chaparral patches within the dominant forest vegetation along the coast.

Authors submitting to Restoration Ecology and other international publishing venues need to give careful thought to framing their manuscripts to maximize the relevance of their message to an international audience. I discuss five questions that all authors should reflect upon in framing their papers. Namely, authors should consider which conclusions will be most relevant to an international audience, the scope of systems to which these conclusions apply, and the amount of data supporting these conclusions. Authors should also think about the breadth of the literature cited and the degree of replication of the study. Localized studies are critical to implementing ecological restoration, but all authors, regardless of their intended outlet, need to carefully consider their audience. To publish successfully in an international journal, such as Restoration Ecology, authors need to frame their results within a broad context.

Tropical forests are being cleared at an alarming rate although our understanding of their ecology is limited. It is therefore essential to design restoration experiments that both further our basic knowledge of tropical ecology and inform management strategies to facilitate recovery of these ecosystems. Here we synthesize the results of research on tropical montane forest recovery in abandoned pasture in Costa Rica to address the following questions: (1) What factors limit tropical forest recovery in abandoned pasture? and (2) How can we use this information to design strategies to facilitate ecosystem recovery? Our results indicate that a number of factors impede tropical forest recovery in abandoned pasture land. The most important barriers are lack of dispersal of forest seeds and seedling competition with pasture grasses. High seed predation, low seed germination, lack of nutrients, high light intensity, and rabbit herbivory also affect recovery. Successful strategies to facilitate recovery in abandoned pastures must simultaneously overcome numerous obstacles. Our research shows that establishment of woody species, either native tree seedlings or early-successional shrubs, can be successful in facilitating recovery, by enhancing seed dispersal and shading out pasture grasses. On the contrary, bird perching structures alone are not an effective strategy, because they only serve to enhance seed dispersal but do not reduce grass cover. Remnant pasture trees can serve as foci of natural recovery and may enhance growth of planted seedlings. Our results highlight the importance of: (1) understanding the basic biology of an ecosystem to design effective restoration strategies; (2) comparing results across a range of sites to determine which restoration strategies are most generally useful; and (3) considering where best to allocate efforts in large-scale restoration projects.

The question of how society is going to pay for restoration has received little open discussion. We review existing literature and examples to explore two questions: How should ecological and economic considerations be balanced in determining expenditures on restoration projects? and How is society going to pay for the substantial costs involved? We discuss a number of different techniques for determining the amount of money to allocate to restoration efforts, including ecosystem replacement costs, quantifying ecosystem services, contingent valuation, and surrogate market price techniques. We then review different strategies for paying for restoration including private funding by the party responsible for the damage, public funding through taxes, voluntary contributions, and various public/private partnerships. We conclude by discussing other considerations in developing strategies to pay for restoration, including uncertainty, time-scale, evaluating success, and regional planning.

Efforts to reforest tropical pasture with native tree species have increased in recent years, yet little is known about the physiology of most tropical trees. The goal of this study was to assess the effect of habitat on photosynthetic responses to light for seedlings of four native rainforest species (Calophyllum brasiliense, Ocotea glaucosericea, Ocotea whitei, and Sideroxylon portoricense) planted to facilitate tropical rainforest recovery in southern Costa Rica. Seedlings were planted in primary forest, in open abandoned pasture, and in the shade of remnant trees within the pasture. Growth, morphology, photosynthetic gas exchange responses to light, and chlorophyll fluorescence (an indication of the integrity of photosynthetic processes) were measured in the three habitats. Height and leaf area were generally greater for seedlings in tree shade compared to those in the forest and open pasture. Photosynthetic rates were higher for plants in open pasture and tree shade compared to those in the forest for two of the four species. Chlorophyll fluorescence results indicated flexibility in the photosynthetic processing of light energy that may help plants tolerate the bright light of the pasture. This study demonstrates that, for certain species, seedlings under remnant pasture trees do not exhibit the level of photosynthetic stress experienced in open abandoned pasture. Seedling responses to light, in combination with other factors such as increased nutrient input through litterfall, help explain the enhanced growth of seedlings under remnant pasture trees. Planting seedlings under remnant trees may increase the success of future efforts to restore tropical forest in abandoned agricultural land.

Vegetation, seed rain, seed germination, microclimate, and soil physical and chemical parameters were measured in a recently abandoned pasture and adjacent primary rain forest in southern Costa Rica. The goal of this study was to assess the importance of these factors in limiting forest regeneration in abandoned pastures. Seed rain of animal dispersed species decreased dramatically in the pasture >5 m from the forestlpasture edge; fewer wind dispersed seeds fell in the pasture than in the forest, but the difference was much less than for animal dispersed seeds. Percent seed germination of most species studied was similar in the forest and in pasture with grasses; seed germination was lower during the dry season in areas of pasture cleared of grasses. Air temperature, vapor pressure deficit (VPD), and photon flux density (PFD) were much higher in the pasture than in the forest at 1 m above the ground. VPD and PFD at ground level and soil temperature were similar in the pasture and the forest, indicating that pasture grasses strongly modify microclimatic conditions near the soil surface. The lowest gravimetric water content recorded in the pasture during the dry season was 0.5 and leaf relative water contents of the two species measured in the forest and pasture were identical, suggesting that plants in the pasture were not water stressed. Levels of most soil nutrients were lower in the pasture as compared to the forest; however, aboveground and root biomass for seedlings grown in pasture and forest soils did not differ significantly. Although a number of factors impede forest recovery in abandoned pastures, these results suggest that the most important limitation is lack of seed dispersal.

Previous research indicates that a number of factors may limit forest seedling growth in abandoned tropical pastures; however, mammalian seedling herbivory has not been previously reported as a major factor inhibiting tropical pasture restoration. Seedlings of four native tree species were planted in abandoned pasture in southern Costa Rica to test their suitability for reforestation. Overall, the stems of 64% of the seedlings were cut by rabbits and only 26% of the seedlings survived 2 years after planting. Those seedlings that were able to survive and resprout after cutting by rabbits showed much lower growth rates than uncut seedlings. This study suggests that mammalian herbivory may be a more important factor in tropical reforestation than previously assumed. Experimental tests over larger spatial and temporal scales are needed to ascertain the degree to which it limits reforestation efforts.

A clear understanding of human population growth, consumption patterns, and their effects on the environment, particularly amongst our future leaders, is essential for proper allocation of conservation efforts. We report on the results of a written questionnaire assessing the knowledge and attitudes of undergraduate university students majoring in a range of disciplines in the United States of America (USA) and in Costa Rica (CR) regarding population- and environment-related issues. Our results indicated limited knowledge about human population growth and the environment, with USA students and male students more often responding correctly to factual questions on demography and global environmental change than CR students, who nonetheless were generally more pessimistic about environmental quality and the carrying capacity of the planet. USA students, however, more often recognized the link between human population size and environmental quality. Education on population and environmental issues will be improved if: (1) linkages between population size, consumption, and environmental quality are taught; (2) the effects of individual actions on environmental quality are emphasized; and (3) environmental education is tailored to local issues.

We agree with Prach and del Moral that passive recovery is often a desirable and effective restoration strategy. Passive and various active restoration approaches need to be weighed on a case-by-case basis and depend on the goals, relative rates of recovery desired, and various social and financial costs implicit in each option. That said, we stress that passive restoration has a unique set of challenges and costs, which we highlighted in our original article and briefly reiterate here.

Book Review BOOK REVIEW Large-Scale Forest Restoration David Lamb (2015) Routledge, London, 302 pages, $145.00 (hardback), ISBN ver the past few years, there O have been numerous global, regional, and national targets set for large-scale forest restoration to con- serve biodiversity, provide a range of ecosystem services, and ensure the well-being of human communities. Most notable of these are the Bonn Challenge and the more recent New York Declaration on Forests, which aim to restore 150 million hectares of forest worldwide by 2020 and 350 million hectares by 2030. David Lamb’s recent book Large-Scale For- est Restoration provides a timely overview of the complex issues that must be addressed to achieve these ambitious goals. Lamb draws on a range of examples from his three decades of experience teaching forest ecology and advising on numerous forest restoration projects worldwide for international organizations, includ- ing the World Bank, the Food and Agriculture Organization, and the International Union for the Con- servation of Nature. He recognizes the complexity of the topic and its many interwoven strands, offering glimpses into an array of contentious debates without taking a strong stance, thus inviting readers to draw their own conclusions. This book fills a niche as the first to synthesize the vast arena of work on large-scale forest restoration, and most impor- tantly, to integrate the ecological, social, and economic factors. Unlike Lamb’s prior book, Regreening the Bare Hills (2011), which focuses on restoration in the Asia-Pacific region, Large-Scale Forest Restoration spans a Restoration Ecology range of countries, forest types, and sociopolitical systems. The beginning of the book pro- vides a context for large-scale forest restoration by discussing factors leading to degradation, and the extent to which reforestation can serve both human and ecological goals. The second chapter provides a succinct historical perspective on the evolution of the timber industry over the past century. The next two chapters describe landscape-level ecological constraints and silvi- cultural management practices associated with natural and planted forest regrowth. The subsequent chapters address questions of where and how much restoration is needed as a function of different land uses and ecosystem services (e.g. hydro- logic processes, carbon sequestration, and biodiversity conservation). Chapter 7 discusses the choices and trade-offs facing landholders as they attempt to reconcile production and conservation objectives to achieve multifunctionality. The penultimate chapter investigates market-based, regulatory, and institutional policies needed to carry out and sustain future large-scale restoration efforts. The book closes by putting forth questions on governance, scale, and climate change certain to elicit fur- ther consideration by the reader. Lamb uses a combination of pho- tographs, tables, and diverse case studies in each chapter to high- light main points, and includes an extensive bibliography. Although the intended audi- ence for the book is not explicitly stated, this book is a broad entree to the extensive literature on the many facets of forest restoration and will be useful to forestry stu- dents and others in related fields. Moreover, we think that the book could be particularly relevant to restoration practitioners who imple- ment projects on the ground and are seeking to integrate their work into a larger global restoration con- text. Unfortunately, the price of the book may make it prohibitive for those who could most benefit. A paperback version and transla- tion into other languages would make it more accessible to a broader audience. As an interdisciplinary team of primarily graduate students with expertise in both natural and social sciences, and experience in tropical and temperate forest restoration, we brought diverse perspectives to this review. We found the treat- ment of certain topics to be uneven, which is not surprising for a single author writing on such a complex subject. The book emphasizes plan- tation silviculture, while overlooking agroforestry and underemphasiz- ing technical assistance and rural extension as public policy options. Discussion of international forest policies and regulations, institutional arrangements, and livelihood issues was patchy. Despite the focus on large-scale reforestation (>10,000 ha) and on the challenge of “scaling-up,” the book lacked an analytical frame- work for integrating diverse types of land managers—both small and large—in reforestation projects. More sustained attention to the challenge of how to coordinate dif- ferent actors, including cooperative or community-based approaches, would have been welcome. Although the book offers valuable case studies and models regarding various silvi- cultural techniques and ecological approaches, it falls short of repre- senting the variety of constraints within which land managers make decisions on the ground. Perhaps due to the large breadth of topics, the book’s organization often felt erratic and transitions were not always intuitive. Chapter titles and section headings were sometimes misleading relative to the content. For example, Chapter 6 (“How much forest restoration is

Lack of seed dispersal has been shown to be a major factor limiting tropical forest recovery in abandoned pasture land. The goal of this work was to determine whether bird perching structures serve to enhance seed dispersal and seedling establishment in an abandoned pasture in Costa Rica. Two types of perching structures (crossbar and branch) were tested. Bird visitation rates were significantly higher on branch than on crossbar perches. The number of animal-dispersed seeds was significantly higher below branch perches than below crossbar perches or in open pasture. Despite differences in seed rain, percent cover of animal-dispersed plants and the number of seedlings of animal-dispersed plant species were similar below both perch types and in open pasture. Baiting perches with bananas did not increase either bird visitation rates or seed rain. These results suggest that, although bird perching structures increase seed dispersal, they do not overcome other barriers to tropical forest recovery such as seed predation and low seed germination.

Early-successional vegetation is often a major factor that limits recovery of tropical forest in abandoned pastures by outcompeting seedlings of forest trees. The goal of this study was to compare the effects of above- and below-ground competition of pasture grasses and shrubs on the growth of tree seedlings in abandoned tropical pasture in Costa Rica. Seedlings of Calophyllum brasiliense were planted in areas of dense pasture grass and below shrub patches. In each vegetation type seedlings were subjected to one of four treatments: control, root trenching, above-ground clearing, or trenching and clearing. Seedling height was measured and above- and below-ground biomass was harvested after one year. Seedling height and biomass were higher for seedlings grown under grass than under shrubs. Above-ground clearing had a strong positive effect on seedling height and all biomass measurements (stem, leaves, tap root, and fine roots). Trenching had a significant effect on height and all biomass measurements except tap root mass; however, trenching had a weaker effect on plant growth than above-ground clearing. Root:shoot ratios were significantly affected by trenching. These results suggest that both pasture grasses and early-colonizing shrubs may slow succession of forest in abandoned pasture. Moreover, the results highlight the importance of reducing above-ground competition to improve the success of reforestation efforts.

Restoration in Mediterranean-climate grasslands is strongly impeded by lack of native propagules and competition with exotic grasses and forbs. We report on a study testing several methods for exotic plant control combined with planting native grasses to restore prairies in former agricultural land in coastal California. Specifically we compared tarping (shading out recently germinated seedlings with black plastic) once, tarping twice, topsoil removal, herbicide (glyphosate), and a control treatment in factorial combinations with or without wood mulch. Into each treatment we planted three native grass species (Elymus glaucus, Hordeum brachyantherum, and Stipa pulchra) and monitored plant survival and cover for three growing seasons. Survival of native grass species was high in all treatments, but was slightly lower in unmulched soil removal and control treatments in the first 2 yr. Mulching, tarping, and herbicide were all effective in reducing exotic grass cover and enhancing native grass cover for the first 2 yr, but by the third growing season cover of the plant guilds and bare ground had mostly converged, primarily because of the declining effects of the initial treatments. Mulching and tarping were both considerably more expensive than herbicide treatment. Topsoil removal was less effective in increasing native grass cover likely because soil removal altered the surface hydrology in this system. Our results show that several treatments were effective in enhancing native grass establishment, but that longer term monitoring is needed to evaluate the efficacy of restoration efforts. The most appropriate approach to controlling exotics to restore specific grassland sites will depend not only on the effectiveness, but also on relative costs and site constraints. Nomenclature: Glyphosate; blue wild rye, Elymus glaucus Buckley; meadow barley, Hordeum brachyantherum Nevski; purple needlegrass, Stipa pulchra Hitchc.

We examined the effects of species, habitat type (open pasture, forest, and beneath isolated pasture trees), and distance from the forest/pasture edge (25 m and 250 m) on post-dispersal seed predation of ten animal-dispersed species near the Las Alturas Biological Station in southern Costa Rica. We also compared the amount of seed predation due to vertebrate and insect predators. Levels of seed predation were extremely species-specific, ranging from 20–100 percent of seeds consumed during the 30 day study period. However, the proportion of seeds remaining was not correlated with seed size. Overall, seed mortality did not differ between the forest and open pasture habitats, but was significantly lower under isolated pasture trees. Individual species differed in which habitat they suffered the highest levels of predation. For eight of ten species studied, levels of seed predation did not vary significantly with distance from the foredpasture edge in any habitat. The majority of the post-dispersal seed predation was due to mammalian predators. The results of this and other studies suggest that post-dispersal seed predation may influence patterns of forest regeneration in disturbed areas. RESUMEN Investigamos el efecto de la especie, el tipo de habitat (pastizal abierto, bosque, y debajo de arboles aislados en el pastizal), y la distancia a la orilla del bosque, sobre la depredacion de semillas de diez especies dispersadas por animales cerca de la Estacion Biologica Las Alturas en el sur de Costa Rica. Ademas comparamos la depredacion causada por vertebrados e insectos. Los niveles de depredacion fueron muy variables entre especies, entre el 20 y 100 por ciento fue depredado durance los 30 dias del estudio. No hubo correlacion entre la proporcion de semillas no depredadas y su tamano. No existio una diferencia entre el bosque y el pastizal en la mortalidad total de las semillas, pero la mortalidad fue menor debajo de 10s arboles aislados. La depredacion de semillas de diferentes especies vario en relacion al habitat. Para ocho de las diez especies los niveles de depredacion no variaron en relacion con la distancia a la orilla del bosque en ninguno de 10s habitats. La mayoria de la depredacion fue ocasionada por mamiferos. Los resultados de este y otros estudios sugieren que la depredacion de semillas influye en la regeneracion del bosque en tierras degradadas.

Landfills are subject to public scrutiny because of potential environmental hazards, low aesthetic value, and rising costs of regulations governing landfill operation. In southwestern Virginia, landfill operators commonly seed landfills with nonnative perennial forbs and grasses. Our goal was to determine if wildflowers were a feasible alternative to the standard revegetation mixture. A standard landfill revegetation mixture and a wildflower mixture were sown at a landfill in Spring 1993 and were evaluated after one growing season. The number of species established in the wildflower mixture subplots was greater than in the standard mixture subplots, whereas cover of the two mixtures did not differ significantly. Rudbeckia hirta, Coreopsis lanceolata, Coreopsis tinctoria, and Hesperis matronalis thrived. Lespedeza cuneata was a confounding factor in determining cover estimates. Results of our study suggest that several native and naturalized species have potential for landfill restoration.

Birds both promote and prosper from forest restoration. The ecosystem functions birds perform can increase the pace of forest regeneration and, correspondingly, increase the available habitat for birds and other forest-dependent species. The aim of this study was to learn how tropical forest restoration treatments interact with landscape tree cover to affect the structure and composition of a diverse bird assemblage. We sampled bird communities over two years in 13 restoration sites and two old-growth forests in southern Costa Rica. Restoration sites were established on degraded farmlands in a variety of landscape contexts, and each included a 0.25-ha plantation, island treatment (trees planted in patches), and unplanted control. We analyzed four attributes of bird communities including frugivore abundance, nectarivore abundance, migrant insectivore richness, and compositional similarity of bird communities in restoration plots to bird communities in old-growth forests. All four bird community variables were greater in plantations and/or islands than in control treatments. Frugivore and nectarivore abundance decreased with increasing tree cover in the landscape surrounding restoration plots, whereas compositional similarity to old-growth forests was greatest in plantations embedded in landscapes with high tree cover. Migrant insectivore richness was unaffected by landscape tree cover. Our results agree with previous studies showing that increasing levels of investment in active restoration are positively related to bird richness and abundance, but differences in the effects of landscape tree cover on foraging guilds and community composition suggest that trade-offs between biodiversity conservation and bird-mediated ecosystem functioning may be important for prioritizing restoration sites.

Enrichment planting in naturally recovering secondary forests or in tree plantations is increasingly being used as strategy to restore later-successional, large-seeded tropical forest trees. We seeded two tree species (Otoba novogranatensis and Ruagea glabra) in three agricultural sites in Southern Costa Rica: abandoned pastures, eight to ten year old secondary forests and three year old tree plantations (containing two N-fixing of four total tree species). We measured micrometeorological conditions, soil water content, plant water potential, leaf area, foliar C and N, and photosynthesis to better understand mechanistic responses of seedlings to conditions in the different successional habitats. Micrometeorological conditions, soil water content, and plant water potential were generally similar across habitats. Certain aspects of leaves (such as Specific Leaf Area and foliar N content), and photosynthesis (e.g. quantum yield and electron transport rate) were highest in the plantations, intermediate in the secondary forests, and lowest in abandoned pastures. Enhanced rates of photosynthetic biochemistry (such as Vcmax and Jmax) and Photosystem II efficiency (e.g. thermal energy dissipation) occurred in leaves from the plantations compared to the abandoned pastures, which may be related to higher leaf %N content. Results suggest that foliar N may be of greater importance than soil water content and micrometeorological factors in driving differences in photosynthetic processes across planting habitats. Planting seeds of these two species in plantations containing three year old trees (including two N-fixing species) enhances certain aspects of their photosynthesis and growth, compared to seedlings in abandoned pastures with non-native grasses, and thus can help increase forest recovery on abandoned agricultural lands.

Monitoring protocols are needed to evaluate the millions of hectares of land that are being proposed for forest restoration in the coming decades. Standardized proposals are critical to evaluate efficacy of restoration strategies, identify triggers for corrective actions, compare results across projects, and generally learn from past projects to inform future restoration efforts. We describe an iterative process, including over 200 stakeholders, to develop a protocol for monitoring Brazilian Atlantic Forest restoration. We give an overview of the ecological, socioeconomic, and management criteria, indicators, and metrics included in the protocol. Strengths of the protocol include the following: (a) testing and use across sites with a range of ages, forest types, past land uses, restoration techniques, and implementing institutions; (b) participation by a broad range of government, nongovernment, private, and academic institutions in the protocol development process; and (c) inclusion of socioeconomic and management criteria. Next steps for facilitating the broad adoption of the protocol in the Atlantic Forest region include providing in person and online training courses, establishing an online repository for storing and comparing monitoring data, and developing smartphone applications to facilitate data collection. Although the protocol was developed for the Atlantic Forest context and further refinements are needed, we think that the Atlantic Forest Pact monitoring protocol may serve as a model to inform the development of similar protocols in other regions, which ultimately could be integrated to produce a pantropical protocol for common use by several restoration forest programs worldwide.

Large-scale ecosystem restoration projects seldom undergo comprehensive evaluation to determine project effectiveness. Consequently, there are missed opportunities for learning and strategy refinement. Before our study, monitoring information from California’s middle Sacramento River had not been synthesized, despite restoration having been ongoing since 1989. Our assessment was based on the development and application of 36 quantitative ecological indicators. These indicators were used to characterize the status of terrestrial and floodplain resources (e.g., flora and fauna), channel dynamics (e.g., planform, geomorphology), and the flow regime. Indicators were also associated with specific goal statements of the CALFED Ecosystem Restoration Program. A collective weight of evidence approach was used to assess restoration success. Our synthesis demonstrates good progress in the restoration of riparian habitats, birds and other wildlife, but not in restoration of streamflows and geomorphic processes. For example, from 1999 to 2007, there was a > 600% increase in forest patch core size, and a 43% increase in the area of the river bordered by natural habitat > 500 m wide. Species richness of landbirds and beetles increased at restoration sites, as did detections of bats. However, degraded post-Shasta Dam streamflow conditions continued. Relative to pre-dam conditions, the average number of years that pass between flows that are sufficient to mobilize the bed, and those that are of sufficient magnitude to inundate the floodplain, increased by over 100%. Trends in geomorphic processes were strongly negative, with increases in the amount of bank hardened with riprap, and decreases in the area of floodplain reworked. Overall the channel simplified, becoming less sinuous with reduced overall channel length. Our progress assessment presents a compelling case for what needs to be done to further advance the ecological restoration of the river. The most important actions to be taken relate to promoting river meander and floodplain connectivity, and restoring components of the natural flow regime.

Public understanding of general environment- and population-related issues is critical for successful conservation efforts. We interviewed 300 residents of Costa Rica, distributed among three socioeconomic groups, to survey knowledge and perceptions about the environment. We focused on Costa Rica because it is an international model for sustainable development and because of its direct economic interest in biodiversity preservation for ecotourism. Our results indicate that Costa Ricans generally have a limited awareness of environment- and population-related problems. In all socioeconomic groups environmental problems were considered less important than various other problems, but 91% of respondents indicated a willingness to pay more for water or electricity if the extra money were used to protect biodiversity. Residents of San Jose’s lower-class neighborhoods more strongly perceived the effects of population growth and environmental degradation than did residents of urban, upper-class, or rural neighborhoods. Of those interviewed, 69% thought the rate of population growth should decrease. Only 52% of those surveyed, however, perceived any link between population size or growth rate and environmental quality; of those, 33% could not describe the link. Our findings and others suggest a number of ways to enhance the effectiveness of environmental education programs worldwide: (1) include information on the relationship between population and environmental quality; (2) explain the socioeconomic implications of environmental degradation; (3) in addition to formal education, utilize the mass media more; (4) tailor messages to local circumstances. El entendimiento de los problemas del medio ambiente y de la poblacion es indispensable para el exito en los esfuerzos de conservacion. Entrevistamos a 300 costarricenses de tres diferentes niveles economicos, para evaluar el conocimiento y las percepctones sobre el medio ambiente. Escogimos Costa Rica, parque es un modelo internacional para el desarollo sostenible y por su interes economico directo de preservar la biodiversidad para el ecoturismo. Nuestros resultados muestran que, en general, los costarricenses tienen un conocimiento limitado de los problemas poblacionales y ambientales. La mayoria de los entrevistados en todos los grupos economicos consideraron los problemas del medio ambiente de menor importancia que otros problemas, pero el 91% de estas personas indicaron que pagarian mas dinero por el agua o la electricidad si el dinero se gastara para proteger la biodiversidad. Las consecuencias del crecimiento de la poblacion y la degradacion del medio ambiente son percibidos mas fuertemente por los residentes de los barrios de nivel economico bajo de San Jose que por los residentes de barrios urbanos de nivel economico alto y de los barrios rurales. El 69% de los entrevistados, indicaron que la tasa de crecimiento de la poblacion debe disminuir. Sin embargo, solamente el 52% de los entrevistados notaron una relacion entre el tamano o la tasa de crecimiento de la poblacion y la calidad del medio ambiente; de estos, solamente el 33% pudieron describir esta relacion. Los resultados de esta y otras encuestas sugieren varias maneras de mejorar la eficada de los programas de educacion ambiental en todo el mundo: (1) incluir informacion sobre la relacion entre poblacion y la calidad del medio ambiente; (2) explicar las consecuencias socioeconomicas de la degradacion del medio ambiente; (3) aumentar la utilizacion de los medios de comunicacion masiva; (4) formular informacion educativa para la situacion local.

Despite the critical role insects play in ecosystem functioning, there has been little study of factors affecting their reestablishment in restored ecosystems. The goals of this research were to quantify the nectar resources provided by reclaimed coal surface mines and to examine the role nectar resources play in determining butterfly community composition on these sites. Adult butterfly communities and nectar resources were sampled on 18 reclaimed coal surface-mined sites and five unmined hardwood sites in southwestern Virginia. Recently, reclaimed sites provided an average of 300 times the nectar abundance of the surrounding hardwoods, and nectar abundance and species richness decreased with time since reclamation. Total nectar abundance was highly correlated with total butterfly abundance and species richness for the entire flight season; these variables were also significantly correlated among sites during most of the 12 sampling periods during the flight season. In only a few cases, however, were butterfly and nectar abundance and species richness significantly correlated within individual sites during the flight season. These results suggest that, although adults of many butterfly species move in response to nectar availability, nectar resources are not sufficiently limiting that their life histories have evolved to maximize nectar resources temporally. While planting species in restored areas that provide abundant nectar will likely attract adult butterflies, this is only one of a number of habitat variables that must be considered in efforts to restore butterfly populations. Finally, adult butterflies appear to have limited utility as indicators of revegetation success.

Tropical forest restoration strategies have the potential to accelerate the recovery of the nutrient cycles in degraded lands. Litter production and its decomposition represent the main transfer of organic material and nutrients into the soil substrate. We evaluated litter production, accumulation on the forest floor, and its decomposition under three restoration strategies: plantation (entire area planted with trees), island (trees planted in patches of three different sizes) and control (natural regeneration) plots. We also compared restoration strategies to young secondary forest (7-9 yr). Restoration treatments were established in 50 x 50m plots in June 2004 at six sites in Southern Costa Rica. Planted tree species included two native timber species (Terminalia amazonia and Vochysia guatemalensis) interplanted with two N fixers (Erythrina poeppigiana and Inga edulis). Litter was collected every 15 days between September 2008 and August 2009 in 12 0.25m2 litter traps distributed within each plot; litter that accumulated on the soil surface was collected at four locations (0.25m2 quadrats) within each plot in February and May 2009. Total litter production in plantation (6.3Mg/ha) and secondary forest (7.3Mg/ha) did not differ, but were greater than in islands (3.5Mg/ha) and control (1.4 Mg/ha). Plantation had greatest accumulation of litter on the soil surface (10.6 Mg/ha) as compared to the other treatments (SF = 7.2; I = 6.7; C = 4.9). Secondary forest was the only treatment with a greater annual production of litter than litter accumulation on the soil surface. Carbon storage in litter was similar between plantation and secondary forest, and significantly greater than the other treatments. No differences were found for carbon concentration and storage in the soil among treatments. There was also high variability in the production and accumulation of litter and carbon among sites. Active restoration treatments accelerated the production of litter and carbon storage in comparison to areas under natural recovery. However, the nutrient cycle has not necessarily been restored under these conditions, as high litter accumulation on the soil surface indicates a low decomposition rate, which slows nutrient return to the soil.

Tropical forest restoration strategies have the potential to accelerate the recovery of the nutrient cycles in degraded lands. Litter production and its decomposition represent the main transfer of organic material and nutrients into the soil substrate. We evaluated litter production, accumulation on the forest floor, and its decomposition under three restoration strategies: plantation (entire area planted with trees), island (trees planted in patches of three different sizes) and control (natural regeneration) plots. We also compared restoration strategies to young secondary forest (7-9yr). Restoration treatments were established in 50x50m plots in June 2004 at six sites in Southern Costa Rica. Planted tree species included two native timber species (Terminalia amazonia and Vochysia guatemalensis) interplanted with two N fixers (Erythrina poep-pigiana and Inga edulis). Litter was collected every 15 days between September 2008 and August 2009 in 12 0.25m2 litter traps distributed within each plot; litter that accumulated on the soil surface was collected at four locations (0.25m2 quadrats) within each plot in February and May 2009. Total litter production in plantation (6.3Mg/ha) and secondary forest (7.3Mg/ha) did not differ, but were greater than in islands (3.5Mg/ha) and con-trol (1.4Mg/ha). Plantation had greatest accumulation of litter on the soil surface (10.6Mg/ha) as compared to the other treatments (SF=7.2; I=6.7; C=4.9). Secondary forest was the only treatment with a greater annual produc-tion of litter than litter accumulation on the soil surface. Carbon storage in litter was similar between plantation and secondary forest, and significantly greater than the other treatments. No differences were found for carbon concentration and storage in the soil among treatments. There was also high variability in the production and accumulation of litter and carbon among sites. Active restoration treatments accelerated the production of litter and carbon storage in comparison to areas under natural recovery. However, the nutrient cycle has not necessar-ily been restored under these conditions, as high litter accumulation on the soil surface indicates a low decompo-sition rate, which slows nutrient return to the soil. Tropical forest restoration strategies have the potential to accelerate the recovery of the nutrient cycles in degraded lands. Litter production and its decomposition represent the main transfer of organic material and nutrients into the soil substrate. We evaluated litter production, accumulation on the forest floor, and its decomposition under three restoration strategies: plantation (entire area planted with trees), island (trees planted in patches of three different sizes) and control (natural regeneration) plots. We also compared restoration strategies to young secondary forest (7-9yr). Restoration treatments were established in 50x50m plots in June 2004 at six sites in Southern Costa Rica. Planted tree species included two native timber species (Terminalia amazonia and Vochysia guatemalensis) interplanted with two N fixers (Erythrina poeppigiana and Inga edulis). Litter was collected every 15 days between September 2008 and August 2009 in 12 0.25m2 litter traps distributed within each plot; litter that accumulated on the soil surface was collected at four locations (0.25m2 quadrats) within each plot in February and May 2009. Total litter production in plantation (6.3Mg/ha) and secondary forest (7.3Mg/ha) did not differ, but were greater than in islands (3.5Mg/ha) and control (1.4Mg/ha). Plantation had greatest accumulation of litter on the soil surface (10.6Mg/ha) as compared to the other treatments (SF=7.2; I=6.7; C=4.9). Secondary forest was the only treatment with a greater annual production of litter than litter accumulation on the soil surface. Carbon storage in litter was similar between plantation and secondary forest, and significantly greater than the other treatments. No differences were found for carbon concentration and storage in the soil among treatments. There was also high variability in the production and accumulation of litter and carbon among sites. Active restoration treatments accelerated the production of litter and carbon storage in comparison to areas under natural recovery. However, the nutrient cycle has not necessarily been restored under these conditions, as high litter accumulation on the soil surface indicates a low decomposition rate, which slows nutrient return to the soil.

Many ecosystems worldwide are dominated by introduced plant species, leading to loss of biodiversity and ecosystem function. A common but rarely tested assumption is that these plants are more abundant in introduced vs. native communities, because ecological or evolutionary-based shifts in populations underlie invasion success. Here, data for 26 herbaceous species at 39 sites, within eight countries, revealed that species abundances were similar at native (home) and introduced (away) sites - grass species were generally abundant home and away, while forbs were low in abundance, but more abundant at home. Sites with six or more of these species had similar community abundance hierarchies, suggesting that suites of introduced species are assembling similarly on different continents. Overall, we found that substantial changes to populations are not necessarily a pre-condition for invasion success and that increases in species abundance are unusual. Instead, abundance at home predicts abundance away, a potentially useful additional criterion for biosecurity programmes.

Successful restoration and maintenance of ecological functions often requires understanding local decision making and behavior, as discussed in the introductory and subsequent chapters of this volume. Furthermore, successfully completing and maintaining most restoration projects requires participation and cooperation from a range of stakeholders, including local and state government agencies and officials, and local businesses and neighboring landowners.

Question: What is the most appropriate combination of treatments to reintroduce Nassella pulchra, a perennial bunchgrass, into degraded mediterranean coastal grasslands? Location: Central coast of California, USA. Methods: N. pulchra was sown from seeds and transplanted into a degraded grassland in a multi-factorial experiment testing the effects of (1) two grazing intensities (lightly grazed by native mammal species or ungrazed); (2) topsoil removal and (3) reduction of plant neighbours. The experiment was carried out on two types of surrounding vegetation (exotic annual grasses and exotic forbs). Results: Topsoil removal greatly enhanced establishment from seeds and transplant survival, mainly because it reduced the exotic vegetation and thus reduced competition. While removing neighbours was essential when topsoil was left intact, it had a negative effect on N. pulchra when surrounding species included exotic forbs (Brassica spec. and Asteraceae) at low density (after topsoil removal). Moderate grazing by native mammals (deer, rabbits and gophers) did not affect N. pulchra. Conclusion: Our results suggest that seeding after topsoil has been removed is a promising method to reintroduce N. pulchra to highly degraded sites where there is little to no native seed bank.

The ability of global agricultural systems to supply sufficient food for our rapidly-growing human population is becoming constrained by physical and economic limits to traditional means of agricultural expansion. Pests consume or ruin a staggering proportion of crops and, in general, have not been satisfactorily controlled through the ‘broadcast’ application of pesticides.

Grasslands are hot spots of biodiversity but are now widely threatened by changes in patterns of disturbances, such as grazing and fire regimes, exotic species invasions, and cultivation. The goal of this experiment was to find the most appropriate combination of treatments to reintroduce Danthonia californica, a formerly dominant perennial bunchgrass, into degraded California coastal prairies. Danthonia californica was sown from seed and transplanted at two sites and at two grazing intensities (grazed/ungrazed) in a multifactorial experiment testing the effects of (1) local versus nonlocal seed sources; (2) topsoil removal; and (3) reduction of plant neighbors. Seed emergence was very low, suggesting that transplanting may be a better option to reintroduce D. californica. Although transplants grown from nonlocal seeds survived better initially at both sites, transplants from local seeds had higher survival after 1.5 year at one site. This suggests that short-term plant establishment studies may be misleading. Topsoil removal greatly enhanced transplant survival, and neighbor removal primarily increased transplant growth. Our results suggest that removing topsoil prior to transplanting seedlings grown from local seeds is the most promising method to reintroduce D. californica. However, the benefits of removing topsoil to provide safe sites for plant establishment should be weighed carefully against potential negative effects on the native seed bank and microbial communities on a site-specific basis.

Accurate measurements of seed rain are important for understanding tree reproduction (Greene & Johnson 1994), forest regeneration (Cole et al. 2010, Cubina & Aide 2001, Howe et al. 2010, Zahawi & Augspurger 2006), forest ecology (Muller-Landau et al. 2008, Terborgh et al. 2011) and maintenance of community diversity (Harms et al. 2000). Seed traps generally consist of a bucket or net of a fixed area suspended 0.3–1 m above the ground, and seeds are typically collected once or twice per month. An implicit assumption of all seedrain studies is that traps do not influence seed dispersal. Should birds perch on and defecate seeds into seed traps, seed abundance will be overestimated. This behaviour could produce a directional bias if birds perch on seed traps in one habitat more than others. To our knowledge, no study has considered this potential bias. We attempted to characterize bird bias in seed-rain measurements through observations of seed traps in several habitats in southern Costa Rica (Table 1). Observations were conducted in June–September 2007, 2010, and 2011 near the town of Agua Buena (8◦44′ N, 82◦56′ W; 1100–1300 m asl; rainfall 3–4 m y−1). Seed traps consisted of a 0.25-m2 pocket of fine-gauge (0.5×0.5 mm) mosquito netting suspended 0.5 m above the ground on a metal frame with three legs. All observations were conducted in fair weather between 05h30 and 12h00. Groups of seed traps were observed in a randomized order on any given day. Avian nomenclature follows the American Ornithologists’ Union (1998) and its supplements. Statistics are reported as mean ± SE.

Only recently have studies addressed the effect of early-colonizing vegetation on tree seedling survival and growth during secondary succession in tropical old fields, and few studies have elucidated the physiological responses of tree seedlings to different vegetational communities. We compared growth and various photosynthetic parameters for seedlings of four rain-forest tree species, Cedrela tonduzii, Inga punctata, Ocotea whitei, and Tapirira mexicana, growing in areas of pasture grass and shrubs in early-successional abandoned pasture in Costa Rica; in addition, we made measurements for two species in forest gaps. We tested the general hypothesis that early-colonizing shrubs facilitate growth of forest tree seedlings. Specifically, we measured microclimate, growth, CO2 assimilation, stomatal conductance, photosystem II quantum yield (ΦPSII), and xanthophyll pigment pools for all seedlings. Photosynthetic flux density (PFD) was higher under grass than shrubs or forest gaps, but was highly variable in each growth environment. For three of the four species, height growth was greatest in the grass compared to the shrubs and forest gaps; growth was similar below grass and shrubs for O. whitei. Photosynthetic capacity, apparent quantum yield, and stomatal conductance did not vary across habitats, but light compensation point and PFD at light saturation tended to be higher in the grass compared to forest and shrub growth environments. Water use efficiency differed across growth environments for three of the species. For plants in ambient PFD and dark-adapted plants, the efficiency of excitation energy transfer through PSII was lowest for plants in the grass compared to shrubs and forest gaps and also differed across species. Measurement of steady-state responses of ΦPSII to increasing PFD indicated a significant effect of growth environment at low PFD for all species and significant effects at high PFD only for I. punctata. All species exhibited a high degree of midday xanthophyll de-epoxidation in the different growth environments. Xanthophyll pigment pool size on an area basis was highest in the grass compared to shrubs and forest gaps for all four species. The results suggest that shrubs do not provide a facilitative effect for growth or photosynthesis for ~1.5-year-old seedlings of these four species. We conclude that site differences in success of tree seedlings during succession are a result of complex interactions of facilitation and competition and are not simply based on physiological responses to PFD.

Costa Rica achieved a substantial reduction in its overall fertility rate in a very short period of time. The halving of the fertility rate which occurred in less than ten years in Costa Rica transpired over the course of 100 years in France and 170 in Sweden. The level of contraceptive use in Costa Rica is twice that in other Central American nations. The authors summarize the recent demographic history of Costa Rica and review factors influencing its remarkable fertility decline. They then discuss possible explanations for the ensuing fertility plateau and conclude by suggesting strategies for affecting a further decrease in fertility rates. With regard to the reasons for the fertility plateau, cultural factors, socioeconomic factors, declining government commitment and family planning services, education, and the Church are considered. To reduce the level of fertility even further, the authors recommend that the government adopt a clear population policy which could serve as a basis for other changes such as increased support of family planning programs, improvements in the educational system, increased women's status and employment opportunities, and extensive education in schools and through the mass media on the socioeconomic and environmental effects of overpopulation. It is important to increase Costa Ricans' understanding of the negative impacts of continued population growth and the role of individual family planning decisions in that growth.