Differential ecological filtering across life cycle stages drive old-field succession in a neotropical dry forest

Abiotic and biotic filters may play differential roles in the plant community organization along forest succession in abandoned fields. However, little is known about how life stage-specific filters influence species replacement during succession. We approach this issue by analyzing changes in community attributes (abundance, species density, species diversity, species composition) and the phylogenetic structure of shrubs and trees at different life stages during the old-field succession of a seasonally tropical dry forest (TDF) in Western Mexico. We raised two main questions: (1) How different are the trajectories of change in community attributes and phylogenetic structure along succession for shrub and tree species at different life-stages? (2) Do different stage-specific trajectories result from differential filtering mechanisms? We used a chronosequence of abandoned pastures and forest sites, classified in five successional categories (with three sites each): Pasture ( 100 cm height and < 2.5 cm diameter at breast height (DBH)], adults (shrubs and trees with DBH ≥ 2.5 cm). Additionally, we quantified the phylogenetic mean parwise distance (MPD) among species, and analyzed the phylogenetic community structure, for each successional category and life stage. We found that early in succession the resprout stage was more abundant and diverse than the seedling stage, while the inverse occurred late in succession. Along the first 15 years of succession, the seedling stage showed a clumped phylogenetic structure (with a strong dominance of legume species), while the resprout stage tended to have an overdispersed one (with species from a wide range of clades). Also, community attributes of the juvenile and adult stages approached those of the old-growth forest, and in both stages the phylogenetic structure changed from clustered to random. Overall, our results suggest that the assembly of shrub and trees communities along succession resulted from a combination of abiotic filtering processes, operating mostly on seedlings (selecting primarily legume drought-tolerant species), and biotic filtering processes, operating mostly in resprouts (generating a taxonomic and phylogenetically diverse regenerative pool). The implications of these results for the management of secondary TDF in human modified landscapes are discussed.</p

Functional recovery of secondary tropical forests

One-third of all Neotropical forests are secondary forests that regrow naturally after agricultural use through secondary succession. We need to understand better how and why succession varies across environmental gradients and broad geographic scales. Here, we analyze functional recovery using community data on seven plant characteristics (traits) of 1,016 forest plots from 30 chronosequence sites across the Neotropics. By analyzing communities in terms of their traits, we enhance understanding of the mechanisms of succession, assess ecosystem recovery, and use these insights to propose successful forest restoration strategies. Wet and dry forests diverged markedly for several traits that increase growth rate in wet forests but come at the expense of reduced drought tolerance, delay, or avoidance, which is important in seasonally dry forests. Dry and wet forests showed different successional pathways for several traits. In dry forests, species turnover is driven by drought tolerance traits that are important early in succession and in wet forests by shade tolerance traits that are important later in succession. In both forests, deciduous and compound-leaved trees decreased with forest age, probably because microclimatic conditions became less hot and dry. Our results suggest that climatic water availability drives functional recovery by influencing the start and trajectory of succession, resulting in a convergence of community trait values with forest age when vegetation cover builds up. Within plots, the range in functional trait values increased with age. Based on the observed successional trait changes, we indicate the consequences for carbon and nutrient cycling and propose an ecologically sound strategy to improve forest restoration success.Additional co-authors: Gabriel Dalla Colletta, Dylan Craven, Ben H. J. de Jong, Julie S. Denslow, Saara J. DeWalt, Elisa Díaz García, Juan Manuel Dupuy, Sandra M. Durán, Mário M. Espírito Santo, Geraldo Wilson Fernandes, Bryan Finegan, Vanessa Granda Moser, Jefferson S. Hall, José Luis Hernández-Stefanoni, Catarina C. Jakovac, Deborah Kennard, Edwin Lebrija-Trejos, Susan G. Letcher, Madelon Lohbeck, Omar R. Lopez, Erika Marín-Spiotta, Miguel Martínez-Ramos, Jorge A. Meave, Francisco Mora, Vanessa de Souza Moreno, Sandra C. Müller, Rodrigo Muñoz, Robert Muscarella, Yule R. F. Nunes, Susana Ochoa-Gaona, Rafael S. Oliveira, Horacio Paz, Arturo Sanchez-Azofeifa, Lucía Sanaphre-Villanueva, Marisol Toledo, Maria Uriarte, Luis P. Utrera, Michiel van Breugel, Masha T. van der Sande, Maria D. M. Veloso, S. Joseph Wright, Kátia J. Zanini, Jess K. Zimmerman, and Mark Westob

Demographic Drivers of Aboveground Biomass Dynamics During Secondary Succession in Neotropical Dry and Wet Forests

The magnitude of the carbon sink in second-growth forests is expected to vary with successional biomass dynamics resulting from tree growth, recruitment, and mortality, and with the effects of climate on these dynamics. We compare aboveground biomass dynamics of dry and wet Neotropical forests, based on monitoring data gathered over 3–16 years in forests covering the first 25 years of succession. We estimated standing biomass, annual biomass change, and contributions of tree growth, recruitment, and mortality. We also evaluated tree species’ contributions to biomass dynamics. Absolute rates of biomass change were lower in dry forests, 2.3 and 1.9 Mg ha−1 y−1, after 5–15 and 15–25 years after abandonment, respectively, than in wet forests, with 4.7 and 6.1 Mg ha−1 y−1, in the same age classes. Biomass change was largely driven by tree growth, accounting for at least 48% of biomass change across forest types and age classes. Mortality also contributed strongly to biomass change in wet forests of 5–15 years, whereas its contribution became important later in succession in dry forests. Biomass dynamics tended to be dominated by fewer species in early-successional dry than wet forests, but dominance was strong in both forest types. Overall, our results indicate that biomass dynamics during succession are faster in Neotropical wet than dry forests, with high tree mortality earlier in succession in the wet forests. Long-term monitoring of second-growth tropical forest plots is crucial for improving estimates of annual biomass change, and for enhancing understanding of the underlying mechanisms and demographic drivers.</p

Landscape-scale forest cover drives the predictability of forest regeneration across the Neotropics

Abandonment of agricultural lands promotes the global expansion of secondary forests, which are critical for preserving biodiversity and ecosystem functions and services. Such roles largely depend, however, on two essential successional attributes, trajectory and recovery rate, which are expected to depend on landscape-scale forest cover in nonlinear ways. Using a multi-scale approach and a large vegetation dataset (843 plots, 3511 tree species) from 22 secondary forest chronosequences distributed across the Neotropics, we show that successional trajectories of woody plant species richness, stem density and basal area are less predictable in landscapes (4 km radius) with intermediate (40–60%) forest cover than in landscapes with high (greater than 60%) forest cover. This supports theory suggesting that high spatial and environmental heterogeneity in intermediately deforested landscapes can increase the variation of key ecological factors for forest recovery (e.g. seed dispersal and seedling recruitment), increasing the uncertainty of successional trajectories. Regarding the recovery rate, only species richness is positively related to forest cover in relatively small (1 km radius) landscapes. These findings highlight the importance of using a spatially explicit landscape approach in restoration initiatives and suggest that these initiatives can be more effective in more forested landscapes, especially if implemented across spatial extents of 1–4 km radius

Multidimensional tropical forest recovery

International audienceTropical forests disappear rapidly because of deforestation, yet they have the potential to regrow naturally on abandoned lands. We analyze how 12 forest attributes recover during secondary succession and how their recovery is interrelated using 77 sites across the tropics. Tropical forests are highly resilient to low-intensity land use; after 20 years, forest attributes attain 78% (33 to 100%) of their old-growth values. Recovery to 90% of old-growth values is fastest for soil (12 decades). Network analysis shows three independent clusters of attribute recovery, related to structure, species diversity, and species composition. Secondary forests should be embraced as a low-cost, natural solution for ecosystem restoration, climate change mitigation, and biodiversity conservation

Planning cancer control in Latin America and the Caribbean

Non-communicable diseases, including cancer, are overtaking infectious disease as the leading health-care threat in middle-income and low-income countries. Latin American and Caribbean countries are struggling to respond to increasing morbidity and death from advanced disease. Health ministries and health-care systems in these countries face many challenges caring for patients with advanced cancer: inadequate funding; inequitable distribution of resources and services; inadequate numbers, training, and distribution of health-care personnel and equipment; lack of adequate care for many populations based on socioeconomic, geographic, ethnic, and other factors; and current systems geared toward the needs of wealthy, urban minorities at a cost to the entire population. This burgeoning cancer problem threatens to cause widespread suffering and economic peril to the countries of Latin America. Prompt and deliberate actions must be taken to avoid this scenario. Increasing efforts towards prevention of cancer and avoidance of advanced, stage IV disease will reduce suffering and mortality and will make overall cancer care more affordable. We hope the findings of our Commission and our recommendations will inspire Latin American stakeholders to redouble their efforts to address this increasing cancer burden and to prevent it from worsening and threatening their societies.SCOPUS: re.jinfo:eu-repo/semantics/publishe

I do it for myself : A study on motivational differences between contracted and permanent employees in Sweden

Over the past decades outsourcing decades outsourcing has become an increasing trend.Firms decide to outsource in order to increase their profits or flexibility and many differentfunctions of the firm may be outsourced, one of them being the Human Resource (HR)function. When it comes to HR outsourcing, recruitment and selection are among the morecommon functions to be outsourced (Ordanini &amp; Silvestri, 2008:373). The motivation foroutsourcing of HR is to reduce cost and increase efficiency (Elmuti, Grunewald and Abebe,2010:177). Outsourcing of HR functions like recruitment can also have negative aspect, forexample lack of loyalty and high turnover (Fisher et al, 2008:202). Previous research hasinvestigated how commitment and loyalty is affected by HR outsourcing (Connelly &amp;Gallagher, 2004:963) and one aspect that has been touched upon but not dealt withexclusively is motivation and therefore this paper will explore it further. Using the following research question: How does motivation vary between individuals working at a company butare hired through a staffing firm versus hired directly by the company? This paper tries to both evaluate the existing literature and provide practicalimplications for managers. In order to explore this question and abductive research approachhas been used where the data and theory are intertwined and played of each other to achievethe purpose (Alvesson &amp; Sköldberg, 2009:4). The data collection consists of eight semistructuredinterviews, four with people hired directly by the company and four that are orhave previously been hired through a staffing company. The study found that the theoretical framework does for the most part explain themotivational behavior of both groups studied, and that the two groups are not alwaysmotivated in the same way. Those hired directly by the company are more interested inreceiving praise, relationships at work, and receiving small tokens of appreciation. The grouphired by staffing companies was more often motivated by an internal drive to satisfythemselves and did not value work relationships to the same extent. The research also showedthat the individual rather than the form of employment plays a big role when it comes to howpeople are motivated. It was also made apparent that education and work situation wereimportant factors influencing the respondent’s motivation