Jarcilene Silva de Almeida-Cortez

Biomass resilience of Neotropical secondary forests

Land-use change occurs nowhere more rapidly than in the tropics, where the imbalance between deforestation and forest regrowth has large consequences for the global carbon cycle. However, considerable uncertainty remains about the rate of biomass recovery in secondary forests, and how these rates are influenced by climate, landscape, and prior land use. Here we analyse aboveground biomass recovery during secondary succession in 45 forest sites and about 1,500 forest plots covering the major environmental gradients in the Neotropics. The studied secondary forests are highly productive and resilient. Aboveground biomass recovery after 20 years was on average 122 megagrams per hectare (Mg ha−1), corresponding to a net carbon uptake of 3.05 Mg C ha−1 yr−1, 11 times the uptake rate of old-growth forests. Aboveground biomass stocks took a median time of 66 years to recover to 90% of old-growth values. Aboveground biomass recovery after 20 years varied 11.3-fold (from 20 to 225 Mg ha−1) across sites, and this recovery increased with water availability (higher local rainfall and lower climatic water deficit). We present a biomass recovery map of Latin America, which illustrates geographical and climatic variation in carbon sequestration potential during forest regrowth. The map will support policies to minimize forest loss in areas where biomass resilience is naturally low (such as seasonally dry forest regions) and promote forest regeneration and restoration in humid tropical lowland areas with high biomass resilience.

Caatinga: the scientific negligence experienced by a dry tropical forest

Seasonally dry tropical forests (SDTFs) provide a habitat for a diverse number of species and cover significant land areas. Yet, the amount of scientific research they have attracted is minimal. Recently, an international debate on the generality, consequences and forces keeping SDTFs in a position of relative negligence has begun. This paper assesses and compares biodiversity-related knowledge across the major Brazilian ecosystems to verify in which extent the Caatinga vegetation (a mosaic of scrubs and patches of seasonally dry forest) has been scientifically unappreciated. In fact, Caatinga attracted the lowest scores from semi-quantitative indexes describing biodiversity-survey efforts and knowledge status, with a negligible number of papers published internationally. Caatinga also supports fewer research teams and senior researchers as compared to humid tropical forests (Amazonia and Atlantic Forest). Both the knowledge index and number of published papers were explained by a model combining ecosystem area (km2), inventory index plus the current number of research teams or senior researchers assigned to Brazilian ecosystems. These findings reinforce the notion that SDTFs have experienced lower scientific efforts, but also reveal an apparent connection between institutional capacity, production/accumulation of scientific knowledge and conservation efforts. Although the research agenda for reconciling land-use and biodiversity conservation has been launched, current institutional anemia across SDTFs is likely to limit its impacts and achievements.

Carbon sequestration potential of second-growth forest regeneration in the Latin American tropics

Models reveal the high carbon mitigation potential of tropical forest regeneration. Regrowth of tropical secondary forests following complete or nearly complete removal of forest vegetation actively stores carbon in aboveground biomass, partially counterbalancing carbon emissions from deforestation, forest degradation, burning of fossil fuels, and other anthropogenic sources. We estimate the age and spatial extent of lowland second-growth forests in the Latin American tropics and model their potential aboveground carbon accumulation over four decades. Our model shows that, in 2008, second-growth forests (1 to 60 years old) covered 2.4 million km2 of land (28.1% of the total study area). Over 40 years, these lands can potentially accumulate a total aboveground carbon stock of 8.48 Pg C (petagrams of carbon) in aboveground biomass via low-cost natural regeneration or assisted regeneration, corresponding to a total CO2 sequestration of 31.09 Pg CO2. This total is equivalent to carbon emissions from fossil fuel use and industrial processes in all of Latin America and the Caribbean from 1993 to 2014. Ten countries account for 95% of this carbon storage potential, led by Brazil, Colombia, Mexico, and Venezuela. We model future land-use scenarios to guide national carbon mitigation policies. Permitting natural regeneration on 40% of lowland pastures potentially stores an additional 2.0 Pg C over 40 years. Our study provides information and maps to guide national-level forest-based carbon mitigation plans on the basis of estimated rates of natural regeneration and pasture abandonment. Coupled with avoided deforestation and sustainable forest management, natural regeneration of second-growth forests provides a low-cost mechanism that yields a high carbon sequestration potential with multiple benefits for biodiversity and ecosystem services.

Richness of gall-inducing insects in the tropical dry forest (caatinga) of Pernambuco

Diversity of gall-inducing insects in the tropical dry forest (caatinga) of Pernambuco. We report on the richness of galling insects in the vegetation of caatinga of Pernambuco state, Brazil. We recorded 64 different types of galls collected primarily from leaves and stems of 48 species of host plants belonging to 17 families and 31 genera. The most common gall morphological types were spheroid and discoid, glabrous, predominantly green and with one chamber. The main gall inducing taxon was the Cecidomyiidae (Diptera). The results of this study contribute to existing knowledge of galling insect and host-plant diversity in caatinga.

Caatinga, the Brazilian dry tropical forest: can it tolerate climate changes?

Our review focuses on the projections of climate change in the Brazilian semiarid region, the Caatinga, based on recent publications about global climate change and biology. We found several vulnerable points in the initial estimates, the main one being that the data were collected and analyzed without a multidisciplinary knowledge. This review discusses several studies that show the current knowledge in many semiarid regions around the world. Some of these studies argue for the increase in vegetation greenness responses even under severe and prolonged drought, based on the high resilience the Caatinga native species show under severe drought conditions over the years. Additionally, we include in this review recent data produced by our group on key ecophysiological variables under drought conditions. We also show successful examples of deforested areas recovery in the semiarid region of the Central America. It is critical that the recovery of semiarid areas is coupled with the implementation of socio-environmental policies, engaging the local population and providing subsidies for life wealth improvement. These are key aspects for a long-term recovery and conservation of the Brazilian dry tropical forest.

Interspecific consistency and intraspecific variability of specific leaf area with respect to irradiance and nutrient availability

Abstract Specific leaf area (SLA) is a common variable in comparative plant ecology that is often measured on field-grown plants, yet SLA is known to be a plastic trait. The motivation for this study was therefore to determine the degree to which environmentally induced plasticity in SLA might obscure interspecific trends. Specifically, we tested the hypothesis that SLA is more responsive to nutrient stress at low irradiance than at high irradiance. To test this hypothesis we grew plants of six species of herbaceous Asteraceae in factorial combinations of 500, 250, and 125 µmol m-2 s-1 irradiance and a full strength (1/1), a 1/5, and a 1/10 dilution of a modified Hoagland hydroponic solution. The full strength solution had 8 mM of nitrogen. Plants were harvested at 21, 28, 35, and 42 days from germination. SLA varied significantly between species, harvest dates, and experimental treatments. In general, SLA decreased with age, but more severely at low irradiance. SLA increased with decreasing irradiance. SLA also increased with increasing nutrient concentration, but this effect disappeared in the older plants at the higher irradiance. These trends were not seen in every species. Our hypothesis was supported: SLA is more responsive to nutrient stress at low irradiance than at high irradiance, but the exact response is species-specific. Despite these environmentally induced changes in SLA at the intraspecific level, the interspecific differences were maintained across environments, justifying the use of SLA as a useful trait in comparative plant ecology.

Distribution pattern of herbivorous insects in a remnant of Brazilian Atlantic Forest

In this study we selected three habitats that correspond to a light gradient, and consequently a proportion of pioneer plant species gradient edges, trails and forest core and described their herbivorous insect assemblage. We tested five hypothesis about the herbivorous assemblage: (1) there is a different distribution of abundance and richness of order between habitats, (2) species similarity between habitats is smaller than within habitat, (3) in forest edge the herbivores are more abundant than in trails and interior of the forest, (4) in nuclear areas herbivore richness and diversity are higher than in the trails and edge, and (5) the abundance and richness of herbivores are different between seasons. Herbivorous were sampled during November 2000 - May 2001 by scanning the plants in ten 1,000-m 3 transects per habitat, five per season. We sampled 1,424 adult individuals from 367 species of six orders. Orthoptera and Coleoptera were the most abundant herbivores in the edge and interior, respectively. Coleoptera showed the highest species diversity in the forest edge, while Lepidoptera was in the interior. The similarity of the fauna between habitats was smaller than within habitats. The values of abundance, richness and diversity in the edge were higher than those of trails and interior for both seasons. We suggest that the low richness of herbivores in the interior of the forest is due to a reduction of specialist groups associated to plant species characteristic of mature forest, which are locally extinct in the study area.

Diversity of gall-inducing insects in the high altitude wetland forests in Pernambuco, Northeastern Brazil

We report on the richness of galling insects in the altitudinal wetland forests of Pernambuco State, Northeastern Brazil. We found 80 distinct types of insect galls on 49 species of host plants belonging to 28 families and 35 genera. Most of the galled plant species belong to Nyctaginaceae, Fabaceae, Meliaceae, Sapindaceae and Myrtaceae. The most common gall were spheroid and globoid; most galls were glabrous, predominantly green and with one chamber, and on the leaves. Most galls were induced by Cecidomyiidae (Diptera). The results of this study contribute to existing knowledge richness of galling insects and host-plant diversity in the altitudinal wetland forests of Northeastern Brazil.

Gall-inducing insects from Atlantic Forest of Pernambuco, Northeastern Brazil

An inventory of gall inducing insects and their host plants in the Atlantic forest of Pernambuco, northeastern Brazil is presented. Samples of galls and their host plants were taken in six fragments of Atlantic forest. One hundred thirty-six different morphotypes of insect galls on 79 host plant species belonging to 35 plant families and 53 genera were recorded. The host plant families most attacked by galling insects were: Lecythidaceae, Myrtaceae, and Nyctaginaceae. The most frequent galling taxa were Diptera of the Cecidomyiidae family (95%), followed by Lepidoptera and Coleoptera. Galls occurred most frequently on leaves and stems, had globoid and elliptical shapes, green color and absence of trichomes on the external walls. The data indicate an intermediary richness of gall inducing insects when compared to other Brazilian Atlantic forests.

Ecophysiological performance of Calotropis procera: an exotic and evergreen species in Caatinga, Brazilian semi-arid

To better understand the proliferation of Calotropis procera in a semi-arid region of northeastern Brazil (Caatinga), we designed two experiments to determine which ecophysiological characteristics contribute to the species adaptive success. The first experiment was conducted with young plants under greenhouse conditions and three water regimes. The second experiment was conducted with adult plants under field conditions subject to regional seasonality. Young plants exhibited a high tolerance to water deficits, mainly because of their strong stomatal control, which was observed before any biochemical alterations in leaf metabolism. Only under full suspension of irrigation did the plants show a reduction in relative water content. Under field conditions, adult plants showed a high resilience to the semi-arid environment with respect to gas exchange and other measured biochemical parameters, including photosynthetic pigment, soluble sugars, amino acids and protein content, even under the low soil water availability of the dry season. This season featured high photosynthetically active radiation, low relative humidity and high temperatures, and thus exposed plants to extreme differences between leaf and air temperatures. Calotropis procera remains green throughout the year, indicating that it has developed several means of tolerating the semi-arid climate. Furthermore, this species maintains a high photosynthetic rate despite reduced stomatal conductance, which increases its water use efficiency, a fundamental characteristic for survival in this ecosystem.