Castela senticosa (Simaroubaceae: Sapindales), a New Species from the Caribbean Clade Endemic to Seasonally Dry Tropical Forest on Hispaniola

Abstract— Recent fieldwork in the Sierra Martín García in southwestern Dominican Republic has yielded a new species of the American clade Castela (Simaroubaceae), Castela senticosa sp. nov., from seasonally dry tropical forest. This species has been collected from two separate localities, including Môle St. Nicolas in northwestern Haiti in 1929, but until now fertile material with both flowers and fruit was unknown. We provide a photographic plate and illustration, place it phylogenetically using plastome data, and compare it morphologically with close relatives. This increases the number of known species of Castela on Hispaniola from one to two, both of which are endemic but from different clades, and yields another species for the Greater Antilles, a known biodiversity hotspot and clear center of diversification for this group of arid-adapted, thorny shrubs. This work emphasizes that seasonally dry, tropical forests, although often understudied, house as yet undiscovered biodiversity and deserve far more comprehensive studies.

The global forest above-ground biomass pool for 2010 estimated from high-resolution satellite observations

The terrestrial forest carbon pool is poorly quantified, in particular in regions with low forest inventory capacity. By combining multiple satellite observations of synthetic aperture radar (SAR) backscatter around the year 2010, we generated a global, spatially explicit dataset of above-ground live biomass (AGB; dry mass) stored in forests with a spatial resolution of 1 ha. Using an extensive database of 110 897 AGB measurements from field inventory plots, we show that the spatial patterns and magnitude of AGB are well captured in our map with the exception of regional uncertainties in high-carbon-stock forests with AGB >250 Mg ha−1, where the retrieval was effectively based on a single radar observation. With a total global AGB of 522 Pg, our estimate of the terrestrial biomass pool in forests is lower than most estimates published in the literature (426–571 Pg). Nonetheless, our dataset increases knowledge on the spatial distribution of AGB compared to the Global Forest Resources Assessment (FRA) by the Food and Agriculture Organization (FAO) and highlights the impact of a country's national inventory capacity on the accuracy of the biomass statistics reported to the FRA. We also reassessed previous remote sensing AGB maps and identified major biases compared to inventory data, up to 120 % of the inventory value in dry tropical forests, in the subtropics and temperate zone. Because of the high level of detail and the overall reliability of the AGB spatial patterns, our global dataset of AGB is likely to have significant impacts on climate, carbon, and socio-economic modelling schemes and provides a crucial baseline in future carbon stock change estimates. The dataset is available at https://doi.org/10.1594/PANGAEA.894711 (Santoro, 2018).

Monograph and Molecular Phylogeny of the Mexican Endemic Lasiocarpus (Malpighiaceae) Reveal a New Species for Southern Mexico

Abstract— Lasiocarpus is a genus of bisexual, dioecious, or trioecious shrubs or small trees of Malpighiaceae endemic to the seasonally dry tropical forests of the Pacific slopes of Mexico. In this paper the monophyly of this genus is tested using a molecular phylogeny based on three plastid (ndhF, matK, rbcL) and a single nuclear (PHYC) markers that were newly sequenced for the three currently accepted species in this genus, along with representative taxa from the main phylogenetic groups previously recognized in Malpighiaceae. The three species of Lasiocarpus were retrieved in a well supported clade corroborating the monophyly of this genus. A taxonomic treatment of this genus is presented. Lasiocarpus ovalifolius is synonymized with L. salicifolius, and a new species, Lasiocarpus andersoniorum, endemic to Southern Mexico, is proposed. It is morphologically distinguished by characters such as axillary inflorescences, reflexed sepals, petals with crenate margin and strigose indumentum, large styles, and 2-lobed stigmas. The taxonomic revision includes morphological descriptions and distribution maps for the three accepted species of Lasiocarpus.

Regional and local determinants of drought resilience in tropical forests

The increase in severity of droughts associated with greater mortality and reduced vegetation growth is one of the main threats to tropical forests. Drought resilience of tropical forests is affected by multiple biotic and abiotic factors varying at different scales. Identifying those factors can help understanding the resilience to ongoing and future climate change. Altitude leads to high climate variation and to different forest formations, principally moist or dry tropical forests with contrasted vegetation structure. Each tropical forest can show distinct responses to droughts. Locally, topography is also a key factor controlling biotic and abiotic factors related to drought resilience in each forest type. Both dry tropical forests and ridges (steeper and drier habitats) are more sensitive to droughts than moist tropical forest and valleys (flatter and wetter habitats). The most important biotic factors are leaf economic and hydraulic plant traits, and vegetation structure. The most important abiotic factors are soil nutrients, water availability and microclimate. Here we show that topography has key roles controlling biotic and abiotic factors in each forest type. Our synthesis highlights that gradients of altitude and topography are essential to understand tropical forest’s resilience to future drought events. We described important factors related to drought resilience, however many important knowledge gaps remain. Filling those gaps will help improve future practices and studies about mitigation capacity, conservation, and restoration of tropical ecosystems.

Wind Intensity and Power Density in the Brazilian Dry Tropical Forests (Caatinga)

Wind speed has been widely used for energy purposes. Therefore, studies focused on its knowledge are extremely relevant to better benefit from this resource. The aim of this study is to analyze wind behavior and estimate wind power density (WPD) in the interior of northeastern Brazil, a region with predominance of the semi-arid climate, based on the data made available by the automatic station installed at the Experimental Farm in the municipality of São João do Cariri-PB, which come from the SONDA project and refer to the year 2007. Descriptive analysis techniques were used to identify the periods in which the wind behavior is more favorable to wind harnessing. From the results obtained, there was a predominance of southeast in the wind direction component. However, the values of both the observed wind speed (2, 25 and 50 m) and the wind speed estimated for the levels of 100 and 150 m, as well as the estimates of power density (50, 100 and 150 m) showed that the lowest records are present mainly in the first hours of the day, as well as in the first half of the year, while the highest values occur from 10 a.m. extending to the beginning of the night and prevail in the last six months of the year. These determinations denoted higher values of wind power density available for the second half of the year (mainly from August to December).

Small mammals from the Seasonally Dry Tropical Forests of the Huallaga river basin and new records for San Martín department, Peru

The Seasonally Dry Tropical Forests in Peru are well known for their bird and plant diversity and endemicity, but little is known about the diversity of small mammals. We report the diversity of small volant and non-volant mammals from the Seasonally Dry Tropical Forests of the Huallaga river basin in the San Martín Department, working on both sides of the river, making a sampling effort of 3060 traps-night for non-volant and 104 mist nets-night for volant mammals. We recorded 29 species, including five marsupials, three rodents, and 21 bats. Among the bats, phyllostomids were the most diverse group with 16 species. Short-tailed Spiny-rat, Proechimys brevicauda (Günther, 1877) and Seba's Short-tailed Bat, Carollia perspicillata (Linnaeus, 1758), featured the highest relative abundance. In addition, we report the first records for the San Martín Department of Peropteryx macrotis (Wagner, 1843), Saccopteryx bilineata (Temminck, 1838), Lonchorhina aurita Tomes, 1863, Vampyriscus bidens (Dobson, 1878), and Myotis simus Thomas, 1901. The species richness and diversity indices indicate the study site has a high diversity value; however, fragmentation and rapid changes in land-use are the main threats faced by the biodiversity of these dry forests.

El Niño-Southern Oscillation affects the water relations of tree species in the Yucatan Peninsula, Mexico

We evaluated the effect of ENSO 2015/16 on the water relations of eight tree species in seasonally dry tropical forests of the Yucatan Peninsula, Mexico. The functional traits: wood density, relative water content in wood, xylem water potential and specific leaf area were recorded during the rainy season and compared in three consecutive years: 2015 (pre-ENSO conditions), 2016 (ENSO conditions) and 2017 (post-ENSO conditions). We analyzed tree size on the capacity to respond to water deficit, considering young and mature trees, and if this response is distinctive in species with different leaf patterns in seasonally dry tropical forests distributed along a precipitation gradient (700–1200 mm year−1). These traits showed a strong decrease in all species in response to water stress in 2016, mainly in the driest site. Deciduous species had lower wood density, higher predawn water potential and higher specific leaf area than evergreen species. In all cases, mature trees were more tolerant to drought. In the driest site, there was a significant reduction in water status, regardless of their leaf phenology, indicating that seasonally dry tropical forests are highly vulnerable to ENSO. Vulnerability of deciduous species is intensified in the driest areas and in the youngest trees.