Treesearch

Tropical forests have the highest net primary productivity and soil carbon flux yet bear large uncertainties in being a carbon sink or source under changes in climate. To better understand the responses of tropical soil to climate change, we analyzed the distribution patterns of soil organic carbon and nutrients along an altitudinal gradient in the Luquillo Experimental Forest, northeastern Puerto Rico, which provides a natural approach to study how the altered temperature and precipitation impact tropical soil carbon processes. We collected soil samples at two depths (0–15 cm and 15–30...

Canopy gaps are evidence of disturbances on forest landscapes. A forest stand is in constant flux, with long stretches of biomass accumulation punctuated by episodic disturbances. We used multitemporal airborne laser scanning data to compare the gap dynamics of four Amazon forest sites. We assessed gap dynamics over 1.9–3.8 years between 2017 and 2020 at sites in the central, central eastern, southeastern, and northeastern regions of the Brazilian Amazon, over areas ranging from 590 to 1205 ha at each site. Gap size ranged from a minimum of 10 m2 to a maximum of about 10,000 m2. We...

Uncertainties about controls on tree mortality make forest responses to land-use and climate change difficult to predict. We tracked biomass of tree functional groups in tropical forest inventories across Puerto Rico and the U.S. Virgin Islands, and with random forests we ranked 86 potential predictors of small tree survival (young or mature stems 2.5–12.6 cm diameter at breast height). Forests span dry to cloud forests, range in age, geology and past land use and experienced severe drought and storms. When excluding species as a predictor, top predictors are tree crown ratio and height,...

Background: Tropical forests are critical for the global carbon budget, yet they have been threatened by deforestation and forest degradation by fre, selective logging, and fragmentation. Existing uncertainties on land cover classifcation and in biomass estimates hinder accurate attribution of carbon emissions to specifc forest classes. In this study, we used textural metrics derived from PlanetScope images to implement a probabilistic classifcation framework to identify intact, logged and burned forests in three Amazonian sites. We also estimated biomass for these forest classes using...

The effects of hurricanes Irma and Maria and a severe drought on the temperature, precipitation,and soil moisture (under canopy and in the open) were calculated at 22 sites from 0–1045m in northeastern Puerto Rico from 2001–2021, against the background short-term trend. Medianand minimum air temperatures increased uniformly across the elevational gradient, 1.6 times as fastin the air under the canopy (+0.08 °C/yr) and 2.2 times as fast in the soil under the canopy (+0.11°C/yr) as for air temperature in the open. There were no substantial moisture trends (average decrease<0.01 mm/yr). The...

For centuries, the Caribbean island of Puerto Rico has been subjected to the introduction of nonnative plant species. Various human-related activities such as agriculture, horticulture, and ornamental landscaping have resulted in the naturalization of numerous species, some of which are now representative of the island’s natural landscape. Recent floristic surveys in anthropized areas across the island yielded three new non-native plant records. We present the first reports with vouchers of Asystasia gangetica (L.) T. Anderson subsp. micrantha (Nees) Ensermu, Emilia praetermissa Milne-Redh....

A basic tenant of ecological stoichiometric theory applied to plant nutrition is that, in the absence of metabolic selection of elements, plants should reflect their soil environment. We used ecological and stoichiometric data to gain insight into how stoichiometry might influence the productivity of primary and secondary forest stands dominated by native tree species. The study involved 2 sets of measurements of soil and litter stoichiometry 26 years apart plus results from long-term ecological research in similar forest types and watersheds in the vicinity of our study area within the...

Las briofitas son un grupo diverso de plantas con distribución mundial, también conocidas como musgos, hepáticas y antocerotes. Estas pequeñas plantas absorben agua por sus hojas (filidios) y tallos (caulidios), y no necesitan raíces o sistema vascular para mantenerse hidratadas. Las briofitas se dispersan por esporas producidas en estructuras especializadas (cápsula/ esporofito) y no producen flores ni semillas. Las briofitas cumplen un rol importante en los bosques capturando agua y nutrientes de la atmósfera, manteniendo la humedad, ayudando a estabilizar el suelo y fijando carbono....

Ultramafc ecosystems are renowned for high endemism and habitat specialization. However, most of our understanding of ultramafc plant ecology comes from Medi‑ terranean and temperate climes, raising questions about the generalizability of plant responses to ultramafc soils. This is especially apparent in tropical ultramafc eco‑ systems which exhibit a wide range of endemism and diferentiation between ultra‑ mafc and adjacent non-ultramafc soils. Our objectives were two-fold: 1) synthesize our understanding of tropical ultramafc plant ecology, paying particular attention to generalities...