Characterizing Predictability of Fire Occurrence in Tropical Forests and Grasslands: The Case of Puerto Rico

Global estimates of fire frequency indicate that over 70% of active fires occur in the tropics, and the size and frequency of fires are increasing every year. The majority of fires in the tropics are an unintended consequence of current land-use practices that promotes the establishment of grass and shrubland communities, which are more flammable and more adapted to fire than forests. In the Caribbean, wildland fires occur mainly in dry forests and in grasslands and crop lands. Climate change projections for the Caribbean indicate increasing area of drylands and subsequent increasing potential for wildland fire. We assessed the last decade of fire occurrence records for Puerto Rico to quantify the relative importance of time, climate, land cover, and population to inform predictive models of fire occurrence for projecting future scenarios of fire risk. Kruskal-Wallis, generalized linear models, robust regression, simple and multiple regressions, and tree models were used. We found that hour of the day (time), mean minimum temperature (climate), and percent forest cover (land cover) significantly influenced fire occurrence, while population showed a weak effect. Many variable interactions showed to be important. These significant variables and interactions should be considered in fire-predicting models for the island

Influence of basement membrane proteins and endothelial cell-derived factors on the morphology of human fetal-derived astrocytes in 2D.

Astrocytes are the most prevalent type of glial cell in the brain, participating in a variety of diverse functions from regulating cerebral blood flow to controlling synapse formation. Astrocytes and astrocyte-conditioned media are widely used in models of the blood-brain barrier (BBB), however, very little is known about astrocyte culture in 2D. To test the hypothesis that surface coating and soluble factors influence astrocyte morphology in 2D, we quantitatively analyzed the morphology of human fetal derived astrocytes on glass, matrigel, fibronectin, collagen IV, and collagen I, and after the addition soluble factors including platelet-derived growth factor (PDGF), laminin, basic fibroblast growth factor (bFGF), and leukemia inhibitory factor (LIF). Matrigel surface coatings, as well as addition of leukemia inhibitory factor (LIF) to the media, were found to have the strongest effects on 2D astrocyte morphology, and may be important in improving existing BBB models. In addition, the novel set of quantitative parameters proposed in this paper provide a test for determining the influence of compounds on astrocyte morphology, both to screen for new endothelial cell-secreted factors that influence astrocytes, and to determine in a high-throughput way which factors are important for translation to more complex, 3D BBB models

Land Use, Conservation, Forestry, and Agriculture in Puerto Rico

Global food security concerns emphasize the need for sustainable agriculture and local food production. In Puerto Rico, over 80 percent of food is imported, and local production levels have reached historical lows. Efforts to increase local food production are driven by government agencies, non-government organizations, farmers, and consumers. Integration of geographic information helps plan and balance the reinvention and invigoration of the agriculture sector while maintaining ecological services. We used simple criteria that included currently protected lands and the importance of slope and forest cover in protection from erosion to identify land well-suited for conservation, agriculture and forestry in Puerto Rico. Within these categories we assessed U.S. Department of Agriculture (USDA) farmland soils classification data, lands currently in agricultural production, current land cover, and current land use planning designations. We found that developed lands occupy 13 percent of Puerto Rico; lands well-suited for conservation that include protected areas, riparian buffers, lands surrounding reservoirs, wetlands, beaches, and salt flats, occupy 45 percent of Puerto Rico; potential working lands encompass 42 percent of Puerto Rico. These include lands well-suited for mechanized and non-mechanized agriculture, such as row and specialty crops, livestock, dairy, hay, pasture, and fruits, which occupy 23 percent of Puerto Rico; and areas suitable for forestry production, such as timber and non-timber products, agroforestry, and shade coffee, which occupy 19 percent of Puerto Rico

Hurricane Maria in the U.S. Caribbean: Disturbance Forces, Variation of Effects, and Implications for Future Storms

The impact of Hurricane Maria on the U.S. Caribbean was used to study the causes of remotely-sensed spatial variation in the effects of (1) vegetation index loss and (2) landslide occurrence. The vegetation index is a measure of canopy ‘greenness’, a combination of leaf chlorophyll, leaf area, canopy cover and structure. A generalized linear model was made for each kind of effect, using idealized maps of the hurricane forces, along with three landscape characteristics that were significantly associated. In each model, one of these characteristics was forest fragmentation, and another was a measure of disturbance-propensity. For the greenness loss model, the hurricane force was wind, the disturbance-propensity measure was initial greenness, and the third landscape characteristic was fraction forest cover. For the landslide occurrence model, the hurricane force was rain, the disturbance-propensity measure was amount of land slope, and the third landscape characteristic was soil clay content. The model of greenness loss had a pseudo R2 of 0.73 and showed the U.S. Caribbean lost 31% of its initial greenness from the hurricane, with 51% lost from the initial in the Luquillo Experimental Forest (LEF) from Hurricane Maria along with Hurricane Irma. More greenness disturbance was seen in areas with less wind sheltering, higher elevation and topographic sides. The model of landslide occurrence had a pseudo R2 of 0.53 and showed the U.S. Caribbean had 34% of its area and 52% of the LEF area with a landslide density of at least one in 1 km2 from Hurricane Maria. Four experiments with parameters from previous storms of wind speed, storm duration, rainfall, and forest structure over the same storm path and topographic landscape were run as examples of possible future scenarios. While intensity of the storm makes by far the largest scenario difference, forest fragmentation makes a sizable difference especially in vulnerable areas of high clay content or high wind susceptibility. This study showed the utility of simple hurricane force calculations connected with landscape characteristics and remote-sensing data to determine forest susceptibility to hurricane effects

Morphological analysis of astrocytes cultured on glass with the additional of soluble factors.

<p>(A) Percentage of cells with protrusions. Control (N = 79), PDGF (N = 81), laminin (N = 68), bFGF (N = 71), LIF (N = 74). Immunofluorescence images of (B) control and (C) astrocytes treated with LIF stained for GFAP (green) and DAPI (blue).</p

Influence of surface coatings on astrocyte morphology.

<p>(A) The cell area defined by the area of the cell body. (B) the cell diameter is overall size defined by the diameter of the smallest circle that can enclose the cell and all of its processes. (C) The protrusion length is the total length of all protrusions. (D) The degree of branching is the number of branch points divided by the number of primary protrusions. (E) The number of primary protrusions represents the number of protrusions emanating from the cell body. (F) The number of secondary protrusions represents protrusions emanating from primary protrusions. (G) The number of tertiary protrusions represents protrusions emanating from secondary protrusions. (H) The number of branch points represents the sum of secondary and other higher order protrusions (equivalent to the number of bifurcations). Data represent mean ± SE. Statistical significance was determined using a student’s t-test test. ***P≤0.01, **P≤0.05, *P≤0.1. Only cells with astrocyte-like morphology were analyzed (the total number of cells and the fraction of cells with astrocyte-like morphology are provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092165#pone-0092165-g001" target="_blank">Figure 1</a>).</p

Influence of ECM coating on astrocyte morphology after 24 hours.

<p>Fluorescence images of astrocytes stained for GFAP (green) and DAPI (blue) on (A) glass, (B) collagen I, (C) collagen IV, (D) fibronectin, (E) matrigel, and (F) co-culture on a confluent monolayer of HBMECs. (G) Astrocyte (from panel (F)) seeded on a confluent monolayer of HBMECs, stained for GFAP (green), DAPI (blue), and ZO-1 (red). (H) The percentage of cells with protrusions. Total number of cells analyzed: uncoated (N = 103), collagen I (N = 85), collagen IV (N = 61), fibronectin (N = 63), matrigel (N = 54), co-culture (N = 58).</p

Influence of soluble factors on astrocyte morphology.

<p>Data represent mean ± SE. Statistical significance was determined using a student’s t-test. ***P≤0.01, **P≤0.05, *P≤0.1. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092165#pone-0092165-g004" target="_blank">Figure 4</a> for the number of cells analyzed.</p

Tortuosity of astrocytes.

<p>(A) Immunofluorescence image of an astrocyte on HBMEC-derived ECM. Endothelial cells were grown to confluence on glass-bottom dishes, and removed from the dish with a lysis buffer containing 0.5% Triton X-100 and 20 mM NH₄OH in PBS. (B) Immunofluorescence image of an astrocyte on 50 μm inner diameter fibronectin rings. Astrocytes tended to trace the rings and have smaller cell bodies like those seen in co-culture. Fibronectin (red), GFAP (green). (C) Tortuosity of astrocytes on surface coatings and in co-culture. The tortuosity (τ) is given by τ = <i>l</i>/c where <i>l</i> is the arc length of the processes and c is the shortest end-to-end distance. For a straight line τ = 1, whereas for a circle τ = ∞. While all of the surface coatings result in very small increases over the control, the astrocytes in co-culture have significantly higher tortuosities. Statistical significance was determined using a student’s t-test. ***P≤0.01, **P≤0.05, *P≤0.1.</p

Fire weather and likelihood: characterizing climate space for fire occurrence and extent in Puerto Rico

Assessing the relationships between weather patterns and the likelihood of fire occurrence in the Caribbean has not been as central to climate change research as in temperate regions, due in part to the smaller extent of individual fires. However, the cumulative effect of small frequent fires can shape large landscapes, and fire-prone ecosystems are abundant in the tropics. Climate change has the potential to greatly expand fire-prone areas to moist and wet tropical forests and grasslands that have been traditionally less fire-prone, and to extend and create more temporal variability in fire seasons. We built a machine learning random forest classifier to analyze the relationship between climatic, socio-economic, and fire history data with fire occurrence and extent for the years 2003–2011 in Puerto Rico, nearly 35,000 fires. Using classifiers based on climate measurements alone, we found that the climate space is a reliable associate, if not a predictor, of fire occurrence and extent in this environment. We found a strong relationship between occurrence and a change from average weather conditions, and between extent and severity of weather conditions. The probability that the random forest classifiers will rank a positive example higher than a negative example is 0.8–0.89 in the classifiers for deciding if a fire occurs, and 0.64–0.69 in the classifiers for deciding if the fire is greater than 5 ha. Future climate projections of extreme seasons indicate increased potential for fire occurrence with larger extents.Fil: Van Beusekom, Ashley E.. United States Department of Agriculture; Estados UnidosFil: Gould, William A.. United States Department of Agriculture; Estados UnidosFil: Monmany, Ana Carolina. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Khalyani, Azad Henareh. State University of Colorado - Fort Collins; Estados UnidosFil: Quiñones, Maya. United States Department of Agriculture; Estados UnidosFil: Fain, Stephen J.. United States Department of Agriculture; Estados UnidosFil: Andrade Núñez, María José. Universidad de Puerto Rico; Puerto RicoFil: González, Grizelle. United States Department of Agriculture; Estados Unido