Airborne Laser Scanning (ALS) has been considered as a primary source to model the structure and function of a forest canopy through the indicators leaf area index (LAI) and vertical canopy profiles of leaf area density (LAD). However, little is known about the effects of the laser pulse density and the grain size (horizontal binning resolution) of the laser point cloud on the estimation of LAD profiles and their associated LAIs. Our objective was to determine the optimal values for reliable and stable estimates of LAD profiles from ALS data obtained over a dense tropical forest. Profiles were compared using three methods: Destructive field sampling, Portable Canopy profiling Lidar (PCL) and ALS. Stable LAD profiles from ALS, concordant with the other two analytical methods, were obtained when the grain size was less than 10 m and pulse density was high (>15 pulses m−2). Lower pulse densities also provided stable and reliable LAD profiles when using an appropriate adjustment (coefficient K). We also discuss how LAD profiles might be corrected throughout the landscape when using ALS surveys of lower density, by calibrating with LAI measurements in the field or from PCL. Appropriate choices of grain size, pulse density and K provide reliable estimates of LAD and associated tree plot demography and biomass in dense forest ecosystems.

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Extreme precipitation events affect water quantity and quality in various regions of the world. Heavy precipitation in 2019 resulted in a record high area of unplanted agricultural fields in the U.S. and especially in the Maumee River Watershed (MRW). March−July phosphorus (P) loads from the MRW drive harmful algal bloom (HAB) severity in Lake Erie; hence changes in management that influence P export can ultimately affect HAB severity. In this study, we found that the 2019 dissolved reactive P (DRP) load from March−July was 29% lower than predicted, while the particulate P (PP) load was similar to the predicted value. Furthermore, the reduced DRP load resulted in a less severe HAB than predicted based on discharge volume. The 29% reduction in DRP loss in the MRW occurred with a 62% reduction in applied P, emphasizing the strong influence of recently applied P and subsequent incidental P losses on watershed P loading. Other possible contributing factors to this reduced load include lower precipitation intensity, altered tillage practices, and effects of fallow soils, but more data is needed to assess their importance. We recommend conservation practices focusing on P application techniques and timing and improving resiliency against extreme precipitation events.

Cloud forest in the Central Highlands of Guatemala provides important ecosystem services for the Q'eqchi' Maya but has been disappearing at an increasing rate in recent decades. This research documents changes in cloud forest cover, explores some contributing factors to deforestation, and considers forest preservation and food security implications for Q'eqchi' communities. We used a transdisciplinary framework that synthesized remote sensing/GIS analysis of land cover change, focus group dialogs, and surveys. Expansion of subsistence agriculture is a key proximate cause of cloud forest removal, followed by extraction of fuelwood and larger-scale logging operations. Predisposing environmental factors such as rugged topography, steep slopes, and poor soils contribute to low agricultural productivity that contributes to increased conversion of forest to agricultural land. The key underlying driving forces for deforestation locally are population growth and subdivision of land. Population growth is increasing the demand for agricultural land and, as a result, the Q'eqchi' clear the forest to meet the need for increased food production. Furthermore, population growth is driving subdivision of land, decreasing fallow periods, and putting additional strain on poor soils, all of which exacerbate land degradation. Given the increase in population in the region, food production must be improved on existing agricultural land to avoid the need to put more land into production to meet food requirements. Thus, efforts to sustainably increase agricultural productivity are fundamental to efforts to conserve the cloud forest and to safeguard essential ecosystem services.