Remote sensing of tropical forest degradation from selective logging

Remote sensing is the most accurate and cost effective way to monitor forests at large spatial scales. The preceding decade has seen incredible progress in accurate forest monitoring from space, with operationalized deforestation and fire alerts available in near-real-time globally. In contrast, methods for detecting and mapping forest degradation from selective logging have lagged behind; despite recognition that selective logging is a key driver of both deforestation and forest degradation. In this these I develop novel methods that utilize detailed spatial and temporal logging records to train machine learning algorithms to detect and map tropical selective logging. First, I utilized optical satellite data from the Landsat program and show that imagery acquired before the cessation of logging activities (i.e. the final cloud-free image of the dry season during logging) was best for detection, displaying a 90% detection rate (with roughly 20% commission and 8% omission error rates). Next, I tried extending this methodology to the detection of logging with synthetic aperture radar (SAR) data, but poor performance made logging predictions too uncertain. I go on to show that SAR data from Sentinel-1 display a distinct breakpoint in the time series of pixels logged under higher intensities (> 20 m3 ha-1) and could be used to detect more intensive selective logging within the Amazon. I then assess if combining optical and SAR data improve the detection of logging over the use of either on their own. I show that a combined model performs worse than optical data alone and including SAR data adds uncertainty that lowers model performance. Finally, I refine the optical approach developed in the beginning, generalizing the methodology to facilitate a large spatial and temporal scale assessment of selective logging. We create annual estimates of selective logging between 2000 and 2019 over the Brazilian state of Rondônia. I estimate that 41.0% of the State of Rondônia remained undisturbed forest through 2019, with 3.4% having undergone selective logging and 25.7% being deforested (with 13% Commission Error and 45% Omission Error over the twenty year period). In general, rates of selective logging were twice as high in the first decade relative to the last decade of the period. My results show improved access to data and technologies will enable advances in space-based forest monitoring and reiterate the value of free and open data access policies. Our approach is step in the direction of an operationalized selective logging monitoring system capable of detecting subtle forest disturbances over large spatial scales

The impact of secondary forest regeneration on ground-dwelling ant communities in the Tropical Andes

Natural regeneration of abandoned farmland provides an important opportunity to contribute to global reforestation targets, including the Bonn Challenge. Of particular importance are the montane tropics, where a long history of farming, frequently on marginal soils, has rendered many ecosystems highly degraded and hotspots of extinction risk. Ants play crucial roles in ecosystem functioning, and a key question is how time since abandonment and elevation (and inherent temperature gradients therein) affect patterns of ant recovery within secondary forest systems. Focusing on the Colombian Andes across a 1300 m altitudinal gradient and secondary forest (2–30 years) recovering on abandoned cattle pastures, we find that over time ant community composition and species richness recovered towards that of primary forest. However, these relationships are strongly dependent on elevation with the more open and warmer pasturelands supporting more ants than either primary or secondary forest at a particular elevation. The loss of species richness and change in species composition with elevation is less severe in pasture than forests, suggesting that conditions within pasture and its remaining scattered trees, hedgerows and forest fragments, are more favourable for some species, which are likely in or near thermal debt. Promoting and protecting natural regenerating forests over the long term in the montane tropics will likely offer significant potential for returning ant communities towards primary forest levels

Data from: Toward a mechanistic understanding of human-induced rapid environmental change: a case study linking energy development, nest predation, and predators

1. Demographic consequences of human-induced rapid environmental change (HIREC) have been widely documented for many populations. The mechanisms underlying such patterns, however, are rarely investigated and yet are critical to understand for effective conservation and management. 2. We investigated the mechanisms underlying reduced avian nest survival with intensification of natural gas development, an increasing source of HIREC globally. We tested the hypothesis that energy development increased the local activity of important nest predator species thereby elevating nest predation rates. During 2011–2012, we surveyed predators and monitored 668 nests of Brewer's sparrows Spizella breweri, sagebrush sparrows Artemisiospiza nevadensis and sage thrashers Oreoscoptes montanus breeding at twelve sites spanning a gradient of habitat loss from energy development in western Wyoming, USA. 3. Nine species, representing four mammalian and three avian families, were video-recorded depredating eggs and nestlings. Important nest predator species differed across songbird species, despite similar nesting habitats. Approximately 75% of depredation events were by rodents. 4. Consistent with our predictions, detections of most rodent nest predators increased with surrounding habitat loss due to natural gas development, which was associated with increased probability of nest predation for our three focal bird species. 5. An altered nest predator assemblage was therefore at least partly responsible for elevated avian nest predation risk in areas with more surrounding energy development. 6. Synthesis and applications. We demonstrate one mechanism, i.e. the local augmentation of predators, by which human-induced rapid environmental change (HIREC) can influence the demography of local populations. Given the accelerating trajectory of global energy demands, an important next step will be to understand why the activity and/or abundance of rodent predators increased with surrounding habitat loss from energy development activities

Mouse_trapping_data

Mouse capture

Scent_station_data

Visitations of meso-carnivores to scent station

Nest_records_Sagebrush

Nest records for Sagebrush Sparro

Nest_records_Brewers

Nest check data for Brewer's sparrow dat

Sciurid_survey_data

Detections of Sciurid rodents during survey

Nest_records_Sage

Nest records for Sage Thrasher

Impacts of selective logging management on butterflies in the Amazon

Selective logging for timber production affects vast areas across the tropics, yet we lack detailed understanding of the impacts of logging intensity on biodiversity. These impacts can be studied at two levels: the impacts of logging intensity on overall diversity and community composition; and how logging intensity affects individual species' abundance-logging yield relationships. The latter underpins whether land-sharing logging (i.e. low intensity throughout) or land-sparing logging (i.e. high intensity with retention of some primary forest) is the optimal strategy. We examine both levels to determine the impacts of local-scale logging intensity on butterflies in Rondônia, Brazil, the global epicenter of butterfly alpha-diversity. Overall butterfly abundance was highest at intermediate logging intensity, whereas species richness increased after logging but was not affected by logging intensity, and that species composition increasingly changed from the primary community composition at higher logging intensities. Using individual species' abundance-yield curves, we then simulated species responses to a suite of logging strategies, ranging from total sharing to total sparing. Logging simulations predicted that more butterfly species would benefit from low-intensity land-sharing logging, having higher abundances than under land-sharing scenarios. However, some butterfly clades benefited disproportionally from the retention of primary forest within land-sparing logging concessions. Butterflies overall may benefit from intermediate logging strategies that promote a combination of low and high intensity logged areas, with some protected primary forest