Agents of Forest Disturbance in the Argentine Dry Chaco

Abstract

Forest degradation in the tropics is a widespread, yet poorly understood phenomenon. This is particularly true for tropical and subtropical dry forests, where a variety of disturbances, both natural and anthropogenic, affect forest canopies. Addressing forest degradation thus requires a spatially-explicit understanding of the causes of disturbances. Here, we apply an approach for attributing agents of forest disturbance across large areas of tropical dry forests, based on the Landsat image time series. Focusing on the 489,000 km2 Argentine Dry Chaco, we derived metrics on the spectral characteristics and shape of disturbance patches. We then used these metrics in a random forests classification framework to estimate the area of logging, fire, partial clearing, riparian changes and drought. Our results highlight that partial clearing was the most widespread type of forest disturbance from 1990–to 2017, extending over 5520 km2 (±407 km2), followed by fire (4562 ± 388 km2) and logging (3891 ± 341 km2). Our analyses also reveal marked trends over time, with partial clearing generally becoming more prevalent, whereas fires declined. Comparing the spatial patterns of different disturbance types against accessibility indicators showed that fire and logging prevalence was higher closer to fields, while smallholder homesteads were associated with less burning. Roads were, surprisingly, not associated with clear trends in disturbance prevalence. To our knowledge, this is the first attribution of disturbance agents in tropical dry forests based on satellite-based indicators. While our study reveals remaining uncertainties in this attribution process, our framework has considerable potential for monitoring tropical dry forest disturbances at scale. Tropical dry forests in South America, Africa and Southeast Asia are some of the fastest disappearing ecosystems on the planet, and more robust monitoring of forest degradation in these regions is urgently needed.

Global change impacts on cacti (Cactaceae): current threats, challenges and conservation solutions

“…However, the emerging threat of wildfires to native cacti in tropical dry forests is not driven exclusively by grass invasion and climate change. For example, most of the fires that now occur in the dry Chaco of northern Argentina are from human ignition sources to clear shrubs and promote grass productivity in pastures ( Boletta et al , 2006 ; De Marzo et al , 2022 ). These fires often spread into neighbouring forests that host a high diversity of species of cacti, including the iconic giant cacti Stetsonia coryne and Echinopsis terscheckii .…”

“…For example, in Costa Rica, fire prevention strategies in protected areas have fostered a quantifiable increase in forest structure and species richness ( Powers et al , 2009 ). Likewise, the Argentine Forest Law, passed in 2007, has had some success in preventing fires and reducing land clearance in the Argentine Chaco region ( De Marzo et al , 2022 ). Likewise, in Mexico, the federally supported and publicly available biodiversity informatics database (CONABIO; Soberón, 2022 ) is being used widely to track wildfires in real time ( Ressl et al , 2009 ), thereby increasing the capacity to respond rapidly to wildfires in some of the most biologically sensitive regions of the country.…”

¿Qué es un bosque nativo en la Argentina? Marco conceptual para una correcta definición de acuerdo con las políticas institucionales nacionales y el conocimiento científico disponible

“…En consecuencia, esto podría derivar en la transformación y la pérdida de resiliencia de los ecosistemas bajo manejo (Lund 2002;Romjin et al 2013;Sasaki and Putz 2009). Un ejemplo claro es el manejo ganadero intensivo bajo bosques nativos, que promueve, en general, la pérdida paulatina de la cobertura forestal, con una transformación severa del sotobosque; con el tiempo, esto altera de forma severa la estructura y la capacidad de renovación de dicha cobertura (Cotroneo et al 2021;de Marzo et al 2021de Marzo et al , 2022. El uso del bosque nativo con distintos objetivos (e.g., forestal, maderero, ganadero, recreacional) (Peri et al 2021a(Peri et al ,b, 2022 genera un gradiente de condiciones de rodal.…”

Tropical Forest Disturbance Monitoring Based on Multi-Source Time Series Satellite Images and the LandTrendr Algorithm

“…Although the LandTrendr algorithm has been used extensively to monitor forest disturbances, multiple disturbances are rarely observed [11,12,14,58]. In fact, forests are prone to multiple disturbances over a period of up to 30 years, especially in tropical regions where there are large numbers of fast-growing forests, such as eucalyptus.…”

“…Field surveys are a traditional method for the high-precision monitoring of forest disturbances, but they are time consuming, labor intensive, and limited in terms of time and space [9]. In contrast, remote sensing is a practical solution for forest disturbance monitoring because it allows rapid image acquisition, provides large spatial coverage, and is widely used to monitor forest disturbances caused by human-induced (logging [10,11], disforest), natural (fire [12,13], drought [14,15], pests and diseases [10,16]), or unknown factors [17][18][19]. Developing or selecting an appropriate disturbance monitoring algorithm is a key step in forest disturbance monitoring.…”