Increasing evidence indicates that forest disturbances are changing in response to global change, yet local variability in disturbance remains high. We quantified this considerable variability and ...analyzed whether recent disturbance episodes around the globe were consistently driven by climate, and if human influence modulates patterns of forest disturbance. We combined remote sensing data on recent (2001-2014) disturbances with in-depth local information for 50 protected landscapes and their surroundings across the temperate biome. Disturbance patterns are highly variable, and shaped by variation in disturbance agents and traits of prevailing tree species. However, high disturbance activity is consistently linked to warmer and drier than average conditions across the globe. Disturbances in protected areas are smaller and more complex in shape compared to their surroundings affected by human land use. This signal disappears in areas with high recent natural disturbance activity, underlining the potential of climate-mediated disturbance to transform forest landscapes.
Folivorous insects cause some of the most ecologically and economically important disturbances in forests worldwide. For this reason, several approaches have been developed to exploit the temporal ...richness of available satellite time series data to detect and quantify insect forest defoliation. Current approaches rely on parametric functions to describe the natural annual phenological cycle of the forest, from which anomalies are calculated and used to assess defoliation. Quantification of the natural variability of the annual phenological baseline is limited in parametric approaches, which is critical to evaluating whether an observed anomaly is “true” defoliation or only part of the natural forest variability. We present here a fully self-calibrated, non-parametric approach to reconstruct the annual phenological baseline along with its confidence intervals using the historical frequency of a vegetation index (VI) density, accounting for the natural forest phenological variability. This baseline is used to calculate per pixel (1) a VI anomaly per date and (2) an anomaly probability flag indicating its probability of being a “true” anomaly. Our method can be self-calibrated when applied to deciduous forests, where the winter VI values are used as the leafless reference to calculate the VI loss (%). We tested our approach with dense time series from the MODIS enhanced vegetation index (EVI) to detect and map a massive outbreak of the native Ormiscodes amphimone caterpillars which occurred in 2015–2016 in Chilean Patagonia. By applying the anomaly probability band, we filtered out all pixels with a probability <0.9 of being “true” defoliation. Our method enabled a robust spatiotemporal assessment of the O. amphimone outbreak, showing severe defoliation (60–80% and >80%) over an area of 15,387 ha of Nothofagus pumilio forests in only 40 days (322 ha/day in average) with a total of 17,850 ha by the end of the summer. Our approach is useful for the further study of the apparent increasing frequency of insect outbreaks due to warming trends in Patagonian forests; its generality means it can be applied in deciduous broad-leaved forests elsewhere.
Outbreaks of the Ormiscodes amphimone moth are among the largest biotic disturbances in South America, defoliating vast areas of native Nothofagus pumilio forests in the Chilean and Argentinian ...Patagonia in the last decade. Using MODIS 16-day composites of the enhanced vegetation index and the new functions of the latest release of the “npphen” R-package, we identified new maximum records of continuously defoliated area in the Aysén region (Chilean Patagonia). This approach allowed us to detect 55,193 ha and 62,344 ha of extremely defoliated N. pumilio forest in 2019 and 2022, respectively, in an area locally known as “Mallín Grande”. Extreme defoliation was accounted for by means of negative EVI anomalies with values falling among 5% of the lowest EVI records of the reference period (2000–2010). These new 2019 and 2022 outbreaks in Mallín Grande were the largest reported insect outbreaks in South American Patagonia in this century.
It is widely accepted that global warming is affecting forests near the tree line by increasing tree growth in these cold‐limited environments. However, since about 1970, a reduction in tree growth ...near the tree line has been observed in response to warming and increased drought stress. This reduction in tree growth has been mainly reported in forests of the northern hemisphere but less studied in southern forests. In this study, we investigated tree populations of Nothofagus pumilio located near the arboreal altitudinal limit in the central Patagonian Andes (45–47° S, Aysén region, Chile). In this region, warming has been accompanied by increased drought conditions since the 2000s. We explored whether this climatic variability has promoted or reduced tree growth at the regional scale in tree lines of these broadleaved temperate forests of central Patagonia. We constructed tree‐ring chronologies and determined common growth patterns and trends, and then analyzed the influence of recent climate. We detected a significant change in the slope of regional growth trends between the periods 1955–1985 and 1985–2015. We found that positive growth trends in the period 1955–1985 were associated with warmer and drier springs. However, after 1985, we found a stabilization in N. pumilio growth associated with a steady increase in temperature in autumn. Our results support the idea that more frequent warm autumns, with very thin or no snow cover, have stabilized tree growth due to water deficit at the end of the growing season of N. pumilio. The predicted climate change scenario of increasing temperatures and drought in central Patagonia may increase competition among trees for water, particularly at the end of the growing season. Consequently, we could expect a decreasing forest growth trend in central Patagonia, potentially impacting forest dynamics of these southern forests.
Forest degradation continues to increase globally, threatening biodiversity and the survival of species. In this context, identifying intact, old-growth forest stands is both urgent and vital to ...ensure their existence and multiple contributions to society. Despite the global ecological importance of the Valdivian temperate rainforests, they are threatened by forest degradation resulting from constant and intense human use in the region. Identification of remnant intact forests in this region is urgent to global forest protection efforts. In this paper, we analyzed whether forests-canopy alterations due to logging produce a distinctive canopy gap structure (e.g., a gap area and a fraction of canopy gaps in the forest) that can be used to remotely distinguish intact from altered forests. We tested this question by comparing the canopy gap structure of 12 old-growth temperate rainforests in south-central Chile (39–40° S), with different levels of canopy alterations due to logging. At each stand, we obtained aerial or satellite very high spatial-resolution images that were automatically segmented using the Mean-Shift segmentation algorithm. We validated the results obtained remotely with ground data on the canopy gap structure. We found that the variables, canopy gap fraction, gap area frequency distribution, and mean gap area could be measured remotely with a high level of accuracy. Intact forests have a distinct canopy gap structure in comparison to forests with canopy alterations due to logging. Our results provided a fast, low-cost, and reliable method to obtain canopy gap structure indicators for mapping and monitoring intact forests in the Valdivian ecoregion. The method provided valuable information for managers interested in maintaining and restoring old-growth forest structures in these southern-temperate rainforests.
Wetlands are often vital physical and social components of a country’s natural capital, as well as providers of ecosystem services to local and national communities. We performed a network analysis ...to prioritize Sustainable Development Goal (SDG) targets for sustainable development in iconic wetlands and wetlandscapes around the world. The analysis was based on the information and perceptions on 45 wetlandscapes worldwide by 49 wetland researchers of the Global Wetland Ecohydrological Network (GWEN). We identified three 2030 Agenda targets of high priority across the wetlandscapes needed to achieve sustainable development: Target 6.3—“Improve water quality”; 2.4—“Sustainable food production”; and 12.2—“Sustainable management of resources”. Moreover, we found specific feedback mechanisms and synergies between SDG targets in the context of wetlands. The most consistent reinforcing interactions were the influence of Target 12.2 on 8.4—“Efficient resource consumption”; and that of Target 6.3 on 12.2. The wetlandscapes could be differentiated in four bundles of distinctive priority SDG-targets: “Basic human needs”, “Sustainable tourism”, “Environmental impact in urban wetlands”, and “Improving and conserving environment”. In general, we find that the SDG groups, targets, and interactions stress that maintaining good water quality and a “wise use” of wetlandscapes are vital to attaining sustainable development within these sensitive ecosystems.
Se define y discute el patrimonio natural que representan los árboles monumentales, es decir, árboles de grandes dimensiones de especies nativas de Chile. Se argumenta que se debieran preservar estos ...individuos ya que: 1) potencian la fascinación natural, 2) son rarezas del mundo natural, 3) proveen servicios ecosistémicos, 4) permiten el estudio de adaptaciones de los seres vivos, 5) representan un patrimonio biocultural para el país, y 6) han sido fuertemente explotados. Se propone contar con un catastro a escala nacional de árboles monumentales, como también avanzar en legislación que brinde instrumentos a la sociedad para proteger estos árboles.
Aim: Despite several recent efforts to map plant traits and to identify their climatic drivers, there are still major gaps. Global trait patterns for major functional groups, in particular, the ...differences between woody and herbaceous plants, have yet to be identified. Here, we take advantage of big data efforts to compile plant species occurrence and trait data to analyse the spatial patterns of assemblage means and variances of key plant traits. We tested whether these patterns and their climatic drivers are similar for woody and herbaceous plants. Location: New World (North and South America). Methods: Using the largest currently available database of plant occurrences, we provide maps of 200 × 200 km grid-cell trait means and variances for both woody and herbaceous species and identify environmental drivers related to these patterns. We focus on six plant traits: maximum plant height, specific leaf area, seed mass, wood density, leaf nitrogen concentration and leaf phosphorus concentration. Results: For woody assemblages, we found a strong climate signal for both means and variances of most of the studied traits, consistent with strong environmental filtering. In contrast, for herbaceous assemblages, spatial patterns of trait means and variances were more variable, the climate signal on trait means was often different and weaker. Main conclusion: Trait variations for woody versus herbaceous assemblages appear to reflect alternative strategies and differing environmental constraints. Given that most large-scale trait studies are based on woody species, the strikingly different biogeographic patterns of herbaceous traits suggest that a more synthetic framework is needed that addresses how suites of traits within and across broad functional groups respond to climate.
RESUMEN: La estructura vertical del dosel es determinante en el funcionamiento de los bosques y el sostenimiento de la biodiversidad. En Chile, los bosques antiguos del tipo forestal siempreverde han ...sido caracterizados con una estructura de dosel mutiestratificado, no obstante, no existe certeza del número de estratos que se forman, ni cómo los procesos dinámicos influyen en esta estructuración. En este estudio se exploraron dos hipótesis alternativas para explicar la estructuración del dosel en bosques antiguos siempreverdes, i) la densidad de especies arbóreas tolerantes a la sombra propician un dosel no estratificado, y ii) la ocurrencia de disturbios (e.g. caídas individuales de árboles), permitiría que especies con distintas estrategias de vida se concentren en alturas específicas del dosel, propiciando doseles estratificados. Se pusieron a prueba estas hipótesis en cuatro bosques antiguos del tipo forestal siempreverde, donde se midieron las distribuciones de alturas de árboles y el grado de correlación entre variables verticales. Se encontraron dos a tres estratos en el dosel, cada uno conformado por grupos de especies con similares rasgos funcionales. Estos resultados apoyan la segunda hipótesis y sugieren que el patrón de agregación de copas en estratos definidos, sería explicado por las estrategias de vida de las especies, adaptadas a la ocurrencia de claros en el dosel. La dinámica de claros favorece una estratificación estable del dosel de estos bosques a lo largo de su desarrollo, aspecto relevante a considerar para la elaboración de estrategias de manejo sostenible y la conservación de la biodiversidad de estos ecosistemas.
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