The potential of historical spy-satellite imagery to support research in ecology and conservation.

Remote sensing data are important for assessing ecological change, but their value is often restricted by their limited temporal coverage. Major historical events that affected the environment, such as those associated with colonial history, World War II, or the Green Revolution are not captured by modern remote sensing. In the present article, we highlight the potential of globally available black-and-white satellite photographs to expand ecological and conservation assessments back to the 1960s and to illuminate ecological concepts such as shifting baselines, time-lag responses, and legacy effects. This historical satellite photography can be used to monitor ecosystem extent and structure, species' populations and habitats, and human pressures on the environment. Even though the data were declassified decades ago, their use in ecology and conservation remains limited. But recent advances in image processing and analysis can now unlock this research resource. We encourage the use of this opportunity to address important ecological and conservation questions.

Using historical spy satellite photographs and recent remote sensing data to identify high-conservation-value forests.

High-conservation-value forests (HCVFs) are critically important for biodiversity and ecosystem service provisioning, but they face many threats. Where systematic HCVF inventories are missing, such as in parts of Eastern Europe, these forests remain largely unacknowledged and therefore often unprotected. We devised a novel, transferable approach for detecting HCVFs based on integrating historical spy satellite images, contemporary remote sensing data (Landsat), and information on current potential anthropogenic pressures (e.g., road infrastructure, population density, demand for fire wood, terrain). We applied the method to the Romanian Carpathians, for which we mapped forest continuity (1955-2019), canopy structural complexity, and anthropogenic pressures. We identified 738,000 ha of HCVF. More than half of this area was identified as susceptible to current anthropogenic pressures and lacked formal protection. By providing a framework for broad-scale HCVF monitoring, our approach facilitates integration of HCVF into forest conservation and management. This is urgently needed to achieve the goals of the European Union's Biodiversity Strategy to maintain valuable forest ecosystems.

Uso de Fotografías Históricas de Satélites Espía y Datos Recientes de Telemetría para Identificar Bosques de Alto Valor para la Conservación Resumen Los bosques de alto valor para la conservación (BAVC) tienen una importancia crítica para el suministro de servicios ambientales y biodiversidad pero enfrentan muchas amenazas. En donde hacen falta inventarios sistemáticos de los BAVC, como en partes del este de Europa, estos bosques siguen siendo ignorados y por lo tanto carecen de protección. Diseñamos una estrategia novedosa y transferible para la detección de BAVC con base en la integración de imágenes de satélites espía, datos contemporáneos de telemetría (Landsat) e información sobre las presiones antropogénicas actuales (p. ej.: infraestructura vial, densidad poblacional, demanda de leña, terreno). Aplicamos el método en los Cárpatos rumanos, para los cuales mapeamos la continuidad forestal (1955 - 2019), la complejidad estructural del dosel y las presiones antropogénicas. Identificamos 738,000 ha de BAVC. Más de la mitad de esta área fue identificada como susceptible a las actuales presiones antropogénicas y además carecía de protección formal. Mediante la aportación de un marco de trabajo para el monitoreo a escala amplia de los BAVC, nuestra estrategia facilita la integración de los BAVC dentro de la gestión y conservación de los bosques. Lo último es una necesidad urgente para alcanzar las metas de la Estrategia de Biodiversidad de la Unión Europea para mantener los ecosistemas boscosos valiosos.

Cold War spy satellite images reveal long-term declines of a philopatric keystone species in response to cropland expansion.

Agricultural expansion drives biodiversity loss globally, but impact assessments are biased towards recent time periods. This can lead to a gross underestimation of species declines in response to habitat loss, especially when species declines are gradual and occur over long time periods. Using Cold War spy satellite images (Corona), we show that a grassland keystone species, the bobak marmot (Marmota bobak), continues to respond to agricultural expansion that happened more than 50 years ago. Although burrow densities of the bobak marmot today are highest in croplands, densities declined most strongly in areas that were persistently used as croplands since the 1960s. This response to historical agricultural conversion spans roughly eight marmot generations and suggests the longest recorded response of a mammal species to agricultural expansion. We also found evidence for remarkable philopatry: nearly half of all burrows retained their exact location since the 1960s, and this was most pronounced in grasslands. Our results stress the need for farsighted decisions, because contemporary land management will affect biodiversity decades into the future. Finally, our work pioneers the use of Corona historical Cold War spy satellite imagery for ecology. This vastly underused global remote sensing resource provides a unique opportunity to expand the time horizon of broad-scale ecological studies.

The effect of protected areas on forest disturbance in the Carpathian Mountains 1985-2010.

Protected areas are a cornerstone for forest protection, but they are not always effective during times of socioeconomic and institutional crises. The Carpathian Mountains in Eastern Europe are an ecologically outstanding region, with widespread seminatural and old-growth forest. Since 1990, Carpathian countries (Czech Republic, Hungary, Poland, Romania, Slovakia, and Ukraine) have experienced economic hardship and institutional changes, including the breakdown of socialism, European Union accession, and a rapid expansion of protected areas. The question is how protected-area effectiveness has varied during these times across the Carpathians given these changes. We analyzed a satellite-based data set of forest disturbance (i.e., forest loss due to harvesting or natural disturbances) from 1985 to 2010 and used matching statistics and a fixed-effects estimator to quantify the effect of protection on forest disturbance. Protected areas in the Czech Republic, Slovakia, and the Ukraine had significantly less deforestation inside protected areas than outside in some periods; the likelihood of disturbance was reduced by 1-5%. The effectiveness of protection increased over time in these countries, whereas the opposite was true in Romania. Older protected areas were most effective in Romania and Hungary, but newer protected areas were more effective in Czech Republic, and Poland. Strict protection (International Union for Conservation of Nature [IUCN] protection category Ia-II) was not more effective than landscape-level protection (IUCN III-VI). We suggest that the strength of institutions, the differences in forest privatization, forest management, prior distribution of protected areas, and when countries joined the European Union may provide explanations for the strikingly heterogeneous effectiveness patterns among countries. Our results highlight how different the effects of protected areas can be at broad scales, indicating that the effectiveness of protected areas is transitory over time and space and suggesting that generalizations about the effectiveness of protected areas can be misleading.