Editorial: The Critical Role of Very Long-Term Studies in Ecology and Evolution

Ecological and evolutionary processes are inherently dynamic, driven by processes that often unfold over timescales that far exceed the duration of most studies. Short-term research provides valuable insights, but it captures only snapshots of these complex processes, potentially overlooking long-term patterns, counter-intuitive interactions and delayed responses. This special issue of Ecology Letters, titled ‘Ecological and Evolutionary Insights from Very Long-Term Studies’, highlights the unique and indispensable contributions of studies that have maintained consistent observations for two decades or more. Taken collectively, these studies demonstrate that the value of long-term studies increases with time.

In fact, while very long-term ecological studies are rare, in part because of the sustained commitment required to maintain them, they are essential for understanding the full complexity of natural systems (Jones and Driscoll 2022). Many ecological processes, such as species interactions, population dynamics and responses to environmental change, can only be fully understood by observing them over decades. This is true for unravelling fundamental ecological and evolutionary mechanisms but also to study and model the responses of ecosystems to anthropogenic pressures. The IPBES (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services) and IPCC (Intergovernmental Panel on Climate Change) have indeed both emphasised the urgent need for long-term data to inform our understanding of biodiversity loss and climate change impacts.

These global assessments point to the critical role that long-term monitoring plays in detecting trends, predicting future changes, guiding policy (Hughes et al. 2017) and shaping effective conservation and management strategies. Very long-term studies also have the potential to profoundly shift our thinking with regard to long-standing theoretical paradigms in ecology. Thus, such studies have contributed to recent models of how ecological disturbance plays out over multiple spatio-temporal scales, identifying the conditions that drive the emergence of new ecosystem states and how disturbance influences socio-economic dynamics (Gaiser et al. 2020).

This special issue brings together studies that span from 20 to 54 years, showcasing the power of long-term monitoring to uncover ecological and evolutionary processes that would otherwise remain hidden. The range of taxa studied includes birds, plants, insects and marine species, offering a comprehensive view of how different life forms respond to environmental variability and anthropogenic pressures over extended periods of time.

For example, a 54-year dataset on snow petrels (Pagodroma nivea) reveals how climate change is reshaping pair bond dynamics, with increasing rates of divorce and widowhood linked to changing environmental conditions (Sun et al. 2024). These disruptions are shown to have profound effects on breeding success and population dynamics. Another study draws on 46 years of monitoring shorebirds, revealing a clear trend of shrinking body size and lengthening bills—an adaptation likely driven by global warming (McQueen et al. 2024). Such long-term data are invaluable for understanding how species adjust to slow, gradual changes, as well as to extreme events, which may go unnoticed in shorter studies.

Additionally, a 22-year study of seed production in a wet Amazonian forest has shown that rising night-time temperatures and declining moisture levels are directly impacting plant reproduction, with significant implications for forest structure, species interactions and community composition (Vleminckx et al. 2024). These findings align with IPCC reports that highlight the vulnerability of tropical ecosystems to climate change, especially in terms of biodiversity shifts and ecosystem resilience. Understanding these long-term impacts is critical for predicting how global climate and biodiversity crises will unfold in the coming decades.

Many of the studies featured in this issue also provide insights into the resilience of ecosystems in the face of anthropogenically driven global change. The combination of long-term ecological data and evolutionary perspectives enables researchers to trace how species have adapted—or failed to adapt—over generations, providing critical knowledge for biodiversity conservation. For instance, IPBES has stressed the importance of understanding not just biodiversity loss but also the mechanisms behind species persistence and adaptation, which very long-term studies are uniquely positioned to uncover (Cocciardi et al. 2024).

These long-term datasets are particularly crucial for organisms with multi-year or complex life cycles, allowing researchers to capture the full span of individual life histories and to understand how early-life conditions, extreme climatic events and ongoing anthropogenic pressures shape their futures. Long-term studies also allow us to examine how changes occurring over just a few generations can influence macroevolutionary patterns, reconciling the timescales of ecology and evolution, the subject of a recent Ecology Letters special issue. This is vital for making informed decisions about biodiversity preservation, ecosystem management and restoration efforts.

However, despite their importance, very long-term studies face significant challenges, particularly in securing sustained funding (Lindenmayer et al. 2012). Most ecological studies last < 5 years, making it difficult to obtain the resources needed to continue research for decades. The contributions in this special issue not only highlight the scientific value of long-term studies but also advocate for greater investment in these essential research programmes. Both IPBES and IPCC reports call for enhanced monitoring efforts to track the long-term effects of global change on biodiversity and ecosystems, emphasising the need for sustained support for such initiatives.

We hope this special issue serves as a testament to the profound insights that very long-term studies can provide. It is our hope that these studies will inspire researchers, funding bodies and policymakers alike to recognise the critical importance of long-term ecological research and to commit to supporting these indispensable projects. Only with a long-term vision can we fully understand the complex, ongoing processes that shape the natural world and, ultimately, inform the actions needed to preserve it for future generations.