Gene E. Likens's research while affiliated with Cary Institute of Ecosystem Studies and other places

Publications (498)

Article
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Resilience is the ability of ecosystems to maintain function while experiencing perturbation. Globally, forests are experiencing disturbances of unprecedented quantity, type, and magnitude that may diminish resilience. Early warning signals are statistical properties of data whose increase over time may provide insights into decreasing resilience,...
Article
Applying World Heritage status to highly valuable environmental records would spotlight the vital insights they provide into how Earth is changing and would ensure their longevity and accessibility.
Article
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Atmospheric deposition of dissolved organic carbon (DOC) to terrestrial ecosystems is a small, but rarely studied component of the global carbon (C) cycle. Emissions of volatile organic compounds (VOC) and organic particulates are the sources of atmospheric C and deposition represents a major pathway for the removal of organic C from the atmosphere...
Article
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Ecosystems are influenced by multiple drivers, which shape ecosystem state and biodiversity. In some ecosystems, interactions and feedbacks among drivers can produce traps that confine an ecosystem to a particular state or condition and influence processes like succession. A range of traps has been recognized, with one of these – “a landscape trap”...
Article
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Factors driving freshwater salinization syndrome (FSS) influence the severity of impacts and chances for recovery. We hypothesize that spread of FSS across ecosystems is a function of interactions among five state factors: human activities, geology, flowpaths, climate, and time. (1) Human activities drive pulsed or chronic inputs of salt ions and m...
Article
Aldo Leopold's essay, “Odyssey”, may have contributed to the development of the ecosystem concept and approach.
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In the face of mounting environmental and political challenges in river management, accurate and timely scientific information is required to inform policy development and guide effective management of waterways. The Murray–Darling Basin is Australia's largest river system by area and is the subject of a heavily contested series of water reforms re...
Article
Sitting at the interface of human societies and the natural environment are sentinels tracking environmental change. Across the globe, field stations and marine laboratories (FSMLs) amass crucial information about climate, biodiversity, environmental health, and emerging diseases, anchoring multidecadal data sets needed to solve environmental chall...
Preprint
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In the face of mounting environmental problems, it is essential that accurate and timely scientific information is available to inform policy development and guide management. Scientists have specialised knowledge necessary for evidenced-based decision making, but despite extensive literature on the interface between science and policy, there is li...
Article
Ecosystems constantly adjust to altered biogeochemical inputs, changes in vegetation and climate, and previous physical disturbances. Such disturbances create overlapping ‘biogeochemical legacies’ affecting modern nutrient mass balances. To understand how “legacies” affected watershed-ecosystem biogeochemistry during five decades of studies within...
Preprint
Full-text available
Ecosystems are influenced by multiple drivers which shape ecosystem state and biodiversity. In some ecosystems, interactions and feedbacks between drivers can produce traps that confine an ecosystem to a particular state or condition and influence processes like succession. A range of traps have been recognized, with one of these – “a landscape tra...
Article
Full-text available
Freshwater salinization is an emerging global problem impacting safe drinking water, ecosystem health and biodiversity, infrastructure corrosion, and food production. Freshwater salinization originates from diverse anthropogenic and geologic sources including road salts, human-accelerated weathering, sewage, urban construction, fertilizer, mine dra...
Article
Continuous monitoring of precipitation chemistry began at the Hubbard Brook Experimental Forest, NH in June 1963, and it was there that acid rain was discovered in North America. Some independent monitoring of precipitation chemistry in central New York was done in 1970–1971. The MAP3S network (Charlottesville, VA, Ithaca, NY, Penn State, PA, White...
Chapter
This introduction briefly describes the book’s content. The book defines the ecosystem, describes the chief characteristics of ecosystems and the major tools used to analyze them, and presents major discoveries that scientists have made about ecosystems. It also lays out important questions for the future. In addition, although the book is not spec...
Chapter
Ecosystem science is a young field that is still evolving rapidly. This chapter provides a few examples of how ecosystem science is changing and is likely to change in the future. The chapter briefly considers how ecosystem science may change in response to advances in technology, the need to understand and manage the effects of humans on ecosystem...
Chapter
The wet and dry deposition of acidic substances from the atmosphere to landscapes (acid rain) is a serious environmental problem, negatively impacting aquatic and terrestrial ecosystems. Fog water can be more acidic than rain at a specific site. Because legislation has reduced emissions of sulfur and nitrogen oxides, the precursors to the formation...
Article
Early studies published in Ambio showed large-scale acidification of lakes in southern Sweden and Norway from acid rain. These studies were important for delimiting various scientific issues and thus for eventually contributing to legislation, which reduced emissions of sulfur dioxide and nitrogen oxides and helped to mitigate this major environmen...
Article
Changes in the amount, intensity, and timing of precipitation are increasing hydrologic variability in many regions, but we have little understanding of how these changes are affecting freshwater species. Stream-breeding amphibians—a diverse group in North America—may be particularly sensitive to hydrologic variability during aquatic larval and met...
Article
For the only time in 52 years of monitoring the ice-cover dynamics of Mirror Lake, New Hampshire, USA, complete ice cover formed for 6 continuous days (24–30 Nov 2018), melted to open water for 5 continuous days (30 Nov to 4 Dec 2018), and then refroze from 4 December 2018 through 26 April 2019.
Article
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Widespread changes in water temperatures, salinity, alkalinity and pH have been documented in inland waters in North America, which influence ion exchange, weathering rates, chemical solubility and contaminant toxicity. Increasing major ion concentrations from pollution, human-accelerated weathering and saltwater intrusion contribute to multiple ec...
Article
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While much research over the past 30 years has focused on the deleterious effects of excess N on forests and associated aquatic ecosystems, recent declines in atmospheric N deposition and unexplained declines in N export from these ecosystems have raised new concerns about N oligotrophication, limitations of forest productivity, and the capacity fo...
Article
In many temperate forested watersheds, hydrologic nitrogen export has declined substantially in recent decades, and many of these watersheds show enduring effects from historic acid deposition. A watershed acid remediation experiment in New Hampshire, U.S.A. reversed many of these legacy effects of acid deposition and also increased watershed nitro...
Article
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We propose an important revision to a previously published conceptual model of nutrient retention during terrestrial ecosystem succession, which predicted that ecosystem losses of limiting nutrients such as nitrogen (N) should increase as rates of biomass accumulation slow during late stages of succession. This revision explicitly recognizes that m...
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We summarize past examples of the use of science to document the effectiveness of policy in air quality management. Our goal is to inform public discourse amidst attempts to negate the relevance and value of scientific data and fact-based analysis in favor of partisan opinion and ideology. Although air quality is fundamental to environmental and hu...
Article
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Significance Salinization and alkalinization impact water quality, but these processes have been studied separately, except in arid regions. Globally, salinization has been largely attributed to agriculture, resource extraction, and land clearing. Alkalinization has been attributed to recovery from acidification, with less recognition as an environ...
Book
Long-term monitoring programs are fundamental to understanding the natural environment and managing major environmental problems. Yet they are often done very poorly and ineffectively. This second edition of the highly acclaimed Effective Ecological Monitoring describes what makes monitoring programs successful and how to ensure that long-term moni...
Chapter
Acid rain, or acid deposition, was determined to be a widespread environmental problem in the late 1960s and early 1970s in eastern North America and northwestern Europe. Acid deposition is largely attributed to the burning of fossil fuels, which in turn releases the acid deposition precursors, sulfur dioxide (SO2), mainly from power plants, and ni...
Article
Earth observation networks (EONs) are an emerging, surveillance-based approach to environmental monitoring and research that are fundamentally different than traditional question-driven, experimentally designed approaches. There is an urgent need to find an optimal balance between these approaches and to develop new integrated initiatives that take...
Article
The Hubbard Brook Ecosystem Study officially began on 1 June 1963. This archive contains the results of 50 yr of collection and analysis of (at least) weekly stream water and precipitation samples obtained during the period 1963–2014 (from 1 June 1963 to 30 May 2013). Stream chemistry for the nine gauged watersheds and precipitation chemistry for p...
Article
We introduce a new representation of coupled solute and water age dynamics at the catchment scale, which shows how the contributions of young runoff waters can be directly referenced to observed water quality patterns. The methodology stems from recent trends in hydrologic transport that acknowledge the dynamic nature of streamflow age and explores...
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This study evaluated the contribution of winter rain-on-snow (ROS) events to annual and seasonal nitrate (N-NO3) export and identified the regional meteorological drivers of inter-annual variability in ROS N-NO3 export (ROS-N) at 9 headwater streams located across Ontario, Canada and the northeastern United States. Although on average only 3.3 % of...
Article
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Monitoring solutes in precipitation inputs and stream water exports at small watersheds has greatly advanced our understanding of biogeochemical cycling. Surprisingly, although inputs to and outputs from ecosystems are instrumental to understanding sources and sinks of nutrients and other elements , uncertainty in these fluxes is rarely reported in...
Article
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Biological field stations (BFS) constitute a global network for long-term environmental monitoring and research, education, and public information. On the basis of a comprehensive inventory, we identified 1268 contemporary BFS, located in 120 countries. BFS occur in all biomes and cover terrestrial, freshwater, and marine systems, with the majority...
Article
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In terrestrial ecosystems, a large portion (20-80%) of the dissolved Si (DSi) in soil solution has passed through vegetation. While the importance of this ‘terrestrial Si filter’ is generally accepted, few data exist on the pools and fluxes of Si in forest vegetation and the rate of release of Si from decomposing plant tissues. We quantified the po...
Article
Significance Acid rain has stripped forests of soil calcium, with consequences for forest health and downstream ecosystems. In 1999, researchers initiated a whole-watershed experiment, with the goal of replacing all the calcium lost. This experiment increased the pH and acid-neutralizing capacity of soils and streamwater, and forest growth increase...
Article
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Significance This research breaks new ground by showing that, contrary to generally accepted theories of ecosystem development, calcium depletion has been occurring for millennia as a natural consequence of long-term ecosystem development. This natural process predisposed forest ecosystems in the region to detrimental responses to acid rain in the...
Article
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Altered atmospheric circulation, reductions in Arctic sea ice, ocean warming, and changes in evaporation and transpiration are driving changes in the global hydrologic cycle. Precipitation isotopic (δ18O and δ2H) measurements can help provide a mechanistic understanding of hydrologic change at global and regional scales. To study the changing water...
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Nitrogen (N) supply often limits the productivity of temperate forests and is regulated by a complex mix of biological and climatic drivers. In excess, N is linked to a variety of soil, water, and air pollution issues. Here, we use results from an elevation gradient study and historical data from the longterm Hubbard Brook Ecosystem Study (New Hamp...
Article
Biological field stations (BFS) constitute a global network for long-term environmental monitoring and research, education, and public information. On the basis of a comprehensive inventory, we identified 1268 contemporary BFS, located in 120 countries. BFS occur in all biomes and cover terrestrial, freshwater, and marine systems, with the majority...
Article
We combine experimental and modeling results from a headwater catchment at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA, to explore the link between stream solute dynamics and water age. A theoretical framework based on water age dynamics, which represents a general basis for characterizing solute transport at the catchment scal...
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Wikipedia has quickly become one of the most frequently accessed encyclopedic references, despite the ease with which content can be changed and the potential for 'edit wars' surrounding controversial topics. Little is known about how this potential for controversy affects the accuracy and stability of information on scientific topics, especially t...
Article
In 2050, which aspects of ecosystem change will we regret not having measured? Long-term monitoring plays a crucial part in managing Australia's natural environment because time is a key factor underpinning changes in ecosystems. It is critical to start measuring key attributes of ecosystems - and the human and natural process affecting them - now,...
Article
Precipitation composition was characterized at 14 remote sites between 65°N and 51°S. Anthropogenic sources contributed to non-sea-salt (nss) SO42-, NO3-, and NH4+ in North Atlantic precipitation. Biogenic sources accounted for 0.4-3.3 μeq L-1 of volume-weighted-average (VWA) nss SO42- in marine precipitation. SO42- at the continental sites (2.9-7....
Article
Uncertainty in the estimation of hydrologic export of solutes has never been fully evaluated at the scale of a small‐watershed ecosystem. We used data from the Gomadansan Experimental Forest, Japan, Hubbard Brook Experimental Forest, USA, and Coweeta Hydrologic Laboratory, USA, to evaluate many sources of uncertainty, including the precision and ac...
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Significance Headwater streams are important sources of water for downstream ecosystems and human communities. These streams comprise the vast majority of stream and river kilometers in watersheds and affect regional water quality. However, the actual spatial variation of water quality in headwater streams is often unknown. Our study uses an unusua...
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A holy grail of conservation is to find simple but reliable measures of environmental change to guide management. For example, particular species or particular habitat attributes are often used as proxies for the abundance or diversity of a subset of other taxa. However, the efficacy of such kinds of species-based surrogates and habitat-based surro...
Article
Large old trees are critical organisms and ecological structures in forests, woodlands, savannas, and agricultural and urban environments. They play many essential ecological roles ranging from the storage of large amounts of carbon to the provision of key habitats for wildlife. Some of these roles cannot be replaced by other structures. Large old...
Article
We present a detailed case study of conservation and restoration of the Australian arboreal marsupial Leadbeater's Possum (Gymnobelideus leadbeateri) and its Mountain Ash forest habitat to illustrate the important intersection between forest restoration principles and the general principles for forest biodiversity conservation. Mountain Ash forests...
Chapter
This case study discusses an ecosystem approach to the problem of acid rain, specifically in the White Mountains of NH. Long-term studies of forest, lake, and stream ecosystems have revealed findings about this complexity that are important to the understanding and management of acid rain as an environmental problem, causing changes in sulfur dioxi...
Article
Faison (2013) suggested the dynamics of large old tree populations is more complicated than discussed in Lindenmayer et al. (2013) and presented inventory information indicating the volume of these trees appears to be increasing in some ecosystems. We welcome such temporal changes but suggest the over-simplified perspective by Faison (2013) is misl...
Technical Report
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Research on the hydrogeologic setting of Mirror Lake near West Thornton, New Hampshire (43° 56.5’ N, 71° 41.5’ W), includes the study of the physical, chemical, and isotopic characteristics of groundwater in the vicinity of the lake and nearby Hubbard Brook. Presented here are those physical, chemical, and isotopic data for the period 1983 to 1997....
Article
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After calcium silicate amendment to an entire watershed at the Hubbard Brook Experimental Forest, evapotranspiration (ET) increased by ∼20% for 2 y, broadly attributed to a fertilization of tree physiology (1). We suggested that the increase in ET most likely arose from enhanced transpiration due to increased stomatal conductance (gs) associated wi...
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Forested headwater streams play an important role in watershed nutrient dynamics, and wood is thought to be a key factor influencing habitat structure and nitrate-nitrogen dynamics in many forested streams. Because wood in streams can promote nitrogen uptake through denitrification, we hypothesized that nitrate uptake velocities would decrease foll...
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The 3,519-ha Hubbard Brook Experimental Forest (HBEF) was established in 1955 as the primary hydrological research facility in the northeastern USA. In 1963, FH Bormann, GE Likens, NM Johnson, and RS Pierce initiated the Hubbard Brook Ecosystem Study (HBES) to assess mass balance water and chemical budgets using gauged watersheds. From the study's...
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The interaction between human activities and watershed geology is accelerating long-term changes in the carbon cycle of rivers. We evaluated changes in bicarbonate alkalinity, a product of chemical weathering, and tested for long-term trends at 97 sites in the eastern United States draining over 260,000 km2. We observed statistically significant in...
Chapter
This book summarizes current understanding of the biogeochemistry of a northern hardwood forest ecosystem at the HBEF in the White Mountains of New Hampshire. It emphasizes the usefulness of the small watershed technique for biogeochemical measurement in shedding light on ecosystem function and change. The characteristics of the HBEF watersheds rev...
Chapter
Samples of precipitation and stream water are obtained from the experimental watersheds for chemical analysis. Rain and snow are sampled with continuously open plastic collectors, i.e., bulk precipitation samples (Likens et al. 1967; Buso et al. 2000) collected at weekly intervals. Samples of stream water are collected by hand each week and during...
Chapter
Because our ecosystems are watersheds, the flux of chemicals into the system may be simplified to that in atmospheric deposition (meteorologic vector) and the output to that in drainage waters (geologic vector), at least for those nutrients without a prominent gaseous phase (Bormann and Likens 1967; Likens and Bormann 1972). Theoretically, then, th...
Chapter
Forests and woodlands cover some 57 × 106 km2, which is about 38 % of the total continental area or 11 % of the Earth’s surface. Despite this relatively small area, 92 % of the Earth’s plant biomass and 46 % of its annual net primary production come from forest (Table 33). The ~80 billion metric tons of dry plant matter produced (net) each year by...
Chapter
Because of the vital role of water as a transporting agent, chemical solvent, weathering agent, and catalyst, quantitative data on hydrology are of paramount importance in understanding the biogeochemistry of a forest ecosystem. The U.S. Forest Service has monitored and maintained accurate records of precipitation and streamflow for numerous gauged...
Chapter
Both the qualitative and the quantitative changes in water chemistry elicited during the passage of water through the ecosystem are related in part to the process of chemical weathering. The bulk ionic composition of water entering the Hubbard Brook ecosystem is essentially characterized by acid salts, such as H2SO4, HNO3, and HCl. In contrast, wat...
Chapter
Chemical elements without a prominent gaseous phase at normal biologic temperature, such as calcium, magnesium, and potassium, have what is referred to as a sedimentary biogeochemical cycle (Odum 1959). That is, flux and cycling are affected primarily by hydrologic factors (including dissolution, erosion, and sedimentation), landslides, vulcanism,...
Chapter
An ecological system has a richly detailed series of inputs and outputs of energy and matter. Because of the lack of precise information about these relationships and the internal functions that maintain the ecosystem, it is often difficult to assess the impact of human activities on the biosphere. As a result, land-use managers and planners often...
Article
Acid deposition during the 20th century caused widespread depletion of available soil calcium (Ca) throughout much of the industrialized world. To better understand how forest ecosystems respond to changes in a component of acidification stress, an 11.8-ha watershed was amended with wollastonite, a calcium silicate mineral, to restore available soi...
Chapter
Acid rain is a popular term that can include all forms of precipitation, as well as fog and cloudwater, that is more acidic than expected from natural causes. Natural background levels of precipitation acidity tend to be around pH of 5.1–5.2. This compares with present annual average values of pH 4.3–4.4 for parts of eastern North America, and pH v...
Article
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A current pine beetle infestation has caused extensive mortality of lodgepole pine (Pinus contorta) in forests of Colorado and Wyoming; it is part of an unprecedented multispecies beetle outbreak extending from Mexico to Canada. In United States and European watersheds, where atmospheric deposition of inorganic N is moderate to low (<10 kg⋅ha⋅y), d...
Book
"The goal of this Third Edition is to update long-term data presented in earlier editions and to generate new syntheses and conclusions about the biogeochemistry of the Hubbard Brook Valley based on these longer-term data. There have been many changes, revelations, and exciting new insights generated from the longer data records. For example, the i...
Article
Recent debates have discussed whether a species-approach or an ecosystem-approach is better for protecting biodiversity. Rather than perpetuate this debate, we argue that critical new scientific and conservation insights arise from combining and integrating approaches along a continuum. We present a suite of case studies and other examples, which h...
Article
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In response to decreasing atmospheric emissions of sulfur (S) since the 1970s there has been a concomitant decrease in S deposition to watersheds in the Northeastern U.S. Previous study at the Hubbard Brook Experimental Forest, NH (USA) using chemical and isotopic analyzes ( $ \delta^{34} {\text{S}}_{{{\text{SO}}_{4} }} $ ) combined with modeling...

Citations

... This cycle is dictating the chemical composition of the crust and the oceans. Recently, it has been advocated that humans are beginning to also dominate this cycle on a global scale (Kaushal et al., 2023). Furthermore, the salinity of vapors and supercritical fluids significantly influences the solubility of other solutes in this cycle, directly affecting the formation and localization of valuable ore deposits (Seward et al., 2014;Williams-Jones and Heinrich, 2005;Pokrovski et al., 2013). ...
... Additionally, persistent or older habitats usually present a more complex vegetation structure and a more diverse collection of habitat niches that take time to develop in the ecological succession, such as tree cavities or wood decay, creating favorable conditions for a higher diversity of organisms, particularly specialist species (Janssen et al., 2017;Nordén et al., 2014). Species life-history traits determine their different responses to land cover change and persistence, namely their habitat specificity of different life stages, longevity, and dispersal capability (Lindenmayer et al., 2023;Lira et al., 2019). Species that are habitat specialists at any life stage, long-lived, and with restricted dispersal, tend to show a more delayed response (e.g. ...
... from this near-60 year journey which may contribute a wider reflection on the future goals and value of the increasing number of longterm studies in environmental science (e.g. Holmes & Likens, 2016;Rosi et al., 2023;Tetzlaff et al., 2017) that are perpetually threatened by reduced funding and constrained resources Rosi et al., 2023). We do this from the perspective that we are in unchartered waters with regards to the declining status of Atlantic salmon, associated climate change and the biodiversity crises (Scottish Government, Marine Scotland, 2023). ...
... These sites reflect the diversity of the world's natural and cultural heritage and are considered to be of 'outstanding universal value' [3]. WHs have both natural and cultural attributes, which means we can combine spatial technology with archaeological excavation surveys to build comprehensive database [4,5]. The inclusion of spatial technology provides a new window for the conservation and development of WHs, especially for SDG11. ...
... While it is well established that allochthonous DOM is an important input of energy to rivers (Vannote et al., 1980) and could promote metabolic pathways for N within the Lamprey River (Herreid et al., 2021), this system is not carbon limited to the extent that DOM deposition would have such a measurable impact on denitrification. Nonetheless, the role of wet deposition DON and DOC to terrestrial and surface water chemistry remains relatively unexplored due to the lack of monitoring for wet deposition organic matter (Cornell, 2011;Liptzin et al., 2022). ...
... Global freshwater resources, which provide water for human and livestock consumption and industrial processes, are under increasing threat of salinization-the increase in salt concentrations in soils and aquatic bodies (Cunillera-Montcusí et al., 2022;Jackson et al., 2001;Kaushal et al., 2019;Kaushal et al., 2023). Historically, salinization is attributed to catchment geology, with the rate of weathering and local hydrologic processes determining salt composition and concentration. ...
... Ecosystem integrity refers to the completeness and balance of ecological systems, where ecosystems are able to maintain their characteristic levels of bio-and geodiversity, structures and functions over time. It encompasses the health and functionality of ecosystems, including the interactions and processes within them that allow for the maintenance of bio-and geodiversity, resilience to disturbances and the provision of ecosystem services that support life, including human life [12]. Key aspects of ecosystem integrity include continuous monitoring of bio-and geodiversity, ecosystem structures, functions and processes and their interactions and changes, and resilience. ...
... The interaction of science and policy is a fruitful area of research and many papers have been published on this subject. In many cases, communication for both, policy makers and scientists, is equally challenging (13)(14)(15) . One major challenge is that environmental issues often involve scientific concepts that can be difficult to understand by non-specialists. ...
... Similar levels of spatial dependence were found in the 2019-2020 fires in Victoria . In this way, extensive areas of fire-prone disturbed forest may contribute to the formation of a 'landscape trap'a hypothesised condition in which the rarity of lessflammable older forest in the landscape means that the remaining more widespread and more flammable young forest is at increased risk of repeatedly re-burning at high severity (Furlaud et al., 2021;Lindenmayer, Taylor & Bowd, 2022d). Landscape traps can preclude young forest from growing to an older, less-flammable state. ...
... Knowledge organization is difficult, subjective, and temporal. Disciplinary knowledge is relational to its institutional or organizational features, and this distinguishes from similar organizational terms such as field, domain, or topic [119,124]. The evolution of disciplines rapidly continues [120,121] as disciplinary diversification and specialization is required to address contemporary concerns. ...