Cross-system comparisons elucidate disturbance complexities and generalities

Abstract

. 2011. Cross-system comparisons elucidate disturbance complexities and generalities. Ecosphere 2(7):art81.doi:10.1890/ES11-00115.1Abstract. Given that ecological effects of disturbance have been extensively studied in many ecosystems, it is surprising that few quantitative syntheses across diverse ecosystems have been conducted. Multi-system studies tend to be qualitative because they focus on disturbance types that are difficult to measure in an ecologically relevant way. In addition, synthesis of existing studies across systems or disturbance types is challenging because sufficient information needed for analysis is not easily available. Theoretical advances and improved predictions can be advanced by generalizations obtained from synthesis activities that include multiple sites, ecosystems, and disturbance events. Building on existing research, we present a conceptual framework and an operational analog to integrate this rich body of knowledge and to promote quantitative comparisons of disturbance effects across different types of ecosystems and disturbances. This framework recognizes individual disturbance events that consist of three quantifiable components: (1) environmental drivers, (2) initial system properties, and (3) physical and biological mechanisms of effect, such as deposition, compaction, and combustion. These components result in biotic and abiotic legacies that can interact with subsequent drivers and successional processes to influence system response. Through time, a coarse-scale quasi-equilibrial state can be reached where variation in drivers interacting with biotic processes and feedbacks internal to the system results in variability in dynamics. At any time, a driver of sufficient magnitude can push the system beyond its realm of natural variability to initiate a new kind of event. We use long-term data from diverse terrestrial ecosystems to illustrate how our approach can facilitate cross-system comparisons, and provide new insights to the role of disturbance in ecological systems. We also provide key disturbance characteristics and measurements needed to promote future quantitative comparisons across ecosystems.

Disturbance interactions: characterization, prediction, and the potential for cascading effects

“…The topic of disturbances is broad, encompassing such diverse events as wildfires, insect outbreaks, hurricanes, coral bleaching, and floods, but there is value in looking for generalities despite these differences (e.g., Frelich and Reich 1999, White and Jentsch 2001, Wilson et al 2006, Peters et al 2011. Many disturbances are rare relative to the timescales of human investigation, and it is only through synthetic approaches which cover multiple events and event types that generalities and idiosyncrasies can be described between and across events.…”

“…Natural disturbances, frequent or severe, are integral parts of an ecosystem regime (the suite of biotic components, abiotic processes, and disturbance dynamics which characterize an ecosystem). In all cases, disturbances result in functional, structural, biological, and biogeochemical legacies (Pickett and White 1985, Turner et al 1993, Peters et al 2011, McLauchlan et al 2014, Seidl et al 2014), a template left on the ecosystem with which a subsequent disturbance may interact in some fashion. These legacies take the form of altered functioning (e.g., rapid growth of surviving individuals, altered nutrient cycling), dead material, residual (e.g., survivors) and regenerating individuals and communities, and unique spatial patterns in cover types, ranging from undisturbed to highly disrupted.…”

Effects of volcanic and hydrologic processes on forest vegetation: Chaitén Volcano, Chile

“…In the terminology of ecologists, geophysical processes act as disturbance agents that disrupt ecosystems (White and Pickett, 1985). In the case of a volcanic eruption, an individual primary disturbance type (e.g., volcanic processes such as tephra fall or pyroclastic flow) involves one or more disturbance mechanisms, such as erosion, burial, heating, abrasion, and impact force (Swanson and Major, 2005;Peters et al, 2011). Primary disturbances may lead to secondary disturbances (e.g., fluvial redeposition of tephra, debris slides resulting from loss of root strength of killed trees).…”

Effects of a tropical cyclone on a pelagic ecosystem from the physical environment to top predators

“…ncep.noaa.gov/products/Epac_hurr/background_in formation.html). The temporal and spatial dynamics of these atmospheric storms and oceanic eddies comprise a disturbance regime (Turner 2010, Peters et al 2011. This pattern may be fundamental to the functioning of the ecosystem by enhancing resources for both resident and seasonally migrating top predators.…”