Landscape Ecology: Conclusions and Future Directions

What have we learned? 1. The complex patterns observed on today’s landscape result from many causes, including variability in the abiotic template, biotic interactions, natural disturbances, and both past and present patterns of human settlement and land use.

What have we learned? 2. There is no right scale for landscape ecological studies, but scale effects must be considered carefully; concepts such as equilibrium and species persistence are scale dependent.

Urban et al Disturbance Regime Forest Process Environmental Constraint Vegetation Pattern

What have we learned? 3. Many metrics are available for quantifying landscape patterns; one metric is insufficient for characterizing a landscape, yet there is no standard recipe for determining how many and which ones should be used.

What have we learned? 4. Organisms are influenced by spatial pattern, but pattern-process interactions involving organisms are scale dependent and require an organism-based view.

What have we learned? 5. Disturbances both create and respond to landscape heterogeneity, and thus landscapes may be strongly influenced by shifts in disturbance regimes. Fire both creates and responds to patterns of fuel availability. Fire suppression on the east side of the Cascades has profoundly alter fuel loads. This has lead to fires of unprecedented severity.

What have we learned? 6. Because pattern matters, natural disturbance can be very important for biodiversity and for ecosystem function. The characteristics of a disturbance regime (frequency, severity and size) selects for a particular suite of life history attributes. This suite of life history attributes in turn influences ecosystem function.

What have we learned? 7. Populations or guilds can produce important feedbacks to ecosystem processes and landscape patterns.

What have we learned? 8. Ecosystem function in terrestrial and aquatic ecosystems can be influenced by landscape position.

Swanson et al. 1988

What have we learned? 9. Elements of the landscape may serve as sources or sinks for nutrients that move across the terrestrial landscape or from the land to aquatic ecosystems. Patches of red alder along streams serve as a nitrogen source

What have we learned? 10. Human influences (e.g., land-use change) may be dominant factors controlling ecological dynamics at broad scales.

Research Directions 1. Spatial heterogeneity and ecosystem processes.

Research Directions 2. Relating landscape metrics to ecological processes. Statistical properties and behavior of metrics need to be better understood. Some metrics yield similar values for very different patterns. The relative sensitivity of different metrics to detecting changes in the landscape is not known The empirical relationships between landscape patterns and ecological processes of interest must be better documented and the underlying mechanisms understood. What should we measure and why and when is a change in a metric ecologically significant?

Research Directions 3. Thresholds, nonlinearities and rules for scaling.

Research Directions 4. Feedbacks between organisms and ecosystems in space.

Research Directions 5. Causes and consequences of land-use change

Research Directions 6. Sampling over large areas. How do we do it in a way that permits inferences about the effect of heterogeneity? This may require the development of new statistical tools.