The IGBP Mountain Research Initiative strives to achieve an integrating, interdisciplinary character and comprehensiveness, which implies the following:
1) Integration and further development of ongoing monitoring and observation networks in mountain regions, equating to Level 3 of the Global Hierarchical Observation System (GHOST), i.e. including sites from the World Glacier Monitoring Service, high mountain ecological field stations, research watersheds, biosphere reserves, etc., with a particular emphasis on including long historical and paleorecords covering a broad variety of disciplines. These long-term observation systems will be used to detect and analyse signals of global change (Activity 1).
2) Comparative assessment of the sensitivity and vulnerability of the mountain regions of the world with respect to environmental and societal change, including their complex interactions and feedbacks. This will be based on the development and application of an integrated modelling framework (Activity 2).
3) Further development and integration of our understanding of mountain-specific hydrological, ecological, and socio-economic processes so as to improve our ability to detect and analyse signals of global change (cf. item 1, above) and to contribute to the development of the integrated modelling framework (item 2, above). This will be achieved through process studies in mountain environments, in particular along altitudinal gradients and in associated headwater basins (Activity 3).
4) The derivation of strategies for sustainable resource management in mountain regions, which are intended to avoid or mitigate damaging effects of disastrous events (Activity 4).
To achieve its overall objectives, the research under the Mountain Initiative will be structured around the above four Activities. Below, a number of cross-cutting issues are discussed, and a nested design for research activities is proposed. Then, the four Activities outlined above are refined by setting up specific research Tasks, including descriptions of their suggested implementation.
There are a number of general issues that need to be kept in mind when implementing the research under the four Activities:
1) It is necessary to understand and describe both the separate effects and the potential interactions of key drivers of environmental change, as many of them operate at global scales and have an impact on mountain environments. These include the separate as well as interactive effects of increasing concentrations of CO2 and other trace gases, nitrogen deposition, greenhouse-gas induced climatic change, increasing UV-B radiation, and changes in land use and land cover. It should be kept in mind that the importance of these global change forcing factors will vary from region to region, and a critical step will be the appropriate assessment of the interactions between climate and land surface processes in complex mountainous terrain, using both present day observations and reconstructions from paleo data.
2) The understanding developed under item 1) needs to be applied to project the direction and rate of change of key indicators of environmental change in mountain environments under differing drivers. Candidate indicator variables might include: glacier characteristics (extent, mass balance etc.); snowline; catchment runoff; streamflow chemistry; species occurrence, abundance, and phenology; trends in lake status recorded in recent sediments, ecotone dynamics, etc. Comparison of different scenarios of change will allow an estimation of the sensitivity of the different indicators to global environmental change, and consequently their classification in terms of response times (phase shifts) and the establishment of generalised interrelations.
3) The observed or reconstructed trajectories of key indicators need to be compared with those predicted under different scenarios of change with particular attention to region-to-region variation. ‘Detection’ of global change effects in mountain systems will be based on an identification of spatial and temporal patterns of change in a suite of indicators that are consistent with predicted patterns derived from the scenario analyses in item 2).
4) A key supporting argument for the imprint of human activities on patterns of mountain ecosystems will be a series of indicator variables that exceed the range of variability reconstructed for pristine systems. In many cases (e.g., treeline, retreat rates of glaciers) these data are readily available, e.g. from various PAGES archives. For example, natural "background" rates of chemical deposition are recorded with annual resolution in ice cores from mountain glaciers. Varved sediments in lakes provide records of natural variability in climate and lake ecosystem dynamics with a similarly high resolution. For the past century, anthropogenic effects, ranging from catchment disturbance to inputs from both local and remote sources of atmospheric pollution, are also reflected in these records.
In the application of the approach, i.e. across all the research activities described below, a "nested design" should be used that is capable of capturing the systematic variation of ecological, hydrological and socio-economic processes across various spatial scales, and in particular along strong altitudinal gradients. Often, a watershed approach is most appropriate because numerous process gradients change at watershed boundaries. Within a watershed, a major subcatchment should be identified, and successively smaller subcatchments within it should be selected until the highest (topmost) subcatchment in the watershed is identified. In the ideal case, this will provide a series of nested watersheds along an altitudinal gradient which will encompass the scale-related variation in the larger watershed. Assuming that instrumentation and monitoring activities are allocated equally to each subcatchment, finer scale processes can be examined in the smallest subcatchments and scaled up to the entire basin with quantitative adjustments made for altitudinal changes (made possible because of the inherent altitudinal transect of the instrumented nested design). Where lakes occur within nested catchment systems, their sediment record can serve as a basis for combining temporal with spatial integration.
The intensity of such a nested design implies that it cannot be implemented widely. It will be important to have broad geographic coverage and to be able to support monitoring systems over the long term. This approach must be coupled with an extensive, low-effort monitoring program. Therefore, similar sites and basins should be indexed to the intensive site ("Master station") by collecting data at lower spatial and temporal resolutions (cf. Fountain et al. 1997). With this approach, a small number of "Master stations" and "Headwater catchments", where detailed, high-intensity sampling is conducted with high priority (P1 sites; cf. Fig. 2), can be complemented by a substantially larger number of lower-intensity sampling sites and watersheds (P2 sites), where only a subset of the measurements of the P1 sites is conducted. Thus, it becomes possible to elucidate and test hypothesized relationships between properties measured only at P1 sites and those measured at P2 sites, including scale relations, which then serve to describe the systematic variation of the properties of interest across the whole gradient and range of scales.
Figure 2: Idealized setup of altitudinal gradient studies distinguishing "Master stations"/"Headwater catchments" (P1 sites) vs. secondary sites and watersheds (P2). The design in geographical space (panels a and b) should be arranged so that the sampling points define a monotonic gradient of the underlying environmental variable (e.g., temperature, soil moisture, CO2, etc.) that is of interest (panel c).
