Justification
Much scientific and political interest is now being directed towards a better understanding of global climate changes and their effects on the environment. It has been predicted that High Arctic ecosystems are especially sensitive to climatic changes. However, long-termed monitoring of biotic as well as abiotic parameters that can document such effects only takes place at exceedingly few sites. Until ZERO (Zackenberg Ecological Research Operations) started in 1995 no such sites existed in Greenland.

The concept for ZERO was developed by eight Danish university institutes and outlined in the report ‘Analytic Studies of High Arctic Ecosystems. A Multidisciplinary Programme at Zackenberg, NE Greenland’ (Danish Polar Center 1993), which subsequently was approved by the Danish Natural Science Research Council.

Zackenberg was selected for its high diversity of both landscape and biological elements. The site is close to the interface between the ‘mid-Arctic’ and the extreme High Arctic regions of Northeast and North Greenland. Hence, several plant species have their northern or southern limits in the area. On both a north-south and an east-west gradient, the area is intermediate between the snow rich southern and eastern, more maritime regions, and the mesic northern and westernmost continental regions. Therefore, pronounced changes may be expected in this area following climatic changes.

Zackenberg is located in the middle of the world’s largest national park. The area was virtually untouched by man, until the research station was established, and great efforts are made to keep human influence at a minimum. Few research sites can offer such pristine research opportunities, where the effects of environmental variations and changes - man-made or not - can be studied.

1. Basic quantitative documentation of the ecosystem structure around Zackenberg. Study resolution will range from a regional scale (km²) to habitat and plot scale (m²). The survey will include establishment of permanent measuring areas or "target plots" allowing for subsequent repeated measurements.
2. Creation of baseline studies of intrinsic short-term and long-term variations in ecosystem functions with appropriate considerations to guaranteed provision for repeated measurements of long-term changes.
3. Retrospective analyses (range: years to thousands of years) of organic material directed to detect past ecosystem changes in the area and designed as correlative tools for predicting effects of future Global Change.
4. Research proposing to increase the knowledge of basic ecosystem processes and providing an improved and advanced temporal platform for predicting responses to Global Change events in the ecosystem.

These aims are targeted partly through specific research projects, partly through the long-term monitoring programmes, ClimateBasis, GeoBasis and BioBasis. The aim of these monitoring programmes, that have a time frame of 50+ years, is to provide data relevant mainly for items 1 and 2, while items 3 and 4 are targeted through research projects. This even include in depth analyses pertinent to items 1 and 2, as the monitoring programmes must be backed up by specific research e.g. including experimental studies.

The ambition has been to develop a monitoring programme that at the same time is simple, comprehensive (covering a wide range of organisms and processes) and standardised. It should provide data on typical High Arctic plant and animal populations and interactions between them that can be expected to be sensitive to year to year variation as well as long-term changes in the local ecosystem, data that can direct research projects into the study of the causal connections behind such variations. The programme intends to be as integrated as possible within the practical and economical limits that it works under. This means that we aim to cover chains of parameters that are expected to be interdependent. (Please see the annual reports for contents of ClimateBasis and GeoBasis.)

The output will be documentation of the natural variation and long-termed trends in the selected parameters together with knowledge on interrelations between them. Together with the results from specific research projects, this is expected to enable modelling and predictions of likely ecological scenarios for High Arctic Greenland and elsewhere in the High Arctic resulting from e.g. higher/lower temperatures (for specific seasons), more/less snow, later/earlier snow and ice melt, more/less summer precipitation, more/less incoming radiation, higher/lower frequency of above zero temperatures in winter, etc. Please see below for the most likely scenarios.

The results of the monitoring programme will enable the National Environmental Research Institute of Denmark to provide baseline data and analyses of interannual variation and long-term trends in this High Arctic ecosystem as well as identification of key indicators of and ecosystem resilience to climate change. The potential external users of the data are researchers planning or undertaking projects at Zackenberg, which may benefit from baseline data and time series already established through BioBasis, the international scientific community, particularly researchers working with modelling and predictions of effects of climate change on the Arctic environment, the Greenland nature management administration responsible for the management of the national park, and the Danish and Greenlandic authorities responsible for the national implementation of the United Nations Framework Convention on Climate Change, the Arctic Monitoring and Assessment Programme (AMAP), the Conservation of Arctic Flora and Fauna (CAFF), the Convention on Biological Diversity, the Convention on the Conservation of Migratory Species of Wild Animals (the Bonn Convention) including the African-Eurasian Migratory Water Bird Agreement and the Convention on Wetlands of International Importance Especially as Waterfowl Habitat (the Ramsar Convention), which all holds obligations for monitoring. Furthermore, methodologies developed at Zackenberg may provide standards for similar monitoring programmes elsewhere in the Arctic.

The programme is designed to be carried out during the ‘summer’ season late May - late August. The elements that must be monitored annually as well as methods have been selected to be manageable by non specialists (general naturalists and students), while elements necessitating specialists are covered at 5-10 years intervals (plant community and lichen monitoring that are expected to show slow changes). The programme is run by a part time senior researcher and two part time assistants (two persons during June-July plus one during July-August). The senior researcher is responsible for data quality, maintenance of sampling procedures (development of the manual) and annual reporting.

All ITEX plots have dataloggers that automatically record microclimate temperatures 12 times per day year round, and the annual snow melt is monitored manually in each plot.

In 1999, the programme was extended with greening indexes (RVI) measured weekly in 22 plots and backed up by satellite images. Recent analyses in certain temperate and Low Arctic regions have documented that plant growth has increased and that growth now starts seven days earlier due to earlier snow melt (Myneni et al., Nature 386: 698-702, 1997).

Together, these elements cover the vegetation development better both qualitatively and quantitatively than the other biotic elements are covered. We expect that the results will demonstrate pronounced reactions on different climatic variations and trends. Furthermore, the results are important particularly in relation to the herbivore mammals.

About 50,000 individuals have been sampled each year, and they provide a particularly qualified picture of the annual occurrence and phenology of virtually all important groups of arthropods. As most of the groups are only sorted to family or order level, subsamples must be identified to species, if insight into possible fluctuations and phenological differences between the species are desired.

The arthropod monitoring is expected to provide results that will demonstrate very pronounced reactions upon different climatic factors (Danks, Arctic 45: 159-166, 1982), and the results are highly important for the analyses of the bird data, especially.

The breeding bird census provides data of the same quality as those obtained by the Danish field stations (run by the National Environmental Research Institute) for seven common species together with data for a further six less common species. The monitoring of breeding phenology (and nesting success) provides good data for four species and supplementary data for a further six. Data are provided for ‘Arctic Waterfowl: An international breeding condition survey’ run by Wetlands International.

Population sizes together with breeding phenology and success particularly in waders are expected to be highly dependent on spring snow cover and progress of snow melt, and the breeding phenology furthermore by the availability of invertebrates (Meltofte, Meddr Grønland, Biosci. 16, 1985). Large population fluctuations have been documented by counts in the non-breeding areas, but their causes which are expected to be found on the breeding grounds are largely unknown (Boyd, Wader Study Group Bull. 64, Suppl.: 144-152, 1992). Recently, is has been documented that 20 British bird species now breed on average nine days earlier than 25 years ago (Crick et al., Nature 388: 526, 1997).

The populations of both lemmings, musk oxen and Arctic foxes are known to fluctuate considerably over time - both short termed and long termed. Especially for the lemmings, the causes for these fluctuations are still poorly understood. The ratio of blue to white Arctic foxes was much higher in Northeast Greenland at the beginning of this century, while the musk ox population was at a minimum. After a population build up of musk oxen in Northeast Greenland during this century, the population has crashed in the central parts (just north of Zackenberg). Together, these fluctuations may be related to climatic factors (Vibe, Meddr Grønland 170, 1967; Forchhammer & Boertmann, Ecography 16: 299-308, 1993). The monitoring programme is expected to provide data that can contribute to analyses of the population dynamics of the species involved and their relations to climatic fluctuations.

So far, it is evident that we have expelled about half the population of moulting pink-footed geese (c. 230 individuals) from the area, and that a number of barnacle goose families have been prevented from utilising parts of their former feeding grounds. However, the barnacle geese have benefited from the decrease in moulting pink-footed geese numbers, so that more families now spend the fledging period in the valley. It is also possible that the distribution of rutting musk oxen was altered during the 1997-season, when much activity took place close to their preferred area. In general, however, musk oxen have shown good adaptability to the traffic of aeroplanes and persons.

There are two different intensities or directions that these changes can take, particularly concerning summer temperatures. One is a development in the direction of present conditions further south in East Greenland (e.g. Scoresby Sund; Scenario A), the other involves even more maritime conditions like the present situation in Spitzbergen (Scenario B). In Scenario A, summer temperatures will be significantly warmer, while in Scenario B, summer temperatures will not change much, but the microclimate will get cooler due to reduced solar radiation.

Hypotheses pertinent to Scenario A
Brackets denote sections in the BioBasis manual that addresses the issue in question.

1. Plant production will increase (NDVI/RVI).
2. The nutritional value of the vegetation will increase (to be developed).
3. Plant species diversity will increase (1.3).
4. Vegetation cover will expand into presently xeric habitats (1.3, 1.7).
5. Fen communities will expand (1.3).
6. Vegetation growing in new snow accumulation areas will change significantly, and snow patch vegetation will expand (1.3).
7. Plant species affiliated with mesic and xeric habitats will suffer from competition from species growing on moist habitats, but they will disperse into habitats that are barren to day (1.3).
8. Flowering phenology will be delayed in snow accumulation areas. Hence, plant species dependant on an extended period for development of viable seeds will show reduced reproductive fitness in such areas (1.1).
9. Grazing by musk oxen may decrease (see below).
10. Grazing by lemmings will increase (see below).
11. Invertebrate production will increase (2.1, 2.2).
12. Invertebrate species diversity will increase (2.1, 2.2).
13. Invertebrate phenology will be delayed in snow accumulation areas (2.1).
14. Most bird populations will decrease due to later snow melt and reduced food resources available in spring (3.1, 3.7, 4.6).
15. Ground nesting birds will have their breeding phenology delayed, so that even fledged juveniles will suffer from lower survival during autumn migration (3.2).
16. Ground nesting birds will experience increased predation on nests (more predators and less snow free land to disperse on) and reduced chick survival (due to increased predation; see below) (3.2, 3.3).
17. The frequency of pronounced poor breeding seasons (including non-breeding years) for birds may increase (3.3)
18. The population of skuas will benefit from more lemmings, but suffer from increased predation by foxes (see below) (3.1, 3.2, 3.7, 4.6, 4.9).
19. The population of barnacle geese will increase following increased growth and nutritional value of the vegetation (3.4, 4.6).
20. The magnitude of the lemming peaks will increase due to heavier and more extensive snow cover, more extensive and lush vegetation and higher nutritional quality of the food (4.1).
21. The density of lemming winter nests will change between habitats (4.1, 4.6).
22. The fox population will increase following magnified lemming peaks (4.5, 4.8, 4.9).
23. The musk ox population will suffer from reduced reproduction and winter survival, but benefit from more extensive and lush vegetation and higher nutritional quality of the food (4.2, 4.3, 4.6).
24. A higher frequency of above zero temperatures in winter may cause significant cut backs in the musk ox population (4.2, 4.3, 4.6).
25. The habitat use of the musk oxen will change as a result of increased snow cover and more extensive vegetation cover (4.2, 4.3, 4.6).
26. Ice-free periods in lakes and ponds are extended which may lead to increases in primary (benthic) production and secondary production (to be developed).

1. Plant production will increase in presently xeric habitats, but decrease in areas already receiving enough water (due to reduced solar radiation) (1.3, 1.7).
2. The nutritional content of the vegetation will decrease due to reduced solar radiation and reduced accessible amounts of nutrients in the soils (to be developed).
3. Plant species diversity will decrease (1.3).
4. Plant species growing on moist habitats will expand (1.3).
5. Vegetation growing in new snow accumulation areas will change significantly, and snow patch vegetation will expand (1.3).
6. Plant species affiliated with mesic and xeric habitats will suffer from competition from species growing on moist habitats, but they will disperse into habitats that are barren to day (1.3).
7. Flowering phenology will be delayed and the amount of flowering will decrease. Hence, plant species dependant on an extended period for development of viable seeds will show reduced reproductive fitness (1.1, 1.2).
8. Grazing by invertebrates on flowers and by musk oxen will decrease (2.3, 2.4, 2.5 and below).
9. Grazing by lemmings may decrease (see below).
10. Invertebrate production will decrease (2.1, 2.2).
11. Invertebrate species diversity will decrease (2.1, 2.2).
12. Invertebrate phenology will be delayed (2.1, 2.2).
13. Most bird populations will decrease and some may even disappear due to later snow melt and reduced invertebrate food resources in spring (3.1, 3.7, 4.6).
14. Ground nesting birds will have their breeding phenology delayed, so that even fledged juveniles will suffer from lower survival during autumn migration (3.2).
15. Ground nesting birds may experience increased predation on nests (less snow free land to disperse on) (3.2, 3.3).
16. Wader chicks will more often experience spells of inclement weather with reduced availability of invertebrate food and hence reduced survival (3.2, 3.3).
17. The frequency of pronounced poor breeding seasons (including non-breeding years) for birds will increase (3.2, 3.3)
18. The population of skuas will decrease due to a reduced lemming population and it may suffer from increased predation on nests (3.1, 3.2, 3.7, 4.6, 4.9).
19. The lemmings may benefit from heavier and more extensive snow cover, but they will suffer from regular thaw in winter and reduced quality of the food. Periodically, the population may be wiped out by alternating thaw and frost in winter (4.1, 4.6).
20. The density of lemming winter nests will change between habitats (4.1, 4.6).
21. The fox population will decline due to reduced lemming peaks (4.5, 4.8, 4.9).
22. The musk ox population will suffer from reduced reproduction and winter survival, and possibly from reduced quality of the food (4.2, 4.3, 4.6).
23. A higher frequency of above zero temperatures in winter may cause significant cut backs in the musk ox population, and periodically, the population may even be wiped out by alternating thaw and frost in winter (4.2, 4.3, 4.6).
24. The habitat use of the muskoxen will change as a result of increased snow cover and more extensive vegetation cover (4.2, 4.3, 4.6).
25. Deceased plankton and benthic primary production (due to reduced light) and shorter summer periods (due to slower ice-melt) leading to incomplete life cycles of invertebrates (to be developed).