Current issue: 54(1)

Under compilation: 54(2)

Impact factor 1.683
5-year impact factor 1.950
Silva Fennica 1926-1997
1990-1997
1980-1989
1970-1979
1960-1969
Acta Forestalia Fennica
1953-1968
1933-1952
1913-1932

Articles containing the keyword 'indicators'.

Category: Research article

article id 52, category Research article
Mirja Rantala, Teppo Hujala, Mikko Kurttila. (2012). Measuring and monitoring socio-cultural sustainability in the action of forest biodiversity cooperation networks. Silva Fennica vol. 46 no. 3 article id 52. https://doi.org/10.14214/sf.52
To safeguard overall sustainability in forest resource management, the ecological, economic, social, and cultural dimensions of sustainability should all be considered. However, the socio-cultural impacts are frequently contemplated only weakly in sustainability assessments. Hitherto, attempts to operationalize socio-cultural impacts arising from economic utilization or conservation of forest resources have been perceived as vague when compared to rigorous ecological and economic indicators. One reason is that socio-cultural impacts of forest management on individuals and communities are many and by nature context- and case-specific: they need local definition, which hampers diffusion of good solutions. This study developed a multi-criteria method for measuring and monitoring socio-cultural impacts of forest resource management; the case of cooperation network projects within Forest Biodiversity Programme for Southern Finland (METSO) provided empirical data. Based on a literature review, a set of 10 criteria and 25 indicators was compiled. Cumulative utility scores, presenting networks’ contributions to socio-cultural sustainability, were generated using performance, expert evaluation and weighting data and an additive utility model. The method enables longitudinal monitoring of socio-cultural impacts, which is beneficial because outcomes are different at different time points of projects’ life cycles and some appear with a delay. The method can be used in comparing sub-utility distributions i.e. monitoring units’ performance profiles, providing valuable information for policy-makers. The multi-criteria approach and the list of socio-cultural criteria are internationally transferable to other countries and contexts such as forest bioenergy, nature tourism, watershed management, that call for analysing socio-cultural impacts of forest resource management activity on private lands.
  • Rantala, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Hujala, Finnish Forest Research Institute, Vantaa Unit, Vantaa, Finland ORCID ID:E-mail:
  • Kurttila, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland ORCID ID:E-mail: mikko.kurttila@metla.fi (email)
article id 83, category Research article
Inari Ylläsjärvi, Håkan Berglund, Timo Kuuluvainen. (2011). Relationships between wood-inhabiting fungal species richness and habitat variables in old-growth forest stands in the Pallas-Yllästunturi National Park, northern boreal Finland. Silva Fennica vol. 45 no. 5 article id 83. https://doi.org/10.14214/sf.83
Indicators for biodiversity are needed for efficient prioritization of forests selected for conservation. We analyzed the relationships between 86 wood-inhabiting fungal (polypore) species richness and 35 habitat variables in 81 northern boreal old-growth forest stands in Finland. Species richness and the number of red-listed species were analyzed separately using generalized linear models. Most species were infrequent in the studied landscape and no species was encountered in all stands. The species richness increased with 1) the volume of coarse woody debris (CWD), 2) the mean DBH of CWD and 3) the basal area of living trees. The number of red-listed species increased along the same gradients, but the effect of basal area was not significant. Polypore species richness was significantly lower on western slopes than on flat topography. On average, species richness was higher on northern and eastern slopes than on western and southern slopes. The results suggest that a combination of habitat variables used as indicators may be useful in selecting forest stands to be set aside for polypore species conservation.
  • Ylläsjärvi, Rovaniemi University of Applied Sciences, School of Forestry and Rural Industries, Jokiväylä 11 c, FI-96300 Rovaniemi, Finland ORCID ID:E-mail: inari.yllasjarvi@ramk.fi (email)
  • Berglund, University of Helsinki, Department of Forest Sciences, Helsinki, Finland ORCID ID:E-mail:
  • Kuuluvainen, University of Helsinki, Department of Forest Sciences, Helsinki, Finland ORCID ID:E-mail:
article id 103, category Research article
Luis Diaz-Balteiro, Roberto Voces, Carlos Romero. (2011). Making sustainability rankings using compromise programming. An application to European paper industry. Silva Fennica vol. 45 no. 4 article id 103. https://doi.org/10.14214/sf.103
This paper characterizes the sustainability of the European paper industry. To undertake this task the sustainability of each country is defined by using fourteen indicators of a diverse nature (economic, environmental and social). These indicators are aggregated into a composite or synthetic index with the help of a compromise programming model. In order to associate different weights with each indicator, a survey among international experts has been carried out. In this way, a ranking of seventeen European countries analysed in terms of the sustainability of the European paper industry has been established, where Finland is the most sustainable paper industry in Europe except when the most balanced solution is chosen. Also, the results are robust when different preferential weights are attached. Finally, this methodology can be applied at a more disaggregated level and other indicators can be introduced.
  • Diaz-Balteiro, Research Group “Economics for a Sustainable Environment”, Technical University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain ORCID ID:E-mail: luis.diaz.balteiro@upm.es (email)
  • Voces, Research Group “Economics for a Sustainable Environment”, Technical University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain ORCID ID:E-mail:
  • Romero, Research Group “Economics for a Sustainable Environment”, Technical University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain ORCID ID:E-mail:
article id 451, category Research article
Thomas P. Sullivan, Druscilla S. Sullivan, Pontus M. F. Lindgren, Douglas B. Ransome. (2010). Green-tree retention and life after the beetle: stand structure and small mammals 30 years after salvage harvesting. Silva Fennica vol. 44 no. 5 article id 451. https://doi.org/10.14214/sf.451
We report on a retrospective investigation of the impacts of salvage harvesting of lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Wats.), killed by an outbreak of mountain pine beetle (Dendroctonus ponderosae Hopk.) in the 1970s, with variable retention of Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco). Our inference to biodiversity was coniferous stand structure and four mammal species: the southern red-backed vole (Myodes gapperi Vigors), common shrew (Sorex cinereus Kerr), red squirrel (Tamiasciurus hudsonicus Erxleben) and northern flying squirrel (Glaucomys sabrinus Shaw). We tested hypotheses that, at 30 years after salvage harvest of beetle-killed lodgepole pine trees, (1) abundance and diversity of stand structure, and (2) abundance of mammal species, will increase with higher levels of green-tree retention (GTR). Stand structure attributes and small mammals were sampled during 2005–2008 in young pine stands, with a range of GTR seed-trees (none, dispersed, and aggregated Douglas-fir), and uncut forest in south-central British Columbia, Canada. Diameters and heights of Douglas-fir and lodgepole pine and basal area of total conifers supported hypothesis (1). Mean abundance of the red-backed vole was consistently higher (2.3 to 6.4 times) in the uncut forest than other stands. Overall mean patterns of abundance for common shrews, red squirrels, and northern flying squirrels were similar among treatment stands. Mean abundance of the red-backed vole supported hypothesis (2), but numbers of the other three species did not. There is “life after the beetle” at 30 years after salvage harvesting, and this was enhanced by GTR.
  • Sullivan, Department of Forest Sciences, Faculty of Forestry, University of BC, 2424 Main Mall, Vancouver, BC, Canada V6T 1Z4 ORCID ID:E-mail: tom.sullivan@ubc.ca (email)
  • Sullivan, Department of Forest Sciences, Faculty of Forestry, University of BC, 2424 Main Mall, Vancouver, BC, Canada V6T 1Z4 ORCID ID:E-mail:
  • Lindgren, Applied Mammal Research Institute, 11010 Mitchell Avenue, Summerland, BC, Canada V0H 1Z8 ORCID ID:E-mail:
  • Ransome, Applied Mammal Research Institute, 11010 Mitchell Avenue, Summerland, BC, Canada V0H 1Z8 ORCID ID:E-mail:
article id 155, category Research article
Minna Räty, Annika Kangas. (2010). Segmentation of model localization sub-areas by Getis statistics. Silva Fennica vol. 44 no. 2 article id 155. https://doi.org/10.14214/sf.155
Models for large areas (global models) are often biased in smaller sub-areas, even when the model is unbiased for the whole area. Localization of the global model removes the local bias, but the problem is to find homogenous sub-areas in which to localize the function. In this study, we used the eCognition Professional 4.0 (later versions called Definies Pro) segmentation process to segment the study area into homogeneous sub-areas with respect to residuals of the global model of the form height and/or local Getis statistics calculated for the residuals, i.e., Gi*-indices. The segmentation resulted in four different rasters: 1) residuals of the global model, 2) the local Gi*-index, and 3) residuals and the local Gi*-index weighted by the inverse of the variance, and 4) without weighting. The global model was then localized (re-fitted) for these sub-areas. The number of resulting sub-areas varied from 4 to 366. On average, the root mean squared errors (RMSEs) were 3.6% lower after localization than the global model RMSEs in sub-areas before localization. However, the localization actually increased the RMSE in some sub-areas, indicating the sub-area were not appropriate for local fitting. For 56% of the sub-areas, coordinates and distance from coastline were not statistically significant variables, in other words these areas were spatially homogenous. To compare the segmentations, we calculated an aggregate standard error of the RMSEs of the single sub-areas in the segmentation. The segmentations in which the local index was present had slightly lower standard errors than segmentations based on residuals.
  • Räty, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland ORCID ID:E-mail: minna.s.raty@helsinki.fi (email)
  • Kangas, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
article id 297, category Research article
Antti Marjokorpi, Jukka Salo. (2007). Operational standards and guidelines for biodiversity management in tropical and subtropical forest plantations – How widely do they cover an ecological framework? Silva Fennica vol. 41 no. 2 article id 297. https://doi.org/10.14214/sf.297
The development of standards and guidelines to secure sustainable forest management at different geographical scales has expanded greatly during the past fifteen years. Most of these efforts, however, have been formulated for natural forests only; those designed specifically for forest plantations are relatively few. The global forest plantation area is expanding rapidly, with obvious positive and negative impacts on biodiversity. We characterize the key concepts of biodiversity in tropical and subtropical forest plantations and present an analysis of how these elements are covered in the eight principal operational standards and guidelines for sustainable plantation forestry. We also examine the applicability of standards and guidelines in plantations established and managed under different initial settings. The results indicate that the standards and guidelines address certain key elements of biodiversity comprehensively, meanwhile others are ignored or receive only slight attention. There is also substantial variation between the sets in their nature (performance- vs. process-based), scope, congruity in concepts and hierarchy, and specificity. The standards and guidelines seldom take into account the varying initial settings for plantation establishment and the consequent variation in critical factors in biodiversity conservation and management. We recommend that standards and guidelines should be developed so as to pay more attention to the type and operating environment of plantations, to cover all key factors of biodiversity, and to consider building closer relationships between the social and ecological aspects of biodiversity.
  • Marjokorpi, Stora Enso, Wood Supply, Talvikkitie 40 C, FI-01300 Vantaa, Finland ORCID ID:E-mail: antti.marjokorpi@storaenso.com (email)
  • Salo, Department of Biology, University of Turku, FI-20140 Turku, Finland ORCID ID:E-mail:
article id 485, category Research article
Helen Uliczka. (2003). Nature conservation efforts by forest owners – intentions and practice in a Swedish case study. Silva Fennica vol. 37 no. 4 article id 485. https://doi.org/10.14214/sf.485
Before a forest operation Swedish forest owners need to fill in a registration form. Since 1994, when a new Swedish Forestry Act came into force, intended nature conservation measures can also be noted on the form. I evaluate 1) if the self-reported nature conservation intentions displayed any trends from 1995 to 2000, and 2) if the intentions were implemented. All forms from these years, in one municipality, were analysed and the stand structure retention was measured on 40 clear-cuts. The intentions, noted as check-marks on the form, showed an increasing trend during these years. However, the increase may be an artefact of changes the form during the time period. The number of check-marks on the forms and the stand structure items actually present on the 40 clear-cuts showed a positive relation. The clear-cuts with ≤ 3 check-marks on the form had lower amounts of the three most common items, than those with ≥ 4 check-marks. To conclude 1) a true increase in the self-reported intentions of the forest owners could not be established; 2) the intentions were generally followed by associated practices on the clear-cuts; 3) the amounts of stand structures retained were probably not enough to reach the biodiversity goal of the Forestry Act. The registration form could be improved to become less open for interpretation and contain quantified recommendations. Self-reported intentions of the forest owners could then possibly be used as indicators of real structural retention, which could facilitate planning and allow for making predictions about the future forests.
  • Uliczka, Swedish University of Agricultural Sciences, Forest Faculty, Department of Conservation Biology, Grimsö Wildlife Research Station, SE-730 91 Riddarhyttan, Sweden ORCID ID:E-mail: helen.uliczka@nvb.slu.se (email)
article id 565, category Research article
Sybille Haeussler, Lorne Bedford, Alain Leduc, Yves Bergeron, J. Marty Kranabetter. (2002). Silvicultural disturbance severity and plant communities of the southern Canadian boreal forest. Silva Fennica vol. 36 no. 1 article id 565. https://doi.org/10.14214/sf.565
Boreal forest ecosystems are adapted to periodic disturbance, but there is widespread concern that conventional forest practises degrade plant communities. We examined vegetation diversity and composition after clearcut logging, mechanical and chemical site preparation in eight 5- to 12-yr old studies located in southern boreal forests of British Columbia and Quebec, Canada to find useful indicators for monitoring ecosystem integrity and to provide recommendations for the development and testing of new silvicultural approaches. Community-wide and species-specific responses were measured across gradients of disturbance severity and the results were explained in terms of the intermediate disturbance hypothesis and a simple regeneration model based on plant life history strategies. Species richness was 30 to 35% higher 5 to 8 years after clearcut logging than in old forest. Total and vascular species diversity generally peaked on moderately severe site treatments, while non-vascular diversity declined with increasing disturbance severity. On more-or-less mesic sites, there was little evidence of diversity loss within the range of conventional silvicultural disturbances; however, there were important changes in plant community composition. Removing soil organic layers caused a shift from residual and resprouting understory species to ruderal species regenerating from seeds and spores. Severe treatments dramatically increased non-native species invasion. Two important challenges for the proposed natural dynamics-based silviculture will be 1) to find ways of maintaining populations of sensitive non-vascular species and forest mycoheterotrophs, and 2) to create regeneration niches for disturbance-dependent indigenous plants without accelerating non-native species invasion.
  • Haeussler, C2 Site 81 RR#2 Monckton Rd., Smithers, B.C., Canada V0J 2N0 ORCID ID:E-mail: skeena@bulkley.net (email)
  • Bedford, B.C. Ministry of Forests, P.O. Box 9513 Stn. Prov. Govt., Victoria, B.C., Canada, V8W 9C2 ORCID ID:E-mail:
  • Leduc, Groupe de recherche en écologie forestière interuniversitaire, Université du Québec à Montréal, CP 8888, Succursale A, Montréal, Québec, Canada, H3C 3P8 ORCID ID:E-mail:
  • Bergeron, Groupe de recherche en écologie forestière interuniversitaire, Université du Québec à Montréal, CP 8888, Succursale A, Montréal, Québec, Canada, H3C 3P8 ORCID ID:E-mail:
  • Kranabetter, B.C. Ministry of Forests, Bag 5000, Smithers, B.C., Canada, V0J 2N0 ORCID ID:E-mail:

Category: Article

article id 5507, category Article
John L. Innes. (1993). Methods to estimate forest health. Silva Fennica vol. 27 no. 2 article id 5507. https://doi.org/10.14214/sf.a15668

A range of different indices are available for assessing the health of trees in forests. An even larger range can be used for the assessment of the health of forest ecosystems. Most studies made in connection with ”forest decline” and the impact of air pollution and other environmental stresses on forests have concentrated on the assessment of crown transparency and crown discoloration in individual trees. These are non-specific indicators which are now known to be sometimes of relatively little value when determining the health of a forest ecosystem. Numerous problems exist with both, and the standardisation of assessments between and even within countries has not been achieved. Consequently, studies claiming to compare ”defoliation” between different countries cannot be substantiated. The emphasis on crown transparency and crown discoloration has resulted in the neglect of a number of other indices that could be of considerable value. These include a variety of visual measures of crown condition and also several non-visual bioindicators. Some of these techniques are objective, reducing the present reliance on observed standardization. A large number of potential techniques are currently at the research stage and have yet to be adequately tested in field trials. This represent an area where a substantial amount of further research is required.

  • Innes, ORCID ID:E-mail:
article id 5343, category Article
R. J. K. Rinne, A. I. Mäkinen. (1988). Regional and species variations in metal content of two woodland mosses Pleurozium schreberi and Hylocomium splendens in Finland and northern Norway. Silva Fennica vol. 22 no. 1 article id 5343. https://doi.org/10.14214/sf.a15500

The woodland mosses Pleurozia shcreberi (Willd. ex Brid.) Mitt. and Hylocomnium splendens (Hedw.) Schimp. were used in air pollution monitoring. During late summer and autumn 1977, 44 samples of Pleurozia shcreberi were collected in semi-open coniferous forests from Southern Finland (60°N) to Northern Finland and Northern Norway (70°N). Additional 26 samples of Hylocomnium splendens were collected in similar places south of 61°30’N. Analysis of both moss species revealed decreasing concentration gradients from south to north for Cu, Fe, Pb and Zn. Conversely, Mn and Mg levels increased with latitude, while Ca did not change significantly. Some decreasing west to east concentration gradients for Cu, Zn and Pb were measured in P. schreberi and in H. splendends collected from Southern Finland.

A comparison between these two mosses showed significant differences in Cu content (ave. 22% higher in H. splendends) and Zn content (ave. 8% higher in P. schreberi). However, the differences were considered minor in relation to regional differences in Finland.

In local study of emissions from the Koverhar steel works in Southern Finland, Fe and Zn concentrations in P. schreberi and H. splendens were found to decrease significantly with increasing distance up to 6 kilometres north and south of the source.

The PDF includes a summary in Finnish.

  • Rinne, ORCID ID:E-mail:
  • Mäkinen, ORCID ID:E-mail:
article id 5154, category Article
Satu Huttunen, Sinikka Kallio, Marketta Karhu. (1981). The effect of air pollution on transplanted mosses. Silva Fennica vol. 15 no. 4 article id 5154. https://doi.org/10.14214/sf.a15381

The use of forest mosses as bioindicators was tested with transplanted experiments. One transplantation experiment was made to study effects of air pollutants on two forest moss species, Hylocomnium splendens (Hedw.) Schimp. and Pleurozium schreberi (Willd. ex Brid.) Mitt. Another transplantation was used to study the nitrogen fixation capacity of blue-green algae in the Hylocomnium and Pleurozium moss layers. The surface structure of the moss species was studied by scanning electron microscopy. The air pollution induced changes in the surface structure of moss cells were observable soon after the transplantation. In polluted industrial areas the fertilizing effect of air-borne nitrogen compounds increased the photosynthetic activity of mosses before their destruction. Stress respiration was also observable in polluted areas. The nitrogen fixing capacity decreased or was almost inhibited in all the air-polluted environments.

  • Huttunen, ORCID ID:E-mail:
  • Kallio, ORCID ID:E-mail:
  • Karhu, ORCID ID:E-mail:
article id 5150, category Article
Hilkka Mikkonen, Satu Huttunen. (1981). Dwarf shrubs as bioindicators. Silva Fennica vol. 15 no. 4 article id 5150. https://doi.org/10.14214/sf.a15377

Several studies of air polluted forest environments have shown that dwarf shrubs suffer from air pollution. In many cases the disturbances have been attributed to the susceptibility of the dwarf shrubs, while in some cases the vegetational competition factor has been discussed. The growth pattern of dwarf shrubs is very complicated and a single individual can cover large areas due to vegetative reproduction. Since dwarf shrub individuals cannot be transplanted for the purpose of laboratory or field tests, the only possibility is to use small cuttings for the bioindication studies. Some preliminary results are discussed.

  • Mikkonen, ORCID ID:E-mail:
  • Huttunen, ORCID ID:E-mail:
article id 5149, category Article
Toini Holopainen. (1981). Alterations in the ultrastructure of epiphytic lichens Hypogymnia physodes and Alectoria capillaris caused by air pollution. Silva Fennica vol. 15 no. 4 article id 5149. https://doi.org/10.14214/sf.a15376

The ultrastructure of Hypogymnia physodes (L.) Nyl. and Alectoria capillaris (Bryoria capillaris (Ach.) Brodo & D. Hawksw.) grown or transplanted near a fertilizer plant and a pulp mill was compared to normal ultrastructure of these lichen species. The ultrastructural changes observed were highly similar in the symbionts of both species and near both the factories although the emissions are different. In the lichens grown near the factories the number of algae had clearly increased. The appearance of the chloroplasts was roundish compared to controls. The pyrenoglobuli and cytoplasmic storage bodies were smaller than normally and the number of polyphosphate bodies had increased. Also, in mycobionts storage droplets were very small or absent and many vacuoles and dark inclusions appeared to hyphae in contrast to controls. In transplanted lichen there existed mainly the same ultrastructural changes as in the lichen grown near factories. Near the fertilizer plant the damage was, however, more severe because all the lichens died during 6–7 months after transplantation. Near the pulp mill part of the lichens survived and seemed to adapt to air pollution.

  • Holopainen, ORCID ID:E-mail:
article id 5142, category Article
Lars Moseholm. (1981). Responses of transplanted lichens to sulphur dioxide dosages - a new semi-statistical dosage/injury model. Silva Fennica vol. 15 no. 4 article id 5142. https://doi.org/10.14214/sf.a15369

A semi-statistical model is suggested for monitoring injuries of plants for long-time field exposures (months). The model is based on the following assumptions:

1. The concentrations of air pollutants in the atmosphere follow the Johnson SB distribution.

2. The degree of plant injury is proportional to the logarithm of air pollutant dose.

3. No injuries occur below a certain dose level.

4. A dose is defined as the air pollutant concentration multiplied by the duration of exposure raised to an exponent.

Based on the air pollutant frequency distribution a total dose for the exposure period is calculated by integration, and the total dose is related to the observed plant injury by non-linear regression. The model is tested for long-time exposures of sulphur dioxide to transplant lichen in natural environment.

  • Moseholm, ORCID ID:E-mail:
article id 5141, category Article
Lisbeth Mortensen, Knud V. Weisberg. (1981). A method for measurement of actue leaf injury on tobacco indicator plants. Silva Fennica vol. 15 no. 4 article id 5141. https://doi.org/10.14214/sf.a15368

A technique for instrumental scoring of damaged leaves on tobacco (Nicotiana tabacum) indicator plants caused by ozone in the lower atmosphere is being developed. The leaves are photographed in situ with an integrated unit, which illuminates the leaf from behind and keeps the camera in a well-defined position. By using microfilm and a minus green filter, it is possible to obtain negatives where the necrotic flecks appear as dark spots on a white leaf. The negatives are scanned in a TV-system and the size of the damaged fraction of the leaf is calculated by a microprosessor and is shown as a percentage of the leaf.

  • Mortensen, ORCID ID:E-mail:
  • Weisberg, ORCID ID:E-mail:
article id 5140, category Article
Lars Westman. (1981). Monitoring of coniferous forest ecosystems in Sweden. Silva Fennica vol. 15 no. 4 article id 5140. https://doi.org/10.14214/sf.a15367

A monitoring program is planned for the terrestrial environment around industries in Sweden, which emit acid compounds and heavy metals. Directions for the County Government Boards are being prepared. The paper deals with the present pollution situation in Sweden, based on recent scientific results, the justifications for local monitoring, and the organizing of the monitoring including the parameters suggested.

Four examples from a case study at an oil power station illustrate reporting of the data and the difficulties in interpreting the results. The examples are the distribution of a lichen indicator, heavy metal content and phosphatase activity in the moor layer, soil respiration and tree growth.

  • Westman, ORCID ID:E-mail:

Register
Click this link to register for Silva Fennica submission and tracking system.
Log in
If you are a registered user, log in to save your selected articles for later access.
Contents alert
Sign up to receive alerts of new content
Your selected articles

Committee on Publication Ethics A Trusted Community-Governed Archive