0762-B1
Antonio Tagliaferri, Alberto Gubertini 1
Data on the sanitary state of woods in Lombardia are helpful to implement wood planning choices and management of the regional forest property. Owing to the high land anthropologization the forest strategic role on environmental equilibrium is studied.
The monitoring system employed by the Regional Forest Service has allowed to gather information needed in drawing up a historical compilation of useful data in interpreting natural eco-system answers to exo - and endogenous stimuli.
According to 1985 Natural Forest Inventory, Lombardia's wooded surface is 432,000 hectars including 146,000 high forest and 285,300 coppice (Castellani, 1988). The assessment is by all means faulty as the last decade recorded a further small growing in the Lombard forest property.
As for the forest landscape, Lombardia comprises a high-diversity vegetation formation, from the lowest soil up to the highest buttresses of the Alpine arch. Deciduous forest mixed to prevailing oak zones is present on plains where conditions are favourable, along rivers with black alder (Ostrya carpinifolia), white poplar (Populus alba) and willow (Salix sp.). Along southern sunny sides of pre-Alps there are oak shrubs mixed to pubescent oak (Quercus pubescens) and cultivated olive tree.
On mean-high mountains the forest consists of beech (Fagus sylvatica)-prevailing woods, white fir (Abies alba) (which may change into prevailing species when more humidity is present) in the rainiest zones, and pine in driest ones. Higher altitudes are dominated by evergreen fir, sheer or prevailing with larch and/or cembran pine (Pinus Cembra), variously mixed to rhododendron (Rhododendron sp.) and other heather shrubs. Mountain pine (Pinus mugus) woods are found on the contrary on limestone and detritus sides. Moors and altitude grasslands finally prevail on high mountain extreme environment.
Continuous and correctly planned monitoring on the health state of so an extensive forest heritage, joined to a detailed analysis of the collected data, allows gathering basic information required for the assessment of any variation; locating particular problems needing specific surveyings; singling out possible causal factors to be tested by experimental researches; constructing, validating and calibrating forecasting models; adjusting initial hypotheses; establishing deepened studies and fulfilling lightening actions (Innes, 1994). Ferris-Kaan and Patterson (1992) describe monitoring as "a singling out process when a change has occurred, establishing its direction and measuring its spread degree".
Stevens' (1994) statement of "monitoring" is more operative: ".......to follow a specific environmental entity through the time, to watch its conditions and their changes, as an answer to a clearly defined stimulus". The Reg.CCE/86 was published in 1986, regarding the particular forest field, aimed at constituting a forest monitoring action at a communitarian level. It produced a regulations whole subsequently become the "European Scheme on Forest Protection against Atmospheric Pollution".
A trans-national inventory of forest state is nowadays carried out in 38 Nations (UN-ECE and EC, 2001) following the approval of these Regulations. The communitarian monitoring now implemented in Lombardia works on an extensive watching of areas under observation (called "level I", for a total of 122 areas); these areas have been located within the various territorial Unities which make up the Region. The monitoring is also employed as an intensive watching on fixed areas (called "level II", 3 areas) The monitoring network studies the most widespread arboreal species in Lombardia, equally divided in hardwoods and softwoods (fig.1) in order to get more information from them.
Woods are exposed to atmospheric pollution both directly (through contact and absorption of polluting agents by leaf surface) and indirectly (alteration caused by pollution agents in soil composition and chemical characteristics). Physical and chemical mechanisms through which these agents act is quite easy to know under checked conditions; much work is still to be done on the contrary in order to know what is actually happening in the wood reality where many and different factors are operating in the ecosystem regulating processes.
A lot of papers (Innes, 1993; Landmann and Bonneau, 1995) did not have succeed so far in revealing direct and probable widespread evidences of casual relationships between pollution and damages to woods, except for specific situations depending on particular and well identified polluting agents (Kandler and Innes, 1995; Skelly and Innes, 1994; Bussotti and Ferretti, 1998). Complex phenomena are likely to be hypothesized, where atmospheric polluting agents role mingles with other a - and -biotic stresses. Alerts for a wood widespread plague (Schutt et al., 1984) seem to have not been substantiated by the results of 12 years of monitoring on European trees conditions: the mean defoliation of main European woods species is proved to be generally steady from 1989 to 2000 (UN/ECE e EC, 2001).
Three particular parameters among the ones employed in the forest ecosystem state monitoring, are of primary importance due to the meaningful information they can give.
Fig. 1: Total transparency variation shared out among species checked (1995 - 1999)
The analysis of foliage transparency data (Fig. 1 and 2) checked on 122 level I zones during 1995-1999 shows a clear stability of hardwood trees conditions together with a fair improvement on softwood trees. The conditions of the ecosystems studied are therefore on a better quality level than other European ones, bearing in mind that up to this date the analyses are restricted to a short period of time.
Fig. 2: Total transparency variation for hardwood and softwood trees checked (1995 - 1999)
All of the researches making up - as in a mosaic - the monitoring on forest ecosystems presume continuous and repeated measurements, as only a great number of data, allows defining possible negative or positive tendency of forest's health. A steady, prolonged monitoring is desirable; it must be aimed at improving the analysis methods and selecting the descriptive parameters of environmental conditions.
The level one system planned and implemented by Regione Lombardia has highlighted that the studied forest evolution state is a specific-species one, undergoing inter-yearly strong swayings. A peak of trees in the series 1990-1994 comprising hardwoods and softwoods was highlighted in 1992 as damaged. At that time non immediately understandable damages underwent a deterioration trend lasting up to 1994. The conditions of the trees seem settling by 1995 to 1999 and in some cases even improving as for the Scots pine (Pinus sylvestris). Pedunculate oak (Quercus pedunculata) is the only exception. During the second period of time damages to be ascribed to directly understandable reasons begin to be valuable on Norway spruce (Picea abies), scots pine (Pinus sylvestris) and European beech (Fagus sylvatica), but on pedunculate oak (Quercus pedunculata) above all. The presence of big dead branches on ramifications ("dieback") presumably to be related to these happenings, has grown in all the species (except for the European larch), and especially in the pedunculate oak.
The temporal series of understandable damages shows punctual disturbing events: in 1995 on the Scots pine (Pinus sylvestris), in 1997 on the European beech (Fagus sylvatica) and in 1999 a peak on the Pedunculate oak (Quercus pedunculata), caused by both mushrooms and phytophagi agents. The 1997 monitoring brought into evidence at a total sample level the role of biotic agents (chiefly insects) in determining the sample's general conditions.
The research has pointed out the difficulty to achieve a general definition of forest state in a chosen area. Clear and remarkable foliage density swayings have been picked out. The research indicates also (Innes and Boswell, 1991) that the whole forest condition may be swaying around an average value, and that the swayings themselves are determined by a considerable inner dynamism of the sample. In principal the influence of various environmental agents may explain this situation, chiefly the climatic ones and those connected with parasite swarms and pathologic and pathogenic attacks. Atmospheric pollution influence does not fit well this swift inter - yearly individual evolution.
Intensive studies on permanent observation areas carried out by programs financed with the European Union Reg. 3528/86 have allowed to gather extremely interesting data in order to determine the state of important ecosystems of Lombard woods like those with prevailing Norway spruce (Picea abies), and those with prevailing European beech (Fagus sylvatica). The data obtained have pointed out a clear difference as regards to soil, nutritional and apparent state of trees in the areas of Valtellina (Sondrio) on soils sensitive to polluting agents, and the area of Valcamonica (Brescia) on non-sensitive soils. These consistent differences emphasize a worsening in the tree state when nutrients in leaf contents are decreasing, when nutrient relative relationships deteriorate and - the whole - when soil mutual acidity grows. The observed fall rates seem to rule out their role in determining the soil state, which is very likely to be ascribed to natural differences among the studied ecosystems. The greater sensitivity of the soils in the two Valtellina's areas is if anything responsible for their being conditioned by smaller polluting quantities than it would have been on lesser sensitive soils. This bearing in mind, it is undoubted that ecosystems similar from the estimated sensitivity point of view - as in the case of the two Valtellina's areas - show tree state differences as regard to the leaf potassium level, to the estimated foliage nutrient loss due to the rain action (K, Ca, N-NO3) and particularly to the ozone exposure. It must be pointed out that some compatibility problems are present between the two areas that make the comparison remarkably uncertain; it is also to be noticed that the way the checked phenomena are connected and working is still to be defined at all.
It follows that few years of work are enough to build up hypotheses but not enough to be able to know how ecosystems are working. The data remarkable temporal variability shows how actually the hypotheses themselves undergo great uncertainties. It is certainly true that it is impossible to dedicate years of work only aiming at proving hypotheses, but it is also true that to understand the ecosystem working way when it answers endo - and exogenous stimuli, requires protracted temporal outlooks. As for the atmospheric pollution, fall levels of acidifying agents and nitrogen, and above all the exposure to concentrations and high quantities of ozone - verified by the data gathered in the project together with the sensitivity of a number of Lombardia's forest zones - call for a continuous watching.
Data gathered and results achieved by the projects developed in Lombardia, are therefore to be regarded as a valuable property to be utilized in the two new programs now being studied to create a III level area network in cooperation with other Italian Regions and towns of the Alpine arch.
Rapporto sullo stato dell'ambiente in Lombardia 1999 - Regione Lombardia Direzione Generale Tutela Ambientale (2000), pp. 97-99 - Milano
Rapporto sullo stato dell'ambiente in Lombardia 2001 - ARPA, pp. 26-33 - Milano
Lo stato delle foreste lombarde - Azienda Regionale Foreste (2002) pp.62 - Milano
AA.VV., 2002. Lo stato delle foreste lombarde. Un panorama sulle condizioni dei boschi in Lombardia attraverso i risultati di 10 anni di indagini. Azienda Regionale delle Foreste della Lombardia, Quaderni di ricerca e sperimentazione. 65 pp. Edizioni ARF, Milano.
Ferris-Kaan, R., Patterson, G., 1992, Monitoring vegetation changes in conservation management of forests. Forestry Commission Bullettin 108, London: HMSO: 30 pp.
Innes J. L., Boswell R. C., 1991, Monitoring of Forest Condition in Great Britain 1990. Forestry Commission, Bullettin 98, 54 pp.
Innes J. L., 1993, Forest Health: Its Assessment and Status. Commonwealth Agricultural Bureau, Wallingford: 667 pp.
Kandler O, Innes J. L., 1995, Air Pollution and forest decline in central Europe. Environmental Pollution, 90 (2): 171-180.
Landmann G., Bonneau M. (eds.), 1995, Forest decline and atmospheric deposition effects in the French mountains. Springer Verlag, Berlin Heidelberg. 453pp.
Schutt P., Blaschke HG., Holdenrieder O., Koch W., Lang K.J., Schuck H.J., Stimm B., Summerer H., (1984) - Der wald stribt an stress. C. Bertelsmann Verlag, Munich.
Skelly J. M., Innes J. L., 1994, 'Waldsterben in the forests of Central Europe and Eastern North America: fantasy or reality?', Plant Disease, 1021-1031
Stevens D. L., 1994, Implementation of a national monitoring program. Journal of Environmental Management, 42(1): 29.
UN-ECE e EC, 2001, Forest Condition in Europe. 2001 Executive report. UN/ECE, CEC, Geneva, Brussels, 33 pp.
1 Haryana State Remote Sensing Application Centre (HARSAC),
CCS HAU Campus, Hisar - 125004, Haryana, India
Phone: +91 1662 32632/ 31046, Fax: +91 1662-25958/71369
Email: [email protected]
Regione Lombardia - E.R.S.A.F., Ente Regionale per i Servizi all'Agricoltura e alle Foreste
20129 Milano, Italy