2. A general description of permanent observation plots and the programme for forest monitoring in 2002

Plate 3. The Second-level Permanent Observation Plot in Jagiełek Forest District - photo by Jerzy Wawrzoniak

Permanent observation plots (POPs) form the main element to the structure of the forest monitoring system. There are 1461 of them within Poland's forests, in Scots pine, spruce, fir, oak, beech and birch stands aged 20 years and over - giving an average of one plot per c. 60 km2 of the area of Poland under forest (Fig. 1). Within the total, some 433 permanent observation plots are distributed in a 16 x 16 km grid system and fall within the Europewide monitoring network.

Each first-level permanent observation plot comprises a group of 20 numbered trees selected from the predominating stand. The centres of the plots are marked permanently in the field. In 1995, a circular plot varying in size covering area related to the stand age was established within each POP. All trees with DBH equal or greater than 7 cm located within the circular plot were numbered and their biosocial position, defoliation, discolouration of crown, DBH (with 1mm accuracy) and tariff were taken. The number of dead trees was taken also. The first-level POPs are the subject of basic research programme.

In 1994, a selection was made of 122 plots from among the First-Level POPs located in coniferous stands. In 1996, a similar procedure was applied in relation to 26 first-level POPs located in broadleaved stands. Second-level permanent observation plots were established here (100 of pine, 22 of spruce, 15 of oak and 11 of beech). The second-level POPs (148 in total) are subject to a research programme with a considerably expanded scope of observation and analysis. The second-level POPs are located in such a way that each natural-forest district of Poland is represented by 2 or (in the case of certain very extensive districts) 3 plots.

Fig. 1. Distribution of first- and second-level permanent observation plots in natural-forest regions

Both first- and second-level POPs are the subject of research programmes whose methodology is, to a great extent, harmonized with methodology recommended by the ICP-Forests (International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests) [5] with an exclusion to assessment of biotic elements of forest ecosystems which methodology was developed by the team performing the programme. A detailed description of measurements and methods applied in forest monitoring programme in Poland is published in annual reports [8, 9, 10, 11].

As of 2002, the programme of forest monitoring took in the following measurements, and observations:

    Monitoring of damage to stands
    - assessments of the defoliation and discolouration of the assimilatory apparatus, and of other morphological features of tree crowns, as well as measurement of breast-height diameters, on 1461 first-level POPs with trees aged 20 years or more, including 148 second-level POPs.
    Monitoring of the chemistry of trees' assimilatory apparatus
    - chemical analysis of foliage samples taken in 2001 from sample trees located on each of the 122 second-level POPs (100 plots with pine and 22 with spruce stand. The needle samples consisted of 1 and 2-year-old needles. Chemical analyses covered the following elements: N, P, K, Ca, Mg, S, B, Fe, Mn, Zn, Al, Cu, Pb, Cd.
    Monitoring of the health of pine seeds
    - evaluations of cones and seeds obtained from pine stands on 100 second-level POPs.
    Entomological monitoring
    - estimation of the population densities of folivorous insects in the coniferous stands of ca. 1130 first-level POPs, including: nun moth (using pheromone traps), pine sawflies, beauty moth, pine looper moth, pine hawk moth, pine lappet, pine webworm (on the basis of autumn searches) and pine shoot beetles (on the basis of the collection of twigs damaged by pine shoot beetles). The numbers of ground beetles were determined on 61 selected second-level POPs.
    Phytopathological monitoring
    - assessment of the phytopathological threat posed to forest by fungi causing dieback of Scots pine shoots and root pathogens and assessment of fungal infection of stumps were also included in the study.
    Monitoring of pollutant deposition
    - measurement of air pollutants on the 148 second-level POPs (determinations of concentrations of SO2 and NO2 using a passive method, as well pH and the chemical composition of precipitation waters). Chemical analyses covered the following elements: Ca, K, Mg, Na, NH4, Cl, NO3, SO4, Al, Mn, Fe and heavy metals (Cd, Pb, Cu i Zn).

  Raport 2002