## 2 Data and Methods
### LAI Measurements  
LAI measurements were performed with the LAI 2000 instrument [12]. This device calculates LAI and other canopy features by measuring solar radiation with a \"fish-eye\" optical sensor (148 degrees field of view). Measurements made above and below the canopy serve for the identification of sky radiation penetrating the canopy. LAI is calculated using these measurements as an input for a model of light radiation transfer through plant canopies. An advantage of LAI 2000 measurements is that it is quick. Moreover, LAI 2000 does not require direct solar radiation, hence the measurements do not need to await sunny days or a change in the angle of solar radiation. Furthermore, measurements can be carried out in different cloudiness conditions; the best condition is when the sun is covered by clouds, but it is also possible to measure on sunny days if an appropriate protocol is applied. LAI 2000 can be utilized in various types of afforestation, from short grasses to the tree stand. The same LAI measurement protocol was applied at each site. At the survey planning stage dominant areas within the sites were determined on the basis of uniform vegetation cover. The number of LAI \begin{table}
\begin{tabular}{c c c} \hline
**No.** & **Research Site** & **Habitat Characteristics** & **N. LAI** \\ \hline
1 & Józefów (Joz) & Xerothermic grassland found on carbonaceous rocks. Adjacent to it is dry and moderately moist coniferous forest. & 5 \\
2 & Wielkie Bagno (Wbag) & Mixed coniferous forest and alder carriferous forest. Mixed coniferous forest soil is mainly represented by fine-grained sands located on alluvial & 4 \\  & & sand-dune soil. Water-logged soils are typical for alder carr habitat. & \\
3 & Zaskroncowa & Moderately moist coniferous forest on mineral deposits in podzolic soil & \\  & Polana (ZP) & and rusty soil of exceptionally thin layer of acid mor-humus. Groundwater & 6 \\  & Zwierzyniec Dom & Private timber forests with species resembling moderately moist mixed & \\
4 & (Dom) & coniferous forest. Forests strongly degraded by the remains of the owners’ & 8 \\  & & residential buildings. & \\
5 & Borowe Mlyny II (BM) & Marshy coniferous forest on peaty earth soil formed in hollows in the terrain without flow. This area is located within the reach of acid & 6 \\
6 & Borowina (Bor) & Moderately moist coniferous forest located on mineral deposits on & 3 \\  & & sod-podzolic soil. Habitat present on peat- and peat-earth soils. & \\
7 & Bukownica (Buko) & Ploughland, isolated by a railway crossing. Each year monocotyledon plants not exceeding 1.5 meters are planted. & 3 \\
8 & Edwardów Nowy & Dry soil coniferous forest located in immediate proximity of a brook. & 3 \\  & Most (Edg) & Adult tree stand on fine-grained sands. & \\  & & Coniferous forests on moderately moist and moist soils. The area situated & \\
9 & Fryszarka (Frz) & on podzolic type of soil, predominantly fine-grained sands. Peat or, in & 4 \\  & & places, peaty earth soil is present in depressions. & \\
10 & Kruglik (Krl) & Mixed coniferous forest on specific podzolic soil formed on the basis of & 3 \\
11 & Józefow rondo (Roj) & Mixed forest located partly on moderately moist brown soil and, partly, & 4 \\  & & on podzolic soil. Large open areas in close proximity. & \\ \hline \end{tabular} The column “N. LAI” shows the number of LAI measurements points at given research site.  
\end{table} 
Table 1: Characteristics of research sites. measurement points for the survey sites is shown in Table 1. The Trimble Juno SB GPS receiver registered coordinates of measurement points. This allowed measurements to be taken in the same places over the entire period of the experiment. The accuracy of the GPS measurements of x and y coordinates was at the level of 20 m in the forests and about 2 m in open areas. At each point, LAI measurement consisted of one reference measurement relative to the non-canopy covered vegetation and nine measurements made below the vegetation. LAI measurements were carried out in invariable atmospheric conditions.