Antoni Tadeusz Miler, Andrzej Czerniak, Sylwester Grajewski, Bogusław Kamiński,  Bernard Okoński

Department of Forest Engineering

The August Cieszkowski Agricultural University of Poznań, Poland

 

 

Marshlands of the Forest Promotion Complex “Lasy Rychtalskie” – water and soil

 

 

Summary

The aim of the present work is a description of a multi-year complex  field research (hydrological, chemical and geotechnical) carried out on the area of the Forest Promotion Complex ”Lasy Rychtalskie”. The work focused on characterizing the present state, forecasting future changes, as well as indicating the stability threats which the areas face. The marshlands in focus are characteristic for their high storage capabilities. Water relation changes forecast for the investigated areas, expressed by groundwater level changes, was based on the negative annual atmospheric precipitation trend. It was assumed that significant changes in marshland ecosystems would occur in the situation of at least 50 % decrease of the present mean groundwater level. It will take about 100 years. The carried out chemical tests did not reveal any excessive cumulation of chemical pollutants either in soil or both ground and surface waters of the Complex. Dirt roads based on marshy subsoil did not meet, in the period of the whole year, the bearing strength requirements defined for forest roads.

 

Key words: forest marshlands, water condition, water and soil quality, road bearing strength 

 

INTRODUCTION

 

The Forest Promotion Complex ”Lasy Rychtalskie” (with its area of approx. 48 thou. ha) comprises the forests of both two inspectorates of the Regional Directorate of State Forets in Poznań; namely Syców and Antonin, and those of the Experimental Forest Complex in Siemianice. The area is located on the grounds belonging to the III Wielkopolsko-Pomorska Region, the 9 Province of the Zmigrodzko-Grabowska Valley, as well as the V Silesian Region of the 2 Breslau Province. The marshy habitats in focus cover the following areas of the total acreage expressed in percentage: Antonin 1.2 %, i.e. 239 ha, Syców 1.0 %, i.e. 221 ha, and Siemianice 6.3 %, i.e. 375 ha (Miler et al. 2005).

Some worldwide recognised scientific centers suggest that the process of intensive cumulation of chemical pollutants, taking place both in organic soils and waters of marshy areas, may have been going on for a long period of time; the supposition corresponds to trace elements and dioxins generated by industrial centers.

The existing road network is a significant element of the marshy lands technical infrastructure. Both its density and technical state of forest roads provide, to a high degree, conditions for proper management of forests. Mineral marshy areas, particularly organic ones, are characterized by low bearing capacity, which is further lowered at the time of high groundwater levels.

The aim of the work is to describe and present the results of the multi-year complex field investigations (hydrological, chemical and geotechnical) carried out in the marshy areas of the Rychtal Forests Complex. The final aim is to define the present state, to forecast the changes, as well as indicating the possible danger to the stability of the areas.

 

MATERIALS AND METHODS

 

Description of the experimental plots and general range of investigations

 

Three experimental plots were selected for the detailed investigations. They were microcatchments (8.58; 30.61 and 32.00 ha), which are almost entirely situated on forest marshlands. This is the most significant element in the proposed experiment since the core of it is an evaluation of the outflow from the defined area with excessive moisture.

The field research was begun in 2004. It comprised among others, limnigraphic water levels measurements in watercourses at Thomson overflows, weekly ground water levels measurements, collecting samples of surface and ground water, as well as soil for chemical determination (twice a year) and testing the bearing capacity of road; it was carried out applying the VSS apparatus (periodically). The meteorological data were obtained from the Siemianice station.

An assumption of the water relation changes for the area was worked out utilizing the temporal trends of mean annual air temperatures, as well sums of annual atmospheric precipitation. The conceptual Nash model (Miler 1994) was employed to model the storm flow outflows from the marshy areas. It was attempted to measure the effective precipitation applying SCS-CN method. An evaluation of the Forest Complex areas was attempted focusing on the potential capabilities of the area to retain water. The pilot type activities were carried out for the Marianka Experimental Forest Range.

 

Model SCS-CN

Model SCS-CN is a conceptual model of division of the total precipitation in its original form worked out in the 50’s of XXc. by the Natural Resources Conservation Service in the USA. The model is based on an assumption that the factors decisive in dividing the total precipitation into effective precipitation bringing about storm flow, are dependent upon the catchment cover, the type of ground, and initial moisture before the storm flow causing precipitation. The non-dimensional indicator CN is a synthetic parameter comprising the features. And thus the effective precipitation is a model-function of CN parameter (USDA-NRCS 1985).

The basic assumptions of the model state the equality of the proportions of factual storage (F) to maximum catchment storage (S), as well as effective precipitation to the total precipitation decreased by the initial loss (1), balance assumption stating that the total precipitation (P) is the sum of the initial loss (Ia), factual infiltration (F) and effective precipitation (Pe) (2). Parameter CN is bounded by empirical dependence with (S) parameter. Additionally the value of the initial loss (Ia) was bound to the potential storage maximum value (S) (3) (Mishra, Singh 2003) basing on the principle of equality of empirical dependence.

Thus:

                                                                       (1)

                                                               (2)

                                                                           (3)

It was empirically proved that λÎ[0; 0.3], in the original model it was accepted that λ is 0.2 (USDA-NRCS 1985).

Simple transformations deliver the following:

     for  P>Ia                                      (4)

        for P£Ia                                                         (5)

Maximum storage S is bound with the non-dimensional CN Î [1; 100], for P, Pe, S values expressed in millimeters, S is calculated from the dependence:

                                                        (6)

The method SCS-CN was initially constructed for agricultural areas. Forest was regarded as a category of land utilization which was homogenous in its structure (Mishra, Singh 2003, Okoński 2006). The methodology, basing on the features of the forest environment, for calculating parameter CN for Polish forest ecosystems was suggested by Okoński (2006). The suggested modification of the method utilizes hydro-meteorological data, as well as data of the area cover features obtained from a spatial unit – catchment or a few catchments and makes possible calculating of CN values ascribed to physico-geographical conditions. The basic equation of the modified SCS-CN method facilitating calculating of CN parameter value based on the original version of the method into the parameter values ascribed to a given spatial unit is given below:

                                             (7)

where: CNemp – empirical value of CN parameter, CN – parameter value according to the original method, a, b – empirical coefficients.

Making use of pairs of corresponding parameter CN values i.e. the values calculated basing on the original method (CN), as well as calculated for a given catchment on the basis of empirical data (CNemp), coefficients a and b are calculated for the equation  (7) from a regression dependence.

Basing on the parameterized equation the values of CN are recalculated according to the original method taking into consideration the given catchment outflow conditions in relation to the varied features of forest cover.

 

Potential storage capabilities

Both climatic and non-climatic physico-chemical elements modify the local capabilities of water storage. The elements such as: relief, soils and geological structure, watercourses network, stagnant waters and plant cover (species and age structure etc.) condition potential water storage capabilities. Evaluating of a potential storage capability consists in ascribing to each elementary homogenous area a parameter which considers a total impact of most significant physico-geographical parameters (Miler et al. 2001). Subsection is accepted here as an elementary surface. It facilitates almost direct utilization of the data stored in the bases constructed during forest management activities (Grajewski 2006). Each of the subsection was ascribed certain parameters which were regarded as crucial in determining its potential storage capability. The following parameters were regarded as determinants: mean ground slope [%], habitat moisture type [-], distance from watercourses network [m], distance from stagnant waters [m], mean weighted soil filtration coefficient [mm∙s-1], stand compaction index [-], type of soil cover [-], stand age [years], type of forest habitat [-], and  stand dominating species [-]. Next the ranges of changes of each parameter values were divided into three classes corresponding to: ”low”, ”medium” and ”high” storage capability, coding them as: 1, 2 and 3. ”Low” (code 1) potential storage capability of a given subsection was associated with the dry type of habitat’s moisture, short distances from the watercourses network, high soil filtration coefficients, low index of forest compaction, exposed soil cover, young stands, dry oak habitats, as well as deciduous species. Whereas, ”high” potential storage capacity of a given sub series was associated with marshy type of habitat moisture, long distances from the watercourses network, low values of soil filtration coefficient, high ratio of stand compaction, moss soil cover, mature stands, marshy and riparian habitats, as well as coniferous species. What followed was summing up of codes of all the parameters separately for each of the sub series. And thus a certain numerical value was obtained for each of the sub series, which was an indicator of potential storage capabilities from the range   (min = 10 ÷ max = 30). It results from a simple valuation:  min = 10(characteristics) · 1(min codes) = 10, and max = 10(characteristics) · 3 (max codes) = 30. Spatial distribution of the indicator, in the form of a map, enables indicating the areas of ”low”, ”medium” and ”high” potential storage capabilities of the analysed area.

 

Chemical investigations

Within the framework of the chemical investigations the following steps were taken:

1.        Determination of major soil, ground and surface water pollutants indexes,

2.        Estimation of heavy metals cumulation on the basis of soil magnetic susceptibility distribution in both horizontal and vertical system,

3.        Determination of dioxins content in soil.

 

Ad. 1. Methods of determination of major indexes of soil, ground and surface water chemical pollutants – Polish Norms.

 

Ad. 2. Magnetic susceptibility is an easily measurable geophysical value describing an ability of a given substance to magnetizing changes under an influence of the exterior magnetic field.

The procedure of measurements of magnetic susceptibility is based on an evident relation between an increase of magnetic susceptibility, and the content of heavy metals in soil. Strzyszcz (2003) comments that soil surface magnetic susceptibility reaching from 30´10-5 to 50´10-5 may indicate that the amount of at least one metal exceeds the boundary value permitted for forest soils. Magnometry is a method alternative to expensive geochemical methods. The method is specially useful in forest areas where a long-period deposition of pollutants (including magnetic particles) is not disturbed by agro-technical practices.

Soil magnetic susceptibility was analysed applying the determination of surface and vertical distribution of ferromagnets.

The surface measurements were carried out applying a magnetic susceptibility meter equipped with an English field sensor MS2D produced by Bartington Instruments Company, integrated with GPS Pathfinder American system manufactured by Trimble firm.

Vertical distribution of magnetic susceptibility was analysed using Czech produced SM 400 magnetic susceptibility meter, type - ZH Instruments – Brno. The measurements of value κ in vertical system were analysed down to the depth of 20 cm with resolution equal to 0.2 mm.

 

Ad. 3. Dioxins come into existence as an undesirable side-effect of some industrial or combustion processes, or as a result of various damages. The basic source of emissions into the environment are: industrial refuse, herbicides, pesticides, and transformer oils.

Dioxins are also produced as a result of an uncontrolled coal combustion which takes place in stoves, boiler rooms and refuse heaps containing chlorine bounded in both organic and inorganic form. Fires can also be a source of the elements. Dioxin content identification in soil was carried out by help of gas chromatography technique in combination with mass spectometry with a double fragmentation of the investigated molecule applying type MAT GCQ and  GC-MS/MS (Grochowalski 2000) appliances.

The level of toxicity of the analysed samples expressed as standardized value TEQ, was calculated applying the so-called equivalent toxicity coefficient TEF on the basis of the chemical analyses of mass content of congeners PCDDs and PCDFs having chlorine atoms in positions 2, 3, 7 and 8.

 

Forest roads bearing strength

The aim of the research was determining the influence of the water table level in soil sub grade on bearing strength of forest roads pavements.

Bearing strength investiagtions were carried out of roads with soil and non-rehabilitated paved surfaces built from debris, slag and melafire break stone. Constructions of non-rehabilitated paved surfaces were founded on a filtering off course having 0.2 m thickness.

All the experimental road sections were founded on soil-marsh subsoil, and bearing strength investigations were carried out in the conditions of extreme groundwater table level in the subsoil. VSS apparatus with a pressure slab of 0.30 m in parameter was applied to determine bearing strength. Reformation index Io was also calculated.

 

RESULTS AND DISCUSSION

 

Water relations

Annual outflow from the areas in focus is relatively low approx. 4 % of the annual sum. The watercourses disappear seasonally – in hydrological years 2004/2005 and 2005/2006 there was an observed outflow during the periods of respectively 202 days ((15.11.2004–5.6.2005) and 192 days (1.12.2005–10.6.2006). In the period of the investigations no typical, i.e. basing on surface runoff, storm flows were observed. Normally they last in the investigated catchments for no longer than a few hours during heavy rainfalls. The observed storm flows – increased outflows of rain-thaw or rain type-were fed by both subsurface and ground outflows. The above proves a relatively high storage capability of the marshlands in focus. (stands, forest bed, ground depressions, soils).

Average groundwater levels (51 wells) are placed shallow i.e. 97.5 cm below ground level, with standard deviation 55.5 cm. Outflows occur in watercourses when groundwater levels are higher than their approximated mean annual values.

Nash model – a conceptual catchment model – was used to model the observed precipitation-storm flows incidents: N-identical, linear reservoirs with time-constant T (Miler 1994). A proper evaluation of effective precipitation is crucial in case of precipitation-outflow models. Effective precipitation can be calculated on the basis of coefficients of storm flow outflows i.e. quotients of storm flow outflows and sums of precipitations causing the storm flows. Then the results of Nash model simulation are fairly good for the investigated catchments. An exemplary result of simulation for ditch G-8 catchment is presented in Fig. 1.

The following trends were calculated basing on the data from Siemianice (1957-2006): mean annual air temperatures (+0.041 oC/year) and annual atmospheric precipitation sums (-1.573 mm/year). The above trends are significant statistically respectively at the significance level a=0.05 and 0.25. Positive air temperature trend will undoubtedly stimulate evapotranspiration growth which depends on many factors, among others access to water. It can be thus assumed in the forecast that evapotranspiration will not undergo significant changes. The outflow from the investigated areas is insignificant so it can be not taken into consideration in the prediction.

 

Fig. 1. Example result of storm flow modelling in marshlands on the Promotion Forest Complex “Lasy Rychtalskie” (H – measured outflow, Hs – simulated outflow) 

 

Finally the prediction of water relation changes in the area in focus, expressed by groundwater level changes, can be founded on negative atmospheric precipitation trend. If it is assumed that significant changes in marshy ecosystems will occur alongside with a decrease of average groundwater level by approx. 50 cm (50 % of the present average groundwater level),  as a result of decreasing annual atmospheric precipitation sums, it can be calculated that this will happen in about 100 years.

Alongside with the accepted assumptions and soil porosity in the aquifer of 30 %, after 100 years decreasing precipitations will bring about lowering of groundwater levels on average by 46.3 cm. The above calculations show only the order of magnitude corresponding to the period, after which such a drain up of forest marshlands is probable that will lead to changes in their character, and they will not stay abundantly moisture habitats.

 

Modelling of effective precipitation

 

Modelling of effective precipitation accompanied by the modified SCS-CN model was carried out on the basis of the empirical data gathered in 2005 hydrological year from the forest marshland catchment (ditch G-8) having the area of 32 ha. Storm flows episodes, as well as precipitation sums, connected with them were taken into consideration in the period of the year. Modelling assumptions were met by three storm flow incidents, which were qualified for the modelling procedure i.e. the episodes from the periods 17.01–28-01.2005, 06.04–21.04.2005, 01.05–14.05.2005.

The procedure of calculating parameter CN empirical values was carried out, taking into consideration initial moisture values for precipitation episodes, in agreement with factual soil moisture (soil before precipitation bringing about storm flow – AMC). Results of subsequent precipitation episodes are gathered in Tab.1. 

 

Tab. 1. Results of modelling for ditch G-8 catchment

Rainfall episode period

 

Period

 

Actual antecedent moisture

of soil before rainfall

(AMC)

Average empirical

value of CN parameter for the catchment

Maximum storage

 

Total rainfall

 

Direct runoff

 

Empirical runoff coefficient

 

Direct runoff according to the model

 

Runoff coefficient according to model

 

 

t

AMC

CN

S

P

Pe

Α

Pe

Α

 

[days]

[-]

[-]

[mm]

[mm]

[mm]

[-]

[mm]

[-]

17.01-28-01.

2005

8

III

76.4

78

25.1

0.56

0.022

1.12

0.0446

06.04-21.04.

2005

3

II

33.9

495

24.3

2.75

0.113

Condition of the model

P>0.2×S

01.05-14.05.

2005

9

I

20.4

991

42.4

1.69

0.04

 

Results of effective precipitation modelling with help of SCS-CN model in the version adjusted to the conditions of the catchment cover can be viewed only in estimating categories.

The features of ditch G-8 catchment (marshland) are unfavourable for creating surface and subsurface outflow. And thus SCS-CN model has noticeably limited applications for marshlands.

 

Potential storage capabilities in the Marianka Experimental Forest Range

 

The map depicting spatial variability of potential storage capability index of the Experimental Forest Range areas was worked up. The analysis of the index shows its high spatial variability. The map can be utilized e.g. while designing plans for increasing water storage for the area.

 

Chemical investigations

As a result of the carried out chemical tests of both soils and waters of the marshlands in the Mariak and Marianka Forest Ranges no strong cumulation processes of anthropogenic origin pollutants were found. The obtained research results were compared with corresponding standards of soil quality (Polish Standard), and boundary values of surface and underground water quality indexes, the manner of monitoring procedures, as well as ways of interpreting the results and presenting the levels of the waters (Polish Standard).

Water-soil environment of the analysed marshlands poses no danger to the neighbouring forest complexes from the chemical point of view (Miler et al. 2006). 

As far as grounds are concerned, the content of heavy metals, apart from cadmium, was found to be within the value range accepted for areas protected by legal regulations concerning the cleanest natural reserves belonging to group A. The content of cadmium at some research plots insignificantly exceeded the permissible values defined for cadmium, but did not exceed the values for group B areas i.e. arable, forest and afforestation areas. The investigated soils were characterized by a high variability of iron concentration.

An increased cumulation of heavy metals (apart from iron) was not confirmed by the initially conducted magnometric investigations. It is assumed that non-polluted soils are characterized by a natural magnetic susceptibility (below 30´10-5). Magnetic susceptibility within the range from 30´10-5 to 50´10-5 indicates an increased content of anthropogenic ferromagnets. Magnetic susceptibility from 50´10-5 to 100´10-5 is regarded as high, and above100´10-5 as very high. The average Polish magnetic susceptibility for forest soils is defined on the basis of the Map of Magnetic Susceptibility of Soils of Poland and equals to 22´10-5.

Investigations of the surface magnetic susceptibility of marshy areas soils showed an increased concentration of iron, while the share of other ferromagnets proved to be low. Κ values were contained within the range from 15´10-5 to 70´10-5. The distribution of ferromagnets was correlated with the type of the investigated soils.

The investigations of the vertical magnetic susceptibility distribution proved that the maximum κ values generally did not exceed the value of 50´10-5. The maximum of κ value was found at the depth of 4.0 to 10.0 cm in all of the investigated research plots.

As a result of the carried out chemical analyses the total value of congeners PCDDs and PCDFs in the investigated soil samples did not exceed the value of 8.0 ng PCDD/F- TEQ/kg. To compare the content of PCDDs and PCDFs in agriculturally utilized soils must not exceed 10 ng/kg, and for non-arable soils the value is 50 ng/kg.

 

Road bearing strength  investigations

Synthetic results of forest road bearing strength investigations carried out on the area of the Lasy Rychtalskie Complex marshlands are gathered in Tab.2. From among four investigated forest road on bog - basis best showed pavement with broken trick / concrete broken stone.

 

Tab. 2. Reformation modules of forest roads pavements for extremely deep groundwater levels in road subsoil

Location and type of pavement

Primary E1 and secondary E2 pressure value

Reformation modules in MPa and Io = E2/E1

Terms of tests and groundwater level b.g.s.

 

Range of primary pressures in MPa

0.05 – 0.15

0.15 – 0.25

0.25 – 0.35

Marianka – broken trick/

concrete broken stone

E1

91.8

78.9

104.6

August 2005

183 cm

E2

83.3

107.1

125.0

Io

0.91

1.36

1.19

E1

30.8

34.9

40.9

April 2006

73 cm

E2

51.7

62.5

72.6

Io

1.68

1.79

1.77

Marianka –  dirt road

E1

12.3

8.9

4.0

August 2005

182 cm

E2

17.2

18.0

6.7

Io

1.40

2.03

1.66

E1

5.9

6.7

2.1

April 2006

61 cm

E2

4.2

-

-

Io

0.71

-

-

Mariak – melafire broken stone

E1

46.4

43.7

31.5

August 2005

38 cm

E2

48.9

70.3

80.4

Io

1.05

1.61

2.55

E1

24.9

30.6

36.0

April 2006

33 cm

E2

54.2

69.2

73.8

Io

2.18

2.26

2.05

Mariak –  slag

E1

84.9

67.2

54.9

August 2005

45 cm

E2

84.9

100.0

166.7

Io

1.00

1.49

3.04

E1

48.9

54.2

43.7

April 2006

33 cm

E2

69.2

70.3

67.2

Io

1.41

1.30

1.54

 

The surface met the criteria of bearing strength for forests roads with traffic load of KR – 1 E1 > 100 MPa. It must be noticed though that the bearing strength (E1 = 104.6 Mpa) was reached in dry conditions, when groundwater level decreased to below 180 cm. The same surface lost up to 60 % of its bearing strength in the situation of groundwater table increase by 110 cm.

In the Mariak forest range the roads with slag pavement were situated in the areas where ground waters were shallow i.e. 33 to 45 cm below ground level.

Both pavements reached the strength meeting the bordering requirements set for road foundation and improved subsoil. Increased bearing strength can be achieved by lowering the groundwater level within the road frame. The changes will influence a decrease of water level in the neighbouring forest stand, which will have an impact on decreasing the area of protected marshes. And thus the solutions for an improvement of marshlands roads bearing strength should be searched for in the areas of various types of pavement construction and road subsoil reinforcements. Geosynthetics provide for obtaining good results in the construction of pavements (Kamiński, Czerniak 2003, Czerniak, Kamiński 2003).

 

SUMMING UP AND CONCLUSIONS

 

The annual outflow from the investigated marshlands is relatively low at 4 % of the annual precipitation sum. Watercourses periodically take water away, mainly in the winter half-year. No typical storm flows were observed; only increased precipitation-thaw or subsurface or ground- fed rain outflows were recorded. Modelling the outflows from the areas, especially storm flow type one is significantly restricted by difficulties to evaluate the effective precipitation.

Water deficit which will occur in a relatively close future is the main threat to the ecosystems of the Lasy Rychtalskie Complex. It will take about 100 years – degradation of marshlands.

The carried out chemical investigations did not show an excessive cumulation of chemical pollutants in soils, as well as surface and ground waters of the Complex.

Dirt roads situated on marshy subsoil did not meet the conditions of bearing strength ascribed to forest roads. The strength of hard not improved roads depended mostly on the groundwater table level in the subsoil.

 

REFERENCES

 

Czerniak A., Kamiński B. Przydatność geokraty do budowy dróg leśnych. PTPN, Wydz. Nauk Roln. i Leś., Prace Kom. Nauk Roln. i Leś. T. 94. 41 – 48, 2003.

Grajewski S. Stosunki wodne oraz zdolność retencyjna obszarów leśnych Parku Krajobrazowego Puszcza Zielonka. Wyd. AR w Pozn. Ser. Rozpr. Nauk. nr 382, 2006.

Grochowalski A. Badania nad oznaczaniem polichlorowanych dibenzodioksyn, dibenzofuranów i bifenyli. Zesz. Nauk. Politech. Krakow., Monograf. 272, Kraków, 2000.

Kamiński B., Czerniak A. Zastosowanie geokraty komórkowej do wzmocnienia gruntowej drogi leśnej na podłożu spoistym. Wyd. AR w Pozn. 478 – 486, 2003.

Miler A. Modelowanie matematyczne zdolności retencyjnych małych zlewni nizinnych. Rocz. AR, Rozpr. Nauk. z.258, Pozn. 1994.

Miler A.T., Grajewski S., Okoński B. Stosunki wodne w wybranych ekosystemach Puszczy Zielonka. Monograf. Wyd. AR Pozn. 2001.

Miler A.T., Kamiński B., Krysztofiak A., Sobalak M. Inwentaryzacja obszarów mokradłowych na terenie Leśnego Kompleksu Promocyjnego Lasy Rychtalskie oraz wstępne wyniki badań hydrologicznych. Infrastruktura i Ekologia Obszarów Wiejskich, PAN Kom. Techn. Infrastruktury Wsi 4, 2005, 85-98.

Miler A.T., Kamiński B., Czerniak A., Grajewski S., Okoński B., Stasik R., Krysztofiak A., Sobalak M., Poszyler-Adamska A., Przysiecka K., Kamiński M. Opracowanie strategii ochrony obszarów mokradłowych na terenie leśnych kompleksów promocyjnych na przykładzie LKP Lasy Rychtalskie. Nr zad. 18.  DGLP (typescript), 2006.

Mishra S.K., Singh V.P. Soil Conservation Service Curve Number (SCS-CN) Methodology, Kluwer Academic Publishers, Dordrecht, 2003.

Okoński B. Modelowanie odpływu bezpośredniego w zależności od stanów pokrycia zlewni leśnej. Ser. Rozpr. Nauk. Zesz., 374, Wyd. AR, Pozn. 2006.

Strzyszcz Z., Magiera T. Ocena zanieczyszczenia gleb leśnych na podstawie podatności magnetycznej na przykładzie nadleśnictwa Katowice. Prace IBL, W-wa, A: 961, 19-30, 2003.

Trampler T., Kliczkowska A., Dmyterko E., Sierpińska A. Regionalizacja przyrodniczo-leśna na podstawach ekologiczno-fizjograficznych. Wyd. UAM Pozn. 1990.

USDA-NRCS National Engineering Handbook Hydrology, Section 4, US Dept. of Agriculture, National Resources Conservation Service, Washington D.C., 1985.