Articles containing the keyword 'ditch'

The influence of different fertilization treatments and ditch spacings on the height growth of young Scots pine (Pinus sylvestris L.) seedling stands growing under various climatic regimes were determined. Comparisons were made between naturally regenerated and planted seedling stands. The effective temperature sum had a stronger effect on the height growth of planted seedlings, and in Northern Finland the planted seedlings seemed to be influenced to a greater degree by the adverse climatic conditions. The heavier the dose of fertilizer that had been applied, the greater the difference in growth caused by macroclimate. A considerably larger proportion of natural seedlings were located on hummocks compared with that of planted seedlings, irrespective of the region. On plots with wider ditch spacings, seedlings growing on hummocks were superior in height growth to those on flat surfaces.

The PDF includes an abstract in Finnish.

• Miyazava, E-mail: tm@mm.unknown
• Laine, E-mail: jl@mm.unknown

The effects of variations in the intensity of drainage and NPK fertilization on the natural regeneration and planting results and the subsequent development of seedling stands under various climatic conditions on drained nutrient poor pine bogs was investigated in a 16-year-old study.

Comparison of height development of Scots pine (Pinus sylvestris L.) stands on drained peatlands to that of pine stands growing in mineral soil sites show that in Southern Finland the most efficient forest improvement measures (10 m ditch spacing and 1,000 kg/ha NPK-fertilization) resulted in growth that corresponds a to a height index of a stand in a Vaccinium type site. Less efficient treatment (30 m ditch spacing and no fertilizer) resulted in growth corresponding the development of young stand in a Calluna type site. In Northern Finland the effect of fertilization on height growth was almost negligible. This is possibly due to a decrease in the nitrogen mobilization from south to north of Finland. Thus, it seems evident that fertilization of young Scots pine stands on nutrient poor drained peatlands can be recommended only in the southern part of the country.

The effect of ditch spacing is same in the whole country. The narrower the spacing the better the height growth. In the south planted stands thrive better than naturally regenerated stands, but the situation is reversed in the north.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Laine, E-mail: jl@mm.unknown
• Lepola, E-mail: jl@mm.unknown

The paper describes the results obtained from an investigation into the effect of ditch spacing, ditch depth and furrowing on ground water table and on development of a Scots pine (Pinus sylvestris L.) plantation on open small-sedge bog in Central Finland (60° 50’ N; 24° 20’ E), drained in 1967. The area was planted in 1968 with 2+1 Scots pine transplants, and fertilized with Y fertilizer for peat soils. The seedlings were measured in 1972.

The depth of the ground water table was greater, the narrower the ditch spacing. The water furrows shortened the duration of the high ground water and lowered the ground water table particularly in the case of ineffective drainage. The narrower the ditch spacing within the blocks, the higher were the young trees. On the other hand, the differences in the height of the trees between the ditch spacings were eliminated by the effect of the furrows.

The PDF includes a summary in English.

• Päivänen, E-mail: jp@mm.unknown

The changed in size and shape of ditches made by draining plows and tractor diggers were followed over a one-year period after the draining in four different peatland types. The material consists of 51 ditches made with each method in dwarf-shrub pine bog, herb-rich spruce swamp, in herb-rich sedge bog and sedge pine bog. The measurements were made immediately after the digging, and one month and a year later.

Ditches made by plowing and surrounded by peat became shallower quickly during the first 2–3 days after plowing due to the pressure of the surrounding peat. Ditches made with tractor diggers did not become shallower as fast, and their bottom did not widen to the same extent than plown ditched. During the first year, machine-made ditches change in a same way as handmade ditches, especially when compared to ditches made by tractor digger.

Immediately after digging the ditches made by tractor digger were 10 cm deeper and 0.13 m³ larger than plown ditches. One year later the values were 7,5 cm and 0.09 m³, respectively. Plown ditches made in the peat were 14.4 cm deeper than ditches that penetrated into the subsoil, for tractor digger the value was 13.2 cm. Ditches made with a tractor digger were deeper than plown ditches both in soils with deep and shallow peat layer.

The changes were largest and fastest in the wettest peatland type herb-rich sedge bog. In herb-rich spruce swamps, which have a shallow peat layer, the shallower plown ditches kept their form better than ditches dug by tractor digger.

The PDF includes a summary in English.

• Timonen, E-mail: et@mm.unknown

The present paper is a preliminary report of a project designed to determine the order of profitability of various forest improvement measures – seeding and planting, drainage, and fertilization – in various types of stands and in different parts of the country on drained peatlands. Sample plot data on the effect of draining on increment was derived from areas drained 28– 36 years ago. The study was carried out in the southern half of Finland.

The observations on increment changes are based on two measurements of the sample stands 12 years apart. Supplementary calculations indicate that the stands on drained peatland, depending on site quality and tree species, have either continued to grow like mineral-soil sites of similar fertility or have somewhat increased their growth rate.

The effect of draining intensity was studied using strip measurements. It was found that both the total amount of wood produced (current stand + cutting removal + natural removal) and the current annual volume increment for the 5-year period systematically decrease as the ditch interval increases. The decrease is, however, relatively slight. In Eriophorum vaginatum pine swamps, the total amount of wood produced and the increment show a decrease of ca. 20% with an increase in ditch interval from 20 to 60 metres. In other sites, the decrease is ca. 5-10%

It can be concluded that if the increase in ditch interval do not result in considerably poorer timber assortment distributions than indicates by stand production and increment, it is profitable to pan for a relatively large ditch interval and a slightly smaller than maximum wood production. Supplementary data and check calculations may cause some changes in these preliminary results.

The PDF includes a summary in English.

• Seppälä, E-mail: ks@mm.unknown

When ditches are dug in forest drainage, smaller stones are removed by hand, but the larger ones require the use of explosives or stone lifting machinery. Use of explosives have been a more common method for the larger stones. Due to development of detonation methods, it has also been used for smaller stones than earlier.

The investigation was a time study comparing five different stone lifting machines. Time needed for different stages of the work was measured. The stages lasted approximately as long for all of the machines. However, the effectivity of the machines could not be determined, because the stones removed were not similar enough. Stone lifting machine Pekka appeared slightly more effective than the other four machines. It was also easy to assemble, disassemble and move.

The article includes a summary in German.

• Yli-Vakkuri, E-mail: py@mm.unknown

The aim of the study is to find out 1) whether and how the original moor type can be found out based on vegetation regardless the phase of drainage; 2) whether the different phases of draining can be distinguished based on the vegetation; and 3) is it possible to classify the well drained moors into vegetation types that would reflect the productive capacity of the land.

The data consists of samples collected from ditched areas. There are 11 moor types from two climatic ditching zones. The results show that the original moor type can be determined based on vegetation, the phase of drainage can be determined under some limitations, and the classification for productivity can be done for practical purposes.    

The PDF contains a summary in Finnish. 

• Sarasto, E-mail: js@mm.unknown

The article deals with forest ditches dug by manual labour in drained peatlands in Central and Southern Finland, ranging in age from 16 to 25 years. The ditches have been allowed to develop in a natural state. A total 1,160 of randomly selected sample plots were studied.

The results show that the originally dug ditch depth has not been the decisive factor from the viewpoint of maintaining the ditch repair. Ditches dug in thick peat layer have maintained their repair better than those dug in thin peat layer. Apparently, the influencing factor is the type of soil, to a certain extent parallel to the thickness of peat layer. In ditches dug mainly in mineral soil, the type of soil has essentially contributed to maintaining the ditch repair. Ditches in coarse-grained soils maintained a better repair than those in fine-grained soils. Also, the steeper the gradient of the ditch the better the ditch repair has been maintained. There was no relationship between the thickness of peat and the filling up of ditch bottom, because of the influence of mineral soil. Filling up of a ditch seems to be mainly due to the sinking of peat. The filling up of ditch bottom was more pronounced in clay-silt soil than in other soil types. The filling up of ditch bottom by varying gradient is due to the fact that with a small gradient the speed of water is so slow as to permit the soil particles to sink to the bottom. Another factor affecting filling up of the ditches is wetness of the peatland. Deepening of ditches happens mainly through erosion, if the gradient is large enough. The study suggests that a 50-m spacing with about 60-cm ditchc depth would be most profitable.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown

The aim of the study was to investigate how the drain network and dimensions of ditches change after the drainage. The studied drained peatlands were situated in the municipalities of Parkano and Virrat in Central Finland. The ditches were in average 15 and 17 years old. The depth and width in the surface of the peatland were in average one quarter smaller than after the drainage. The width at the bottom of the ditch has, however, almost doubled. Peat had sunken more in peatlands with thick peat layer and higher humidity. Sinking of peat influenced the depth of the ditches. The volume of the ditches decreased about 30%. The decrease of the ditches by the drying and sinking of the peat was greater than the increase caused by erosion.

The PDF includes a summary in German.

• Multamäki, E-mail: sm@mm.unknown

Approximately 320,000 hectares of peatlands and paludified lands had been drained for agriculture and forestry purposes in Finland by 1920. The ditch network was not optimal in the early drained areas, and the condition of the ditches declined over time. In this study, the condition of drainage system, and the natural processes that affect them, was inspected in 18 drained peatlands.

Several processes can reduce of the size of the ditches. The process of crumbling of soil in the sides of the diches can last up to three years after the draining. Erosion of the main drains, caused by water flow can, however, continue longer. The ditches also sink when the peat dries. Soil frost can affect the ditches, but as the vegetation grows its effect gradually decreases. The vegetation that grows in the ditches may finally block the ditch completely.

The PDF includes a summary in English.

• Kokkonen, E-mail: pk@mm.unknown

An extensive field-based survey was conducted to establish the distribution of site types on drained peatlands, the condition of the drainage networks, the post-drainage development of the tree stands, their structure and silvicultural condition and the corresponding requirements for operational measures. The data is based on sampling of the forest drainage undertaking during 1930–78 and consists of 1,312 km inventory transect, 6,030 relascope sample plots and 21,700 studied ditches.

Of the studied peatlands more than 60% were Scots pine (Pinus sylvestris L.) mires, slightly under 20% Norway spruce (Picea abies) mires, and under 10% each treeless mires and paludified upland forest sites. The remaining peatland area that is to be considered suitable for forest drainage according to criteria used by Heikurainen (1960) now consists mainly of spruce mires and paludified upland forest types; about 1 million ha both groups still remain undrained.

The proportion of ditches in need of ditch cleaning was estimated to be under 10% in the youngest drained areas and under 30% in the oldest. The mean tree stand volumes of the drained peatlands of different site types show the same dependence on the trophic level as in earlier studies but the volumes seem to be some 5–10% lower. These results compare favourably with those of the 7th national forest inventory.

Trends in the post-drainage development of tree stand volumes and increment are also, generally, in accordance with earlier findings but have somewhat lower values. The development of the nutrient-poor site type stands, especially in Northern Finland, seems to be significantly poorer than was earlier assumed.

The PDF includes a summary in English.

• Keltikangas, E-mail: mk@mm.unknown
• Laine, E-mail: jl@mm.unknown
• Puttonen, E-mail: pp@mm.unknown
• Seppälä, E-mail: ks@mm.unknown

The aim of this investigation was to examine the dependence of stand volume and increment on different growth factors on drained peatlands drained 20 years ago. Measurements were made in 1977-79 on 35 sample plots in Central Finland on relatively poor pine bogs with a thick peat layer.

It became evident that the stand volume, increment and radial growth and growth development are primarily functions of groundwater depth. Groundwater depth is dependent, in the first place, on ditch depth and ditch condition. With regard to the variation in ditch spacing (ca. 35-70 m) under examination, the effect of ditch spacing on the stand was insignificant. As a practical recommendation it was concluded that ditches should be kept deep enough (> 70 cm) in order to maintain undisturbed stand development.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown

The paper presents some preliminary results of a 10-year-old study the purpose of which is to determine the effect of simultaneous variations in the intensity of drainage and fertilization on the development of planted and natural seedlings on peatlands under various climatic conditions. The development of the Scots pine (Pinus sylvestris L.) seedlings appeared to be better the more intensive the degree of drainage and fertilization used. The increase in the temperature sum had a positive effect on the development of pine seedlings and decreased the mortality rate.

The best growth result was obtained with a 10 m ditch spacing and strong fertilization. As it is difficult to decrease the 10 m ditch spacing for cost reasons, it can be concluded that on such oligotrophic peatlands as were used in this experiment, only an average growth level in the seedling stands can be reached even with the most efficient forest improvement measures. Broadcast fertilization used in the experiment, at least in large doses, increases seedling mortality, as well as the coverage of the ground vegetation, particularly that of cottongrass and fireweed, and also the shrub height, thus increasing competition. It cannot be recommended for afforestation, and today spot fertilization is used. According to this experiment natural seedlings seem once they have recovered after the first years, to grow better than the planted seedlings. This was true especially in the north and in areas, where drainage was not efficient. The height and height growth of the seedlings were to a large extent dependent on the temperature sum.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Laine, E-mail: jl@mm.unknown

The study deals with the development during the 1950s and 1960s of a stand growing on peatlands which had been drained in the 1930s. The following characters were determined by measurements: the volume of the growing stock, the volume increment, the relative increment, the increment percent and the increment curves. Moreover, the possible changes taking place in the difference between tree growth along the ditches and in the middle of the strip between ditches were studied. In addition, the regional variation in increment was studied; this question was studied as the regression between the relative growth and the temperature sum. The results were compared with other Finnish investigations into the regional variation of increment.

The volumes of the growing stock had increased during the course of twelve years by 70–10 m³ /ha depending on the site type and climatic zone concerned. The relative increment had dropped in each case studied. As a matter of fact, this is only to be expected because the volumes had increased and the absolute growth had remained more or less unchanged. The development of the increment percent was compared with mineral soil stands in the case of Southern Finland, both uncut stands and stands treated with cuttings. According to the results obtained, the development of the increment percent was better in the present material than in uncut forests, but in some cases it did not reach the level of tended stands. The revival of the tree crop after draining takes place at different rates in the vicinity of and, on the other hand, at greater distances from the ditches and that this relationship is dependent on the fertility of the site.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Seppälä, E-mail: ks@mm.unknown

The paper is based on data collected from 411 sample plots in various parts of Finland situated on peatlands which had been drained in the 1930's. The purpose of the study was to determine the influence of ditch spacing on the volume, increment and structure of timber crops growing on drained peatlands. The ditches had been spaced 70–90 m apart, and the sample plots were placed strip wise along the ditches.

The results of the study indicate that the influence of ditch spacing on both the total volume and the volume increment is greater, the poorer the site. On the other hand, the influence of ditch spacing on the structure of the stand as described by means of the mean diameter as weighted by the basal area, seems to be of similar magnitude in all the sites covered by the study.

Generally speaking, the influence of ditch spacing on stand development is surprisingly small, even in extreme cases. The total volume and the increment of the growing stock decrease by about 20% when the ditch spacing increases from 20 to 60 m, the corresponding decrease in the mean diameter having a magnitude of 10%. This was interpreted to be due to the fact that the main part of the superior growth along the margin of the ditch is spent in compensating for the space lost in the area taken up by the ditches.

On the basis of the results obtained it was concluded that the best solution in forest drainage from the economic viewpoint is to employ relatively wide ditch spacings, which leads to a rate of stand development somewhat below the potential.

The PDF includes a summary in Finnish.

• Seppälä, E-mail: ks@mm.unknown

We used a process-based hydrological model SUSI to improve guidelines for ditch network maintenance (DNM) operations on drained peatland forests. SUSI takes daily weather data, ditch depth, strip width, peat properties, and forest stand characteristics as input and calculates daily water table depth (WTD) at different distances from ditch. The study focuses on Scots pine (Pinus sylvestris L.) dominated stands which are the most common subjects of DNM. Based on a literature survey, and consideration of the tradeoffs between forest growth and detrimental environmental impacts, long term median July–August WTD of 0.35 m was chosen as a target WTD. The results showed that ditch depths required to reach such WTD depends strongly on climatic locations, stand volume, ditch spacing, and peat thickness and type. In typical ditch cleaning areas in Finland with parallel ditches placed about 40 m apart and tree stand volumes exceeding 45 m³ ha^–1, 0.3–0.8 m deep ditches were generally sufficient to lower WTD to the targeted depth of 0.35 m. These are significantly shallower ditch depths than generally recommended in operational forestry. The main collector ditch should be naturally somewhat deeper to permit water outflow. Our study brings a firmer basis on environmentally sound forestry on drained peatlands.

• Hökkä, Natural Resources Institute Finland (Luke), Natural resources, Latokartanonkaari 9, P.O. Box 2, FI-00791 Helsinki, Finland E-mail: hannu.hokka@luke.fi
• Laurén, University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: ari.lauren@uef.fi
• Stenberg, Natural Resources Institute Finland (Luke), Natural resources, Latokartanonkaari 9, P.O. Box 2, FI-00791 Helsinki, Finland E-mail: leena.stenberg@luke.fi
• Launiainen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Latokartanonkaari 9, P.O. Box 2, FI-00791 Helsinki, Finland E-mail: samuli.launiainen@luke.fi
• Leppä, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Latokartanonkaari 9, P.O. Box 2, FI-00791 Helsinki, Finland E-mail: kersti.leppa@luke.fi
• Nieminen, Natural Resources Institute Finland (Luke), Natural resources, Latokartanonkaari 9, P.O. Box 2, FI-00791 Helsinki, Finland E-mail: mika.nieminen@luke.fi

Habitat loss and degradation are the main threats to biodiversity worldwide. For example, nearly 80% of peatlands in southern Finland have been drained. There is thus a need to safeguard the remaining pristine mires and to restore degraded ones. Ants play a pivotal role in many ecosystems and like many keystone plant species, shape ecosystem conditions for other biota. The effects of mire restoration and subsequent vegetation succession on ants, however, are poorly understood. We inventoried tree stands, vegetation, water-table level, and ants (with pitfall traps) in nine mires in southern Finland to explore differences in habitats, vegetation and ant assemblages among pristine, drained (30–40 years ago) and recently restored (1–3 years ago) pine mires. We expected that restoring the water-table level by ditch filling and reconstructing sparse tree stands by cuttings will recover mire vegetation and ants. We found predictable responses in habitat structure, floristic composition and ant assemblage structure both to drainage and restoration. However, for mire-specialist ants the results were variable and longer-term monitoring is needed to confirm the success of restoration since these social insects establish perennial colonies with long colony cycles. We conclude that restoring the water-table level and tree stand structure seem to recover the characteristic vegetation and ant assemblages in the short term. This recovery was likely enhanced because drained mires still had both acrotelm and catotelm, and connectedness was still reasonable for mire organisms to recolonize the restored mires either from local refugia or from populations of nearby mires.

• Punttila, Finnish Environment Institute, P.O. Box 140, FI-00251 Helsinki, Finland E-mail: pekka.punttila@ymparisto.fi
• Autio, Centre for Economic Development, Transport and the Environment in South Ostrobothnia, P.O. Box 252, FI-65101 Vaasa, Finland E-mail: olli.autio@ely-keskus.fi
• Kotiaho, University of Jyväskylä, Department of Biology & Environmental Sciences, P.O. Box 35, FI-40014 Jyväskylä, Finland E-mail: janne.kotiaho@jyu.fi
• Kotze, University of Helsinki, Department of Environmental Sciences, P.O. Box 65, FI-00014, University of Helsinki, Finland E-mail: johan.kotze@helsinki.fi
• Loukola, University of Oulu, Department of Biology, P.O. Box 3000, FI-90014 Oulu, Finland E-mail: olli.loukola@gmail.com
• Noreika, University of Helsinki, Department of Environmental Sciences, P.O. Box 65, FI-00014, University of Helsinki, Finland; University of Helsinki, Department of Biosciences, P.O. Box 65, FI-00014 University of Helsinki, Finland E-mail: norbertas.noreika@gmail.com
• Vuori, University of Jyväskylä, Department of Biology & Environmental Sciences, P.O. Box 35, FI-40014 Jyväskylä, Finland E-mail: anna@kureniemi.fi
• Vepsäläinen, University of Helsinki, Department of Biosciences, P.O. Box 65, FI-00014 University of Helsinki, Finland E-mail: kari.vepsalainen@helsinki.fi

• Nieminen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mika.nieminen@metla.fi
• Ahti, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ea@nn.fi
• Koivusalo, Department of Civil and Environmental Engineering, Aalto University School of Science and Technology, P.O. Box 15200, FI-00076 Aalto, Finland E-mail: hk@nn.fi
• Mattsson, Finnish Environment Institute, P.O. Box 140, FI-00251 Helsinki, Finland E-mail: tm@nn.fi
• Sarkkola, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ss@nn.fi
• Laurén, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: al@nn.fi

• Nieminen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mika.nieminen@metla.fi
• Ahti, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ea@nn.fi
• Nousiainen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: hn@nn.fi
• Joensuu, Forestry Development Centre Tapio, Soidinkuja 4, FI-00700 Helsinki, Finland E-mail: sj@nn.fi
• Vuollekoski, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mv@nn.fi

At sites with either peat or mineral soils in large areas of boreal forests, high soil-water contents hamper tree growth and drainage can significantly increase growth. Hence, areas covering about 15 × 10⁶ ha of northern peatlands and wet mineral soils have been drained for forestry purposes. Usually ditches gradually deteriorate, thus reducing their functionality as drains, and ditch-network maintenance (DNM) might be needed to maintain stand growth rates enabled by the original ditching. This article reviews current knowledge on establishing the need for DNM in boreal forest stands, subsequent growth responses, and the financial outcome of the activity. The issues covered in the review are: (i) ditching, changes in ditches over time and the need for DNM; (ii) interactions between soil water and both stand properties and stand management; (iii) ground-water level (GWL) and tree growth responses to DNM; and (iv) financial viability of DNM. Conclusions about the current understanding of issues related to DNM are drawn and implications for DNM in practice are summarized. Finally, gaps in knowledge are identified and research needs are suggested.

• Sikström, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: ulf.sikstrom@skogforsk.se
• Hökkä, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: hannu.hokka@luke.fi