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Flooded Land is defined as water bodies where human activities have caused changes in the amount of surface area covered by water, typically through water level regulation. Former peat extraction fields are a type of flooded lands which are often mentioned as significant source of greenhouse gas (GHG) emissions. In Latvia, the area of flooded lands in former peat extraction fields is 5.3 kha. The aim of the study is to evaluate GHG emissions from flooded former peat extraction fields to define that the flooded lands are the key source of GHG emissions and approve that further studies are necessary to elaborate country specific emission factors. The study is implemented in three areas in central part of the country, where peat extraction was stopped 25-35 years ago. Measures continued for 12 months, in 9 subplots, each was represented by 3 measurement points. Water and air temperature, as well as water level was measured during the study. According to the study results, flooded areas are a significant source of CO2 emissions (967±107 kg CO2-C ha-1 yr-1); however, the most significant agent of GHG emissions in flooded areas is methane (CH4) - 435±98 kg CH4-C kg ha-1 yr-1. Flooded areas are not significant source of nitrous oxide (N2O) emissions. The net emissions from flooded areas are 18.1±3.7 tons CO2 eq ha-1 yr-1. According to the study results, flooded lands are a significant (one of the largest) source of emissions, and further studies are necessary to improve GHG modelling solutions and activity data. [ABSTRACT FROM AUTHOR]

The aim of the study is to clarify the compliance of machinery information systems used by Latvian logging service providers with the requirements of the Forest Machine Data and Communications Standard StanForD 2010. For determining the number of logging machines and structure registered in Latvia, data from the State Technical Control Agency of Latvia (VTUA) has been used. This dataset includes 2094 registered machinery units from which 1663 units recorded as harvesters and forwarders are distributed for data processing. Using the national AS Latvian State Forests (LSF) database, where 541 machinery units have been recorded, of which 239 harvesters and 302 forwarders, it is determined what and how many machines already use the standard StanForD 2010, how many machines can implement it and which machines are not suitable for the implementation of StanForD 2010. The study showed that the VTUA register does not fully reflect the true quantity of harvesting machines in Latvia and does not provide information about the use of machines. The LSF data provide reliable information on the possibilities of using StanForD 2010 in harvesters in national forests. From the harvesters working in the country’s forests, 52% of the machines uses the StanForD 2010 standard. Work should be continued to clarify the possible use of the standard in the machines working in private forests. Similarly, work should be continued with dealers of harvesting machines to identify models for which it is possible to adjust the StanForD 2010 standard and what the cost of adapting the indicative information systems is. [ABSTRACT FROM AUTHOR]

The aim of the study is to evaluate carbon stock in litter and organic forest soils in Latvia as well as to characterize accumulation of carbon in litter in afforested lands. The study is providing empirically valid information about soil and litter carbon changes for the National greenhouse gas (GHG) inventory by using data from National forest inventory (NFI), forest soil monitoring demonstration project BioSoil and other studies. The study proves significance of organic forest soil carbon pool in Latvia and demonstrates necessity to extend NFI incorporated forest soil monitoring program to improve data on soil density in wet organic soils, as well as to integrate data characterizing water regime in forests. The acquired data also proves that the conservative approach of calculation of carbon stock changes in litter in afforested lands applied in the Latvia’s National GHG inventory avoids overestimation of CO2 removals. The data on litter carbon stock collected in this study is sufficient to estimate total carbon stock for stands dominated by most common tree species and long term impact of changes of species composition. Measurements of organic soil and litter thickness should be continued by NFI and integrated with more detailed soil monitoring to increase accuracy of carbon stock estimates and gather data necessary for verification of modelling data, particularly in afforested lands and due to change of dominant species. [ABSTRACT FROM AUTHOR]

National forest inventory (NFI) is an efficient way to monitor forest resources, including increment, mortality, and harvest rate. It provides accurate statistical information about land use data, land use change and biomass stock change and enables to tie the specific increment, mortality and harvest data to defined land use category, dominant tree species, site types etc. Recently there have been introduced changes in land use calculation method using NFI data in Latvia. New calculation method takes into account present land use data and land use data from two previous cycles considerably reducing uncertainty of the estimates and takes into account possible land management practices which may alter the land use category in long-term, also usage of auxiliary data has been introduced to increase accuracy of determination of final land-use category. Changes in land use calculation method directly affects distribution of data on increment, morality and harvests between land use categories. The aim of the study is to determine increment, mortality and harvest rate in Latvia between the first and third NFI cycle (2004-2018) using updated land use data and to compare obtained result with data from the most recent greenhouse gas (GHG) inventory report. [ABSTRACT FROM AUTHOR]

Aim of this study is to develop a method for automatic shallow drainage ditch generation to drain terrain depressions using four factor least cost surface which is obtained using LiDAR (light detection and ranging) data and Sentinel-2 multispectral satellite imagery. LiDAR data are used for depression mapping in DEM, flow accumulation and slope modelling as well as CHM (canopy height model) to obtain relative vegetation height. Sentinel-2 imagery was used for land cover type identification as well as separating coniferous and deciduous forest stands. Study area is located in western Latvia and is 25 km2 large. Least cost surface connects DEM depressions and already existing drainage ditches by best possible path for shallow ditch network digging. Different methods are applied to determine depressions which can be drained as well as changes of affected drained area and depression depth. This results in suitable areas where to create shallow ditches to improve water runoff. Results show that using this method average reduction of area of depressions is 79% and average length of shallow ditches on each drained depression hectare is 370 m. [ABSTRACT FROM AUTHOR]

The aim of the study is to evaluate the impact of drainage on soil carbon stock in a transitional mire drained for forestry. The study site is located in the central part of Latvia representing hemiboreal vegetation zone. Site was drained in 1960. It is located in a catchment area of the river Veseta. An undrained site at the same catchment area was chosen for control (ca. 2.5 km between sites). In both sites, the depth of peat is 4 - 4.5 m. Drained site is dominated by coniferous trees. Soil samples collected in 2014 were used to determine bulk density and carbon content, and to calculate soil carbon stock. Samples were collected down to 80 cm depth. Ground surface elevation was measured before and several times after the drainage to determine peat subsidence. Carbon stock has increased by 0.3 tons ha-1 yr¹ after drainage, although peat has subsided on average by 26 cm (13 - 48 cm). Subsidence was mainly caused by physical shrinkage of peat not by organic matter oxidation. Drainage was followed by compaction of aerated soil layer, which has caused most of the subsidence, especially during the first years after drainage. Soil bulk density has increased almost twice at soil surface layer 0 - 10 cm (from 75 kg m³ to 141 kg m³). Differences decrease at deeper sampling depths. It is concluded that drainage is not always followed by reduction of carbon stock in soil. Increased above and below ground litter production rates may offset accelerated decomposition of organic matter after drainage. [ABSTRACT FROM AUTHOR]

Assessment of changes in carbon (C) stocks in mineral soils typically relies on the steady-state C stock values, which are influenced by various long-term land-use and management scenarios. This conventional approach limits understanding of the short-term soil C balance, including in lands not subject to land-use or management changes. Additionally, the role of the soil moisture condition impact on the mineral soil C balance is not broadly studied. To enhance our understanding of the effects of the soil moisture on C balances of mineral soils, this research conducted soil CO2 emission monitoring in forests with both drained and naturally wet mineral soils. The study was implemented across 18 forest sites with dominant species of aspen (Populus tremula L), birch (Betula pendula Roth, Betula pubescens Ehrh.), black alder (Alnus glutinosa (L.) Gärtner) and Scots pine (Pinus sylvestris L.). Emission monitoring was performed using the closed static opaque chamber method. Concurrent measurements of the soil temperature and the groundwater level depth were also conducted. Our research revealed that CO2 emissions resulting from soil respiration in both naturally wet and drained soils showed no notable differences, indicating that the mineral soil moisture regime has a minimal impact on C outflows from these soils. This finding implies that the C balance in mineral soils is largely dictated by the influx of C from vegetation residues and litter. Thus, for the conservation or enhancement of C stocks in mineral soils, maintaining the soil moisture regime that optimizes the decomposition and accumulation of vegetation litter is essential. [ABSTRACT FROM AUTHOR]

Recent studies have demonstrated the occurrence of different needle cast (Lophodermium spp.) species in young Scots pine Pinus sylvestris L. stands in different regions of Latvia. The impact of these fungi has been known also historically, but is predicted to increase in future due to climate changes that are forecasted to have a positive impact on presence and vigour of various species of fungi. The aim of the study was to characterize the needle cast damage in young Scots pine stands in central Latvia. Material was collected in 12 Scots pine stands at the age of 3 to 26 years in 28 plots with a total area of 8.1 ha in the middle of two consecutive growing seasons (years 2012 and 2013). The impact of disease was visually assessed using a 5 grade scale, depending on the proportion of damaged (brown) one-year old needles. Incidence of damaged trees (P, %) and damage intensity (R, %) was calculated and used to characterize the occurrence and severity of the infection in the stands as well as its link to other stand parameters. Damage incidence (ranging from 20 to 100%), as well as the intensity (from 4 to 35%) was slightly (incidence-also significantly) higher in 2013 in comparison to 2012; correlation between those two parameters was strong in both years (r = 0.94 and r = 0.84, respectively). The stand age, density (ranging from 1200 to 6900 trees ha-1) and tree height did not significantly correlate with the damage incidence or intensity. Forest type (Hylocomiosa or Myrtillosa mel.) was not a significant factor, too. [ABSTRACT FROM AUTHOR]