Soil data for mapping paludification in black spruce forests of eastern Canada

Soil data and soil mapping are indispensable tools in sustainable forest management. In northern boreal ecosystems, paludification is defined as the accumulation of partially decomposed organic matter over saturated mineral soils, a process that reduces tree regeneration and forest growth. Given this negative effect on forest productivity, spatial prediction of paludification in black spruce stands is important in forest management. This paper provides a description of the soil database to predict organic layer thickness (OLT) as a proxy of paludification in northeastern Canada. The database contains 13,944 OLT measurements (in cm) and their respective GPS coordinates. We collected OLT measurements from georeferenced ground plots and transects from several previous projects. Despite the variety of sources, the sampling design for each dataset was similar, consisting of manual measurements of OLT with a hand probe. OLT measurements were variable across the study area, with a mean ± standard deviation of 21 ± 24 cm (ranging from a minimum of 0 cm to a maximum of 150 cm), and the distribution tended toward positive skewing, with a large number of low OLT values and fewer high OLT values. The dataset has been used to perform OLT mapping at 30-m resolution and predict the risk of paludification in northeastern Canada (Mansuy et al., 2018) [1]. The spatially explicit and continuous database is also available to support national and international efforts in digital soil mapping.


a b s t r a c t
Soil data and soil mapping are indispensable tools in sustainable forest management. In northern boreal ecosystems, paludification is defined as the accumulation of partially decomposed organic matter over saturated mineral soils, a process that reduces tree regeneration and forest growth. Given this negative effect on forest productivity, spatial prediction of paludification in black spruce stands is important in forest management. This paper provides a description of the soil database to predict organic layer thickness (OLT) as a proxy of paludification in northeastern Canada. The database contains 13,944 OLT measurements (in cm) and their respective GPS coordinates. We collected OLT measurements from georeferenced ground plots and transects from several previous projects. Despite the variety of sources, the sampling design for each dataset was similar, consisting of manual measurements of OLT with a hand probe. OLT measurements were variable across Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/dib the study area, with a mean 7 standard deviation of 21 7 24 cm (ranging from a minimum of 0 cm to a maximum of 150 cm), and the distribution tended toward positive skewing, with a large number of low OLT values and fewer high OLT values. The dataset has been used to perform OLT mapping at 30-m resolution and predict the risk of paludification in northeastern Canada (Mansuy et al., 2018) [1]. The spatially explicit and continuous database is also available to support national and international efforts in digital soil mapping. Crown

Subject area
Forestry More specific subject area Soil Science Type of data Value of the data In the boreal forests of eastern Canada, organic layer thickness (OLT) is used as a proxy of the paludification process [1].
Paludification is defined as the accumulation of partially decomposed organic matter over saturated mineral soils, a process that reduces tree regeneration and forest growth.
Spatially explicit information about OLT is of particular importance in forest management, given the negative effect on forest productivity when OLT is greater than 40 cm.
Soil organic matter is fundamental to soil and ecosystem functions across a wide range of scales.
Continuous data of OLT has numerous applications in sustainable land management, including carbon accounting, soil fertility, biodiversity and forest bioeconomy [2].
Soil mapping is experiencing a surge of activity with the launch of various international soil programs and networks that are producing digital global soil attribute maps at various resolutions, However, soil data are still currently fragmented and at risk of getting lost if they are not curated [3]. Spatially explicit and continuous OLT database could therefore support national and international efforts in digital soil mapping [4,5].

Data
The database contains 13,944 OLT measurements and their respective GPS coordinates that have never been published before. We combined in one unique database multiple OLT measurements from georeferenced ground plots and transects from several previous projects realized in northeastern Quebec ( Table 1). The study area covers about 180,000 km 2 in the province of Quebec in eastern Canada (Fig. 1) and encompasses the black spruce-feather moss bioclimatic domain, which is part of the Boreal Shield ecozone in the south and the Hudson plain ecozone in the north. The landscape of the region is shaped by the draining of the former Glacial Lake Ojibway around 8200 BP, forming the physiographic unit known today as the Clay Belt, which stretches across the Quebec-Ontario border and covers an area of 145 000 km 2 (Fig. 1). OLT measurements were variable across the study area, with a mean 7 standard deviation of 21 7 24 cm (ranging from a minimum of 0 cm to a maximum of 150 cm), and the distribution tended toward positive skewing, with a large number of low OLT values and fewer high OLT values (Fig. 2). The attached excel table contains the OLT values (in cm) with their respective GPS coordinates (latitude and longitude).

Experimental design, materials, and methods
Despite the variety of sources, the sampling design for each dataset was similar, consisting of manual measurements of OLT with a hand probe. The method is summarized here but has previously been described in detail [7]. At each sampling point, the hand probe bored through the organic layers until the mineral soil was encountered. For each soil pit, the total OLT was measured as the combination of the fibric horizon, the mesic horizon and the humic horizon (Fig. 3). The whole dataset has been used to perform OLT mapping at 30-m resolution and predict the risk of paludification in northeastern Canada [1]. Before that, subsamples of the database have been used to distinguish and map reversible and permanent paludified landscapes [8] and to measure the effects of mechanical site preparation to mitigate the paludification process in northeastern Canada [9]. Table 1 Sources and descriptions of the organic layer thickness (OLT) dataset from various projects and inventories.