by Marie-Claude Boileau | 30 January 2019
Published in For. Sci. 62(2): 237-246 https://doi.org/10.5849/forsci.15-058
We investigated short-term regeneration dynamics after group selection cutting with understory vegetation control and soil scarification in a northern hardwood forest. We used three gap sizes based on mean height (H) of neighboring trees in a replicated experiment: small (0.75H), medium (1.25H), and large (1.75H) gaps. After 5 years, all gap sizes led to abundant density of yellow birch (Betula alleghaniensis Britt.) and sugar maple (Acer saccharum Marsh.) regeneration, associated with sufficient light (>38% of canopy transmittance), favorable seedbeds (50% of ground cover in disturbed leaf litter or exposed mineral soil), and reduced competition from noncommercial species due to vegetation control. We found no differences in tree species diversity patterns among gap sizes, but diversity patterns changed over time due to increased density of shade-tolerant conifers. After 5 years, yellow birch regeneration was positively influenced by increasing distance from the gap center and stand species composition, but negatively influenced by percent cover of undisturbed leaf litter, graminoid cover, and raspberry cover. The percent variation explained was relatively low (R2 = 0.26). Overall, group selection with soil scarification and vegetation control was successful in establishing desired tree species, especially yellow birch and sugar maple, but further monitoring is required to determine its long-term efficacy.
by Marie-Claude Boileau | 30 January 2019
Published in ISPRS – International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-1/W4: 281-285. https://doi.org/10.5194/isprsarchives-XL-1-W4-281-2015
Several thousand hectares of forest blocks are regenerating after harvest in Canada. Monitoring their performance over different stages of growth is critical in ensuring future productivity and ecological balance. Tools for rapid evaluation can support timely and reliable planning of interventions. Conventional ground surveys or visual image assessments are either time intensive or inaccurate, while alternate operational remote sensing tools are unavailable. In this study, we test the feasibility and strength of UAV-based photogrammetry with an EO camera on a UAV platform in assessing regeneration performance. Specifically we evaluated stocking, spatial density and height distribution of naturally growing (irregularly spaced stems) or planted (regularly spaced stems) conifer regeneration in different phases of growth. Standard photogrammetric workflow was applied on the 785 acquired images for 3D reconstruction of the study sites. The required parameters were derived based on automated single stem detection algorithm developed in-house. Comparing with field survey data, preliminary results hold promise. Future studies are planned to expand the scope to larger areas and different stand conditions.
by equipewp | 30 January 2019
Published in Applied Geochemistry 53: 1-12. Seventy-two forested lake catchments were studied in Quebec (Canada) to examine the influence of climate, atmospheric deposition and catchment characteristics on base cation (BC) concentrations in lake waters (BCC) and base cation budgets at the catchment scale (BCQ). The catchments are located along a bioclimatic gradient in a vast (180000 km2) study area underlained by the Canadian Shield. Multivariate statistical approaches are used to simultaneously assess the effects of multiple environmental factors on cation fluxes (…).
by Claire Morin | 30 January 2019
Published in Canadian Journal of Soil Science 95: 187-199. https://doi.org/10.4141/CJSS-2014-048
After 16 to 19 yr, we revisited four experimental trials set up in the early 1990s to evaluate the long-term impact of municipal biosolids applied in forest plantations. Tree growth and the soil were sampled to determine the effects of a single application of biosolids applied at (liquid equivalent) rates of 0, 130, 200, and 400 m3 ha-1. Tree radial growth responded markedly to biosolids in the young plantations, increasing from 18% for Pinus resinosa to 62% for Picea glauca, and up to 700% for Quercus sp. Increases in phosphorus (P) concentrations in the tree foliage in response to biosolids could still be detected in the conifer trials. In the top 0-5 cm soil layer, organic carbon (C), total nitrogen (N), P, and copper (Cu) concentrations and pools increased, while soil compaction and bulk density decreased. In the deepest soil layer sampled (20-40 cm depth), the total N and calcium (Ca) pools were reduced by the biosolids treatments, while the pool of exchangeable acidity increased. Our observations indicate that a single application of liquid biosolids up to 400 m3 ha-1 (30 t ha-1 DM) in young forest plantations is a sustainable practice without undue risk to such podzolic soils.
by equipewp | 30 January 2019
Published in Tree Seed Working Group – News Bulletin. 61(June): 11-13.
