Habitat selection of sympatric Siberian Grouse and Hazel Grouse in natural and exploited forests of the lower Amur region

The Siberian Grouse (Falcipennis falcipennis), which is endemic to the “dark-needle” taiga of the Russian Far East, is one of the least studied grouse species in the world. We examined post-breeding habitat selection of Siberian Grouse and contrasted it with that of the better examined Hazel Grouse (Tetrastes bonasia) in two areas near Komsomolsk na Amure, Russia. To infer species-specific preferences, we used field sampling, logistic regression, and AIC model selection, and compared late summer habitats of Siberian Grouse and Hazel Grouse in a mountain- and hilly area in the dark needle taiga. Our study is the first to explain Siberian Grouse habitat relationships with an empirical modelling approach. Results indicate proportions of coniferous/ pioneer trees forest and rejuvenation to be the most important covariates separating Siberian and Hazel Grouse observation sites in forests from both areas. Siberian Grouse tended to select sites with low proportions of pioneer trees and rejuvenation but availability of dwarf shrubs. Bunchberry (Cornus canadensis) appeared to be of high importance for the presence of Siberian Grouse in both regions. Hazel Grouse were common in places dominated by pioneer trees with high canopy cover, and high proportions of grass/herb cover. Hazel Grouse also occurred more often in forest sites with dense vertical layering and rejuvenation. Modern forestry, which results in increasing amounts of forests at younger successional stages, is likely to favour the Hazel Grouse at the expense of the Siberian Grouse.

Active Restoration Initiates High Quality Forest Succession in a Deforested Landscape in Amazonia

Amazonia is well known for its high natural regeneration capacity; for this reason, passive restoration is normally recommended for the recovery of its degraded forests. However, highly deforested landscapes in southern Amazonia require active restoration. Since restoration methods can shape the quality and speed of early forest recovery, this study aimed to verify how active restoration pushes sites stably covered with exotic grasses towards forest recovery. We evaluated early forest succession at active restoration sites, i.e., soil plowing, direct seeding of pioneer species, and seedling stock planting at low density. We analyzed forest structure, diversity, and species composition in two age classes, 0.5–3.5 and 4.5–7.5 years old. As reference, we evaluated sites able to naturally regenerate in the same region. We sampled 36 active restoration and 31 natural regeneration sites along the Madeira River, southern Amazonia. Active restoration triggered succession to similar or higher levels of forest structure than sites where natural regeneration was taking place. The most dominant species did not overlap between active restoration and natural regeneration sites. The overall composition of species was different between the two restoration methods. Dominant species and size class distribution show that active restoration is performing successfully. Soil preparation combined with a high availability of seeds of pioneer trees resulted in a high stem density and basal area of facilitative pioneer trees. Planted seedlings added species diversity and increased density of large trees. Interventions to increase the odds of natural regeneration can be effective for non-regenerating sites in resilient landscapes.

Comparing 3D Point Cloud Data from Laser Scanning and Digital Aerial Photogrammetry for Height Estimation of Small Trees and Other Vegetation in a Boreal–Alpine Ecotone

Changes in vegetation height in the boreal-alpine ecotone are expected over the coming decades due to climate change. Previous studies have shown that subtle changes in vegetation height (<0.2 m) can be estimated with great precision over short time periods (~5 yrs) for small spatial units (~1 ha) utilizing bi-temporal airborne laser scanning (ALS) data, which is promising for operation vegetation monitoring. However, ALS data may not always be available for multi-temporal analysis and other tree-dimensional (3D) data such as those produced by digital aerial photogrammetry (DAP) using imagery acquired from aircrafts and unmanned aerial systems (UAS) may add flexibility to an operational monitoring program. There is little existing evidence on the performance of DAP for height estimation of alpine pioneer trees and vegetation in the boreal-alpine ecotone. The current study assessed and compared the performance of 3D data extracted from ALS and from UAS DAP for prediction of tree height of small pioneer trees and evaluated how tree size and tree species affected the predictive ability of data from the two 3D data sources. Further, precision of vegetation height estimates (trees and other vegetation) across a 12 ha study area using 3D data from ALS and from UAS DAP were compared. Major findings showed smaller regression model residuals for vegetation height when using ALS data and that small and solitary trees tended to be smoothed out in DAP data. Surprisingly, the overall vegetation height estimates using ALS (0.64 m) and DAP data (0.76 m), respectively, differed significantly, despite the use of the same ground observations for model calibration. It was concluded that more in-depth understanding of the behavior of DAP algorithms for small scattered trees and low ground vegetation in the boreal-alpine ecotone is needed as even small systematic effects of a particular technology on height estimates may compromise the validity of a monitoring system since change processes encountered in the boreal-alpine ecotone often are subtle and slow.

Active Restoration Initiates High Quality Forest Succession In A Deforested Landscape In Amazonia

Background: Amazonia is well known for its high natural regeneration capacity; for this reason, passive restoration is normally recommended for the recovery of its degraded forests. However, highly deforested landscapes in southern Amazonia require active restoration. Since restoration methods can shape the quality and speed of early forest recovery, this study aimed to verify how active restoration pushes non-resilient sites towards forest recovery. Methods: We evaluated early forest succession at active restoration sites, i.e. soil plowing, direct seeding of pioneer species and seedling stock planting at low density. We analyzed forest structure, diversity and species composition in two age classes, 0.5 – 3.5 and 4.5 – 7.5 years old. As reference, we evaluated natural regeneration as performed on more resilient sites in the same region. We sampled 36 active restoration and 31 natural regeneration sites along the Madeira river, southern Amazonia. Results: Active restoration triggered succession to similar or higher levels of forest structure than sites where natural regeneration was taking place. The most dominant species did not overlap between active restoration and natural regeneration sites. The overall composition of species was different between the two restoration methods. Dominant species and size class distribution indicate that active restoration is performing successfully. Conclusions: Soil preparation combined with a high availability of seeds of pioneer trees resulted in a high stem density and basal area of facilitative pioneer trees. Planted seedlings added species diversity and increased density of large trees. Interventions to increase the odds of natural regeneration can be effective for non-resilient sites located in resilient landscapes.

Effects of tree species on root exudation and mineralization of organic acids in a tropical forest

&lt;p&gt;Tropical forests can develop by roots foraging nutrients in the highly weathered soils. In rhizosphere, soil volume affected by roots, tree species modify carbon (C) and nutrient cycles directly through root exudation and indirectly through increased microbial activity. We test whether root exudation and rhizosphere C fluxes of organic acids and sugars differ between dominant dipterocarp trees and pioneer trees (Macaranga gigantea). To quantify the C fluxes of organic acids in the rhizosphere soils, we measured in situ root exudation from mature trees, concentrations of monosaccharides and organic acids (acetate, oxalate, malate, and citrate) in the rhizosphere and bulk soil fractions, and mineralization kinetics of &lt;sup&gt;14&lt;/sup&gt;C-radiolabelled substrates. Organic acid exudation increases with increasing root surface area. Dipterocarp roots release greater amounts of malate, while monosaccharides are dominant exudates of pioneer trees. Microbial activities of malate mineralization increase in the rhizosphere soil both under dipterocarp and pioneer trees. The greater C fluxes of malate mineralization, compared to root exudation, suggests rhizosphere microbes are another malate producer under dipterocarp trees. Both root exudation composition and rhizosphere microbes increase malate production with increasing phosphorus demands and with increasing soil acidity.&lt;/p&gt;

Intra- and Interspecific Interactions among Pioneer Trees Affect Forest-Biomass Carbon Accumulation in a Nutrient-Deficient Reclaimed Coal Mine Spoil

Pioneer trees play a key role in the recovery of a reclaimed ecosystem that is nutrient-deficient in the initial stage of reclamation. Clarifying the growth of pioneer trees and their response to intra- or interspecific competition is of great importance to help stewards manage reclaimed forest. Nevertheless, such documents are lacking. We utilized forestry inventory data from a R. pseudoacacia and P. tabuliformis mixed forest plot with an area of 8000 m2 to find out the effect of trees interaction on their growth (indicated by the amount of biomass carbon per stem) in a nutrient-lacking reclaimed ecosystem 17 years after reclamation in Pingshuo opencast coal mine, Shanxi Province, China. In total, 2133 tree individuals were measured and tagged; the kriging interpolation method was applied to map spatial variation of forest-biomass carbon (C). Univariate and bivariate mark correlation functions were employed to examine the effect of intra- and interspecific interactions on tree’s biomass C accumulation. The results showed that tree biomass C was 27.84 Mg ha−1 in the forest. C class structure of planted R. pseudoacacia followed inversed J-shaped distribution and seeded-in R. pseudoacacia and Ulmus pumila (a spontaneous species) had L-shaped distribution. P. tabuliformis, however, followed a nearly normal distribution. Patchy distribution was observed with regard to C spatial arrangement of all tree species. In terms of the intraspecific correlation of biomass C, no significant competitive or facilitative interactions (GoF p ≥ 0.05) was observed among conspecific trees of seeded-in R. pseudoacacia and P. tabuliformis. In contrast, significant negative interactions (GoF p < 0.05) or repulsion correlations between biomass C of planted R. pseudoacacia individuals and U. pumila individuals were found at the scale of 1–2 and 0–8.5 m, respectively. In term of the interspecfic spatial correlation of biomass C, a significant positive interaction between the heterospecific individuals of planted R. pseudoacacia and seeded-in R. pseudoacacia was observed at the scale of 2.5–4 and 12.5–15 m. Similarly, seeded-in R. pseudoacacia and U. pumila were found to be attracted by P. tabuliformis at 7–9 and 0–2 m, respectively. Conversely, significant departure effect was observed at the scale of 1–3 m between the biomass C of U. pumila and planted R. pseudoacacia and 4.5–5.5 m between the biomass C of U. pumila and seeded-in R. pseudoacacia. Consequently, R. pseudoacacia and P. tabuliformis could coexist for a long term and P. tabuliformis was a species that facilitated the accumulation of C of other tree species. Overall, complex intra- and interspecific interactions in nutrient-limit reclamation ecosystem affected biomass C accumulation. R. pseudoacacia–P. tabuliformis mixed forest could be an efficient reclamation pattern to restore biomass C in the Loess Plateau area.