Forest Type Composition Research Articles

Network analysis can guide resilience-based management in forest landscapes under global change.

Forests are projected to undergo dramatic compositional and structural shifts prompted by global changes, such as climatic changes and intensifying natural disturbance regimes. Future uncertainty makes planning for forest management exceptionally difficult, demanding novel approaches to maintain or improve the ability of forest ecosystems to respond and rapidly reorganize after disturbance events. Adopting a landscape perspective in forest management is particularly important in fragmented forest landscapes where both diversity and connectivity play key roles in determining resilience to global change. In this context, network analysis and functional traits combined with ecological dynamic modeling can help evaluate changes in functional response diversity and connectivity within and among forest stands in fragmented landscapes. Here, we coupled ecological dynamic modeling with functional traits analysis and network theory to analyze forested landscapes as an interconnected network of forest patches. We simulated future forest landscape dynamics in a large landscape in southern Quebec, Canada, under a combination of climate, disturbance, and management scenarios. We depicted the landscape as a functional network, assessed changes in future resilience using indicators at multiple spatial scales, and evaluated if current management practices are suitable for maintaining resilience to simulated changes in regimes. Our results show that climate change would promote forest productivity and favor heat-adapted deciduous species. Changes in natural disturbances will likely have negative impacts on native conifers and will drive changes in forest type composition. Climate change negatively impacted all resilience indicators and triggered losses of functional response diversity and connectivity across the landscape with undesirable consequences on the capacity of these forests to adapt to global change. Also, current management strategies failed to promote resilience at different spatial levels, highlighting the need for a more active and thoughtful approach to forest management under global change. Our study demonstrates the usefulness of combining dynamic landscape-scale simulation modeling with network analyses to evaluate the possible impacts of climate change as well as human and natural disturbances on forest resilience under global change.

Chemical properties of soils in relation to forest composition in moist temperate valley slopes of Garhwal Himalaya, India

The present study was undertaken in moist temperate forest of Mandal-Chopta area in the Garhwal region of Uttarakhand, India. The aim of the present study was to assess the chemical properties of soils in relation to the forest structure and composition. Twelve forest types according to the altitude, slope aspect, and species composition were selected for the study. Chemical properties of the soil, i.e., total nitrogen (N), available phosphorus (P), available potassium (K), organic carbon (C), soil organic matter (SOM), pH and C:N ratios were analyzed for three different depths viz., (i) ‘Upper’ (0–10 cm), (ii) ‘Middle’ (11–30 cm), and (iii) ‘Lower’ (31–60 cm) in all the selected forest types. Phytosociological and diversity parameters viz. total basal cover (Gha−1), stem density (Nha−1), tree species richness (SR), Simpson concentration of dominance and Shannon–Wiener diversity index ( $$ \overline{\rm H} $$ ) were also calculated for each forest type. Values of N, P, K, C, SOM, C:N ratio and pH ranged from 0.17 to 0.45 %, 2.73 to 20.17 ppm, 40.67 to 261.17 ppm, 2.29 to 4.31 %, 3.95 to 7.43 %, 8.12 to 14.49 and 5.47 to 6.67, respectively. N showed a positive relationship with C and K. P was positively correlated with C and negatively correlated with altitude. P was higher in the soil of lower horizons of all the forest types. K was found to be positively correlated with altitude, C and N. pH of all the forest types was slightly acidic. C was comparatively higher in mixed broad-leaved forest types. No relationship between altitude and C was observed, which may be due to different composition of forest types along the altitudinal gradient and their differential decomposition rates. C content decreased with the depth of the soil. C showed positive correlation with N, P, and K. N showed a positive correlation with Gha−1. K showed a negative correlation with SR and $$ \overline{\rm H} $$ . P showed no relationship with the phytosociological parameters. This study also provides the comparisons between the results of chemical analysis of the present study with numerous other previous studies in the temperate Himalayan region of the Uttarakhand. The values of soil chemical properties of the present study in most of the forest types are on the higher end than the values previously recorded for the other similar forests of the region. The possible reason being luxuriant vegetation and undisturbed nature of these forest types, which is evident from higher values of diversity and other phytosociological parameters.

Effects of slope aspects on forest compositions, community structures and soil properties in natural temperate forests of Garhwal Himalaya

The present study was undertaken in seven natural forest types of temperate zone (1500 to 3100 m, a.s.l.) of Garhwal Himalaya to understand the effects of slope aspects viz., north-east (NE), north-west (NW), south-east (SE) and south-west (SW), on the forest structure, composition and soil characteristics of each selected forest type. The sample plots in each forest type were laid out by using stratified random approach. The indices i.e., the Importance Value Index, Shannon-Wiener diversity index, Simpson’s concentration of Dominance, Simpson diversity index, Pielou equitability and Margalef species richness index were calculated statistically using standard softwares to elucidate the differences in forest structure and composition of forest types on different slope aspects of the sites. The composite soil samples were taken from each forest stand and the physico-chemical properties of the soil i.e., moisture content (MC), water holding capacity (WHC), pH, organic carbon (OC), phosphorus (P), potassium (K) and available nitrogen (N) were analyzed. The results show that the higher values of total basal cover (74.4 m2·ha−1 in Quercus semecarpifolia forest), Concentration of dominance (0.85 in Pinus roxburghii forest) and Tree diversity (1.81 in Quercus floribunda forest) in the forests were recorded in the northern aspects. MC (40.8% in Quercus leucotrichophora forest), WHC (48.9% in Cupressus torulosa forest), OC (3.8% in Cedrus deodara forest), P (31.9 kg·ha−1 in Quercus leucotrichophora forest) and N (1.0% in Pinus roxburghii forest) had also higher values in the soils of northern aspects. Consequently the higher productivity of the forests was also noticed on the northern aspects.

Seasonal Habitat Selection by Marten in an Untrapped Forest Preserve

American marten (Martes americana) are often associated with mature conifer-dominated forests; however, marten may require complex vertical and horizontal woody structure, rather than a coniferous overstory. To evaluate whether marten prefer forests with a mature conifer overstory, we investigated landscape-and stand-scale habitat selection of 38 (20 M, 18 F) resident (≥25 locations collected during ≥3 months), nonjuvenile (≥1 year [YR]) marten in a forest preserve in northcentral Maine where trapping and timber harvesting had been excluded for >35 years. At the landscape scale, nearly all of the available habitat was used by marten. Further, composition of forest types within home ranges of radiocollared resident marten was similar to areas outside of home ranges. At the stand scale, marten used forest types disproportionately (P = 0.03) from availability within their home ranges during summer (1 May-31 Oct), but exhibited no apparent selection (P = 0.83) during winter. During summer, stands with substantial spruce-budworm (Choristoneura fumiferana)-caused mortality (<50% overstory canopy closure) had the highest selection index. No significant difference in stand-scale selection was detected among mature, well-stocked coniferous, deciduous, or mixed forest types during summer or winter. Mature, well-stocked coniferous forest was the least abundant forest type in home ranges of both sexes in both seasons, whereas mature, well-stocked deciduous forest was the most abundant. Further, much variability was observed in the amount of coniferous (range 0.8-36.3%) and deciduous (range 6.3-66.1%) habitat occurring in marten home ranges. Nine of 10 adult females captured in late spring were lactating, despite that their home ranges composed only 3-36% (median = 10.5%) mature coniferous forest. Our results suggest that marten do not require a dense or coniferous forest overstory and are consistent with the hypothesis that vertical and horizontal structure may be more important habitat components than age or species composition of the forest overstory. Thus, forest practices, such as on-site delimbing, cull-tree retention, and slash management may provide opportunities to maintain use of regenerating forest habitat by marten after harvesting. Structural complexity often may be associated with age and species composition of forests; however, conservation practices should consider structural attributes that functionally, influence the quality of forested habitats for marten, rather than merely age, species composition, and canopy closure of the forest overstory.