Forests, Volume 5, Issue 2 (February 2014) – 9 articles , Pages 214-383

The objective of this study was to evaluate the applicability of using a low-density (1–3 points m⁻²) discrete-return LiDAR (Light Detection and Ranging) for predicting maximum tree height, stem density, basal area, quadratic mean diameter and total volume. The research was conducted at the Penobscot Experimental Forest in central Maine, where a range of stand structures and species composition is present and generally representative of northern Maine’s forests. Prediction models were developed utilizing the random forest algorithm that was calibrated using reference data collected in fixed radius circular plots. For comparison, the volume model used two sets of reference data, with one being fixed radius circular plots and the other variable radius plots. Prediction biases were evaluated with respect to five silvicultural treatments and softwood species composition based on the coefficient of determination (R²), root mean square error and mean bias, as well as residual scatter plots. Overall, this study found that LiDAR tended to underestimate maximum tree height and volume. The maximum tree height and volume models had R² values of 86.9% and 72.1%, respectively. The accuracy of volume prediction was also sensitive to the plot type used. While it was difficult to develop models with a high R², due to the complexities of Maine’s forest structures and species composition, the results suggest that low density LiDAR can be used as a supporting tool in forest management for this region. Full article

Fusiform rust resistance can involve gene-for-gene interactions where resistance (Fr) genes in the host interact with corresponding avirulence genes in the pathogen, Cronartium quercuum f.sp. fusiforme (Cqf). Here, we identify trees with Fr genes in a loblolly pine population derived from a complex mating design challenged with two Cqf inocula (one gall and 10 gall mixtures). We used single nucleotide polymorphism (SNP) genotypes at sufficient density to ensure linkage between segregating markers and Fr genes identifying SNPs that explained high proportions of variance in disease incidence using BayesCp, that also were significant using Bayesian Association with Missing Data (BAMD) software. Two SNPs mapped near Fr1 and generated significant LOD scores in single marker regression analyses for Fr1/fr1 parent 17 as well as four other parents. One SNP mapped near Fr8 and was significant for parent 28. Two SNPs mapped to linkage groups not previously shown to contain Fr genes and were significant for three parents. Parent 2 showed evidence of Fr gene stacking. Our results suggest that it is feasible to identify trees segregating for Fr genes, and to map Fr genes, based on parental analysis of SNPs that cosegregate with disease incidence in designed resistance screening trials. Full article

The ecosite unit in Ontario’s boreal forest ecological land classification system is a polygon of common vegetation type and soil conditions intended to provide a standardized provincial framework to inform meso-scale forestry and planning applications. To determine whether the physical factors used for ecosite classification relate to patterns in ecological function over finer spatial scales, we examined 14 soil properties in replicate boreal forest plots representing eight mineral soil ecosite classes and three organic soil ecosite classes in the Hearst Forest. Despite large differences in vegetation composition, we found few statistically significant differences in properties when compared for individual classes or for more general groupings based on vegetation type and soil texture or expected fertility status. However, some properties (soil organic carbon, total nitrogen, and C:N ratio) were approaching significance in the 0–10 cm depth increment, and there were distinct differences between organic soil and mineral soil sites. Overall, these results suggest few explicit links between ecosystem function and ecosite class at this scale of measurement, highlighting the potential importance of non-steady-state relationships between vegetation species and soil properties in disturbed forests and the potential need for finer-scale characterization to capture patterns in ecosystem function. Full article

Many studies have quantified uncertainty in forest carbon (C) storage estimation, but there is little work examining the degree of uncertainty in shrubland C storage estimates. We used field data to simulate uncertainty in carbon storage estimates from three error sources: (1) allometric biomass equations; (2) measurement errors of shrubs harvested for the allometry; and (3) measurement errors of shrubs in survey plots. We also assessed uncertainty for all possible combinations of these error sources. Allometric uncertainty had the greatest independent effect on C storage estimates for individual plots. The largest error arose when all three error sources were included in simulations (where the 95% confidence interval spanned a range equivalent to 40% of mean C storage). Mean C sequestration (1.73 Mg C ha^–1 year^–1) exceeded the margin of error produced by the simulated sources of uncertainty. This demonstrates that, even when the major sources of uncertainty were accounted for, we were able to detect relatively modest gains in shrubland C storage. Full article

The canopy photosynthesis and carbon balance of the subtropical forests are not well studied compared to temperate and tropical forest ecosystems. The main objective of this study was to assess the seasonal dynamics of Normalized Difference Vegetation Index (NDVI) and potential canopy photosynthesis in relation to seasonal changes in leaf area index (LAI), chlorophyll concentration, and air temperatures of NE Argentina subtropical forests throughout the year. We included in the analysis several tree plantations (Pinus, Eucalyptus and Araucaria species) that are known to have high productivity. Field studies in native forests and tree plantations were conducted; stem growth rates, LAI and leaf chlorophyll concentration were measured. MODIS satellite-derived LAI (1 km SIN Grid) and NDVI (250m SIN Grid) from February 2000 to 2012 were used as a proxy of seasonal dynamics of potential photosynthetic activity at the stand level. The remote sensing LAI of the subtropical forests decreased every year from 6 to 5 during the cold season, similar to field LAI measurements, when temperatures were 10 °C lower than during the summer. The yearly maximum NDVI values were observed during a few months in autumn and spring (March through May and November, respectively) because high and low air temperatures may have a small detrimental effect on photosynthetic activity during both the warm and the cold seasons. Leaf chlorophyll concentration was higher during the cold season than the warm season which may have a compensatory effect on the seasonal variation of the NDVI values. The NDVI of the subtropical forest stands remained high and fairly constant throughout the year (the intra-annual coefficient of variation was 1.9%), and were comparable to the values of high-yield tree plantations. These results suggest that the humid subtropical forests in NE Argentina potentially could maintain high canopy photosynthetic activity throughout the year and thus this ecosystem may be a large carbon sink. Full article

Wild plants in forests provide valuable living resources for rural communities. The location where local people harvest various species is important to the wise use of forest ecosystem services. Using global positioning system (GPS) tracking of harvesters’ activities as well as geographic information system (GIS) and a generalized linear model (GLM), this study analyzed the spatial differences among harvesting sites of three popular edible ferns, i.e., ostrich fern (Matteuccia struthiopteris), bracken (Pteridium aquilinum), and royal fern (Osmunda japonica), in mountainous villages of Northeastern Japan. The explanatory variables used were vegetation classes, terrain features, and proximity to roadways. The GLM yielded clear differences in harvesting sites among species that were affected by both the species’ ecological characteristics and human behavior. Ostrich fern was harvested mainly in canopy openings along valley floors, whereas royal fern harvest sites were frequently located in snow avalanche scrublands. Bracken was mainly harvested in deforested areas or young conifer plantations. Whereas ostrich fern and bracken harvest sites were restricted by the accessibility from roadways, this was not the case for royal fern. Potential harvest sites of ferns were estimated with the highest value for bracken. Our results suggest that local harvesters seriously consider various natural and anthropogenic factors to maintain effective and sustainable harvesting. Full article

Restoration of second-growth riparian stands has become an important issue for managers of redwood (Sequoia sempervirens [D. Don] Endl.) forest reserves. Identifying differences between old-growth and second-growth forest vegetation is a necessary step in evaluating restoration needs and targets. The objective of this study was to characterize and contrast vegetation structure and composition in old-growth and unmanaged second-growth riparian forests in adjacent, geomorphologically similar watersheds at Redwood National Park. In the old-growth, redwood was the dominant overstory species in terms of stem density, basal area, and importance values. Second-growth was dominated by red alder (Alnus rubra Bong.), Douglas-fir (Pseudotsuga menziesii [Mirbel] Franco), and redwood. Understory species were similar in both forests, with several key differences: Oxalis oregana Nutt. and Trillium ovatum Pursh had greater importance values in the old-growth, and Vaccinium parvifolium Sm., Dryopteris spp. and sedges Carex spp. had greater importance values in the second-growth. Notable differences in structure and composition suggest that restoration practices such as thinning could expedite the acquisition of old-growth characteristics in second-growth riparian forests. Full article

REDD+ has been proposed as a viable option for addressing climate change in the near term, and at relatively low cost. There is a broad consensus that clearly defined tenure rights are important for the implementation and success of REDD+, both to manage forests effectively and to protect local communities’ livelihoods. We use primary data from 23 villages in six REDD+ pilot sites in Tanzania to identify causes of deforestation and forest degradation, and tenure rights issues, at the village level prior to project implementation. Further, interviews with project proponents and examination of project documents yields insights into how the proponents plan to address tenure issues. Most villages perceive their tenure as secure and have exclusion rights, while collective action challenges are prevalent in villages experiencing deforestation and forest degradation. These findings suggest that the main tenure issues are related to internal institutional arrangements. While we find that tenure is high on the agenda for all the project proponents, they are mainly focusing on formalization and securing tenure rights from state to community level. Though we do find this to be a precondition for reducing deforestation and degradation, some of their focus should be shifted to strengthening village institutions and enhancing internal compliance. Full article

China has experienced extensive forest transition, from net deforestation to net forestation. Existing theories have highlighted economic growth, the intensification of agriculture and forest scarcity as the pathways of this transition, and studies, in particular from China, have also highlighted the contribution of a huge state afforestation program and the improved implementation and enforcement of forest protection policy and law. However, few studies have paid attention to local dynamics to provide a contextualized understanding of how forest transition has taken place at the local level and the significance of local factors in this change. This paper examines forest transition pathways in two villages in China. We consider the historical perspective and compare their local dynamics and variations to reach an understanding of the process of forest recovery at the local level. The results show that state forestry policies, including afforestation policy and tenure reform, arguably contribute to forest increase, while local processes including livelihood change and institutional factors play a key role in driving and shaping forest transition. We argue that there is a need for local-level studies and recommend including local institutions in forest transition analysis, contextualizing the socio-ecological interactions within the broader concept of political economy. Full article