Tree mycorrhizal associations determine how biodiversity,large trees,and environmental factors drive aboveground carbon stock in temperate forests

Biodiversity,large trees,and environmental conditions such as climate and soil have important effects on forest carbon stocks.However,recent studies in temperate forests suggest that the relative importance of these factors depends on tree mycorrhizal associations,whereby large-tree effects may be driven by ectomycorrhizal(EM)trees,diversity effects may be driven by arbuscular mycorrhizal(AM)trees,and environment effects may depend on differential climate and soil preferences of AM and EM trees.To test this hypothesis,we used forest-inventory data consisting of over 80,000 trees from 631 temperate-forest plots(30 m×30 m)across Northeast China to examine how biodiversity(species diversity and ecological uniqueness),large trees(top 1%of tree diameters),and environmental factors(climate and soil nutrients)differently regulate aboveground carbon stocks of AM trees,EM trees,and AM and EM trees combined(i.e.total aboveground carbon stock).We found that large trees had a positive effect on both AM and EM tree carbon stocks.However,biodiversity and environmental factors had opposite effects on AM vs.EM tree carbon stocks.Specifically,the two components of biodiversity had positive effects on AM tree carbon stocks,but negative effects on EM tree carbon stocks.Environmental heterogeneity(mean annual temperature and soil nutrients)also exhibited contrasting effects on AM and EM tree carbon stocks.Consequently,for the total carbon stock,the positive large-tree effect far surpasses the diversity and environment effect.This is mainly because when integrating AM and EM tree carbon stock into total carbon stock,the opposite diversity-effect(also environment-effect)on AM vs.EM tree carbon stock counteracts each other while the consistent positive large-tree effect on AM and EM tree carbon stock is amplified.In summary,this study emphasized a mycorrhizal viewpoint to better understand the determinants of overarching aboveground carbon profile across regional forests.

Optimization models of stand structure and selective cutting cycle for large diameter trees of broadleaved forest in Changbai Mountain

The optimum models of harvesting yield and net profits of large diameter trees for broadleaved forest were developed, of which include matrix growth sub-model, harvesting cost and wood price sub-models, based on the data from Hongshi Forestry Bureau, in Changbai Mountain region, Jilin Province, China. The data were measured in 232 permanent sample plots. With the data of permanent sample plots, the parameters of transition probability and ingrowth models were estimated, and some models were compared and partly modified. During the simulation of stand structure, four factors such as largest diameter residual tree （LDT）, the ratio of the number of trees in a given diameter class to those in the next larger diameter class （q）, residual basal area （RBA） and selective cutting cycle （C） were considered. The simulation results showed that the optimum stand structure parameters for large diameter trees are as follows： q is 1.2, LDT is 46cm, RBA is larger than 26 m^2 and selective cutting cycle time （C） is between 10 and 20 years.

Mapping tree canopies in urban environments using airborne laser scanning (ALS):a Vancouver case study

Background: The distribution of forest vegetation within urban environments is critically important as it influences urban environmental conditions and the energy exchange through the absorption of solar radiation and modulation of evapotranspiration. It also plays an important role filtering urban water systems and reducing storm water runoff.Methods: We investigate the capacity of ALS data to individually detect, map and characterize large(taller than15 m) trees within the City of Vancouver. Large trees are critical for the function and character of Vancouver’s urban forest. We used an object-based approach for individual tree detection and segmentation to determine tree locations(position of the stem), to delineate the shape of the crowns and to categorize the latter either as coniferous or deciduous.Results: Results indicate a detection rate of 76.6% for trees > 15 m with a positioning error of 2.11 m(stem location). Extracted tree heights possessed a RMSE of 2.60 m and a bias of-1.87 m, whereas crown diameter was derived with a RMSE of 3.85 m and a bias of-2.06 m. Missed trees are principally a result of undetected treetops occurring in dense, overlapping canopies with more accurate detection and delineation of trees in open areas.Conclusion: By identifying key structural trees across Vancouver’s urban forests, we can better understand their role in providing ecosystem goods and services for city residents.

Diversity, composition and host-species relationships of epiphytic orchids and ferns in two forests in Nepal

Epiphytic plant species are an important part of biological diversity. It is therefore essential to understand the distribution pattern and the factors influencing such patterns. The present study is aimed at observing the patterns of species richness, abundances and species composition of epiphytic orchids and ferns in two subtropical forests in Nepal. We also studied the relationship of host plants(Schima wallichii and Quercus lanata) and epiphyte species. Data were collected in Naudhara community forest(CF) and the national forest(NF) in Shivapuri Nagarjun National Park. The data were analyzed using univariate and multivariate tests. In total, we recorded 41 species of epiphytes(33 orchid and 8 fern species). Orchid species abundance is significantlyhigher in CF compared to NF. Orchid species richness and abundance increased with increasing southern aspect whereas it decreased with increasing canopy cover, and fern species richness increased with host bark roughness. Orchid abundance was positively correlated with increasing bark p H, stem size, tree age and tree height and negatively correlated with increasing steepness of the area. Likewise, fern abundances were high in places with high canopy cover, trees that were tall and big, but decreased with increasing altitude and southern aspect. The composition of the orchid and fern species was affected by altitude, aspect, canopy cover, DBH, number of forks and forest management types. We showed that the diversity of orchid and fern epiphytes is influenced by host characteristics as well as host types. The most important pre-requisite for a high epiphyte biodiversity is the presence of oldrespectively tall trees, independent of the recent protection status. This means:(i) for protection, e.g.in the frame of the national park declaration, such areas should be used which host such old tall trees;and(ii) also in managed forests and even in intensively used landscapes epiphytes can be protected by letting a certain number of trees be and by giving them space to grow old and tall.

Synergistic effects of tropical cyclones on forest ecosystems:a global synthesis

Tropical cyclones are large-scale strong wind disturbance events that occur frequently in tropical and subtropical coastal regions and often bring catastrophic physical destruction to ecosystems and economic disruption to societies along their paths. Major tropical cyclones can infrequently move into the midaltitudes and inland areas. Ecologically, tropical cyclones have profound impacts on diversity, structure, succession and function of forest ecosystems. The ecological effects are both dramatic and subtle. The dramatic effects can be visible, noticeable and to some extent predictable over the short-term and relatively well documented in the literature. However, the subtle effects are often invisible, complex and at smaller scale relatively unpredictable in the long-term. Many factors, meteorologic, topographic and biologic, simultaneously interact to influence the complexity of patterns of damage and dynamics of recovery. I present a global synthesis on the effects of tropical cyclones on forest ecosystems and the complexity of forest responses, with particular attention on the response to large hurricanes in the neotropics and the temperate North America, and strong typhoons on the subtropical and temperate forests in the East and Southeast Asia. Four major aspects provide on organizational framework for this synthesis：（1） consistent damage patterns,（2） factors that influence response patterns and predict damage risks,（3） complexity of forest responses and recovery, and（4） the long-term effects. This review reveals highly variable and complex effects of tropical cyclones on forest ecosystems. A deep understanding of the synergistic effects of tropical cyclones is essential for effective forest management and biodiversity conservation.

Stand structure and species diversity regulate biomass carbon stock under major Central Himalayan forest types of India

Background:Data on the impact of species diversity on biomass in the Central Himalayas,along with stand structural attributes is sparse and inconsistent.Moreover,few studies in the region have related population structure and the influence of large trees on biomass.Such data is crucial for maintaining Himalayan biodiversity and carbon stock.Therefore,we investigated these relationships in major Central Himalayan forest types using nondestructive methodologies to determine key factors and underlying mechanisms.Results:Tropical Shorea robusta dominant forest has the highest total biomass density(1280.79 Mg ha^(−1))and total carbon density(577.77 Mg C ha^(−1))along with the highest total species richness(21 species).The stem density ranged between 153 and 457 trees ha^(−1) with large trees(>70 cm diameter)contributing 0–22%.Conifer dominant forest types had higher median diameter and Cedrus deodara forest had the highest growing stock(718.87 m^(3) ha^(−1));furthermore,C.deodara contributed maximally toward total carbon density(14.6%)among all the 53 species combined.Quercus semecarpifolia–Rhododendron arboreum association forest had the highest total basal area(94.75 m^(2) ha^(−1)).We found large trees to contribute up to 65%of the growing stock.Nine percent of the species contributed more than 50%of the carbon stock.Species dominance regulated the growing stock significantly(R^(2)=0.707,p<0.001).Temperate forest types had heterogeneous biomass distribution within the forest stands.We found total basal area,large tree density,maximum diameter,species richness,and species diversity as the predominant variables with a significant positive influence on biomass carbon stock.Both structural attributes and diversity influenced the ordination of study sites under PCA analysis.Elevation showed no significant correlation with either biomass or species diversity components.Conclusions:The results suggest biomass hyperdominance with both selection effects and niche complementarity to play a complex mechanism in enhancing Central Himalayan biomass carbon stock.Major climax forests are in an alarming state regarding future carbon security.Large trees and selective species act as key regulators of biomass stocks;however,species diversity also has a positive influence and should also reflect under management implications.

Towards more-than-human heritage:arboreal habitats as a challenge for heritage preservation

Trees belong to humanity’s heritage,but they are more than that.Their loss,through catastrophic fires or under business-as-usual,is devastating to many forms of life.Moved by this fact,we begin with an assertion that heritage can have an active role in the design of future places.Written from within the field of architecture,this article focuses on structures that house life.Habitat features of trees and artificial replacement habitats for arboreal wildlife serve as concrete examples.Designs of such habitats need to reflect behaviours,traditions and cultures of birds,bats,and other animals.Our narrative highlights the nonhuman aspect of heritage,seeking to understand how nonhuman stakeholders can act as users and consumers of heritage and not only as its constituents.Our working definition states that more-than-human heritage encompasses tangible and intangible outcomes of historical processes that are of value to human as well as nonhuman stakeholders.From this basis,the article asks how the established notions of heritage can extend to include nonhuman concerns,artefacts,behaviours and cultures.As a possible answer to this question,the hypothesis tested here is that digital information can(1)contribute to the preservation of more-than-human heritage;and(2)illuminate its characteristics for future study and use.This article assesses the potential of three imaging technologies and considers the resulting data within the conceptual framework of more-than-human heritage,illuminating some of its concrete aspects and challenges.