In vitro propagation of conifers using mature shoots

Micropropagation mostly leads to the production of innumerable true-to-type plants. However, establishing pathogen-free explants through in vitro culture requires a precise management of time for the exposure of explants to antimicrobial chemicals. The application of antimicrobial chemicals must also be managed to impose the least injury on explants. This review discusses the contributions of micropropagation procedures, explant types, subculture duration, media ingredients and plant growth regulators to the in vitro response of conifer explants. Even though regeneration from mature conifer explants such as mature shoots are laborious, the chances of variation, induced in vitro, are unlikely.     

A Community Forestry Model Linking Research,Management, Education,and Stakeholder Engagement: Case Study Results from the Town of Weston,Massachusetts, USA

Forested land in the eastern United States is owned by a complex mix of public and private owners, often with highly varied objectives and uses. There is an increasing trend at local scales of community forestry programs that use community-based decision making to determine what type of management will occur on town-owned forests. Within the suburban town of Weston, Massachusetts, this type of coordinated approach has been ongoing for nearly 4 decades. This article describes the integration of forest ecology and management research, including a forest inventory and long-term monitoring program, to educate townspeople about their forests, engage students in ecological research, and provide data that the town can use to make informed management decisions. This article presents a novel model for a research-based community forestry program, results from the first inventory and plot measurement period, and describes how other towns can use this type of program to supplement existing active forest management, or provide a baseline for future management. Results are applicable to municipalities that own forest land, as well as land trusts or other private entities that wish to manage their forests using a community based forestry model.     

Does the persistence of sweet chestnut depend on cultural inputs? Regeneration,recruitment, and mortality in <Emphasis Type="Italic">Quercus</Emphasis>- and <Emphasis Type="Italic">Castanea</Emphasis>-dominated forests

Key message

Quercus secondary forests show a gradual transition toward mixed forests, with sweet chestnut ( Castanea sativa ) becoming increasingly abundant in the western Spanish Central System. Additionally, in chestnut-dominated stands, it shows a certain resistance to competitive displacement by Quercus pyrenaica . Our results partially refute the traditional view that C. sativa is unable to recruit in the absence of cultural inputs.

Context

Sweet chestnut, Castanea sativa, is a component of European broadleaf forests and is one of the most managed trees. Due to a reduction in cultural inputs, chestnut-dominated stands tend to be invaded by other species, and it is unclear how chestnut is able to persist in natural mixed forests.

Aims

Our work aimed to identity the main factors that limit the establishment of C. sativa and to analyze the recruitment and mortality processes of C. sativa trees.

Methods

The age, growth ring patterns, regeneration density, and the spatial structure of trees and saplings in 11 plots in the Spanish Central System were analyzed.

Results

Chestnut seedling density increased with C. sativa basal area, but transition toward the sapling stage appeared limited owing to light availability. In Quercus pyrenaica secondary forests, sparse canopies did not constrain chestnut regeneration, and in old chestnut stands, C. sativa showed a certain resistance to competitive displacement. By contrast, mixed young coppices showed a high mortality, most likely due to competition with other vigorous resprouters.

Conclusion

Quercus secondary forests showed a gradual transition toward mixed forests with sweet chestnut becoming increasingly more abundant. In old stands, C. sativa is likely to persist under a gap-phase mode of regeneration. Our results partially refute the traditional view that C. sativa is unable to recruit in the absence of cultural inputs.

     

Relationships between agroforestry and community development according to practitioners

Post-adoption studies are relatively uncommon in the agroforestry literature. Thus little is known about progress and permanence following adoption. To better understand the relationship between agroforestry implementation and community development, seventy-seven practitioners in Cameroon with three or more years of experience were surveyed about the relationships between agroforestry and community development. Hypotheses were that they have observed differences in the association between agroforestry and community capitals. They were also surveyed about their satisfaction with agroforestry. Hypotheses were that satisfaction is high and negatively skewed when compared to community capitals measurements. Game play was used to collect responses. Friedman’s two-way non-parametric statistic was used to test for inter-item differences within the community capitals and satisfaction response sets. Shapiro–Wilk statistic was used to test for normality in both response sets and a bootstrap procedure and t-tests were used to test for differences in data skewness and kurtosis. Natural capital scored highest but did not differ significantly from built, human, and social capitals. Financial capital was significantly lower than natural capital, but not built, human, or social capitals. Political and cultural capitals were significantly lower compared to all others. Satisfaction was significantly higher when compared to community capitals, but the data were also negatively skewed suggesting capitals are a more representative and useful metric for researchers and technical assistance professionals focused on long-term practitioner support.     

Home garden system dynamics in Southern Ethiopia

Home gardens in southern Ethiopia are regarded as efficient farming systems, allowing interactions and synergies between crop, tree and livestock components. However, these age-old traditional home gardens are evolving rapidly in response to changes in both the socio-economic and biophysical environment. Altered cropping patterns, farm size and component interactions may affect the systems’ sustainability. Home gardens exhibit a huge diversity in farms and farming systems, which needs to be understood in order to design interventions for improvement. Dynamics of home gardens were studied over two-decades (1991–2013) based on a survey of 240 farm households and focus group discussions. Farms were grouped into five types: Khat-based, Enset-cereal-vegetable, Enset-based, Enset-coffee and Enset-livestock. Farm trajectories revealed a shift from food-oriented Enset-based and Enset-livestock systems to (1) cash crop oriented khat-based systems, and (2) combined food and cash crop oriented Enset-cereal-vegetable systems. In densely populated, market proximate areas a major trend was expansion of khat, from 6 to 35% of the area share per farm, while the combined area share of enset and coffee decreased from 45 to 25%. Concurrently, the cattle herd size fell from 5.8 TLU to 3.9 TLU per household. In medium populated, less accessible areas the trend was consolidation of combined production of food and cash crops. Enset and coffee together maintained a share of over 45%. Easy transport and marketing of the perishable cash-generating khat compared with traditional crops favoured its cultivation among smallholders located close to markets. The insights in home garden change in response to increasing population pressure, decreasing farm size and market development may help to design interventions to increase system sustainability.     

Why seedlings grow: influence of plant attributes

Successful forest restoration requires planting quality seedlings with optimal growth potential. Thus, nurseries need to produce seedlings with plant attributes that favor the best chance of successful establishment once they are field planted. From the mid-twentieth century on, research foresters have critically examined plant attributes that confer improved seedling growth under various restoration site conditions. This review examines the value of commonly measured seedling quality attributes (i.e., height, diameter, root mass, shoot-to-root ratio, drought resistance, freezing tolerance, nutrient status, root growth potential, and root electrolyte leakage) that have been recognized as important in explaining why seedlings with improved attributes have better growth after planting. Seedlings with plant attributes that fall within the appropriate range of values can increase the speed with which they overcome planting stress, initiate growth, and become “coupled” to the forest restoration site, thereby ensuring successful seedling establishment. Although planting high quality seedlings does not guarantee successful seedling establishment, it increases chances for successful establishment and growth.     

A probabilistic model for tropical tree seed desiccation tolerance and storage classification

Knowledge of seed desiccation tolerance is fundamental for conservation and use of forest species. The protocol used for classification of seed desiccation tolerance and storage is time consuming and many times limited by the lack of information about optimum conditions for seed germination and treatments to overcome seed dormancy. This study evaluated 66 Brazilian tree species aiming to correlate seed characteristics with desiccation tolerance. For this purpose, a model was established to explain the relationship of tegument/seed mass ratio (SCR), seed mass, and water content of embryo + endosperm with desiccation tolerance. The principal component analysis showed the establishment of two groups, indicating the interaction between desiccation tolerance and seed characteristics. Recalcitrant seeds are more often associated with the water content of embryo + endosperm and water content of tegument + endocarp, while orthodox seeds are more associated with SCR and number of seeds per kilogram. The classification found using the model proposed was significantly correlated with desiccation tolerance and storage, with 92% confidence for the analyzed species. Seeds morphological characteristics can be used for prediction of desiccation tolerance and storage behavior; however, the use of a model that combines more variables increases the chance of accurate classification.     

Increase of forest carbon biomass due to community forestry management in Nepal

Community forest management helps in mitigating deforestation and forest degradation by addressing the negative aspects of rural livelihoods such as poverty and social exclusion. It is important in regulating global climate by encouraging sequestration of carbon in shoots, roots and soils. We studied the status of community forest management, forest resource harvest and carbon stocks in two community forests of the mid hill region of central and western Nepal. The study was based on primary and secondary data collected through carbon stock measurement from field visits and allometric equations, household surveys, focus group discussions, key informant interviews, and review of past studies. Socioeconomic variables such as gender, age group, livestock and landholding status were related to resource utilization, conservation, and management of community forest. Forest resources such as timber, firewood, fodder and leaf litter were harvested in sustainable ways. People were involved in forest thinning, co-management meetings, guarding and planting trees for forest conservation and management. Density and carbon stock of trees increased gradually in comparison to a previous study. We recommend further research on other community forests for more accurate and better results.     

Effects of six years of simulated N deposition on gross soil N transformation rates in an old-growth temperate forest

Elevated atmospheric nitrogen(N) deposition has been detected in many regions of China, but its effects on soil N transformation in temperate forest ecosystems are not well known. We therefore simulated N deposition with four levels of N addition rate(N0, N30, N60, and N120) for6 years in an old-growth temperate forest in Xiaoxing'an Mountains in Northeastern China. We measured gross N transformation rates in the laboratory using ~(15)N tracing technology to explore the effects of N deposition on soil gross N transformations taking advantage of N deposition soils. No significant differences in gross soil N transformation rates were observed after 6 years of N deposition with various levels of N addition rate. For all N deposition soils, the gross NH_4~+ immobilization rates were consistently lower than the gross N mineralization rates,leading to net N mineralization. Nitrate(NO_3~-) was primarily produced via oxidation of NH_4~+(i.e., autotrophic nitrification), whereas oxidation of organic N(i.e., heterotrophic nitrification) was negligible. Differences between the quantity of ammonia-oxidizing bacteria and ammonia-oxidizing archaea were not significant for any treatment, which likely explains the lack of a significant effect on gross nitrification rates. Gross nitrification rates were much higher than the total NO_3~- consumption rates,resulting in a build-up of NO_3~-, which highlights the high risk of N losses via NO_3~- leaching or gaseous N emissions from soils. This response is opposite that of typical N-limited temperate forests suffering from N deposition,suggesting that the investigated old-growth temperate forest ecosystem is likely to approach N saturation.