Woody Species Diversity and Management in Homegarden Agroforestry: The Case of Shashemene District, EthiopiaRead the full article
International Journal of Forestry Research publishes research about the management and conservation of trees or forests, including tree biodiversity, sustainability, habitat protection and the social and economic aspects of forestry.
International Journal of Forestry Research maintains an Editorial Board of practicing researchers from around the world, to ensure manuscripts are handled by editors who are experts in the field of study.
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Vertical Distribution of Soil Organic Carbon and Nitrogen in a Tropical Community Forest of Nepal
This paper reports the findings of a research conducted in Kankali community forest, Chitwan, Nepal, to quantify the vertical distribution of soil organic carbon (SOC) and nitrogen in 1 m soil profile depth. This community forest represents a tropical Shorea robusta-dominated community forest. It was found that the soil had 122.36 t/ha SOC and 12.74 t/ha nitrogen in 1 m soil profile in 2012, with 0.99% soil organic matter and 0.10% nitrogen concentration in average. Carbon and nitrogen ratio (C/N ratio) of the soil was found to be 9.90. Both bulk density and C/N ratio were found increasing with increase in soil depth. The SOC and nitrogen were found significantly different across different soil layers up to 1 m soil profile depth. The average pH of the forest soil was found to be 5.3. Looking into the values of stocks of SOC and nitrogen, it is concluded that Kankali community forest has played a role in global climate change mitigation by storing considerable amounts of SOC. Involvement of local community in management of tropical forest cannot be overlooked in the process of climate change mitigation.
Mating System among Provenances of Sclerocarya birrea (A. Rich.) Hochst.
Mating system of a species is critically important both genetically and ecologically in developing plans for breeding and gene conservation. This study was conducted to assess twenty provenances of Sclerocarya birrea (A. Rich.) Hochst. planted in Malawi. The trial was assessed for mating system and sex ratio at eighteen years of age. The results revealed that the mating system in S. birrea occurred from selfing, insect, and wind-mediated pollination. There were no significant (P>0.05) differences on seed germination percentage among the three mating systems. The germination percentages were 47%, 44%, and 43% for insect, wind, and self-pollinations, respectively. This implies that the seeds were viable in all the three mating systems. Production of viable seed from selfed flowers ruled out the possibility of apomixes in S. birrea. Most frequent flower visitors were the orders Hymenoptera and Lepidoptera with peak visitation period being from 7:00 to 11:30 hours in the morning and then 15:30 to 18:00 hours in the afternoon (+2 GMT) when temperatures were cooler. There were significant (P<0.05) variations in sex ratio among the provenances. Five provenances (Marracuene, Magamba, Tanzania pooled, Ngundu, and Matebeleland South) did not deviate significantly from sex ratio equality. The other provenances showed male-biased sex ratios.
Height-Diameter Allometry for Tree Species in Tanzania Mainland
Total tree height (H) and diameter at beast height (D) are important independent variables in predicting volume, biomass, and other forest stand attributes. However, unlike D measurement, which is easy to measure with high accuracy, H measurement is laborious. This study, therefore, developed H-D relationships for ten different forest types in Tanzania Mainland. Extents in which climate and forest stand variables explain the variation in H-D allometry were also assessed. A total of 31782 sample trees covering miombo woodlands, humid montane, lowland forests, bushlands, grasslands, mangroves, cultivated land, wetlands forests, and pines and Eucalyptus species plantations were used for model development. The H estimating model without climate and forest stand variables referred herein as “base model” was first developed followed by “generalized model” which included climate and stand variables. All the data were fitted using nonlinear mixed effect modelling approach. Results indicated that generalized H estimating models had better fit than the base models. We therefore confirm a significant contribution of climate and forest structure variables in improving H-D allometry. Among the forest structure variables, basal area (BA) was far more important explanatory variable than other variables. In addition, it was found that the mean tree H tends to increase with the increase of mean precipitation (PRA). We therefore conclude that forest specific generalized H model is to be applied when predicting H. When forest type information is not available, generalized regional model may be applied. Base model may be applied when forest stand or climate information are missing.
Evaluating Sensitivity of the Ranking of Forest Fuel Treatments to Manager’s Risk Attitudes and the Importance of Treatment Objectives, Montana, USA
This study develops a conceptual framework for evaluating the sensitivity of the ranking of forest fuel treatment strategies (FTSs) to variation in managers’ risk attitudes and the importance ratings managers assign to fuel treatment objectives and demonstrates the application of the framework using a case study. The conceptual framework involves (1) defining a utility function on an index that is a weighted average of fuel treatment objectives and incorporates a manager’s risk attitude; (2) using the utility function to calculate utility values for FTSs; (3) applying the stochastic efficiency with respect to a function method to utility values to obtain certainty equivalents (CEs); and (4) ranking FTSs based on statistically significant differences in median CEs for pairs of FTSs. The case study involves three (federal, state, and private) forested areas in Flathead County, Montana, USA, three FTSs (i.e., Community Wildfire Protection Plan (CWPP) Priority; CWPP & Wildland-Urban Interface Priority; and No Priority), three treatment objectives (i.e., minimizing expected residential monetary losses from wildfire, minimizing expected deviation of forest ecological conditions from their historic range and variability, and maximizing expected net returns from timber harvesting associated with fuel treatment), two risk attitudes (i.e., almost risk neutral and highly risk averse), and 35 weight scenarios for treatment objectives. Case study results are used to test the hypothesis that the ranking of FTSs is sensitive to manager’s risk attitudes and the importance ratings for management objectives. The ranking of FTSs for the three forested areas was insensitive for an almost risk neutral manager and sensitive for a highly risk averse manager. In general, the case study indicates that the ranking of FTSs is sensitive to both a forest manager’s risk attitudes and the importance ratings assigned to fuel treatment objectives.
Biomass and Volume Models Based on Stump Diameter for Assessing Degradation of Miombo Woodlands in Tanzania
Models to estimate forest degradation in terms of removed volume and biomass from the extraction of wood fuel and logging using stump diameter (SD) are lacking. The common method of estimating removals is through estimating diameter at breast height (D) by applying equations relating measured D and SD. The estimated D is then used to estimate biomass and volume by means of allometric equations, which utilize D. Through this sequence of procedures, it is apparent that there is an accumulation of errors. This study developed equations for estimating volume, aboveground biomass (ABG), and belowground biomass (BGB) using SD in miombo woodlands of mainland Tanzania. Volume models were developed from 114 sample trees while AGB and BGB models were developed from 127 and 57 sample trees, respectively. Both site specific and regional models were developed. Over 70% of the variations in BGB, AGB, and volume were explained by SD. It was apparent that SD is inferior compared to measured D in explaining variation in volume and BGB but not AGB. However, the accuracy of BGB and volume estimates emanating directly from SD were far better than those obtained indirectly, i.e., volume or BGB estimates obtained from estimated D from SD, since the latter is affected by accumulation of regression equation errors. For improved accuracy of ABG, BGB, and volume estimates, we recommend the use of site specific models. However, for areas with no site specific models, application of regional models is recommended. The developed models will facilitate the addition of forest degradation as a REDD+ activity into the forthcoming FREL.
Provenance Variation on Early Survival Rate and Growth Performance of Oxytenanthera abyssinica (A. Rich.) Munro Seedlings at Green House: An Indigenous Lowland Bamboo Species in Ethiopia
Background. Lowland Bamboo (O. abyssinica) is an indigenous multipurpose species in Ethiopia and endemic to Africa. Aims. The present study was aimed at investigating provenance variation on early survival rate and growth performance of O. abyssinica seedlings so as to obtain suitable provenance for production of high quality seedlings. Methods. Seeds were collected from Pawe and Sherkole districts. Following raise of seedlings data on survival count, culm height, root collar diameter (RCD), number of leaves, and biomass were recorded. Results. Pawe provenance had slightly higher survival rate (91%). Except seedlings RCD, rhizomes length, and roots fresh and dry weights, higher mean values of other morphological parameters were recorded in Sherkole provenance. Biomass of leaves and culms was higher in Shekole provenance, while root biomass was exceeded by the Pawe provenance. However, significant variations (P<0.05) between provenances were observed in RCD, rhizomes length, weight of fresh culms, and fresh and dry root system. Seedlings growth parameters (height and RCD) were positively and significantly correlated with Biomass variables and hence could be considered as better evaluation criteria for seedling quality at green house. Conclusion. Sherkole provenance should be considered for raising O. abyssinica seedlings at green house.