The impacts of anthropogenic activities on the vegetation communities and structure in the western part of Rungwe forest reserve, Tanzania

Rungwe Forest Reserve is among degraded southern Tanzania tropical montane forests. It was investigated the effects of illegal anthropogenic activities on the plant community structure on the western part of Rungwe mountain forest reserve. The study area was classified the into three levels of disturbance (least disturbed, moderately disturbed and highly disturbed) and transect method was used to collect data. Two clusters (cluster A and B) of plant communities based on Two Way Indicator Species Analysis (TWINSPAN) were found. Cluster A included communities from the least and moderate disturbed sites and cluster B had plant communities from the highly disturbed site The least, moderately and highly disturbed sites had many individuals within the DBH range of 19-57 cm10-47 cm and 11-14 cm respectively. The observed variation in size class structure among the sites was caused by the intensity of anthropogenic disturbance. The inverted J shaped patterns of diameter size class distribution were indicative of regeneration and active recruitment from lower tree growth sizes. It was concluded that the existing plant community structure was shaped by the impacts of anthropogenic activities. Thus, conservation management interventions are necessary for protection of the forest.Keywords: Plant communities, disturbance, montane forest, population size structure, Rungwe

Identification and Characterization of Cassava Mosaic Begomoviruses in Non-crop Plants from Unguja and Pemba Islands

Cassava mosaic disease caused by cassava mosaic begomoviruses (CMBs) remains one of the major constraints to cassava production since it causes yield losses up to 100%. Researches showed that some of CMBs infecting cassava plants may be coming from non-crop plants. This study intended to identify and characterize CMBs isolated from non-crop plant species in Unguja and Pemba Islands. A total of 108 viral symptomatic and asymptomatic non-crop leaf samples were collected using stratified sampling. DNA was extracted by using CTAB protocol followed by polymerase chain reaction using universal and specific primers for cassava mosaic begomoviruses identification. Results showed that, among eleven samples that were amplified, four were African cassava mosaic viruses (ACMV) and seven were East African cassava mosaic viruses (EACMV). DNA sequencing by Sanger method showed 97–99% similarities with isolates of ACMV and EACMV reported elsewhere in Africa. Using RbcL and MatK plant barcode genes, Datura stramonium, Solanum melongena and Solanum incanum were found associated with ACMV, while Senna occidentalis, Sida acuta and Ricinus communis harboured EACMV. These findings are a key in understanding the epidemiology of cassava mosaic disease and are potential in the development of sustainable management strategies for this disease. Keywords: Begomoviruses, Cassava mosaic disease, East African cassava mosaic virus, Non crop plants