Weeds are plants that are unwanted in a given situation and may be harmful, dangerous or economically detrimental. They are responsible for substantial losses of farm production and extensive damage to the environment. Weeds, through competition with other plants, would almost always have deleterious effects on them and can have a lethal effect on livestock through consumption of weeds containing poisonous chemicals in the pasture. Weed invasion has become the most dreaded and deleterious impact of weeds in nature; it adversely affects agriculture, alters the balance of ecological communities, disrupts the natural diversity and interferes in the aesthetic value of the environment. Weeds can interfere in water management, thereby reducing the economic value of water. Weeds, however, besides their deleterious impacts in nature, have many beneficial properties, which include, but not limited to benefits of weeds to companion plants, ethnomedical and ethnopharmaceutical uses of weeds, ethnobotanical uses of wild edible weeds, and the use of weeds as feed for livestock. In the light of myriads of deleterious effects and benefits accompanying weeds, it is suggested that more studies should be carried out on weed control and weed management. Also, further explorations on the potential uses of weeds to man, his environments and livestock should be undertaken.

The study on ecological survey of plant species biodiversities and abundance in Southeastern Nigeria was conducted between January 2012 and 2013 at Anambra State, Nigeria to determine the plant species biodiversities and abundance in three forest fringes viz: community, shrine and reserves using measures based on floristic, stratified random sampling, plotless measure and point centre quarter methods, respectively. Shannon-wienners index of diversity analysis proved that Umunze community forest was highest in biodiversity (0.95) with Afzelia africana as the most dorminant species (148.93) while Pterocarpus sp. has the highest importance value index (25.36). Achala forest reserve has Chlorophora exdelsa as the most dominant (686.09), while Tectora grandis recorded the highest importance value index (62.53). The dominant species in Iyiocha forest was Pterocarpus species (451.31), while Newbouldia levis has the highest importance value index. Regression analysis showed that at P<0.05, there is a significant relationship between species abundance and species diversity.

The main objective of this paper is to integrate the distribution of gully sites in the Ohafia area of Southeastern Nigeria using remote sensing technique. The Landsat thematic mapper (TM) data of parts of Ohafia was studied with objective of identifying the structures associated with the area and to infer their influence on the gully erosion initiation and propagation. The Landsat TM data was processed using the ILWIS 3.2 Academic and ERDAS software packages.In the course of this study, activities such as laterite excavations, bad farming practices, unplanned road construction and urbanization, wood harvesting for fuel and bush burning to clear lands for farming, among others were identified as factors that cause gully erosion. These activities, coupled with annual flooding from rain water were causing havoc and untold hardship as gullies continue to develop and expand rapidly in the area. Utilizing the opportunities offered by Remote Sensing, this research project came up with vital spatial datasets on the spatial distribution, development and impact of gully erosion in Southeastern Nigeria.The composite images gotten reveal the drainage pattern of the study area to be dendritic.The area is affected by tectonic activities on the geologic formation of the area is responsible for the increasing gully and landslide in the area. Lineament trend in the area correlated well with the measured strokes of the geologic formations.The study revealed that gully developments are more pronounced in areas with high terrain undulation and therefore affected areas should be reclaimed by extensive afforestation and other agricultural programme.

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This article reviews some of the main areas of landscape ecology. It includes the ideas and views of authors to the knowledge and understanding of the interplay between spatial heterogeneity and ecological processes, both in terrestrial and aquatic habitats at their varying scales. Moreover, the ecological consequences of landscape disturbance and landscape fragmentation are reviewed. Man and fire are discussed as the main agents of alternation of the natural landscape both at local and global scales. Studies on landscape restoration and management that emphasize the integration of various stakeholders for effective landscape restoration and management for sustainable biodiversity and socioeconomic benefits to man are as well reviewed. This paper further highlights the integration of the innovative remote sensing and Geographic Information System (GIS) technologies in the generation and analyses of spatial data. The current integration of population genetics in landscape ecology is also visited in this review.