Assessment of multifunctional landscapes dynamics in the mountainous basin of the Mo River (Togo,West Africa)

In this study, historical landscape dynamics were investigated to (i) map the land use/cover types for the years 1972, 1987, 2000 and 2014; (ii) determine the types and processes of landscape dynamics; and (iii) assess the landscape fragmentation and habitat loss over time. Supervised classification of multi-temporal Landsat images was used through a pixel-based approach. Post–classification methods included systematic and random change detection, trajectories analysis and landscape fragmentation assessment. The overall accuracies (and Kappa statistics) were of 68.86% (0.63), 91.32% (0.79), 90.66% (0.88) and 91.88% (0.89) for 1972, 1987, 2000 and 2014, respectively. The spatio-temporal analyses indicated that forests, woodlands and savannahs dominated the landscapes during the four dates, though constant areal decreases were observed. The most important dynamic process was the decline of woodlands with an average annual net loss rate of–2%. Meanwhile, the most important land transformation occurred during the transition 2000–2014, due to anthropogenic pressures. Though the most important loss of vegetation greenness occurred in the unprotected areas, the overall analyses of change indicated a declining trend of land cover quality and an increasing landscape fragmentation. Sustainable conservation strategies should be promoted while focusing restoration attention on degraded lands and fragmented ecosystems in order to support rural livelihood and biodiversity conservation.     

Dissolved inorganic carbon (DIC) and hydrologic mixing in a subtropical riverine estuary,southwest Florida,USA

Physical and chemical parameters were measured in a subtropical estuary with a blind river source in southwest Florida, United States, to assess seasonal discharge of overland flow and groundwater in hydrologic mixing. Water temperature, pH, salinity, alkalinity, dissolved inorganic carbon (DIC), δ¹⁸O, and δ¹³C_DIC varied significantly due to seasonal rainfall and climate. Axial distribution of the physical and chemical parameters constrained by tidal conditions during sampling showed that river water at low tide was a mixture of freshwater from overland flow and saline ground-water in the wet season and mostly saline groundwater in the dry season. Relationships between salinity and temperature, δ¹⁸O, and DIC for both the dry and wet seasons showed that DIC was most sensitive to seawater mixing in the estuary as DIC changed in concentration between values measured in river water at the tidal front to the most seaward station. A salinity-δ¹³C_DIC model was able to describe seawater mixing in the estuary for the wet season but not for the dry season because river water salinity was higher than that of seawater and the salinity gradient between seawater and river water was small. A DIC-δ¹³C_DIC mixing model was able to describe mixing of carbon from sheet flow and river water at low tide, and river water and seawater at high tide for both wet and dry seasons. The DIC-δ¹³C_DIC model was able to predict the seawater end member DIC for the wet season. The model was not able to predict the seawater end member DIC for the dry season data due to secondary physical and biogeochemical processes that altered estuarine DIC prior to mixing with seawater. The results of this study suggest that DIC and δ¹³C_DIC can provide additional insights into mixing of river water and seawater in estuaries during periods where small salinity gradients between river water and seawater and higher river water salinities preclude the use of salinity-carbon models.