Browsing by Author "Esaete, Josephine"

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    Colonization of woody seedlings in the understory of actively and passively restored tropical moist forests Running head: Seedling colonization in afrotropical forests
    (Restoration Ecology, 2019) Ssekuubwa, Enock; Muwanika, Vincent B.; Esaete, Josephine; Tabuti, John R. S.; Tweheyo, Mnason
    The status of woody seedling colonization gives clues about the self-sustainability of restored forests, a tenet of restoration success. Little is known about woody seedling colonization in restored afrotropical forests. We evaluated effects of restoration methods (active vs. passive), sampling year, restoration age and distance from old-growth forests on seedling colonization in restored afrotropical moist forests. Seedlings were measured in 2011 and 2014 in 71 clusters of 284 permanent sampling plots (12.6 m2 each) in actively (initially 3–16 years old) and 21 clusters of 63 plots in passively restored forests (initially 16 years old) in Kibale National Park, western Uganda. Seedlings were also measured in nearby old-growth forests in 3 clusters of 5 plots in 2014. We determined species diversity, richness and abundance per plot, and species composition as measures of seedling colonization in restored and old-growth forests. We found that diversity, richness, and abundance of seedlings were significantly higher in passively than actively restored forests. Diversity and richness, but not abundance significantly increased between sampling years and with restoration age. Distance from old-growth forests did not significantly affect diversity, richness and abundance. Species composition of actively and passively restored forests was different from that of old-growth forests after 19 years since restoration started. Our results show that passive restoration should be the preferred method for recovering afrotropical forests, and highlight the effect of continued management on biodiversity of restored forests.
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    Conversion of native vegetation in protected areas fuels co2-equivalent losses in Uganda
    (Nova Publishers, 2017) Olupot, Giregon; Otukei, John R.; Muwanika, Vincent B.; Esaete, Josephine; Tabuti, John R.S.
    Protected areas (PAs) play many unique yet, irreplaceable ecosystem functions, most importantly, mitigation of CO2 emissions. However, the influence of land use and land cover (LULC) change on the sequestration of carbon in these PAs and related ecosystems is strikingly limited. This chapter consolidates the scanty data on the impact of LULC change on biomass and soil carbon stocks for evaluation of the impact of such LULC changes on CO2-equivalent (CO2-e) fluxes in the PAs of Uganda. The gist of the study was to test the hypothesis that any change in LULC or shift away from the pristine LULC type (PAs in our case), would lead to a net CO2-e loss. The results indicate that deliberate revegetation of an old (39–63 years) pine plantation segment of Kibale National Park with indigenous tree species resulted in a net 56.8% increase in CO2-e sequestration (18.10 Mg CO2-e ha-1) in 10 years. In Mt Elgon National Park (MENP) with mature native forest (>80 years), over 87% of the CO2-e was sequestered by mature trees in the intact tropical high forest (ITHF). A change in LC from an ITHF to a degraded tropical high forest (DTHF) to grassland has resulted in net losses of 91.5% and 93.6% of the CO2-e sequestered by the ITHF, respectively. In Bwindi Impenetrable National Park, a shift from closed forest canopy (CFC) to open forest canopy (OFC) translated into a net loss of over 76.8% of CO2-e. There was a significant effect of LULC change on the depth distribution of soil carbon stocks in KNP. Highest soil carbon stocks (19.0±0.86 Mg C ha-1) were observed under maize whereas the smallest (16.4±1.54 Mg C ha-1) were under ITHF. However, about 70% of the soil carbon stocks under the forest covers (11.2 Mg C ha-1) were accumulated deeper than 0–0.15 m compared with only about 47% (about 8.9 Mg C ha-1) under maize. The 2.3 Mg C ha-1 in the 0.15–0.6 m layer of soil under ITHF and restored forest in excess of what we observed under maize, highlights the importance of the forests in sequestering carbon in the area and potentially in related ecosystems elsewhere in Uganda. Our synthesis indicates that change in LULC or shift away from native LULC type leads to a net loss of CO2-e. Therefore, conservation of such PAs in Uganda is not an option but mandatory for climate change mitigation.