Browsing by Author "Holm, Sille"

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    Recovery of fruit-feeding butterfly communities in Budongo Forest Reserve after anthropogenic disturbance
    (Forest Ecology and Management, 2021) Oloya, Joseph; Malinga, Geoffrey M.; Nyafwono, Margaret; Akite, Perpetra; Nakadai, Ryosuke; Holm, Sille; Valtonen, Anu
    Understanding of how biodiversity can recover after anthropogenic disturbances, such as selective logging, is important for planning conservation strategies for tropical forests and for more sustainable timber harvest regimes. However, the knowledge of insect community compositions in regenerating logged forests is still limited, especially in the Afrotropics. Here, we evaluated the recovery patterns of fruit-feeding butterfly communities in four different-aged secondary forest compartments and one primary forest compartment in the Budongo Central Forest Reserve, Uganda. In each compartment, butterflies were sampled monthly for five consecutive months in 2017 using traps baited with fermented bananas. A total of 3,778 individuals, representing 82 species (78 identified at the species level and four morphogroups) were recorded. The fruit-feeding butterfly community composition differed among forest compartments and study months. Fruit-feeding butterfly communities of the oldest 72-year-old secondary forest compartment were similar to the primary forest compartment. In the younger secondary forest compartments the seasonal variation was large; especially the communities of the “core” rainy season months were distinct from the communities in primary and oldest secondary forest. The majority of individuals captured from both primary and secondary forests represented forest-dependent species. Primary forests are irreplaceable for preserving the diversity of tropical forests in the long-term. Nevertheless, our study demonstrates that selective logging can allow fruit-feeding butterfly community composition to recover if enough time (>70 years) is allowed for recovery.
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    Remotely-sensed vegetation greening along a restoration gradient of a tropical forest, Kibale National Park, Uganda
    (Land Degradation & Development, 2021) Valtonen, Anu; Korkiatupa, Eveliina; Holm, Sille; Malinga, Geoffrey M.; Nakadai, Ryosuke
    Restoration has now emerged as a global priority, with international initiatives such as the “UN Decade on Ecosystem Restoration (2021-2030)”. To fulfil the large-scale global restoration ambitions, an essential step is the monitoring of vegetation recovery after restoration interventions. The aim of this study was to evaluate the utility of remotely-sensed vegetation indices, Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI), to monitor the progress of forest regeneration across a tropical forest restoration project area in Kibale National Park, Uganda. Using the chronosequence approach, results indicated non-linear patterns in NDVI and EVI across the first 25 years of recovery. Both NDVI and EVI increased for the first 10 years of forest regeneration. This “greening” phase could be used as the indicator of successful onset of forest recovery. In particular, the decline of elephant grass, and the consequent arrival of shrubs and trees, can be detected as an increase in NDVI. Primary forests differed from the 25-year-old regenerating forests based on the unique combination of low mean and low seasonal variation in EVI. Our results, therefore, suggest that the long-term success of forest restoration could be monitored by evaluating how closely the combination of mean, and degree of seasonal variation in EVI, resembles that observed in the primary forest.