Anu Valtonen

African elephants ( Loxodonta spp.) are well‐known keystone ecosystem engineers in savannas, rainforests, and riparian forests in Africa; yet their role in tropical rainforests during the restoration and recovery process remains poorly understood. In this study, we assess their role in actively restored Afrotropical forests using two indicators: (a) the count of dung piles; and (b) the count of trees knocked down by elephants. Our research was conducted in restored forest compartments aged 4–26 years and in the adjacent primary forest of Kibale National Park, Uganda. We observed more dung piles and knocked down trees in younger restored forests (4–10 years old) compared to restored forests aged 13–26 years and primary forest. In the younger restored forest, the estimated median count of trees felled by elephants was 12.5 trees per hectare, and the estimated median dung pile count was 50 piles per hectare. Based on our results, elephants can have an important role as ecosystem engineers in restored tropical forests by providing dung, altering forest structure and potentially influencing successional pathways. However, elephants' ability to fell trees (at their population density in 2021) did not prevent forest recovery after active restoration in this study.

Forest restoration is an essential tool for conserving biodiversity in tropical regions; yet, restoration outcomes in the Afrotropics remain largely understudied. Here, we investigated how the forest structure, tree diversity, community, life‐history traits and habitat associations recovered over three decades of active restoration in an East African rainforest in Uganda. The vegetation surveys were initially conducted in 2013 and repeated in 2021. Altogether, the study included 45 actively restored forest sites (aged 4–26 years) and 10 primary forest reference sites. The results showed increased tree taxa richness, basal area, tree height and community similarity (i.e., the similarity of community composition of restored forests to the composition of primary forest) along the age gradient. After 20 years of planting, Simpson's diversity and canopy cover reached similar values recorded in the reference primary forest. In contrast, restored forests had not attained levels of tree taxa richness, basal area, stem density, or community similarity comparable to those of the reference primary forest within three decades. We found an age gradient from younger restored to older restored to the primary forest in the composition of tree communities. The proportion of species with animal‐dispersed seeds was similar in the restored and the primary forest. The proportion of shade‐tolerant and forest‐interior species had increased along the age gradient in the 2021 survey. In conclusion, forest structure, diversity and community showed early signs of recovery, but the rate of change slowed over time.

The degree to which individuals within populations vary in whether, how far and what direction they disperse is central in order to understand many foundational questions in ecological entomology, including factors determining population and invasion dynamics, species' ability to respond to climate change or when designing conservation strategies for threatened species. This study combined stable hydrogen isotope analysis of nymphal and adult wing chitin with population genetic analysis of the cytochrome c oxidase subunit I (COI) gene to understand long‐distance movements of African edible bush cricket ( Ruspolia differens ) in East Africa. Results revealed that at most 77% of non‐swarming adults and 85% swarming adults originated locally, that is, within a range of a few hundred kilometres. In contrast, non‐local adults captured in Uganda likely originated from Ethiopia, Kenya or South Sudan based on the H isotopic evidence. Genetic analysis revealed 150 COI haplotypes with no significant differentiation among geographic source regions and no evidence of genetic isolation by movement distance. The observed frequent long‐distance movements, together with the historical records, which indicate that the swarm movements can be irregular in their direction, suggest that the movements represent nomadism rather than regular long‐distance migration. Our results thus provide a valuable case study of what characterizes nomadic movements in insects, which have been one of the outstanding open questions in movement ecology of animals.

Restoration of forests is now considered an essential tool to combat climate change and the global biodiversity decline. However, our understanding of how animal communities recover after restoration interventions in tropical forests is limited. Here, we aim to reveal the recovery patterns of fruit‐feeding butterfly communities across a large‐scale rainforest restoration area in Kibale National Park, Uganda. Our study represents a chronosequence resampling of fruit‐feeding butterfly communities across actively restored Afrotropical forest planted between 1995 and 2011 and primary forest reference sites. Sampling of 40 study sites was done first in the period 2011–2012 and again in the period 2020–2021 (including 5 new study sites), allowing a direct comparison of how communities have changed in nine years and to follow the progress of 26 years of active restoration. Fruit‐feeding butterfly community composition showed a directional pattern from the younger restored to older restored and primary forests. However, over the nine years, the similarity of community composition to primary forest increased only in younger restored forests. Furthermore, different characteristics of community structure and different diversity facets recovered at different paces. For example, the count of individuals, the count of species, and phylogenetic diversity increased in the restored forests; however, Simpson's diversity increased only in the older restored forest. Our study shows that active restoration can help fruit‐feeding butterfly communities become increasingly similar to communities found in primary forests, and such changes can be relatively fast in the early‐successional phases of tropical forests but slow down at later phases.

World‐wide declines in arthropod abundance and diversity are a major concern, particularly given their importance in ecosystem functioning. Yet, data documenting long‐term trends are rare from the tropics, particularly the Afrotropics. Here we evaluate changes in the arthropod communities in Kibale National Park, Uganda across almost four decades. Systematic sweep‐net sampling was conducted in two forested sections of the park that had been logged and in one old‐growth forest area over 12 consecutive months in 1983/1984 and 2020/2021. This data was augmented with intermittent samples taken in 1986 and 1995. Arthropod abundance declined in all areas, but only significantly so in the moderately logged forestry compartment (41%). Permutational multivariate analysis of variance indicated that community compositions of arthropods differed between the censuses. Understanding the drivers of changes in the arthropod communities is difficult as the system is complex and dynamic. We document an increase in temperature, but no change in rainfall, increases in 11 mammal species, including a marked increase in elephant numbers, and changes in forest structure. We also report on changes in the landscape outside of the park, which includes the human population increasing by a factor of four and agricultural intensification that now includes the use of pesticides. We document that many components of the ecosystem we studied changed simultaneously, which signals that for effective conservation planning, more long‐term multi‐disciplinary efforts are needed.

Restoration has now emerged as a global priority, with international initiatives such as the “UN Decade on Ecosystem Restoration (2021–2030)”. To fulfill the large‐scale global restoration ambitions, an essential step is the monitoring of vegetation recovery after restoration interventions. This study aimed to evaluate the utility of remotely sensed vegetation indices, using the 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 the 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.

Aim: It is generally assumed that the degree of resource specialization in herbivorous insects increases towards lower latitudes. However, latitudinal patterns in herbivore diet breadth at large spatial scales remain poorly understood. In this work, we investigated the drivers of latitudinal variation in lepidopteran ‘fundamental’ resource specialization, which we defined as the host breadth when not limited by interspecific interactions at the same trophic level.Location: The Japanese archipelago (22°N–45°N), including hemiboreal, temperate and subtropical zones.Taxon: Herbivorous butterflies.Methods: Species‐specific fundamental host breadth was calculated based on pooled host‐use records. We investigated the latitudinal pattern and significant drivers of the degree of specialization in regional species pools at a 10‐km grid level. As potential drivers, we focused on geography, current climate and diversity and body size of butterflies. Through Bayesian structural equation modelling, we investigated the complicated relationships between these variables and community‐level resource specialization represented by three different indices of host breadth.Results: We found that the fundamental resource specialization of butterfly communities increases towards higher latitudes. This pattern is contrary to the presumed general trend found in studies based on realized resource specialization within local communities. We found that the observed pattern is driven mainly by factors related to climate, butterfly diversity and body size in each community. Above all, annual mean temperature most strongly drove community‐level fundamental host breadth of herbivorous butterflies.Main conclusions: Our findings suggest that the fundamental resource specialization may show different latitudinal patterns from the conventional prediction based on knowledge of realized resource specialization. Our results emphasize the importance of the current climate as a major factor regulating butterfly morphology and fundamental host breadth, regardless of whether the impact is direct or indirect.

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 rate of forest regeneration across a tropical forest restoration project area in Kibale National Park, Uganda. As a result, we observed non-linear patterns in NDVI and EVI across the first 25 years of recovery. Both NDVI and EVI increase 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, which suppresses the natural regeneration of trees in our area, 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.

The African edible bush‐cricket, Ruspolia differens (Serville) (Orthoptera: Tettigoniidae), is an economically valuable insect in sub‐Saharan Africa. For its mass‐rearing, suitable diets that can sustain its performance need to be identified. This study aimed at finding inflorescence diets of 10 host plant species and their mixtures that result in the highest R. differens production. We reared newly hatched nymphs to adults on inflorescences of single host species, and also on a gradient of five diversifying dietary mixtures consisting of one and mixtures of two, three, five, and seven host plant species. For the single host‐plant diets, the developmental time was shortest on Pennisetum purpureum, Chloris gayana, and Brachiaria ruziziensis (approximately 63 days), whereas the fresh weight was highest on B. ruziziensis and P. purpureum (approximately 0.383 g). Survival was highest (>65%) on C. gayana, P. purpureum, B. ruziziensis, Setaria sphacelata, and Sporobolus pyramidalis, and lowest on Panicum maximum, Hyparrhenia rufa, Cynodon dactylon, and Paspalum scrobiculatum (P. purpureum, C. gayana, B. ruziziensis, and S. sphacelata, and on dietary mixtures of inflorescences. These findings are important in designing large‐scale rearing programs for this species.

The use of food industry by‐products in insect feeds has gained increasing attention recently. However, the understanding of how well the economically valuable edible insect Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) can grow and develop with plant‐based by‐product feeds is currently lacking. It is important to determine the nutritional requirements, especially protein demand, of this species before developing artificial feeds for mass‐rearing. We reared R. differens with four control diets and 12 plant‐based by‐product diets in which the major protein source came from food industry by‐products, including potato‐protein, barley mash, barley feed, turnip rape, a mix of broad bean and pea, and a mix of potato, carrot, and apple. We asked whether the performance (development time, survival, and weight), feed conversion, and fatty acid composition and content differed among diet treatments. Furthermore, the 12 experimental by‐product diets were designed to reach six protein levels. We found that R. differens can be reared with various by‐product diets, but development time, survival, and weight differed among diets. Barley feed, barley mash, and potato protein diets seem to be good options for rearing, and potato glycoalkaloids do not affect the performance of R. differens. Individuals fed on the various by‐product diets also differed in their fatty acid composition and content. Increasing protein levels in diet up to 17% enhanced growth, development time, and survival, but no further enhancements were seen when fed diets with protein levels higher than this. The high protein levels decreased feed conversion rate. Our results can be valuable for designing feeds for insect mass‐rearing technology. The use of food industry by‐products in the diets for R. differens could increase the re‐use of local resources and enhance circular economy.