Landscape‐scale native woodland habitat restoration using natural tree regeneration provides a biodiversity boost for moths in the uplands

Abstract. Livestock grazing is the most important direct management impact on grasslands in upland areas of the UK. For phytophagous species, such as Lepidoptera, the impact is primarily through grazing altering the species composition and structure of the vegetation. However, specific impacts related to different grazing regimes are not well understood for this group of insects. Within a replicated controlled grazing experiment, nocturnal adult moths were sampled by light trapping in the fifth year after establishment. Sampling effort was standardised between the four grazing treatments by simultaneously using identical traps in each treatment. The highest‐intensity grazing treatment produced the lowest moth abundance and species richness. Ungrazed and low‐intensity sheep grazing treatments produced the highest moth abundance and species richness. Moths that feed exclusively on graminoids and moths that overwinter as larvae were disproportionately well represented in the ungrazed treatment. A sub‐set of species for which large declines have recently been documented in the UK were most abundant in the ungrazed treatment. However, they made up the largest proportion of the overall assemblage in the high‐intensity grazing treatment. Increased grazing inversely affects moth abundance and species richness. However, effects are not even across all moth species. An absence of grazing is likely to negatively affect the abundance of some moths, especially those that overwinter in the egg stage.

Habitat loss is commonly identified as a major threat to the loss of global biodiversity. In this study, we expand on our previous work by addressing the question of how lepidopteran species richness and composition vary among remnants of North American eastern deciduous forest located within agricultural or pastoral landscapes. Specifically, we tested the relative roles of habitat quantity (measured as stand area and percent forest in the greater landscape) and habitat quality (measured as tree species diversity) as determinants of moth species richness. We sampled >19 000 individuals comprising 493 moth species from 21 forest sites in two forested ecoregions. In the unglaciated Western Allegheny Plateau, the species richness of moths with woody host plants diminished as forest stand size and percent forest in the landscape decreased, but the total species richness and abundance of moths were unaffected by stand size, percent forest in the landscape, or tree species diversity. In contrast, the overall species richness and abundance of moths in the glaciated North Central Tillplain were affected primarily by tree species diversity and secondarily by forest size. Higher tree species diversity may reduce species loss from smaller forest stands, suggesting that small, diverse forests can support comparable numbers of species to those in less diverse, large stands. Smaller forests, however, contained a disproportionate number of moth species that possess larvae known to feed on herbaceous vegetation. Thus, although woody plant feeding moths are lost from forests with changes in stand area, new species appear capable of recolonizing smaller fragments from the surrounding habitat matrix. Our study further suggests that when species replacement occurs, local patch size and habitat quality may be more important than landscape context in determining the community structure of forest Lepidoptera.

Large carnivores, including the grey wolf (Canis lupus), play an important role in the carbon cycle through modifying the behaviour and population of wild herbivores. Large carnivores have been eradicated from much of their former range and are now absent from the UK, contributing to increased herbivore populations, which can prevent natural regeneration of trees and woodland. A reintroduction of wolves to the UK could reduce deer populations and associated browsing of tree saplings, but the potential impacts on woodland expansion and carbon sequestration have not been assessed. Here we estimate the impact of a wolf reintroduction in the Scottish Highlands on red deer populations, native woodland colonisation and carbon sequestration. We use a Markov predator–prey model to estimate that a reintroduction would lead to a population of 167 ± 23 wolves, sufficient to reduce red deer populations below 4 deer km−2, the threshold at which we assume browsing to be sufficiently suppressed to enable natural colonisation of trees. Using a model of potential new native woodlands we estimate the subsequent expansion of native woodland would result in an average annual carbon sequestration of 1.0 ± 0.1 Mt CO2, with each wolf contributing an annual carbon sequestration of 6080 t CO2. Practical Implication. Our analysis demonstrates the ecosystem benefit that wolves can provide through control of red deer numbers, leading to native woodland expansion. Large‐scale expansion of woodlands, facilitated through the return of wolves, can contribute to national climate targets and could provide potential economic benefits to landowners and communities through carbon finance.

The establishment of planted trees and the natural regeneration of trees in agroecosystems is challenging. This study evaluated the establishment and natural regeneration of the following six native tree species in two agricultural systems in the Atlantic Forest in Paraguay: Cedrela fissilis Vell., Cordia trichotoma (Vell) Arráb. ex Steud., Handroanthus albus (Cham.) Mattos, Handroanthus impetiginosus (Mart. ex DC.) Mattos, Peltophorum dubium (Sprengel) Taubert, and Cordia americana (L.) Gottschling and J.S.Mill. At the study site in Caaguazú, 18 plots of 100 m2 each were established in 2 agronomic systems (conventional or agroecological) featuring 3 plantation types (pathsides, agricultural field edges, and islets). Trees were planted at this site in spring 2010 at a density of 1800 individuals ha−1, and the site was monitored for six years. At the study site in Itapúa, 30 plots of 50 m2 each were established in three agronomic systems (conventional, traditional, or agroecological). Trees were planted at this site in spring 2012 at a density of 1600 individuals ha−1, and the site was monitored for four years. Survival and relative growth rates of the planted species and natural regeneration were analyzed using generalized linear mixed models that considered species, agronomic system, and plantation type as fixed factors, and time and plot as random factors. At both sites, survival varied among species. Here, C. fissilis showed lower survival and C. trichotoma higher growth than the other species. Naturally regenerated species were C. trichotoma, H. albus, and P. dubium. The agronomic system and species affected growth and natural regeneration at both locations. Plantation type affected survival and growth in Caaguazú only. We conclude that species contributes more than agronomic system or plantation type to determining the survival, relative growth rate, and natural regeneration in agroforestry systems in the Paraguayan Atlantic Forest.

Moths (Insecta: Lepidoptera) of Sri Lanka have not been well studied despite the country being a global biodiversity hotspot. It is known that the moth communities are declining worldwide due to threats such as loss and fragmentation of habitats, urbanisation, light pollution, invasive species, and climate change. Thus, tropical moth assemblages that contribute towards ecosystem functions including pollination should be studied and conserved. The present study was carried out in Indikadamukalana Forest Reserve (IMFR) and in Wattala, an urban habitat, both in Western Province to investigate the moth species diversity, richness, relative abundance and habitat parameters that can affect moth assemblages. Moth diversity was investigated over a 7-month period from February to October 2018. Transect line count method was used to sample diurnal moths and light traps with white reflective sheets were used to study nocturnal moths. Aerial nets and fruit baited traps were also used. A total of 160 species belonging to 20 families which represent 8.37% of the 1,911 moth species recorded from Sri Lanka were recorded from both habitats with IMFR recording 138 species belonging to 19 families and urban habitat recording 26 species belonging to 12 families. The species richness and abundance of moths were highest at IMFR. Least species richness and abundance of moths were recorded from the urban habitat. Family Crambidae was the most specious and dominant group throughout the study period followed by family Erebidae which could be due to habitat strata occupied by the moth groups whereas Families Pterophoridae and Tortricidae were recorded with the least number of individuals at IMFR and urban habitats respectively. At IMFR highest abundance of moths were recorded in May while in the urban habitat it was August. The climate parameters between the two habitats did not depict a significant difference but relative humidity was observed to have the highest impact on the changes in abundance of moths with ambient temperature having the least. This study has provided a baseline for future studies into moths of lowland wet zone forests and has highlighted the importance of natural forests in the maintenance of moths in the country. The diversity observed between the habitats were mainly due to anthropogenic activities and could be most probably due to the presence of host plants, evolutionary adaptations and weather parameters. The study recommends, establishing a scientific database on moth diversity, host plants and other factors of the moth life cycle. Keywords: Moths, Wet zone, Sri Lanka

Restoring native woodlands to areas where they have been lost is a key element for tackling the nature and climate crises. Natural regeneration offers the potential to achieve this cheaply and at scale, but browsing ungulates like deer can inhibit this or alter the pattern of regeneration. This issue is particularly pronounced in the Scottish Highlands, a heavily deforested region with high deer numbers. We describe the work of the 60,000 ha landscape restoration partnership, Cairngorms Connect, in speeding up natural woodland expansion. We use 30 years of regeneration monitoring to show a consistent, large‐scale expansion of native woodland, largely through natural regeneration alongside deer culling, without the use of fences. This was achieved across the partnership, despite differing management histories and land‐managing organisations (comprising two statutory agencies, one private landowner and one non‐governmental organisation). During peak periods of woodland expansion, the area of new woodland (i.e. exceeding 100 trees per hectare) increased by 1.2%, 1.7%, 2.7% and 6.0% annually in the four landholdings' regeneration zones, equating to a total of approximately 164 ha annually of new woodland. Natural regeneration is however patchy and hard to predict. Higher levels of management intervention may be needed to increase species that are rarer, more palatable or further from seed sources; we recommend long‐term field trials to inform this, such as those underway in Cairngorms Connect. Further research should develop techniques for remote sensing of woodland expansion, verified against field data and combined with the development of process‐based models to enable us to predict the outcomes of different management scenarios. Synthesis and applications. We show that collaborative deer management across multiple adjoining landholdings can achieve rapid landscape‐scale native woodland expansion with minimal need for planting or fencing. Our results show the power of monitoring regeneration directly, to inform deer management for an area. We demonstrate that by uniting over a shared vision, organisations with differing management approaches and histories can build understanding alongside landscape‐scale ecological restoration.

The diversity and community composition of moths (both macro- and micromoths) at 32 sites, representing a wide range of habitat types (forests, grasslands, wetlands, agricultural and urban areas) within a restricted region in central Scania, southern-most Sweden, was investigated by use of light moth traps and compared with vascular plant species richness and habitat characteristics. The results revealed a highly significant general association between vegetation composition and the composition of the moth community and multivariate (CCA) analyses indicated light availability and soil fertility parameters (pH and macronutrients) to be the habitat characteristics that best correlated with moth community composition. Less strong, but still significant, positive relationships between moth abundance and local vascular plant diversity were also revealed. Moth species richness was positively correlated with diversity of woody plant genera in the neighborhood, but not with local vascular plant diversity in general. As for more general site characteristics, there were tendencies for higher moth richness and abundance at sites with more productive soils (well-drained, high pH, high nutrient availability), while shading/tree canopy cover, management, soil disturbance regimes and nectar production appeared unrelated to moth community parameters. It is concluded that local moth assemblages are strongly influenced by site characteristics and vegetation composition.Implications for insect conservation:The results show that obtaining moth data on a local scale is useful for conservation planning and does not need to be very cumbersome. Local moth assemblages monitored are indeed related to local site characteristics of conservation relevance.

Invasive trees negatively impact forests, by making the vegetation more homogeneous when invaders are present than when they are absent. Here, we aim to more deeply understand the effects of invasive trees on forests with a focus on seedlings and saplings and how they respond to continuous variation in aboveground biomass of invaders rather than presence/absence. Our findings are useful for close-to-nature silviculture, as they elucidate how much natural regeneration will change under particular biomasses of invasive species. Specifically, we evaluate the relationships of two invasive tree species: black cherry Prunus serotina Ehrh. and black locust Robinia pseudoacacia L. with natural tree regeneration in temperate forests. We established 160 circular 0.05 ha plots in western Poland managed forests, in two different habitat types: nutrient-poor with Pinus sylvestris L. and nutrient-rich with Quercus spp. We assessed natural regeneration by counting all trees < 1.3 m in height, within four circular subplots (r = 3 m). Relationships between invader biomass and regeneration of other tree species were idiosyncratic. Natural regeneration of dominant forest-forming tree species (P. sylvestris, Quercus petraea) decreased with increasing invader biomass, while shade-tolerant, nitrophilous tree and shrub regeneration increased with invader biomass. The most negatively correlated were P. sylvestris in nutrient-poor habitats and Q. petraea in both nutrient-poor and rich habitats. We observed increased density of other non-native species as R. pseudoacacia abundance increased, in line with the invasional meltdown hypothesis.

The largest land use change in Europe is woodland expansion, through planting and natural regeneration. Unforeseen consequences of this could include changes in environmental hazards, such as exposure to parasites and pathogens. Tick‐borne Lyme disease is the most prevalent tick‐borne disease in the northern hemisphere and is often associated with woodlands. Therefore, to inform the planning and management of expanding woodlands, we test how land covers that reflect different types and stages of the woodland expansion process, along with their deer management, impact tick densities and Lyme disease hazard (density of infected nymphs). We also test whether differences in rodent abundance play a mechanistic role in explaining differences in Lyme disease hazard. In Northwest Scotland, a touristic area undergoing woodland expansion, we recorded deer management, rodent densities, Ixodes ricinus nymph densities, pathogen prevalence and Lyme disease hazard between open moorland, young pine and mature pine, and birch and spruce. These represent pre‐, early and late stage woodland establishments, and the three woodland types in the region. Rodents, ticks, pathogen prevalence and Lyme disease hazard were generally lowest in moorland and young pine and highest in mature woodland, especially birch, although variability was high. Deer management reduced tick densities and, marginally, Lyme disease hazard. There was insufficient evidence for rodents increasing Lyme disease hazard, but rodents augmented tick densities and the most abundant Lyme disease pathogen was that transmitted by rodents. Practical implication. woodland expansion could, once mature, eventually lead to higher tick densities, pathogen prevalence and Lyme disease hazard. Importantly, an environmental solution could be to control deer populations.

Simple SummaryBiodiversity loss is one of the biggest challenges faced by humankind. Alarming reports on the rapid decline of insect populations call for the exploration of potential drivers of this process. Here, we test the hypothesis that decreases in the abundance and diversity of insects can be caused by industrial pollution. We found that the diversity of moths and butterflies declined in the severely degraded habitats (termed industrial barrens) adjacent to two metallurgical enterprises located in a polar region, but did not respond to moderate levels of sulphur dioxide and heavy metal pollution. Surprisingly, the overall abundance of these insects was not affected even by the extreme pollution loads. This pattern resulted from idiosyncratic responses of moth and butterfly species to pollution, which vary from significantly negative to significantly positive. The patterns in diversity and abundance do not differ between the areas affected by the two studied enterprises, and they are consistent with patterns previously found near another non-ferrous smelter. We conclude that arctic communities of moths and butterflies are unexpectedly tolerant to industrial pollution.Alarming reports on the rapid decline of insects during the past decades call for the exploration of potential drivers of this process. Here, we test the hypothesis that the overall abundance and diversity of moths and butterflies (Lepidoptera) decrease under the impact of industrial pollution in the fragile arctic environment. For this purpose, experienced collectors netted adult Lepidoptera at five tundra sites located 0.5 to 45.3 km from the ore-roasting plant in Zapolyarnyy and at five forest sites located 1.4 to 37.8 km from the copper–nickel smelter at Nikel, in the Murmansk region of Russia. The analysis of the 100 samples collected from 2003 to 2008 and containing 2312 individuals of 122 species revealed that the diversity of Lepidoptera declined significantly near both of these polluters due to both decreases in species richness and changes in the abundance of individual species, whereas the overall abundance of moths and butterflies was independent of the pollution load. These patterns did not differ between Nikel and Zapolyarnyy, and they were consistent with patterns previously found near the copper–nickel smelter at Monchegorsk. The abundances of Lepidoptera species showed variable changes along pollution gradients, from significantly negative to significantly positive, but individual species showed similar density changes around these three polluters. Disproportional increases in the abundance of a few pollution-tolerant species change the community structure and explain why the overall abundance of moths and butterflies does not decline even in localities experiencing extreme loads of sulphur dioxide and heavy metals.

The abundance and species richness of moths were evaluated at 16 sites in southern South Korea to assess moth diversity and to identify indicator species for different forest types in this area. In total, 975 moth species were identified in the seven 6-mo collection periods (May–October) between 2001 and 2007. A matrix of 536 species and 36 sampling units was adopted for clustering sampling sites, and indicator species were determined after removing species with fewer than five individuals (370 species), and species that were found at fewer than three sites (36 species). Five different forest groups were identified based on clustering analysis: 1) seashore secondary forest, 2) evergreen deciduous forest, 3) inland young secondary forest, 4) inland mixed deciduous forest, and 5) inland high elevation conifer and deciduous forest. Patterns of moth abundance and species richness within four of the five groups were similar, but the abundance and species richness in the high elevation sites were significantly lower than in the other four groups. Sixty-three species were recognized in the five different forests based on indicator species analysis and the adoption of 63 indicator species in nonmetric multidimensional scaling ordination corroborated the grouping of sites into five groups. Many indicator species were woody plant feeders. In the current study, we determined the general pattern of moth diversity in different forest types in southern South Korea and identified indicator moth species that can be used to track future changes in forest structure as the forests age.

Moths respond to key habitat structures in conifer plantations managed as irregular high forest

Urban expansion threatens global biodiversity through the destruction of natural and semi-natural habitats and increased levels of disturbance. Whilst woodlands in urban areas may reduce the impact of urbanisation on biodiversity, they are often subject to under or over-management and consist of small, fragmented patches which may be isolated. Effective management strategies for urban woodland require an understanding of the ecology and habitat requirements of all relevant taxa. Yet, little is known of how invertebrate, and in particular moth, assemblages utilise urban woodland despite being commonly found within the urban landscape. Here we show that the abundance, species richness, and species diversity of moth assemblages found within urban woodlands are determined by woodland vegetation character, patch configuration and the surrounding landscape. In general, mature broadleaved woodlands supported the highest abundance and diversity of moths. Large compact woodlands with proportionally less edge exposed to the surrounding matrix were associated with higher moth abundance than small complex woodlands. Woodland vegetation characteristics were more important than the surrounding landscape, suggesting that management at a local scale to ensure provision of good quality habitat may be relatively more important for moth populations than improving habitat connectivity across the urban matrix. Our results show that the planting of broadleaved woodlands, retaining mature trees and minimising woodland fragmentation will be beneficial for moth assemblages. © 2014 Springer Science+Business Media Dordrecht.

Natural tree regeneration in agricultural landscapes: The implications of intensification

One of the leading concerns for both conservation biology and forestry has been how forest fragmentation affects biodiversity, and how forestry practices can be altered to mitigate diversity losses. However, the effects of habitat fragmentation on ecological functional groups within diverse taxa such as Lepidoptera are poorly known, particularly in boreal forests. We assessed landscape-level changes in moth species richness and abundance in relation to forest fragmentation, measured at multiple scales. We assessed fragmentation effects on three functional groups: tree- and shrub-feeding species, grass- and forb-feeding species, and species that act as hosts for parasitoids of an important forest defoliator, Malacosoma disstria Hubner (Lepidoptera: Lasiocampidae). Total species richness showed a significant decline as a function of fragmentation at all measured spatial scales; both polynomial and threshold models tended to explain more variation than linear models, suggesting that there is little to no change in overall moth diversity between low and moderately fragmented stands. However, changes in diversity patterns within functional groups showed that total diversity measures may mask changes in community structure. Changes in overall diversity were driven largely by a decrease in species richness of tree- and shrub-feeding moths, although forb- and grass-feeding moths also showed marginally lower species richness at high fragmentation levels. Most species of the parasitoid host group decreased in abundance with increasing fragmentation. These findings show that overall diversity measures can mask important community changes, and that the optimal landscape scale at which these changes are measured is taxon dependent. Finally, the decrease in host availability to M. disstria parasitoids in fragmented forests may exacerbate population outbreaks of M. disstria.