Agriculture and biodiversity: the place of invertebrates

Editorial: Green or red: Challenges for fish and freshwater biodiversity conservation related to hydropower

Summary Agriculture represents the dominant land use throughout much of western Europe, and a significant part of European biodiversity is associated with this habitat. We attempted to quantify the changes in agriculture and biodiversity in Britain since the 1940s. There have been widespread declines in the populations of many groups of organisms associated with farmland in Britain and north‐west Europe. The declines have been particularly marked amongst habitat specialists; many of the taxa still common on farmland are habitat generalists. Farming practices have become increasingly intensive in the post‐war period, with a dramatic reduction in landscape diversity. Since 1945, there has been a 65% decline in the number of farms, a 77% decline in farm labour and an almost fourfold increase in yield. Farms have become more specialized; the greatly increased use of machinery has made operations quicker and more efficient, but has resulted in the removal of 50% of the hedgerow stock. Autumn sowing of crops has become predominant, with winter stubbles now far less prevalent. The number and extent of chemical applications has increased greatly, but the net amount applied, and their persistence, has decreased in recent years. Intensification has had a wide range of impacts on biodiversity, but data for many taxa are too scarce to permit a detailed assessment of the factors involved. Reduction in habitat diversity was important in the 1950s and 1960s; reduction in habitat quality is probably more important now. As a case study, the declines in populations of seed‐eating birds populations were assessed in relation to changing agricultural management. Generally, the declines were likely to be caused by a reduced food supply in the non‐breeding season, although other factors may be important for particular species. Agriculture will face a number of challenges in the medium term. While research into the mechanisms underlying species and habitat associations, and their interaction with scale, will be critical in under‐pinning management, consideration of farmer attitudes and socio‐economic factors is likely to be as important. Biodiversity may benefit from integrated farming techniques but these need to incorporate environmental objectives explicitly, rather than as a fringe benefit.

SUMMARY 1. Hypoxia occurs seasonally in many stratified coastal marine and freshwater ecosystems when bottom dissolved oxygen (DO) concentrations are depleted below 2–3 mg O2 L )1 . 2. We evaluated the effects of hypoxia on fish habitat quality in the central basin of Lake Erie from 1987 to 2005, using bioenergetic growth rate potential (GRP) as a proxy for habitat quality. We compared the effect of hypoxia on habitat quality of (i) rainbow smelt, Osmerus mordax mordax Mitchill (young-of-year, YOY, and adult), a cold-water planktivore, (ii) emerald shiner, Notropis atherinoides Rafinesque (adult), a warm-water planktivore, (iii) yellow perch, Perca flavescens Mitchill (YOY and adult), a cool-water benthopelagic omnivore and (iv) round goby Neogobius melanostomus Pallas (adult) a eurythermal benthivore. Annual thermal and DO profiles were generated from 1D thermal and DO hydrodynamics models developed for Lake Erie’s central basin. 3. Hypoxia occurred annually, typically from mid-July to mid-October, which spatially and temporally overlaps with otherwise high benthic habitat quality. Hypoxia reduced the habitat quality across fish species and life stages, but the magnitude of the reduction varied both among and within species because of the differences in tolerance to low DO levels and warm-water temperatures. 4. Across years, trends in habitat quality mirrored trends in phosphorus concentration and water column oxygen demand in central Lake Erie. The per cent reduction in habitat quality owing to hypoxia was greatest for adult rainbow smelt and round goby (mean: )35%), followed by adult emerald shiner (mean: )12%), YOY rainbow smelt (mean: )10%) and YOY and adult yellow perch (mean: )8.5%). 5. Our results highlight the importance of differential spatiotemporally interactive effects of DO and temperature on relative fish habitat quality and quantity. These effects have the potential to influence the performance of individual fish species as well as population dynamics, trophic interactions and fish community structure.

Moths are the most taxonomically and ecologically diverse insect taxon for which there exist considerable time-series abundance data. There is an alarming record of decreases in moth abundance and diversity from across Europe, with rates varying markedly among and within regions. Recent reports from Costa Rica reveal steep cross-lineage declines of caterpillars, while other sites (Ecuador and Arizona, reported here) show no or only modest long-term decreases over the past two decades. Rates of decline for dietary and ecological specialists are steeper than those for ecologically generalized taxa. Additional traits commonly associated with elevated risks include large wingspans, small geographic ranges, low dispersal ability, and univoltinism; taxa associated with grasslands, aridlands, and nutrient-poor habitats also appear to be at higher risk. In temperate areas, many moth taxa limited historically by abiotic factors are increasing in abundance and range. We regard the most important continental-scale stressors to include reductions in habitat quality and quantity resulting from land-use change and climate change and, to a lesser extent, atmospheric nitrification and introduced species. Site-specific stressors include pesticide use and light pollution. Our assessment of global macrolepidopteran population trends includes numerous cases of both region-wide and local losses and studies that report no declines. Spatial variation of reported losses suggests that multiple stressors are in play. With the exception of recent reports from Costa Rica, the most severe examples of moth declines are from Northern Hemisphere regions of high human-population density and intensive agriculture.

Continuous increases in the use of synthetic fertilisers and pesticides in agro-ecosystems have led to an increase in crop production, but also to a simplification of landscape and a decline in biodiversity at the field, cropping system level. Changes at landscape level, such as regional farm specialisation, increases in field size and the removal of hedgerows and woodlots suppression, have strengthened this tendency towards decline. The loss of biodiversity in agro-ecosystems has increased the need for external inputs, as important functions are no longer provided by beneficial species. This has led to an apparently inevitable reliance on petrochemicals in production systems. However, many scientists are arguing that this reliance on pesticides could be considerably reduced by making better use of biotic interactions. This review explores, in the light of recent studies, possible ways to increase beneficial biotic interactions in agro-ecosystems, and to improve bio control pest management at field and landscape scales. This review also points out the possible integrated cropping system on oilseed rape and concludes on the future research that has to be engaged to achieve the goal of improvement the natural bio-control of pests. For example at field scale, it has been shown that the choice of cultivar, the sowing date and nitrogen fertilisation practices can be manipulated to prevent interactions between pests and crop, in either time or space . We have also highlighted that beneficial biotic interactions may result from appropriate changes to the habitats of beneficial species, mediated by soil management and cover or mixing species utilisation. Finally, changes achieved at landscape scale appear promising. However, these approaches frequently also present drawbacks that may not necessarily be outweighed by the beneficial effects. Endly, we propose the approaches to design integrated crop management systems to reduce the damage of pests. However, major research efforts are required to quantify and to use the effects of management practices and to improve our understanding of the interactions between the different levels.

Vanishing of the common species: Empty habitats and the role of genetic diversity

Land use change profoundly impacts habitat quality, necessitating an understanding of historical and future trends for effective regional planning and ecological protection, particularly in ecologically sensitive areas. This study examines the Taihu Lake Basin (TLB), a region undergoing significant land use changes and exhibiting considerable ecological vulnerability. Utilizing the InVEST model (v3.14.2), we analyzed the dynamics of land use and habitat quality in the TLB from 2000 to 2020. We subsequently employed the PLUS model (v1.40) to predict future land use and habitat quality under various scenarios. Our key findings include the following: (1) From 2000 to 2020, TLB experienced a 97.62% increase in construction land, alongside significant reductions in cultivated land and forestland. (2) Population density, precipitation, DEM, and temperature were identified as the main drivers of land use expansion in TLB. (3) Habitat quality declined by 11.20% over the study period, exhibiting spatial disparities including higher quality in the southwest and central regions and lower quality in the east and north. (4) Scenarios prioritizing urban development led to substantial construction land expansion and reduced habitat quality, whereas scenarios emphasizing ecological protection effectively mitigated habitat fragmentation. This study highlights the critical need to integrate ecological protection into regional planning to balance economic development with environmental sustainability. The findings underscore the importance of prioritizing ecological conservation in land use policies to maintain habitat quality and promote sustainable development in the TLB. These insights are valuable for guiding future land use planning and ecological management in similarly sensitive regions.

Spatially explicit drivers of habitat degradation in coastal megacities based on MGWR-GCCM --evidence from Fuzhou, China.

Se evaluó el riesgo de extinción de la población del berrendo peninsular (Antilocapra americana peninsularis) en la península de Baja California, México que presenta distribución restringida y deterioro en la calidad de su hábitat. En el año 2000, el tamaño de la población silvestre del berrendo peninsular era menor a 250 individuos. Se desarrolló un análisis de viabilidad de poblaciones (PVA) usando Vortex, que incluyó variables determinísticas y estocásticas, e información de 25 años para proyectar cambios en la población, y evaluar su riesgo de extinción. Con el PVA se evaluó el concepto de Reproducción de Apoyo. En 1998 se inició el manejo en cautiverio del berrendo peninsular con 22 animales fundadores. Los modelos sugirieron que una población de menos de 100 individuos incrementa considerablemente el riesgo de extinción, siendo uno de los factores más importantes para la viabilidad de la población la sobrevivencia de las crías. Se propone que el éxito del manejo de la población del berrendo peninsular puede incrementarse estableciendo subpoblaciones dentro de su rango histórico de distribución con una perspectiva metapoblacional donde se conecten las subpoblaciones. Y se concluye que la reproducción en cautiverio puede ser un factor importante para disminuir la probabilidad de extinción de esta subespecie.

Assessment and prediction analyses of the ecological environmental quality of river basins are pivotal to realize ecological protection and high-quality coordinated development. Methods: The PLUS and InVEST models were used to analyze the spatiotemporal evolution characteristics of land-use in the Fen River Basin and simulate the spatial pattern of land-use under natural development (ND), ecological protection (EC), and economic development (ED) scenarios in 2030, as well as evaluate habitat quality (HQ) and its spatiotemporal variation characteristics from 2000 to 2030. From 2000 to 2020, the Fen River Basin consisted primarily of cultivated land, followed by forests, and then unused land. Habitat quality in the Fen River Basin showed a downward trend from 2000 to 2020. Between 2010 and 2020, the rate of decline decreased, and by 2030, the HQ in the EC scenario exhibited improvement compared to 2020. However, there was a reduction in HQ in the natural development and economic development scenarios and there was obvious heterogeneity in spatial distribution, showing the characteristics of “low middle and high edge”. The cultivated land was converted into forests, construction land, and grasslands, and the conversion of construction land and forests to cultivated land dominated the changes in HQ in the Fen River Basin.

Global change is not restricted to climate change, and plant species generally face multiple human-driven disturbances constraining their viability. Most importantly, interactions among these drivers frequently generate nonadditive effects that cannot be predicted based on single-factor studies. Our goal was to assess the joint effects of three global change drivers that are especially relevant in Mediterranean ecosystems, namely, fragmentation, reduced habitat quality, and climate change on Centaurea hyssopifolia, a gypsum specialist plant. We carried out a two-year study (2005-2006) in natural populations of this plant in large (>11 ha) and small (< 1.5 ha) fragments. Within each fragment, we identified areas of contrasting habitat quality as revealed by plant cover and nutrient content, and within each combination of habitat quality and fragment size we performed a rainfall manipulation experiment simulating the most likely future climate scenario for the region. Survival, growth, phenology, and reproductive success of selected plants were monitored. The three drivers profoundly affected responses of Centaurea hyssopifolia in both study years, phenology being mainly affected by changes in habitat quality and reductions in rainfall and reproductive traits being mainly affected by fragmentation. Plants in sites of poor habitat quality and plants in the dry treatment advanced most of their phenophases (flowering and dispersing earlier) and showed reduced growth rate and increased fraction of senescent leaves. Plants growing in small fragments had lower survival, lower number of viable seeds, and a reduced seed set compared to those from large fragments. We found significant synergistic interactions among drivers. For example, the interaction between fragmentation and habitat quality led to lower survival and lower relative growth in plants from small and poor-quality habitat sites. Our results highlight the importance of studies addressing simultaneously all relevant drivers of global change potentially affecting plant performance under natural conditions. In addition, the complex responses of phenology and reproductive traits of C. hyssopifolia emphasize the need for studies integrating traits from vegetative to reproductive and from the organ to the whole-plant level.

Habitat loss, fragmentation, and degradation of habitats are among the most pervasive impacts on species persistence. Mammals may vary in their response to these impacts, both in abundance and in physiological parameters. Herein, we verified how habitat quality influenced the small mammal nutritional status and stress levels among five semi‐deciduous forest remnants in the Brazilian Cerrado. To assess species' physiological responses, we used body condition as an indicator of nutritional status and neutrophil/lymphocyte (N/L) ratio as an indicator of chronic stress in Gracilinanus agilis and Rhipidomys macrurus. We sampled 264 animals belonging to the following species: G. agilis, Didelphis albiventris, Akodon montensis, Oligoryzomys spp., Rattus rattus, R. macrurus, Oecomys cleberi, Hylaeamys megacephalus, and three unidentified rodent species. We found no negative effect of reduced habitat quality on the body condition of G. agilis and R. macrurus, however, the N/L ratios of these species were lower only in high‐quality habitats, demonstrating that this parameter is an accurate indicator of chronic stress. Based on preliminary analysis, we also reported an impoverished fauna, mainly dominated by generalist species, in low‐quality habitats. Thus, we conclude that short‐term reduction in habitat quality leads to increased stress levels, which can in turn lead to future population declines and culminate in biotic homogenization.

While animals may use many habitat types, relatively few are preferred and fewer yet are superior in quality (referring to individual fitness as the measure of quality). Historical reduction in habitat quality for some wildlife species has occurred such that we may now have limited reference to original superior-quality habitats. As time passes, managers may be unaware that superior habitats are slowly disappearing and that the slow but cumulative change is significant to a species at the population level. The perception of superior-quality habitat also changes with each successive generation of managers based on their experiences. This paper raises the concern that retrospective work may often be required to determine past forest habitats and associated animal populations to avoid the risk of falling into a trap of not recognizing ever-declining habitat quality through time and relegating animals to what is in fact much poorer quality habitat than those to which they are actually best adapted. Further, the relationship between relative abundance and habitat quality may often be uncertain owing to maladaptive habitat selection by animals, inappropriate survey timing or interannual population differences. While we have begun to appreciate aspects of habitat selection for many forest species, few data are yet available that relate selected habitats to fitness of individual animals. Hence, while we may have models to predict habitat use, considerable research remains to be done to be able to predict long-term sustainability of species in managed landscapes. Key words: habitat quality, forest management, sustainability, biodiversity

Biodiversity is declining at an unprecedented rate with infrastructure development being one of the leading causes. New infrastructure, such as roads, provides new access and results in increased land clearing and wildlife hunting. A number of large infrastructure projects, including new roads and rail, are being planned in Nepal. We show the application of readily available remotely sensed data and geospatial tools to assess the potential impact of these future developments on habitat quality under three protection-level scenarios. Our findings reveal that there is currently large spatial heterogeneity in habitat quality across the landscape as a result of current anthropogenic threats, and that three areas in particular could have up to 40% reduction in habitat quality as a result of the planned infrastructure. Further research is required to determine more precisely the impact on key species. Strengthening protected areas and buffer zones will contribute to mitigating degradation to some degree, however, large areas of biologically significant areas outside protected areas will be affected without new controls. Our geographic information systems (GIS) based methodology could be used to conduct studies in data poor developing countries, where rapid infrastructure development across ecological sites are ongoing, in order to make society, policy makers, and development planners aware.

The reduction in habitat quality (as shown, in part, by the increase in habitat rarity) is an important challenge when protecting the Yunnan snub-nosed monkey. We used the InVEST model to quantitatively analyze the dynamic changes in the habitat of the Yunnan snub-nosed monkey from 1975 to 2022. The results show that in the study period, the degree of habitat degradation increased, with the degradation range at its widest in the south, and the degradation intensity highest in the north, especially along a center "spine" area in the north. Over the latter part of the study period, the habitat quality of most monkey groups improved, which is conducive to the survival and reproduction of the population. However, the habitat quality and monkey populations are still at significant risk. The results provide the basis for formulating the protection of the Yunnan snub-nosed monkey and provide research cases for the protection of other endangered species.