Habitat Value Research Articles

Time and matrix quality increase the relative habitat value of smaller patches in fragmented landscapes

Abstract The landscape‐scale impacts of habitat subdivision (fragmentation per se) on biodiversity are not fully resolved. While smaller patches usually contain more species for equal total area, many implications of this remain unclear. For example, do equal areas of smaller and larger patches provide equivalent habitat value? How might this change over time and under differing matrix conditions? To help address these knowledge gaps, we developed an indicator of relative habitat value based on a species‐individual null model. We used the indicator to compare sets of patches ordered in small‐to‐large and large‐to‐small orders, building hierarchical Bayesian regression models to test the role of time since patch creation and contrasting matrix conditions. This allowed us to assess habitat value for 85 metacommunities inhabiting fragmented landscapes (1354 patches, >4500 species). We expected comparable habitat value following patch creation due to unpaid extinction debts, and the matrix would determine the direction of change over time, a harsher matrix increasing the relative value of larger patches. Averaged over time and matrix quality, the indicator probability density was mostly negative, suggesting slightly greater habitat value among larger patches. This pattern was consistent across taxonomic groups, although amphibians and reptiles were the most affected, and invertebrates least so. Larger patches were of greater value within 20 years of patch creation, but over time smaller patches increased in value under any matrix type, whereas value remained constant for larger patches. Matrix conditions mediated the relative difference: after 100 years under a light matrix, patches of all sizes were essentially of equivalent value, while larger patches were still favoured under a harsh matrix. Policy implications. In long‐fragmented, light matrix landscapes, small and large patches apparently offer comparable per‐unit‐area habitat value. Conversely, under a harsh matrix, larger patches retain slightly greater habitat value. We speculate that this reflects a ‘colonization credit’, which might occur within smaller patches after the initial loss of fragmentation‐sensitive species in disturbed landscapes. Overall, analyses support the need to maintain and enhance total habitat area—regardless of configuration—for biodiversity conservation, especially in long‐fragmented landscapes with light matrices.

Influence of environmental attitudes and time horizons on the valuation of lagoon ecosystem services: A choice experiment approach using principal component analysis.

Coastal lagoon habitats provide multiple ecosystem goods and services that contribute to people's well-being. However, owing to degradation from both anthropogenic and natural causes, these areas require conservation and protection that involve considerable public investment. To help determine this investment, this study estimates the nonmarket economic value of habitat, regulation, and cultural ecosystem services (ESs) using people's environmental attitudes and temporal preferences. Primary data were collected from 517 residents in the Veneto region through an online choice experiment survey. Respondents' environmental attitudes and beliefs were collected using the revised New Ecological Paradigm scale and analyzed using principal component analysis. Mixed logit models were applied to evaluate the marginal willingness to pay under different scenarios. The implicit discount rate linked to the different ESs varied between 2% and 6%, showing ESs should be discounted with distinct rates. Total household indirect and nonuse values for ESs ranged from €93 to €118, according to the model used. The results suggest that people are willing to pay to improve the conservation of lagoon ESs and that the future environmental impacts are valued less than the immediate effects. Additionally, people with environmental attitudes are more likely to contribute to the protection of ESs, and unobservable factors such as motivations, attitudes, perceptions, and beliefs guide people's valuations. These findings can be used to guide policymakers in designing sound conservation policies.

Red mangrove (Rhizophora mangle) roots serve as additional valuable habitat for the eastern oyster (Crassostrea virginica) in a subtropical estuary

Red mangrove (Rhizophora mangle) roots serve as additional valuable habitat for the eastern oyster (Crassostrea virginica) in a subtropical estuary

More than garden plants: extending the conversation of urban gardens as an important refuge for Australian birds

Abstract Inadequacies in public protected area networks dictates that private land will play an important role in the conservation of biodiversity in the coming decades. Household gardens are a key example of private lands that can serve as refuges for biodiversity, with birds as a popular flagship for garden biodiversity. Discussion has focused heavily on the species of plant a resident might select to attract birds to their garden. In this paper, we describe additional and important factors that should form part of this broader conversation on gardens for birds and biodiversity, with a specific aim of drawing attention to species that are at risk of localised extinctions in modern urban landscapes – urban adaptors. We present our commentary in two themes: (a) mitigating threats to birds in the urban environment and (b) enhancing the habitat value of the urban environment for a broader range of bird species. We provide a synthesis of the research of recent years that has explored the urban environment and its ability to support birds, but importantly, we extend on this by bringing together topics that have been somewhat lacking in the discussion to date. In a new approach to this conversation, this paper brings together key topics that can no longer be considered in isolation if we are to make significant conservation gains in the environments were most Australians now reside.

Mechanical management decreases arthropod biomass by changing vegetation structure in fallow fields of high conservation value

Abstract Arthropods play key roles in ecosystems as pollinators or as food resources for many birds. The decline in arthropods in farmland due to agricultural intensification is related to negative population trends in farmland birds. Semi‐natural areas such as fallow land are valuable habitats for arthropod communities in farmland, but the potential of these areas to boost biodiversity greatly depends on their management. We used a field experiment to explore the mechanisms behind the effects of mechanical management on arthropod communities in high conservation value fallow land. We used GLMMs to explore changes in arthropod abundance after treatment application, and pSEM to discriminate direct effects of treatments from indirect effects mediated by changes in vegetation structure. Tillage had stronger negative effects than vegetation shredding on total arthropod, spider and bee abundance, which were mediated by a reduction in vegetation height, green cover and flowering. Coleoptera biomass did not vary between treatments. The differences between treatments disappeared from 2 to 3 months after treatment application for total arthropod and spider biomass, but not for Orthoptera and bees. Synthesis and applications. Low‐intensity mechanical management of fallows has short‐term negative effects on arthropod abundance. For conservation purposes, fallow management should combine untreated fallow fields (or strips within fields) to boost arthropod communities, with low‐intensity management to create suitable breeding habitats for steppe birds.

The ‘other rainforest’: restoring Britain’s green gem

ABSTRACT Climate change and biodiversity loss are two of the most significant challenges currently faced by humanity. Rainforests exemplify the type of biodiverse habitat that can mitigate both these challenges, but they remain threatened in tropical locations and have almost disappeared elsewhere. This article discusses the forgotten temperate rainforests of the British Isles. It introduces their key characteristics and outlines the challenges that conservation managers face in restoring and re-creating these valuable habitats in the UK. Planting new forest takes land from other uses, notably farming, which can be contentious. Forest restoration is, however, necessary and the challenge of reconciling habitual farming practice with the need to ‘climate-proof’ our landscape is outlined.

Plantation management to restore early and late-successional bird habitat under various climatic and seasonal conditions.

Although agriculture and plantation forestry have decreased natural open habitats and old-growth forests, conservation in managed lands is considered essential for achieving "nature-positive" goals that reverse biodiversity trends from negative to positive. From subboreal to temperate regions, mature conifer plantations with broadleaved trees (BLTs) offer suitable habitats for species preferring mature natural BLT forests, whereas young plantations harbor species depending on early successional (ES) habitats. However, the functional forms of stand age and BLT, and their context dependency, remain unknown. We quantified the effects of stand age (3-98 years), BLT proportion (0%-97.5%), and their interaction on ES and BLT bird species in plantations, as well as the dependency of these effects on regional/seasonal climates. For both groups, we also explored whether plantations could be comparable habitats to BLT-dominated natural forests (stand age: 6-134 years) across Hokkaido (78,420 km2), northern Japan. ES bird species' richness and abundance decreased exponentially with stand age in plantations. This pattern was not evident in natural forests although only two ES stands were surveyed due to the rarity of natural forest harvesting. ES plantations in cooler regions showed higher habitat values, reflecting a climate-dependent species composition. No ES species occurred in winter. Both stand age and BLT proportion increased BLT bird species richness and abundance in a concave manner, except for age in stands with few BLTs. The positive effects of BLT were more evident in younger stands with fewer BLTs. Mature plantations with 25% BLTs supported 62% of breeding BLT bird abundance in old natural forests. In winter, lower regional temperatures weakened the positive effects of stand age and strengthened the positive effects of BLT proportion, reflecting temperature-dependent habitat selection across species. Our results suggest that regular plantation harvesting can play a critical role in restoring ES bird species across Hokkaido. To conserve BLT bird species, retaining even small amounts of BLTs within plantations may be more cost-effective than long-rotation plantation forestry or only protecting existing natural old-growth forests. Our study shows that on-site conservation within plantations across regions and seasons, when coupled with nature reserve management, can contribute to restoring biodiversity.

Nearshore fish abundance in an urban estuary is weakly associated with shoreline conditions across spatial scales

Understanding the scale at which species respond to habitat characteristics can improve detection of effects from anthropogenic alterations to marine shorelines. Spatial context matters because habitat alteration may have more of an effect when prevalent throughout a region, depending on the spatial scale at which species experience changes in habitat value. In this study, we examined the associations of 4 highly motile fish species with shorelines that are altered via shoreline armor. We sampled fish for 4 yr in the Salish Sea, Washington, USA, and used model selection to evaluate the weight of evidence for associations between fish abundance and shoreline armor extent within hierarchically nested spatial scales. We evaluated species that inhabit nearshore waters under different contexts during their life histories because we expected different associations with armor between them. Of the species that are beach-associated at multiple times during their life histories, surf smelt showed no association with armor while Pacific herring showed a negative association, particularly at larger spatial scales. Of the species that pass through nearshore habitats during outmigration to the ocean, juvenile Chinook and chum salmon both showed slightly positive associations with armor presence, but these associations were not strong. The stronger association we observed in herring suggests that they may avoid areas with greater armor presence throughout a region. Distributions of anadromous species during migration are likely governed by other factors. This work highlights the importance of maintaining ecological context when considering future research aimed at understanding the impacts of shoreline armor on fish populations.

A Donor Registry: Genomic Analyses of Posidonia australis Seagrass Meadows Identifies Adaptive Genotypes for Future-Proofing.

Globally, anthropogenic climate change has caused declines of seagrass ecosystems necessitating proactive restoration approaches that would ideally anticipate future climate scenarios, such as marine warming. In eastern Australia, estuaries with meadows of the endangered seagrass Posidonia australis have warmed and acidified over the past decade, and seagrass communities have declined in some estuaries. Securing these valuable habitats will require proactive conservation and restoration efforts that could be augmented with restoration focussed on boosting resilience to future climate. Understanding patterns of selection and where seagrass meadows are adapted to particular environmental conditions is key for identifying optimal donor material for restoration. We used single nucleotide polymorphisms and genotype by environment analyses to identify candidate loci under putative selection to environmental stressors and assess genomic variation and allelic turnover along stressor gradients. The most important physicochemical variables driving selection were associated with temperature, water turbidity, and pH. We developed a preliminary 'donor registry' of pre-adapted P. australis genotypes by mapping the distribution of alleles to visualise allelic composition of each sampled seagrass meadow. The registry could be used as a first step to select source material for future-proofing restoration projects. A next step is to establish manipulative experiments that will be required to test whether pre-adapted genotypes confer increased resistance to multiple environmental stressors.

Effects of river infrastructure, dredged material placement, and altered hydrogeomorphic processes: The stress ecology of floodplain wetlands and associated fish communities

Recognition of the habitat values of coastal and floodplain wetlands has inspired research and engineering to restore biological functions after widespread species declines. However, the restoration and management of tidal river floodplains requires a more complete understanding of anthropogenic stressors on hydrogeomorphology and ecological processes. River floodplains near the ocean are affected by localized diking and dredging as well as basin-wide stressors such as dams. We evaluated the effects of stressors versus spatial position, both longitudinal and lateral to the mainstem, using physical and biological response variables in river floodplain wetlands. We categorized historical and modern stressors on the hydrogeomorphic regime of the lower Columbia River and estuary, northeast Pacific coast, including basin-scale management and local impacts. Using this categorization, we analyzed 44 attributes using field-collected data from 50 floodplain wetlands. Attributes represent channels, floods, plant communities, and fish communities. Here we show that plant and fish communities are stratified by position along the estuarine-riverine gradient, in contrast to physical habitat characteristics, which are stratified by stressors on hydrogeomorphic regimes and in some cases the lateral distance from the mainstem river on tributaries. Spatial position relative to water-level dynamics and salinity more strongly affect the biota than does stressor history. Stressor effects were greatest on the geomorphology observed in formerly diked, now reconnected wetlands and in wetlands with a history of dredged material placement; historically diked sites had anomalously deep channels with larger cross-sectional areas while sites with dredged material had shallow channels and lower levels of organic carbon in sediment. In wetlands subject only to landscape-scale stressors such as flow alterations by dams, organic carbon levels were higher. These findings provide natural resource managers with opportunities to enhance similarity to natural conditions and better understand future wetland evolution from different baselines of stressor history and river position.

Predation Risk, Foraging and Reproduction of an Insectivore Fish Species Associated with Two Estuarine Habitats

Pneumatophore fringes and mudflats are extremely valuable habitats and provide structures on which many fish species benefit in terms of food and reduced predation risk. We analyzed the spatiotemporal patterns in feeding habits, reproductive aspects and effects of predatory fish presence to assess the ecological drivers of the common halfbeak, Hyporhamphus unifasciatus, in a Brazilian estuary. Sampling was conducted during the rainy and dry periods. In summary, the results demonstrated that the number of predatory fishes was a strong predictor of population abundance and biomass, followed by pneumatophore complexity. The abundance and biomass values tended to increase with increasing habitat structural complexity towards the upper estuary. There was evidence that fish exhibited movement during the rainy season related to spawning events and subsequent juvenile recruitment in this area. Hymnoptera was the item most frequently ingested and made the greatest contributions to the volume of diet in habitat types throughout the year. There was an increase in the condition factor in the rainy season, which was associated with energy reserves, reproduction and growth (fitness). We concluded that predation is an important ecological process that operates at local spatial scales and that, together with the density of pneumatophores, it could affect the abundance of common halfbeak populations associated with estuarine habitats.

Analysing Turbulence Patterns in Nature‐Like Fishways: An Experimental Approach

ABSTRACTNature‐like fishways are an important measure for restoring fish passage, mitigating the impacts of barriers, and providing valuable habitat benefits in a more natural and effective way than traditional technical fishways. Their ecological advantages make them a preferred solution in many river restoration projects. The turbulence at the fishway's pool is a key challenge in the design of fishways. This study evaluated the hydraulic performance of the nature‐like fishway section of the Zongyang Fishway Project in China. This utilized a trapezoidal cross‐section with a 1:242 bottom slope, 1:2 side slopes, and an operating water depth of 1–3 m. The bottom and sides were paved with 0.2–0.5 m diameter pebbles to create suitable habitat for bottom‐dwelling fish. The target design velocity was 0.7–0.9 m s−1. A physical model was constructed to assess the hydraulic characteristics of the nature‐like fishway, including flow velocities within the slots and turbulence levels in the pools. The results showed that the slot velocities were within the target range, the head loss was parallel to the bottom elevation, and the flow field near the bottom mimicked technical fishway conditions, whereas the surface flow resembled open channel flow. Turbulence intensity remained below 60% of the design velocity. These findings provide valuable insights into the hydraulic performance and suitability of this nature‐like fishway design for facilitating fish passage of the target freshwater species along with directly aiding to SDGs 6 and 14.

Cold-water coral mortality under ocean warming is associated with pathogenic bacteria

Cold-water corals form vast reefs that are highly valuable habitats for diverse deep-sea communities. However, as the deep ocean is warming, it is essential to assess the resilience of cold-water corals to future conditions. The effects of elevated temperatures on the cold-water coral Lophelia pertusa (now named Desmophyllum pertusum) from the north-east Atlantic Ocean were experimentally investigated at the holobiont level, the coral host, and its microbiome. We show that at temperature increases of + 3 and + 5 °C, L. pertusa exhibits significant mortality concomitant with changes in its microbiome composition. In addition, a metagenomic approach revealed the presence of gene markers for bacterial virulence factors suggesting that coral death was due to infection by pathogenic bacteria. Interestingly, different coral colonies had different survival rates and, colony-specific microbiome signatures, indicating strong colony-specific variability in their response to warming waters. These results suggest that L. pertusa can only survive a long-term temperature increase of < 3 °C. Therefore, regional variations in deep-sea temperature increase should be considered in future estimates of the global distribution of cold-water corals.

Aquatic insect biodiversity, water quality variables, and microplastics in the living weir freshwater ecosystem

Most Thai rivers have not yet reached "good" ecological status. Furthermore, the scientific community is deeply concerned about the existence and abundance of microplastics (MPs) in freshwater. The live weirs' river health status was assessed using water quality and a variety of aquatic insect species. The research was conducted along Khlong-La, which was compared in the absence (R1, R2) and presence of living weirs (LWs) (M71, M62, M4, and M2). In 2023, aquatic insects and water samples were gathered during two months: January (rainy season) and July (dry season). The results revealed that the six sampling sites had similar physical and chemical properties, with the exception of total dissolved solids, which varied significantly. A total of 658 aquatic insects from 25 families and 6 orders were identified. The Hydropsychidae dominated the aquatic insect fauna at the LWs locations, followed by Chironomidae, Naucoridae, and Caenidae. Ten genera were discovered at the reference site (R1), whereas 16, 21, 24, and 19 were discovered at LWs (M71, M62, M4, M2), and 16 at the reference site (R2). The results of CCA ordination revealed that the most important factors influencing aquatic insect diversity were dissolved oxygen, water temperature, pH, electrical conductivity, and ammonia nitrogen. This study suggests that because of their significant responses to environmental factors, the species richness of aquatic insects may indicate the conservation value of habitats. The BMWPTHAI score was 41, 51, 57, 58, 73, 54, and the ASPTTHAI score was 5.12, 5.10, 5.18, 5.27, 4.86, and 5.40, respectively. Shannon-Weiner diversity index (Hʼ) values were 2.059, 2.461, 2.839, 2.777, and 2.587, respectively. The results showed that the water quality was average. The physicochemical data, as well as the BMWP and ASPT, revealed that the water at the living well was slightly polluted. Furthermore, larger MPs (&gt;500 µm) were found in the largest concentrations, in the shape of fibers, and primarily in the color violet.

Effects of a large-scale bioretention installation on the species composition of an urban bird community as determined by passive acoustic monitoring.

As urbanization accelerates worldwide, municipalities are attempting to construct new green spaces within their borders. The perceived ecological value of these places is frequently tied to their ability to attract urban wildlife, such as birds, which can easily be observed and enjoyed. As one strategy, stormwater is now frequently managed with green infrastructure: planted areas that retain and treat stormwater rather than merely directing it to surface waters. While these practices have the potential to provide habitat for urban wildlife, the ecological effects of these systems are largely unknown. To assess whether one green infrastructure project increases habitat value, we used passive acoustic monitoring to survey urban bird communities in and near a large green infrastructure project in Columbus, Ohio (USA). Bird communities near bioretention cells (rain gardens) were compared to those at nearby lawns and remnant or restored natural areas. We found that recently installed bioretention cells tended to support more omnivores, lower-canopy foraging species, and species from a higher diversity of feeding guilds than did nearby lawn control sites. We were unable to detect effects of nearby bioretention installations on bird species richness at other sites. The observed differences in species richness were fairly small, and we urge caution when anticipating the habitat value of bioretention cells, at least for bird species. However, the results that we observed suggest that bioretention cells could have a more positive impact on bird communities in different contexts or using different design strategies. The bioretention cells surveyed in this study were small and only planted in grasses and forbs, potentially limiting their ability to offer complex habitat. They were also relatively young, and future work is needed to determine their long-term effect on avian communities and biodiversity of other taxa.

Hessische Rhön – mountain grassland, rough grazing and their birds

Hessische Rhön – mountain grassland, rough grazing and their birds The project is particularly dedicated to conservation and development measures for the species-rich mountain grassland and the protection of endangered bird species in open areas of the Hessian low mountain ranges of the Rhön. By implementing different types of landscape maintaining measures in close cooperation with local farmers and municipalities valuable habitats in the Natura 2000 protected area network were substantially improved.

Biodiversity of a temperate karst landscape-ice cave collapse doline supports high α-diversity of the soil mesofauna.

Caves represent a specific environment with a special microclimate and fauna adapted to it. However, we have still a restricted knowledge on soil fauna communities in an environments with a marked microclimate gradient at the interface between cave and surface habitats. In the present study, we investigated the community patterns of dominant soil microarthropod group, oribatid mites, and their relationship to environmental factors across the microclimate gradient along a transect with seven study sites from cold and wet cave entrance zone to warm and drier deciduous forest. The cold and wet sites showed low oribatid abundances and a high spatial clustering of individuals in comparison to the warm sites. The oribatid mites showed significantly higher abundance and species richness at warm forest sites. Indicator species analysis indicated specific cold-tolerant species that dominated at cold sites of the gradient, but which were absent at the warmest sites. Variance analysis clarified that community composition at sites were significantly driven by environmental factors: temperature, soil moisture, pH and C/N ratio. The study underlines the importance of ice cave entrances as sources of high α-diversity of soil mesofauna and thus the conservation priority of these valuable habitats.

Anthropogenic landscape features affect the ground habitat use of Penelope superciliaris (Cracidae), a large seed disperser bird in southeastern Brazil

AbstractThe expansion of agriculture and forest plantations over tropical biomes has caused significant species loss, while others persist in remnant native areas and anthropogenic lands. Penelope superciliaris, a large seed disperser bird, inhabits human‐modified landscapes; however, its habitat use is poorly known. We investigated how native land covers, distance to water sources, and anthropogenic landscape features affect the species' ground habitat use in disturbed and undisturbed areas of three landscapes in Southeastern Brazil. We expected the species to use the ground more in native areas and near water sources because of the higher habitat quality. We collected presence‐absence data during two dry seasons at 205 sampling stations with camera traps. Using occupancy models, we calculated the cumulative AICc weights of covariates for occupancy (interpreted as probability of use, Ψ) and detection (interpreted as frequency of use, p) parameters. The proportion of managed forests negatively influenced the species' frequency of use. The probability of use was higher when camera trap stations were located on unpaved roads. Model averaged prediction showed that the species uses about 56% of the landscapes. Our results suggest that intensively managed forests are not favorable or attractive habitats for the species. Unpaved roads associated with native vegetation edges may provide valuable habitats for the species during the dry season, possibly associated with movement and resource tracking. These findings may help guide conservation strategies in such modified landscapes, with caution in considering unpaved roads as secure habitats until further data on population abundance are available.Abstract in Portuguese is available with online material.

Native Forbs Provide Pollinator Resources and Improve Forage Nutrient Composition, Animal Performance, and Pasture Productivity

Pollinator declines and expectations for more sustainable agriculture, including pasture-based enterprises, bring attention to strategies to enhance the habitat value of grazing lands. We evaluated native warm-season grass (NWSG) pastures with (FORB) and without (CONT) interseeded native forbs in 2021–2023. An analysis was conducted using R with the significance set at p ≤ 0.05. The grass appeared to be weakened predominantly by grazing management practices. Forb density and mass had an inverse relationship in seasons two and three. Total forage mass declined in response to increased grazing days and weakened stands. The forage nutritive compositions differed, with more stable, season-long crude protein and lower fiber concentrations in late-season FORB, which supported higher bodyweight gains and season-long average daily gain. Black-eyed Susan (Rudbeckia hirta; BESU), lanceleaf coreopsis (Coreopsis lanceolata; LCOR), and showy ticktrefoil (Desmodium canadensis; STTF) were the most abundant forbs, and BESU, LCOR, and purple coneflower (Echinacea purpurea; PURC) produced long flowering windows. Cattle grazed STTF, cup plant (Silphium perfoliatum; CUPP), and oxeye sunflower (Helopsis helianthoides) the most. Under continuous stocking, a blend of BESU, LCOR, PURC, STTF, and CUPP produced acceptable cattle gains and provided pollinator resources, suggesting that this model may be a viable means to enhance the sustainability of pastures.

Riparian buffer strips promote biomass, species richness and abundance of flying insects in agricultural landscapes

Riparian buffer strips promote biomass, species richness and abundance of flying insects in agricultural landscapes