Tri-trophic networks of oak gall-inducing-insects and their parasitoids in Mexican avocado agrosystems: Forest coverage and local climatic variables importance

Functional leaf-trait variability and herbivory in oaks along a Mexican avocado agrosystem mosaic

There is global concern about tropical forest degradation, in part, because of the associated loss of biodiversity. Communities and indigenous people play a fundamental role in tropical forest management and are often efficient at preventing forest degradation. However, monitoring changes in biodiversity due to degradation, especially at a scale appropriate to local tropical forest management, is plagued by difficulties, including the need for expert training, inconsistencies across observers, and lack of baseline or reference data. We used a new biodiversity remote-sensing technology, the recording of soundscapes, to test whether the acoustic saturation of a tropical forest in Papua New Guinea decreases as land-use intensity by the communities that manage the forest increases. We sampled soundscapes continuously for 24 hours at 34 sites in different land-use zones of 3 communities. Land-use zones where forest cover was fully retained had significantly higher soundscape saturation during peak acoustic activity times (i.e., dawn and dusk chorus) compared with land-use types with fragmented forest cover. We conclude that, in Papua New Guinea, the relatively simple measure of soundscape saturation may provide a cheap, objective, reproducible, and effective tool for monitoring tropical forest deviation from an intact state, particularly if it is used to detect the presence of intact dawn and dusk choruses.

Living on the edge: Forest cover threshold effect on endangered maned sloth occurrence in Atlantic Forest

Detecting vulnerability of humid tropical forests to multiple stressors

Forest cover is positively associated with fish biomass and fisheries yield in the Amazon River floodplain, and many species enter flooded forests to feed, spawn, or seek refuge from predation. Floating macrophyte beds, known as floating meadows, in Amazon floodplains support high fish diversity and serve as nursery habitat for many fishes of high commercial importance. We surveyed fish from floating meadows in floodplain lakes along the lower Amazon River to evaluate variation in fish abundance in relation to forest cover and local environmental variables. Species associations with forest cover were estimated with threshold indicator taxa analysis (TITAN2). The analysis identified taxa that gradually increased in abundance and occurrence as forest cover increased. Many species gradually increased at approximately 40% forest cover in the local landscape. Taxa that decreased as forest cover increased exhibited thresholds, whereby their abundance and occurrence declined rapidly when forest cover exceeded approximately 9% and when it was about 20%. Small‐bodied, sedentary species with equilibrium and opportunistic life‐history strategies (i.e. functional groups) and Cichlidae and Characidae (taxonomic groups) were indicators of high forest cover, whereas large‐bodied, migratory species with periodic and intermediate life‐history strategies and Serrasalmidae were indicators of low forest cover. Our findings could be used to predict how the taxonomic and functional structure of fish communities inhabiting floating meadows would respond to deforestation.

Many waterways flow out of forestlands, which tend to maintain higher water quality, into agricultural lands, which tend to degrade water quality. The roles of land cover in impacting key water quality parameters (phosphorus, nitrogen, total suspended solids, bacteria, and conductivity) were investigated for the watershed of the North and South Fork of the Shenandoah River, Virginia. This area has a particularly sharp boundary between heavily forested and heavily agricultural regions. Two datasets were analyzed: 1) a large number of datapoints spanning a 20-year range in the Water Quality Portal (WQP) database, and 2) transects along three representative rivers systems over the span of a 4-year period. All parameters trended better in forested regions than agricultural regions. This was particularly true for nitrogen and conductivity; phosphorus, TSS and bacteria showed more local variability, especially in the agricultural region. Periods of high flow increased phosphorus, sediment and bacteria concentrations, and decreased conductivity, but not when drainage basin forest cover was less than 80%. Transects showed that waterways flowing out of forestland maintained higher water quality for approximately the first 8 km in agricultural land. Both transect and WQP data indicated higher water quality when the percent of forested land cover in a drainage basin was about 70–80%. Thus, forestland does mitigate the impacts of agriculture on water quality to some degree, but this effect rapidly diminishes as forest cover of the watershed lessens. Furthermore, forests themselves have degraded water quality at certain times and places; for instance, nutrients level were in the medium to high stress level for aquatic life in approximately 15% of samples. This study illustrates general trends of land cover effects on water quality, while also highlighting both site-specific variability, and the dynamics of water quality as water flows out of forested areas into agricultural areas.

Habitat loss and land-use intensification are major threats to biodiversity in the Brazilian Atlantic Forest, particularly for bat assemblages that provide key ecosystem services. In this study, we examined how landscape composition (forest and pasture cover) and local forest structure influence the richness and abundance of phyllostomid bats across 20 forest fragments in southern Bahia. Bat sampling was conducted using mist nets, and forest structure was quantified using tree measurements and vertical foliage stratification. We applied structural equation modeling to test the direct and indirect effects of landscape and local variables. Our results show that forest cover has both direct and indirect positive effects on bat diversity, mediated by improved forest structure. In contrast, increased pasture cover negatively affected forest structure and was weakly associated with bat diversity. The most abundant species were generalist frugivores, such as Carollia perspicillata and Rhinophylla pumilio. These findings highlight the importance of maintaining forest cover and structural complexity to support bat diversity in agroforestry-dominated landscapes. Conservation strategies that integrate habitat protection with sustainable land-use practices are crucial to maintaining biodiversity and the ecological functions provided by bats in this globally threatened biome.

Many waterways flow out of forestlands, which tend to maintain higher water quality, into agricultural lands, which tend to degrade water quality. The roles of land cover in impacting key water quality parameters (phosphorus, nitrogen, total suspended solids, bacteria, and conductivity) were investigated for the watershed of the North and South Fork of the Shenandoah River, Virginia. This area has a particularly sharp boundary between heavily forested and heavily agricultural regions. Two datasets were analyzed: 1) a large number of datapoints spanning a 20-year range in the Water Quality Portal (WQP) database, and 2) transects along three representative rivers systems over the span of a 4-year period. All parameters trended better in forested regions than agricultural regions. This was particularly true for nitrogen and conductivity; phosphorus, TSS and bacteria showed more local variability, especially in the agricultural region. Periods of high flow increased phosphorus, sediment and bacteria concentrations, and decreased conductivity, but not when drainage basin forest cover was less than 80%. Transects showed that waterways flowing out of forestland maintained higher water quality for approximately the first 8 km in agricultural land. Both transect and WQP data indicated higher water quality when the percent of forested land cover in a drainage basin was about 70-80%. Thus, forestland does mitigate the impacts of agriculture on water quality to some degree, but this effect rapidly diminishes as forest cover of the watershed lessens. Furthermore, forests themselves have degraded water quality at certain times and places; for instance, nutrients level were in the medium to high stress level for aquatic life in approximately 15% of samples. This study illustrates general trends of land cover effects on water quality, while also highlighting both site-specific variability, and the dynamics of water quality as water flows out of forested areas into agricultural areas.

The influence of forest and topography on snow accumulation and melt at the watershed-scale

Bayesian spatiotemporal dynamic models for regional dynamics of avian populations

Aim We investigated how current and historical land use and landscape structure affect species richness and the processes of extinction, immigration and species turnover.Location The northern part of the Stockholm archipelago, Baltic Sea, Sweden. We resurveyed 27 islands ranging from 0.3 to 33 ha in area.Methods We compared current plant survey data, cadastral maps and aerial photographs with records obtained from a survey in 1908, using databases and a digital elevation model to examine changes in plant community dynamics in space and time. We examined the effects of local and landscape structure and land use changes on plant species dynamics by using stepwise regression in relation to eight local and three landscape variables. The eight local variables were area, relative age, shape, soil heterogeneity, bedrock ratio, number of houses, forest cover change, and grazing 100 years ago. The three landscape variables were distance to mainland, distance to closest island with a farm 100 years ago, and structural connectivity. Hanski’s connectivity measure was modified to incorporate both connectivity and fragmentation.Results The investigated islands have undergone drastic changes, with increasing forest cover, habitation, and abandonment of grassland management. Although the total species richness increased by 31% and mean island area by 23%, we found no significant increase in species richness per unit area. Local variables explain past species richness (100 years ago), whereas both local and landscape variables explain current species richness, extinctions, immigrations and species turnover. Grazing that occurred 100 years ago still influences species richness, even though grazing management was abandoned several decades ago. The evidence clearly shows an increase in nitrophilous plant species, particularly among immigrant species.Main conclusions This study highlights the importance of including land use history when interpreting current patterns of species richness. Furthermore, local environment and landscape patterns affect important ecological processes such as immigration, extinction and species turnover, and hence should be included when assessing the impact of habitat fragmentation and land use change. We suggest that our modified structural connectivity measure can be applied to other types of landscapes to investigate the effects of fragmentation and habitat loss.

We used local and landscape models to predict fish assemblages in the Great Swamp, NY, a region undergoing rapid development. Fish were surveyed across 17 sites. Fish-species richness, diversity, percent intolerant species, and IBI metrics for fish species richness, benthic insectivores, terete minnows, and domi- nant species were calculated. Local stream features were characterized and sur- rounding land cover/use was quantified at four different scales (reach, segment, network, and watershed). Regression analysis and multinomial cumulative logit models were used to predict how fish assemblages varied according to habitat characteristics. Within the local variables, pool variability predicted diver- sity and epifaunal substrate/available cover predicted percent intolerant species and IBI metrics for fsh species richness, benthic insectivores, and terete minnows. The scale of analysis influenced which landscape-level predictors measuring percent wetland, forest cover, or residential land use best explained diversity, percent intolerant species, and IBI metrics for benthic insectivores, terete minnows, and dominant species. Although no single model (local or landscape) best predicted assemblages, the land cover/use at the segment (100-m buffer for 1 km upstream) scale provides sufficient information about fish assemblages to support this scale as optimal for regional land-use plan- ners. Our findings show that forest cover should be maintained to protect fish assemblages in the Great Swamp and development that alters stream-habitat hetero- geneity should be curtailed.

This study basically focuses on an overview of the dynamics of change of forest cover in India using data from the World Bank from 1990 to 2021. This research involves the quantification and analysis of trends in forest cover across different states and classes of forest types, drivers of change, and, finally, assessing the impact of conservation policy. Using World Bank reports, we adopted statistical modeling tools to assess the changes in forest cover, density, and composition. The study integrated other databases on the determinants of socioeconomics, climatic variables, and policy implementations to get an insight into the complex interplay of human activities, environmental conditions, and forest ecosystems. The results bring out a more nuanced picture of changes in forest cover across the country: Presently, some states show significant gains due to successful state policy related to afforestation, capsule restoration programs, and strict protection being followed, while in others, there were persistent pressures of deforestation, linked to urbanization, agricultural expansion, and infrastructure development. Among the various forest types, the denser forests were relatively more resilient to change compared to open and scrub forests, which showed a higher level of vulnerability to anthropogenic and-climate-induced pressures. Policy impact analysis results suggest that while the forest management at community level and the intensity of site-specific conservation interventions yielded effective results, there is also concern regarding qualitative maintenance of forests and biodiversity amidst quantitative increase in forest covers. The value that this research brings is in adding more scope to understanding India’s forest dynamics and in offering, through evidence-based recommendations, policy tools for policymakers. Specific strategies and appropriate management must be a priority in regional needs, perspective monitoring, and integrated land-use planning that can ensure sustainability in forest management and conservation in the face of growing environmental challenges.

Seed predation is an important ecological process that affects the abundance, diversity and distribution of plant species, and it is known to be influenced by defaunation and forest fragmentation. Most studies on seed predation in human‐modified landscapes do not take into account the different spatial scales in which this process operates. In this study, we evaluated how variables at three distinct spatial scales affected the seed predation of a palm that provides a keystone resource to the frugivore community, the queen palmSyagrus romanzoffiana. Thirteen landscapes that vary in forest cover, number of fragments and patch sizes were sampled in the Brazilian Atlantic forest. We also evaluated the contribution of the three main groups of seed predators: squirrels, terrestrial rodents and invertebrates. Our results indicate that seed predation is more affected by fragment and local variables than by landscape influences. In addition, the size of the fragment, its shape and the distance from the nearest forest edge were the main predictors of the proportion of predated seeds. Moreover, the two main seed predators (squirrels and invertebrates) responded to the same fragment and local variables. Because most of the Atlantic forest consists of small fragments, we expect that the seed predation of this keystone palm should be high in most of its distribution, with potential consequences for the frugivore community.

<div> <p>Climate variability is the primary influence on climate extremes and affected by natural forcing from solar irradiance and volcanic eruptions. Global warming impacts climate variability, but there is contradictory and incomplete evidence on the spatio-temporal patterns. Strong volcanic eruptions have been suggested to reduce temperatures less in warmer climate states. However, the underlying question of state-dependent effect of natural forcing on local and global variability remains open. Moreover, there are uncertainties about the role of natural forcing in the mismatch between simulated and reconstructed local, long-term variability. <span> </span></p> </div><div> <p>Using a 12-member GCM ensemble with targeted boundary conditions, we present naturally-forced and equilibrium, millennium-length simulations for the Last Glacial Maximum (LGM) and the Pre-Industrial (PI). We quantify the local and global climate response to solar and volcanic forcing in the LGM and PI, and contrast variability from forced and control simulations on annual-to-multicentennial scales. We differentiate various contributions from the atmosphere, oceans, and particularly that of sea ice using a 2D energy balance model (EBM). Spectral analysis of simulated temperatures shows that global variability is predominately determined by natural forcing. Local mean spectra are more characteristic for the mean climate state and reveal a decrease in local variability with warming. The global and local response to natural forcing is robust against changes in the mean climate. Particularly, the spatial patterns of the surface climate's response to volcanic eruptions widely agree across states. Weak local differences resulted primarily from sea ice dynamics. The sea ice contribution is the strongest on interannual scales. It remains significant on decadal scales and longer, providing a key mechanism of long-term variability. We validate the simulated variability against observational and paleoclimate data. The variance obtained from proxies is increasingly larger on longer timescales compared to that from simulated time series. The inclusion of natural forcing reduces the model-data mismatch on decadal-to-multicentennial scales and, thus, provides a more accurate representation of climate variability. </p> </div><div> <p>Consideration of natural forcing is therefore paramount for model-data comparison and future projections. The robust temperature response suggests that findings on the ability of models to simulate past variability should translate to future climates, and can thus help constrain variability.<span> </span></p> </div>