scholarly journals Decline in Aboveground Biomass Due to Fragmentation in Subtropical Forests of China

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 617
Author(s):  
Chunyu Shen ◽  
Nannan Shi ◽  
Shenglei Fu ◽  
Wanhui Ye ◽  
Lei Ma ◽  
...  
Keyword(s):  
Species Richness ◽  
Forest Fragmentation ◽  
Aboveground Biomass ◽  
Biodiversity Loss ◽  
Average Diameter ◽  
Forest Fragments ◽  
Biomass Storage ◽  
Positive Effects ◽  
Fragmented Forests ◽  
Species Richness And Abundance

Fragmentation has long been considered the primary cause for ecosystem degradation and biodiversity loss worldwide. Forest fragmentation affects ecosystem functioning and biodiversity in multiple ways. Here, we ask how forest fragmentation influences aboveground biomass storage (AGB) in sub-tropical forests in China. We established 207 20 m × 20 m plots within 69 forest fragments of varying size. Forest fragmentation process simulation was carried out via repeated quadrat sampling using different sized quadrats in two non-fragmented stands. AGB was estimated and compared across forest fragments and quadrats with different sizes within two non-fragmented stands. Our results indicate that AGB is significantly lower in forest fragments than in quadrats within two non-fragmented forests. In addition, species richness and abundance were lower in fragmented stands, respectively. In fragmented forests, the average diameter at breast height (DBH) increased with decreasing patch size, while declined for non-fragmented plots. Species richness, abundance, and mean DBH have strongly positive effects on AGB. This was the case both in forest fragments and quadrats within two non-fragmented forests. Forest fragmentation leads to lower richness, lower abundance, and higher mean DBH in forest fragments than in the two non-fragmented forests. Our results suggest that forest fragmentation increases edge habitats, which drastically decreases forests aboveground biomass storage. These results show that land degradation not only reduces the area of forests, but also reduces the aboveground biomass carbon density of forests.

scholarly journals Species richness and abundance of bats in fragments of the stational semidecidual forest, Upper Paraná River, southern Brazil

2009 ◽  
Vol 69 (2 suppl) ◽  
pp. 727-734 ◽  
Author(s):  
H. Ortêncio-Filho ◽  
NR. Reis
Keyword(s):  
Species Richness ◽  
Anthropogenic Impacts ◽  
Paraná River ◽  
Forest Fragments ◽  
Southern Brazil ◽  
Parana River ◽  
Upper Paraná River Floodplain ◽  
Upper Paraná River ◽  
Species Richness And Abundance ◽  
Artibeus Lituratus

The Upper Paraná River floodplain is inserted in a region of the Mata Atlântica biome, which is a critical area to preserve. Due to the scarcity of researches about the chiropterofauna in this region, the present study investigated species richness and abundance of bats in remnants from the stational semidecidual forest of the Upper Paraná River, southern Brazil. Samplings were taken every month, from January to December 2006, using 32 mist nets with 8.0 x 2.5 m, resulting in 640 m²/h and totaling a capture effort of 87,040 m²/h. In order to estimate the species richness, the following estimators were employed Chao1 and Jack2. During the study, a total of 563 individuals belonging to 17 species (Artibeus planirostris, Artibeus lituratus, Carollia perspicillata, Platyrrhinus lineatus, Sturnira lilium, Artibeus fimbriatus, Myotis nigricans, Desmodus rotundus, Artibeus obscurus, Noctilio albiventris, Phylostomus discolor, Phylostomus hastatus, Chrotopterus auritus, Lasiurus ega, Chiroderma villosum, Pygoderma bilabiatum and Lasiurus blossevillii) were captured. The estimated richness curves tended to stabilize, indicating that most of the species were sampled. Captured species represented 10% of the taxa recorded in Brazil and 28% in Paraná State, revealing the importance of this area for the diversity of bats. These findings indicate the need to determine actions aiming to restrict human activities in these forest fragments, in order to minimize anthropogenic impacts on the chiropterofauna.

scholarly journals Trophic structure stability and extinction dynamics of beetles (Coleoptera) in tropical forest fragments

1998 ◽  
Vol 353 (1367) ◽  
pp. 437-451 ◽  
Author(s):  
R. K. Didham ◽  
J. H. Lawton ◽  
P. M. Hammond ◽  
P. Eggleton
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Tropical Forest ◽  
Forest Fragmentation ◽  
Trophic Structure ◽  
Forest Edge ◽  
Forest Fragments ◽  
Trophic Groups ◽  
Predator Species ◽  
Extinction Probabilities

A first analysis of the stability of trophic structure following tropical forest fragmentation was performed in an experimentally fragmented tropical forest landscape in Central Amazonia. A taxonomically and trophically diverse assemblage of 993 species of beetles was sampled from 920 m 2 of leaf litter at 46 sites varying in distance from forest edge and fragment area. Beetle density increased significantly towards the forest edge and showed non-linear changes with fragment area, due to the influx of numerous disturbed-area species into 10 ha and 1 ha fragments. There was a marked change in species composition with both decreasing distance from forest edge and decreasing fragment area, but surprisingly this change in composition was not accompanied by a change in species richness. Rarefied species richness did not vary significantly across any of the sites, indicating that local extinctions of deep forest species were balanced by equivalent colonization rates of disturbed-area species. The change in species composition with fragmentation was non-random across trophic groups. Proportions of predator species and xylophage species changed significantly with distance from forest edge, but no area-dependent changes in proportions of species in trophic groups were observed. Trophic structure was also analysed with respect to proportions of abundance in six trophic groups. Proportions of abundance of all trophic groups except xylomycetophages changed markedly with respect to both distance from forest edge and fragment area. Local extinction probabilities calculated for individual beetle species supported theoretical predictions of the differential susceptibility of higher trophic levels to extinction, and of changes in trophic structure following forest fragmentation. To reduce random effects due to sampling error, only abundant species ( n ≥ 46) were analysed for extinction probabilities, as defined by absence from samples. Of these common species, 27% had significantly higher probabilities of local extinction following fragmentation. The majority of these species were predators; 42% of all abundant predator species were significantly more likely to be absent from samples in forest fragments than in undisturbed forest. These figures are regarded as minimum estimates for the entire beetle assemblage because rarer species will inevitably have higher extinction probabilities. Absolute loss of biodiversity will affect ecosystem process rates, but the differential loss of species from trophic groups will have an even greater destabilizing effect on food web structure and ecosystem function.

scholarly journals A comparison between time-constrained counts and line transects as methods to estimate butterfly diversity in tropical habitats

2021 ◽  
Author(s):  
Suman Attiwilli ◽  
Nitin Ravikanthachari ◽  
Krushnamegh Kunte
Keyword(s):  
Species Richness ◽  
Deciduous Forest ◽  
Biodiversity Loss ◽  
Evergreen Forest ◽  
Population Declines ◽  
Butterfly Diversity ◽  
Dry Deciduous Forest ◽  
Feasible Alternative ◽  
Line Transects ◽  
Species Richness And Abundance

Long-term monitoring programmes have revealed catastrophic population declines that are contributing to biodiversity loss. These discoveries and the underlying programmes have been possible because of standardised methods of counting butterflies. Butterflies have been monitored using modified line transects, known in butterfly monitoring schemes as Pollard walks. However, line transects are not feasible in many tropical and mountainous habitats. To tackle this problem, we devised time-constrained (30-min) counts and compared butterfly diversity as estimated through this method with that estimated through line transects (500 m, 10 min) in three tropical habitats in India (evergreen forest, dry deciduous forest and an urban woodland). We tested the efficacy of the two methods to sample species richness and abundance, as well as numbers of rare, endemic and specialist butterflies. We observed greater species richness, and more species of habitat specialists and endemics per sample in time-constrained counts when compared with line transects in evergreen forest, but not in the other two habitats. Thus, time-constrained counts were more efficient at detecting species than line transects in the species-rich evergreen habitat. Apart from this difference, the two sampling methods captured similar levels of species richness and other measures of diversity. Time-constrained counts may thus be viewed as a feasible alternative to line transects to carry out butterfly surveys in tropical and mountainous landscapes. This method is particularly suited for biodiversity assessments and mapping involving citizen science initiatives, which has considerable potential in populous and tech-ready countries such as India.

scholarly journals Tree species richness attenuates the positive relationship between mutualistic ant–hemipteran interactions and leaf chewer herbivory

2017 ◽  
Vol 284 (1862) ◽  
pp. 20171489 ◽  
Author(s):  
Andreas Schuldt ◽  
Felix Fornoff ◽  
Helge Bruelheide ◽  
Alexandra-Maria Klein ◽  
Michael Staab
Keyword(s):  
Species Richness ◽  
Tree Species ◽  
Positive Relationship ◽  
Biodiversity Loss ◽  
Trophic Levels ◽  
Ecosystem Functions ◽  
Positive Effects ◽  
Tree Species Richness ◽  
Species Richness Gradient ◽  
Herbivore Communities

Interactions across trophic levels influence plant diversity effects on ecosystem functions, but the complexity of these interactions remains poorly explored. For example, the interplay between different interactions (e.g. mutualism, predation) might be an important moderator of biodiversity–ecosystem function relationships. We tested for relationships between trophobioses (facultative ant–hemipteran mutualism) and leaf chewer herbivory in a subtropical forest biodiversity experiment. We analysed trophobiosis and herbivory data of more than 10 000 trees along a tree species richness gradient. Against expectations, chewing damage was higher on trees with trophobioses. However, the net positive relationship between trophobioses and overall herbivory depended on tree species richness, being most pronounced at low richness. Our results point to indirect, positive effects of ant-tended sap suckers on leaf chewers, potentially by altering plant defences. Direct antagonistic relationships of trophobiotic ants and leaf-chewing herbivores—frequently reported to drive community-wide effects of trophobioses in other ecosystems—seemed less relevant. However, antagonistic interactions likely contributed to the attenuating effect of tree species richness, because trophobiotic ant and herbivore communities changed from monocultures to species-rich mixtures. Our findings, therefore, suggest that biodiversity loss might lead to complex changes in higher trophic level effects on ecosystem functions, mediated by both trophic and non-trophic interactions.

Effects of forest fragmentation on assemblages of pollinators and floral visitors to male- and female-phase inflorescences of Astrocaryum mexicanum (Arecaceae) in a Mexican rain forest

2010 ◽  
Vol 27 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Armando Aguirre ◽  
Roger Guevara ◽  
Rodolfo Dirzo
Keyword(s):  
Species Richness ◽  
Forest Fragmentation ◽  
Rain Forest ◽  
Diversity Index ◽  
Fragment Size ◽  
Forest Fragments ◽  
Male And Female ◽  
Female Phase ◽  
Male Phase ◽  
Floral Visitors

Abstract:We examined the consequences of habitat fragmentation on the assemblage of floral visitors and pollinators to male- and female-phase inflorescences of the understorey dominant palm Astrocaryum mexicanum at the Los Tuxtlas tropical rain forest. In six forest fragments ranging from 2 to 700 ha, we collected all floral visitors, pollinators and non-pollinators, to male- and female-phase inflorescences at the time of their greatest activity. We used multivariate and mixed-effects models to explore differences in guild composition between sexual phases of inflorescences and the effects of forest fragment size on several metrics of the assemblages of floral visitors. We detected 228 786 floral visitors, grouped into 57 species, across the six forest fragments. On average, abundance and species richness of floral visitors to female-phase inflorescences were higher than to male-phase ones. Forest fragmentation had no effect on species richness but negatively affected Shannon's diversity index. Overall, the most abundant species of floral visitors were predominantly found in inflorescences of plants from the large fragments. In contrast, most of the less common species were more abundant in the smallest fragments. The abundance of pollinators (those found on inflorescences of both phases and dusted with pollen that was carried to flower stigmas), and the ratio of pollinators to other floral visitors, increased with fragment size in both sexual phases of the inflorescences but these effects were significantly stronger on male-phase inflorescences than on female-phase inflorescences. These results show that tropical forest fragmentation correlates with changes in the composition of flower visitors to a dominant palm, with a reduction in the abundance of pollinators, but that such changes co-vary with the sexual phase of the plants.

scholarly journals Orchid bees in riparian and terra-firme forest fragments in an urban matrix in southwestern Brazilian Amazonia

2021 ◽  
Vol 51 (3) ◽  
pp. 214-223
Author(s):  
Maria Eliene Maia Braga CÂNDIDO ◽  
Patrícia Nakayama MIRANDA ◽  
Elder Ferreira MORATO
Keyword(s):  
Species Richness ◽  
Amazon Basin ◽  
Urban Landscape ◽  
Riparian Forests ◽  
Forest Fragments ◽  
Terra Firme ◽  
Orchid Bees ◽  
Significant Difference ◽  
Terra Firme Forest ◽  
Species Richness And Abundance

ABSTRACT Riparian forests are important ecosystems that support an enormous biodiversity in Brazil. Despite being protected under Brazilian legislation, these forests suffer great impact from the fragmentation of habitats. Orchid bees are a key group of pollinators in the Neotropical region, yet few data are available on the assamblage structure of these bees in riparian forests. We evaluated the role of fragments of riparian and terra-firme forest on the conservation and maintenance of orchid bees in an urban landscape in the southwestern Amazon basin. Specifically, we evaluated whether bee assemblages in riparian and terra-firme forests differed significantly in abundance, species richness and composition. We also evaluated whether species richness and abundance of bees vary with the size of the forest fragment. Male bees were attracted using odoriferous baits and collected with entomological nets in 10 forest fragments. There was no significant difference between riparian and terra-firme fragments in species abundance, richness and composition, but there was a positive correlation between fragment size and species richness and abundance. Our results suggest that, in an urban landscape, the remaining riparian and terra-firme forest fragments still could maintain 62.7% of the orchid bee species known to occur in the region, reinforcing the conservation value of these forest remnants. Our findings indicate that these fragments provide a potentially important habitat for the maintenance of local bee populations in the landscape.

scholarly journals Effect of environmental parameters on squamate reptiles in an urban forest fragment in central Amazonia

2020 ◽  
Vol 50 (3) ◽  
pp. 239-245
Author(s):  
Thais ALMEIDA-CORRÊA ◽  
Luciana FRAZÃO ◽  
Diogo Magalhães COSTA ◽  
Marcelo MENIN ◽  
Igor Luis KAEFER
Keyword(s):  
Species Richness ◽  
Urban Forest ◽  
Structural Parameters ◽  
Environmental Parameters ◽  
Forest Fragments ◽  
Forest Fragment ◽  
Tropical Biodiversity ◽  
Central Amazonia ◽  
Regional Species Pool ◽  
Species Richness And Abundance

ABSTRACT The increasing urbanization of the Amazonian biome has promoted the creation of several forest fragments surrounded by an urban matrix, but the relationship of animal assemblages to the urban environment, especially in forest fragments, is poorly known. Here we aimed to 1) determine the composition of the squamate fauna of the largest urban forest fragment from central Amazonia, in the Brazilian city of Manaus, and 2) evaluate the influence of environmental parameters on assemblage diversity. We sampled 10 standardized riparian plots through visual search in six surveys between 2008/09 and 2015, totaling 360 observer-hours. We found 15 species of lacertoids (lizards and amphisbaenians) and seven species of snakes through active search. After considering occasional encounters and search in museum collections, we recorded a total of 24 lacertoid and 22 snake species. Multiple regression models indicated that species richness and abundance of individuals increased with the distance from the edge of the fragment, while other structural parameters of the environment did not affect the assemblage. We conclude that this forest fragment 1) consists of a subset of the regional species pool, and 2) undergoes reduction of species richness and abundance of individuals from the center to the borders. This and additional urban forest fragments should be continually monitored in order to evaluate their long-term role in maintaining the tropical biodiversity.

scholarly journals Soil Carbon Storage and Its Determinants in Forest Fragments of Differentiated Patch Size

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 1044
Author(s):  
Chunyu Shen ◽  
Lei Ma ◽  
Jiaxi Hu ◽  
Liyang Huang ◽  
Yujuan Chen ◽  
...  
Keyword(s):  
Forest Fragmentation ◽  
Carbon Concentration ◽  
Fine Roots ◽  
Fine Root ◽  
Root Production ◽  
Forest Fragments ◽  
Fine Root Production ◽  
Litter Fall ◽  
Forest Edges ◽  
Biomass Storage

Research Highlights: Soil carbon storage (SOC) decreased due to forest fragmentation through lower proportion of macroaggregate distribution, higher storage of fine roots and litter falls, and lower fine root production rate. Background and Objectives: Globally, forest fragmentation processes lead to enormous losses of SOC in forests. We investigated SOC and its determinants in forest fragments experiencing edge disturbances in south China. Materials and Methods: Soil aggregate characteristics, dynamics of fine roots, and litter fall were studied from forest edges to interiors. Generalized linear mixed models were used to model the contributions of fine root and litter fall dynamics to carbon concentration in aggregates. Results: Large and small macroaggregates had higher proportion of aggregate distribution and contributed more carbon to SOC in all types of plots in the present study. SOC significantly increased from forest edges to interiors due to carbon concentration of these two aggregate types increasing from edges to interiors, while the proportion of different aggregate distributions was similar within each plot. The same trend was found with increasing forest patch size. Fine root biomass storage had the strongest impact on carbon concentration in large macroaggregates and microaggregates, with higher fine root biomass storage associated with lower carbon concentration. In addition, biomass storage and production rates of both fine roots and litter falls decreased from forest interiors to edges. Our results showed that SOC was significantly decreased due to the lower proportion of large and small macroaggregate distribution, and lower fine root production rate in forest fragments. Conclusions: SOC loss due to effects of forest fragmentation and forest edges occurred through decreased concentrations of soil aggregates and fine root production rates. Results from this study will enhance our ability to evaluate soil aggregate, fine root, and leaf litter fall contributions to SOC within forest fragments, and to suggest basic recommendations for the management and conservation of these forest fragments.

scholarly journals Assessing agri-environmental schemes for semi-natural grasslands during a 5-year period: can we see positive effects for vascular plants and pollinators?

2019 ◽  
Vol 28 (14) ◽  
pp. 3989-4005 ◽  
Author(s):  
Åke Berg ◽  
Erik Cronvall ◽  
Åsa Eriksson ◽  
Anders Glimskär ◽  
Matthew Hiron ◽  
...  
Keyword(s):  
Species Richness ◽  
Vascular Plants ◽  
Grazing Intensity ◽  
Landscape Composition ◽  
Negative Effects ◽  
Positive Effects ◽  
Vegetation Height ◽  
Natural Grasslands ◽  
Species Richness And Abundance ◽  
Over Time

Abstract An important function of agri-environmental schemes (AES) is to change management of pastures to better conserve biodiversity. However, the effects of most AES on biodiversity are poorly understood, especially when it comes to effects of AES management over time. The main aim of this study is to investigate if the species richness and abundance of grassland specialists of vascular plants and two important insect pollinator groups (bumblebees and butterflies) differ over time (5 years) in pastures with AES management (two value levels; general values and special values) and pastures without AES management. We also investigate if local vegetation characteristics and landscape composition relate to species richness in semi-natural grasslands. Using data from more than 400 sites we found that species richness of vascular plants (grassland specialists) was higher in pastures with AES management (for special and general values) compared to those without AES, which implies that these schemes do have value of the conservation of plant diversity. However, species richness and abundance of butterflies (grassland specialists) and bumblebees (all species) did not differ significantly among the three AES categories. We found no evidence that the type of AES management caused any changes in species richness of plants, butterflies or bumblebees during the 5 year period of our investigation. It appears that AES management that encourages uniform and minimum levels of grazing can have both positive and negative effects on biodiversity. For example, pollinators may benefit from a lower grazing intensity that could increase flower richness and heterogeneity in vegetation height. However, low grazing intensity may lead to increased cover of trees and shrubs, which can have negative effects for both insect pollinators and vascular plants. The effects of landscape composition were weak and only species richness of bumble bees were associated with landscape composition. Designing management regimes to maintain suitably heterogeneous vegetation layer, and continued long-term monitoring of biodiversity will be critical for safeguarding culturally and functionally important semi-natural grasslands.

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