Bird assemblages in isolated Ficus trees in Kenyan farmland

2006 ◽  
Vol 22 (6) ◽  
pp. 723-726 ◽  
Author(s):  
G. W. Eshiamwata ◽  
D. G. Berens ◽  
B. Bleher ◽  
W. R. J. Dean ◽  
K. Böhning-Gaese
Keyword(s):  
Tropical Forests ◽  
Forest Fragmentation ◽  
Seedling Establishment ◽  
Agricultural Land ◽  
Agricultural Landscapes ◽  
Forest Patches ◽  
Frugivorous Birds ◽  
Fragmented Forest ◽  
Important Group ◽  
Disturbed Areas

Over the last few decades a rapid and extensive conversion of tropical forests to agricultural land has taken place resulting in mosaics of fragmented forest patches, pastures and farmland. While the effects of forest fragmentation on biodiversity have been intensively studied within the remaining forests, relatively little is known about the biodiversity in tropical farmland (Daily et al. 2001, Pimentel et al. 1992). Frugivorous birds are an important group of species in tropical farmland ecosystems. Frugivorous birds are significant seed dispersers and can play a prominent role in transporting seeds into disturbed areas and setting the stage for the regeneration of these systems. Isolated fleshy-fruited trees in agricultural landscapes have been shown to attract birds, leading to an increased seed rain and seedling establishment under their canopies (Carrière et al. 2002, Duncan & Chapman 1999, Guevara et al. 1986, 2004; Slocum & Horvitz 2000).

scholarly journals Estimating landscape structure effects on pollination for management of agricultural landscapes

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Ehsan Rahimi ◽  
Shahindokht Barghjelveh ◽  
Pinliang Dong
Keyword(s):  
Forest Fragmentation ◽  
Landscape Structure ◽  
Crop Production ◽  
Agricultural Landscape ◽  
Agricultural Land ◽  
Unit Area ◽  
Agricultural Landscapes ◽  
Edge Density ◽  
Forest Patches ◽  
New Forest

Abstract Background The growing human population around the world is creating an increased demand for food. In agricultural landscapes, forests are cleared and turned into agricultural land to produce more food. Increasing the productivity of agricultural land per unit area may prevent extreme forest degradation. Since many agricultural products are dependent on pollinators, it is possible to increase crop production by increasing the pollination rate in the agricultural landscapes. Pollinators are highly dependent on forest patches in agricultural landscapes. Therefore, by creating new forest patches around agricultural fields, we can increase the pollination rate, and thus the crop production. In this regard, estimating the effects of different scenarios of forest fragmentation helps us to find an optimized pattern of forest patches for increasing pollination in an agricultural landscape. Methods To investigate the effect of different forest fragmentation scenarios on pollination, we used simulated agricultural landscapes, including different forest proportions and degrees of fragmentation. Using landscape metrics, we estimated the relationship between pollination and landscape structure for each landscape. Results Our results showed that for increasing pollination, two significant factors should be considered: habitat amount and capacity of small patches to supply pollination. We found that when the capacity of small patches in supplying pollination was low, fragmented patterns of forest patches decreased pollination. With increasing capacity, landscapes with a high degree of forest fragmentation showed the highest levels of pollination. There was an exception for habitat amounts (the proportion of forest patches) less than 0.1 of the entire landscape where increasing edge density, aggregation, and the number of forest patches resulted in increasing pollination in all scenarios. Conclusion This study encourages agriculturists and landscape planners to focus on increasing crop production per unit area by pollinators because it leads to biodiversity conservation and reduces socio-economic costs of land-use changes. We also suggest that to increase pollination in agricultural landscapes by creating new forest patches, special attention should be paid to the capacity of patches in supporting pollinators.

scholarly journals Bird communities in a degraded forest biodiversity hotspot of East Africa

2021 ◽  
Author(s):  
Moses Mulwa ◽  
Mike Teucher ◽  
Werner Ulrich ◽  
Jan Christian Habel
Keyword(s):  
Tropical Forests ◽  
Agricultural Land ◽  
Bird Species ◽  
Bird Communities ◽  
Natural Forest ◽  
Tree Plantations ◽  
Agricultural Fields ◽  
Degraded Forest ◽  
Forest Patches ◽  
Small Forest

AbstractTropical forests suffer severe habitat destruction. Thus, tropical forests frequently consist today of only a few small remnants that are often embedded within a matrix of agricultural fields and tree plantations. Forest specialist species have experienced severe population declines under these circumstances. We studied bird communities based on census plots set up in a near-natural forest block, as well as degraded forest patches, tree plantations, and agricultural fields, across the Taita Hills in southern Kenya. We classified each bird species according its ecology and behavior. We quantified the land cover and landscape configuration around each census plot. Typical forest species were mainly observed in the near-natural forest block, and to a lower extent in degraded forest patches. Plantations were almost devoid of birds. Bird communities of small forest fragments were more similar to that of agricultural land than the near-natural forest block. Most frugivorous, insectivorous and nectarivorous birds occurred in forest habitats, while granivorous bird species dominated the bird communities of agricultural land. The surrounding landscape had a marginal impact on bird species composition at local sites. Our study showed that the preservation of near-natural cloud forest, including small forest patches, is essential for the conservation of forest-dependent species, and that plantations do not serve as surrogate habitats.

Observations on the aggregation of adult cicadas (Homoptera: Cicadidae) in tropical forests

1980 ◽  
Vol 58 (5) ◽  
pp. 711-722 ◽  
Author(s):  
Allen M. Young
Keyword(s):  
Tropical Forests ◽  
Tree Species ◽  
Secondary Forest ◽  
Life Cycles ◽  
Direct Sunlight ◽  
Patchy Distribution ◽  
Forest Patches ◽  
Feeding Sites ◽  
Fragmented Forest ◽  
Forest Habitats

The distribution of adult cicadas in various tree species was studied in Costa Rica. These observations indicate that tropical cicadas, mostly males, often congregate in certain tree species in various kinds of secondary forest habitats. Aggregated male cicadas exhibit intense chorusing and females fly into chorusing aggregations, presumably for mating. Trees used for aggregations are also cicada feeding sites. The conspicuous absence of oviposition evidence or nymphal skins suggest that these trees are used primarily for intensive male chorusing which assembles females for mating. Tendency to congregate in particular trees is related to the spatial position of the trees and their exposure to direct sunlight. Highly fragmented forest patches in some regions (central highlands, lowland Guanacaste) function as islands for cicadas to complete their life cycles and mating, whereas the abundant secondary forest habitats in other regions (northeastern lowlands) are being invaded by a few species which use secondary forest trees for completion of life cycles and mating. The apparent absence of dense aggregations of adult cicadas within climax tropical forests, even though nymphal skins are found here, is probably related to the very patchy distribution of individuals of each tree species and perhaps other factors (i.e., shading) affecting the attractiveness of trees for congregating cicadas.

The effects of habitat fragmentation by forestry and agriculture on the abundance of small mammals in the southern boreal mixedwood forest

1998 ◽  
Vol 76 (1) ◽  
pp. 62-69 ◽  
Author(s):  
Erin M Bayne ◽  
Keith A Hobson
Keyword(s):  
Small Mammals ◽  
Agricultural Land ◽  
Deer Mouse ◽  
Abundant Species ◽  
Agricultural Landscapes ◽  
Tamiasciurus Hudsonicus ◽  
Deer Mice ◽  
Forest Patches ◽  
Significant Difference ◽  
Boreal Mixedwood Forest

To determine the effects of forest fragmentation on the abundance of small mammals, we livetrapped at edges and in the interior of forest patches in contiguous, logged, and agricultural landscapes in the southern boreal mixedwood forest of Saskatchewan. From 1994 to 1996, we captured 1548 small mammals (11 species) during 8172 trap-nights. The abundance of all small mammals combined was lower in forest patches isolated by logging than in contiguous forest or farm woodlots surrounded by agricultural land. This pattern was consistent in all years, despite significant annual fluctuations in numbers of the boreal red-backed vole (Clethrionomys gapperi), one of the most abundant species in our study area. Red squirrels (Tamiasciurus hudsonicus) and northern flying squirrels (Glaucomys sabrinus) were more abundant in farm woodlots. The abundance of deer mice (Peromyscus maniculatus) was significantly lower in forest patches surrounded by clearcuts, and we speculate that they may have used clearcuts more than forest patches. In contrast, the numbers of boreal red-backed voles were similar among landscapes. The only species showing a response to edge was the deer mouse, which was significantly more abundant at edges of farm woodlots than in interiors. We also found no significant difference in abundance of any species between small (10 ha) and large (>>20 ha) farm woodlots. For most species, within-landscape attributes such as edge and patch size seemed to have little effect on their abundance. However, for a variety of reasons, small-mammal numbers seem to vary considerably among forest patches in different landscapes.

scholarly journals Themeda quadrivalvis (grader grass).

2020 ◽  
Author(s):  
Julissa Rojas-Sandoval
Keyword(s):  
Dominican Republic ◽  
Seedling Establishment ◽  
Agricultural Land ◽  
New Caledonia ◽  
Indian Subcontinent ◽  
Fire Regimes ◽  
Ecosystem Change ◽  
South East Asia ◽  
Annual Grass ◽  
Disturbed Areas

Abstract Themeda quadrivalvis is an annual grass found as a weed in grasslands, disturbed areas and agricultural land. It is native to the Indian Subcontinent and South East Asia but has been widely introduced to the Americas, Africa and Oceania. It is recorded as invasive in Mexico, Cuba, Dominican Republic, Reunion, Australia, Fiji and New Caledonia. It is spread unintentionally as a contaminant in straw packing, pasture seed and on vehicles and machinery. Once established, it forms dense thickets that prevent seedling establishment; this causes ecosystem change, altered fire regimes and reduced native biodiversity.

scholarly journals The importance of orangutans in small fragments for maintaining metapopulation dynamics

2020 ◽  
Author(s):  
Marc Ancrenaz ◽  
Felicity Oram ◽  
Nardiyono Nardiyono ◽  
Muhammad Silmi ◽  
Marcie Elene Marcus Jopony ◽  
...  
Keyword(s):  
Oil Palm ◽  
Agricultural Landscapes ◽  
Genetic Connectivity ◽  
Forest Fragments ◽  
Multiple Use ◽  
Conservation Areas ◽  
Forest Patches ◽  
Fragmented Forest ◽  
Ground Survey

Orangutans (Pongo spp.) occur at low densities and therefore large areas are necessary to sustain viable metapopulations, defined here as sets of conspecific units of individuals linked by dispersal. Historically, orangutans lived in large contiguous areas of intact rainforest, but are now increasingly found in agricultural and other landscapes modified by people. Here we collate evidence of orangutans utilizing isolated forest fragments (< 500 ha) within multiple-use landscapes dominated by oil palm monoculture across Borneo. Orangutan signs (i.e. nests) were evident in 76 fragments surveyed by helicopter, and in 50 of 70 additional fragments surveyed on the ground; on average 63 ha in size. This includes presence of adult resident females with dependent young confirmed in 40% of the fragments assessed by ground survey. Our study revealed some resident females are raising offspring in isolated forest patches within mature oil palm stands. This not only confirms that some forest patches can sustain orangutans, but indicates migratory males are capable of reaching these fragments scattered throughout the multiple-use landscape. Therefore, orangutans that use or live in even small isolated forest patches are an essential part of the overall metapopulation by maintaining gene flow between, and genetic connectivity within, populations distributed across larger multiple-use landscapes. Orangutan survival is commonly thought to be low in small, isolated forest patches, and the customary management strategy is to remove (translocate) these individuals and release them in larger forests. In some cases, translocations may be necessary, i.e. in case of fire or when the animals are in eminent danger of being killed and have no other refuge. However, the small amount of data available indicates that mortality rates during and after translocations are high, while the impacts of removing animals from spatially dispersed metapopulations are unknown. Therefore, we argue the current policy of routine translocation rather than conserving the species within human-modified landscapes could inadvertently decrease critical metapopulation functionality necessary for long-term viability. It is clear that orangutans need natural forest to survive, but our findings show that fragmented agricultural landscapes can also serve as complementary conservation areas in addition to fully protected areas if they are well designed with ecological connections, and if orangutan killing can be prevented. To achieve this, we call for a paradigm shift from the traditional large single forest model to one that emphasizes metapopulation functionality in the fragmented forest - human use matrix characteristic of the Anthropocene.

scholarly journals Spatial Analysis of the Drivers, Characteristics, and Effects of Forest Fragmentation

2021 ◽  
Vol 13 (6) ◽  
pp. 3246
Author(s):  
Zoe Slattery ◽  
Richard Fenner
Keyword(s):  
Forest Fragmentation ◽  
Forest Fires ◽  
Geographical Information ◽  
Agricultural Expansion ◽  
Forest Patches ◽  
Mato Grosso ◽  
Remote Imaging ◽  
Landscape Characteristics ◽  
High Level

Building on the existing literature, this study examines whether specific drivers of forest fragmentation cause particular fragmentation characteristics, and how these characteristics can be linked to their effects on forest-dwelling species. This research uses Landsat remote imaging to examine the changing patterns of forests. It focuses on areas which have undergone a high level of a specific fragmentation driver, in particular either agricultural expansion or commodity-driven deforestation. Seven municipalities in the states of Rondônia and Mato Grosso in Brazil are selected as case study areas, as these states experienced a high level of commodity-driven deforestation and agricultural expansion respectively. Land cover maps of each municipality are created using the Geographical Information System software ArcGIS Spatial Analyst extension. The resulting categorical maps are input into Fragstats fragmentation software to calculate quantifiable fragmentation metrics for each municipality. To determine the effects that these characteristics are likely to cause, this study uses a literature review to determine how species traits affect their responses to forest fragmentation. Results indicate that, in areas that underwent agricultural expansion, the remaining forest patches became more complex in shape with longer edges and lost a large amount of core area. This negatively affects species which are either highly dispersive or specialist to core forest habitat. In areas that underwent commodity-driven deforestation, it was more likely that forest patches would become less aggregated and create disjunct core areas. This negatively affects smaller, sedentary animals which do not naturally travel long distances. This study is significant in that it links individual fragmentation drivers to their landscape characteristics, and in turn uses these to predict effects on species with particular traits. This information will prove useful for forest managers, particularly in the case study municipalities examined in this study, in deciding which species require further protection measures. The methodology could be applied to other drivers of forest fragmentation such as forest fires.

scholarly journals Analysis of spatiotemporal changes of agricultural land after the Second World War in Czechia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Vít Zelinka ◽  
Johana Zacharová ◽  
Jan Skaloš
Keyword(s):  
Land Use ◽  
Agricultural Land ◽  
Population Change ◽  
Temporal Analysis ◽  
Second World War ◽  
Agricultural Landscapes ◽  
German Population ◽  
World War ◽  
Landscape Type ◽  
Second World

AbstractThe term Sudetenland refers to large regions of the former Czechoslovakia that had been dominated by Germans. German population was expelled directly after the Second World War, between 1945 and 1947. Almost three million people left large areas in less than two years. This population change led to a break in the relationship between the people and the landscape. The aim of the study is to compare the trajectories of these changes in agricultural landscapes in lower and higher altitudes, both in depopulated areas and areas with preserved populations. This study included ten sites in the region of Northern Bohemia in Czechia (18,000 ha in total). Five of these sites represent depopulated areas, and the other five areas where populations remained preserved. Changes in the landscape were assessed through a bi-temporal analysis of land use change by using aerial photograph data from time hoirzons of 2018 and 1953. Land use changes from the 1950s to the present are corroborated in the studied depopulated and preserved areas mainly by the trajectory of agricultural land to forest. The results prove that both population displacement and landscape type are important factors that affect landscape changes, especially in agricultural landscapes.

scholarly journals Evolutionary cascades induced by large frugivores

2017 ◽  
Vol 114 (45) ◽  
pp. 11998-12002 ◽  
Author(s):  
Jedediah F. Brodie
Keyword(s):  
Tropical Forests ◽  
Fruit Size ◽  
Peninsular Malaysia ◽  
Fruit Color ◽  
Small Animals ◽  
Fruit Traits ◽  
Frugivorous Birds ◽  
Large Animals ◽  
Evolutionary Consequences ◽  
Morphologic Changes

Large, fruit-eating vertebrates have been lost from many of the world’s ecosystems. The ecological consequences of this defaunation can be severe, but the evolutionary consequences are nearly unknown because it remains unclear whether frugivores exert strong selection on fruit traits. I assessed the macroevolution of fruit traits in response to variation in the diversity and size of seed-dispersing vertebrates. Across the Indo-Malay Archipelago, many of the same plant lineages have been exposed to very different assemblages of seed-dispersing vertebrates. Phylogenetic analysis of >400 plant species in 41 genera and five families revealed that average fruit size tracks the taxonomic and functional diversity of frugivorous birds and mammals. Fruit size was 40.2–46.5% smaller in the Moluccas and Sulawesi (respectively), with relatively depauperate assemblages of mostly small-bodied animals, than in the Sunda Region (Borneo, Sumatra, and Peninsular Malaysia), with a highly diverse suite of large and small animals. Fruit color, however, was unrelated to vertebrate diversity or to the representation of birds versus mammals in the frugivore assemblage. Overhunting of large animals, nearly ubiquitous in tropical forests, could strongly alter selection pressures on plants, resulting in widespread, although trait-specific, morphologic changes.

scholarly journals On the Issue of Research of Information Support of Sustainable Agricultural Landscapes Formation

2020 ◽  
Keyword(s):  
Agricultural Land ◽  
Ecological Impact ◽  
Arable Land ◽  
Agricultural Landscapes ◽  
Information Support ◽  
Erosion Processes ◽  
Shelter Belts ◽  
Forest Belts ◽  
Methodological Approaches ◽  
The Creation

Purpose. To characterize the methodological approaches that we develop in the formation of a system of information support for the creation and maintenance of the functioning of modern sustainable agricultural landscapes and to show the results of their implementation on the example of the territory of some agricultural enterprises of the Kharkiv region. Methods. Cartographic, geoinformation analysis, calculation, statistical and mathematical. Results. Some results of the work of the collective on the issues of information support for the creation and maintenance of the functioning of modern sustainable agricultural landscapes. Namely, verification of erosion models, studies of the functionality of shelter belts, the formation of an agroeconet (an extensive network of natural and quasi-natural landscapes) on agricultural land massifs, which ensures the maintenance of stable functioning of meso and macrolevel agrolandscapes, as well as the experience of using magnetic prospecting methods to verify the results of mathematical modeling of erosion processes. Conclusions. A number of methodological approaches to information support of the formation of sustainable agricultural landscapes in the natural and socio-economic conditions of Ukraine have been developed. They relate to the functioning of anti-erosion measures of permanent action, the processes of modern transformation of agro-landscapes, the ecological impact of erosion processes on the environment. The connection between the length of forest belts per unit of arable land and soil erosion is shown. A methodical approach has been developed to estimate the amount of soil washed away from arable land and to calculate the measures necessary to eliminate its harmful effects on the environment.

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