Community organization: effects of landscape fragmentation

1988 ◽  
Vol 66 (12) ◽  
pp. 2687-2690 ◽  
Author(s):  
Robert L. Burgess
Keyword(s):  
Community Organization ◽  
Human Impacts ◽  
Landscape Management ◽  
Terrestrial Ecosystems ◽  
Landscape Fragmentation ◽  
Physical Factors ◽  
Natural Area ◽  
Ecosystem Integrity ◽  
Theory Of Island Biogeography ◽  
Future Work

All over the world, natural terrestrial ecosystems have been subjected to a wide variety of human impacts. Most noticeable are activities and processes associated with agriculture, forestry, mining, and urban development. Results range from virtual obliterations of natural communities through varying degrees of fragmentation to a series of preserves and natural areas. Studies of many taxa, both plant and animal, indicate numerous effects associated with the loss of contiguity, reduction in total area, relationship to physical factors, and increasing separation of remaining fragments. The theory of island biogeography has been tested in many kinds of landscapes and for many groups of organisms. The great differences between true islands and terrestrial "habitat islands" lead to inconclusive results in many investigations and to major questions concerning the applicability of the equilibrium model to fragmented terrestrial landscapes. This paper attempts to summarize indicative examples that have a bearing on community structure and organization and to present some ideas for future work in landscape management and its relation to species diversity, natural area preservation, and continued ecosystem integrity, viability, stability, and vitality.

Going with the flow: global warming and the challenge of sustaining river ecosystems in monsoonal Asia

2007 ◽  
Vol 7 (2) ◽  
pp. 69-80 ◽  
Author(s):  
D. Dudgeon
Keyword(s):  
Global Warming ◽  
Human Impacts ◽  
Habitat Destruction ◽  
Dispersal Ability ◽  
Suitable Habitat ◽  
Hydrologic Alteration ◽  
Ecological Processes ◽  
Ecosystem Integrity ◽  
River Ecosystems ◽  
The Rich

River ecosystems in monsoonal Asia are experiencing human impacts to the detriment of the rich biodiversity they support. Threats include hydrologic alteration, pollution, habitat destruction, overexploitation, and invasive exotic species. Global warming will cause further changes to river ecosystems, and may act synergistically with other threat factors. Significant upward or northward range adjustments by the freshwater biota will be necessary to cope with rising temperatures, but there will be significant constraints upon dispersal ability and availability of suitable habitat for many organisms. Global warming will exacerbate existing impacts of hydrologic alteration because of the adaptive human responses that will be engendered by changes in climate and runoff, particularly dams constructed for hydropower generation, flood protection, water storage, and irrigation. The consequences of further hydrologic alteration and habitat fragmentation will be profound, since almost all ecological processes, material transfers and life-cycle events in the rivers of monsoonal Asia are mediated or controlled by flow. Thus a change in the timing or amounts of flow changes everything. Collaborative research to determine the environmental allocation of water flow needed to maintain ecosystem integrity and sustain biodiversity in the human-dominated rivers of monsoonal Asia should be a priority for ecologists, engineers and water-resource managers.

Did prehistoric landscape management retard the post-glacial spread of woodland in Southwest Asia?

Antiquity ◽  
2002 ◽  
Vol 76 (294) ◽  
pp. 1002-1010 ◽  
Author(s):  
Neil Roberts
Keyword(s):  
Bronze Age ◽  
Human Impacts ◽  
Landscape Management ◽  
Southwest Asia ◽  
Mediterranean Environment ◽  
East Mediterranean ◽  
Late Season ◽  
Pollen Diagrams ◽  
New Evidence ◽  
Trees And Shrubs

Pre-Bronze Age human impacts on the East Mediterranean environment have been hard to detect in pollen diagrams and other off-site contexts. New evidence shows that despite a relatively rapid post-glacial wetting-up of the climate, the re-advance of oak woodland across Southwest Asia was slow. Among the factors likely to have contributed to the apparent disjunction between climate and vegetation is Neolithic landscape management, particularly through regular use of late-season ground fires to encourage grasses at the expense of trees and shrubs.

Variability of ecosystem carbon source from microbial respiration is controlled by rainfall dynamics

2021 ◽  
Vol 118 (52) ◽  
pp. e2115283118
Author(s):  
Heng Huang ◽  
Salvatore Calabrese ◽  
Ignacio Rodriguez-Iturbe
Keyword(s):  
Primary Productivity ◽  
Microbial Growth ◽  
Net Primary Productivity ◽  
Carbon Sources ◽  
Terrestrial Ecosystems ◽  
Rainfall Regime ◽  
Physical Factors ◽  
Scale Parameters ◽  
Complex Interactions ◽  
Soil Heterotrophic Respiration

Soil heterotrophic respiration (Rh) represents an important component of the terrestrial carbon cycle that affects whether ecosystems function as carbon sources or sinks. Due to the complex interactions between biological and physical factors controlling microbial growth, Rh is uncertain and difficult to predict, limiting our ability to anticipate future climate trajectories. Here we analyze the global FLUXNET 2015 database aided by a probabilistic model of microbial growth to examine the ecosystem-scale dynamics of Rh and identify primary predictors of its variability. We find that the temporal variability in Rh is consistently distributed according to a Gamma distribution, with shape and scale parameters controlled only by rainfall characteristics and vegetation productivity. This distribution originates from the propagation of fast hydrologic fluctuations on the slower biological dynamics of microbial growth and is independent of biome, soil type, and microbial physiology. This finding allows us to readily provide accurate estimates of the mean Rh and its variance, as confirmed by a comparison with an independent global dataset. Our results suggest that future changes in rainfall regime and net primary productivity will significantly alter the dynamics of Rh and the global carbon budget. In regions that are becoming wetter, Rh may increase faster than net primary productivity, thereby reducing the carbon storage capacity of terrestrial ecosystems.

Rocky-Shore Fishes

2002 ◽  
Author(s):  
Donald A. Thomson ◽  
Matthew R. Gilligan
Keyword(s):  
Open Water ◽  
Oceanic Islands ◽  
Physical Factors ◽  
Terrestrial Plants ◽  
Sea Temperature ◽  
Western Atlantic ◽  
Extinction Rates ◽  
Theory Of Island Biogeography ◽  
Pelagic Eggs ◽  
The Difference

Marine systems have provided little empirical or theoretical support for the equilibrium theory of island biogeography introduced by MacArthur and Wilson (1967; hereafter referred to as MacArthur-Wilson equilibria). In particular, although marine islands represent isolated habitats for shoreline-restricted marine organisms, it is clear that they do not have impoverished biotas relative to adjacent mainland shores as do their terrestrial counterparts. Additionally, it is not clear that colonization rates based on distance from propagule sources, and extinction rates based on island size, play a substantial role in determining the number and kind of species that may exist here. In this chapter we ask whether the gulf islands are biogeographic islands to rockyshore fishes as they are to terrestrial plants and animals. Although the adults and juveniles of most marine shore fishes cannot readily cross the deep waters separating landmasses, most marine fishes have pelagic eggs and larvae which are often found great distances from shore (Leis and Miller 1976; Leis 1991). Certain families of teleostean fishes (e.g., the blennioids and gobioids) have demersal eggs that are attached to a substrate, and only the larvae are dispersed by ocean currents. Some of these fishes have short-lived larvae that are normally found only close to shore (Brogan 1994). Considering such different types of dispersal mechanisms, one must conclude that distance over open water must be as formidable a barrier to dispersal in some fishes as it is to terrestrial organisms. In line with this conclusion, shore-fish faunas of oceanic islands show high degrees of endemism—for example, 23% in Galapagos shore fishes (Walker 1966), 23.1% and 22.2% in Hawaiian and Easter Island fishes, respectively (Randall 1998). It is well known that the marine insular environment differs considerably from the mainland or continental environment (Robins 1971). Essentially, the former is characterized by a more stable, predictable physical regime with moderate fluctuations in physical factors such as sea temperature, salinity, and turbidity, whereas the latter usually has wider and more unpredictable fluctuations in physical parameters. Robins (1971) compared the difference in species richness between insular and continental fish faunas of the tropical western Atlantic to that between a tropical and a temperate forest, respectively.

Human Impacts on Nearshore Shellfish Taxa: A 7,000 Year Record from Santa Rosa Island, California

2007 ◽  
Vol 72 (4) ◽  
pp. 735-756 ◽  
Author(s):  
Todd J. Braje ◽  
Douglas J. Kennett ◽  
Jon M. Erlandson ◽  
Brendan J. Culleton
Keyword(s):  
Behavioral Ecology ◽  
Human Impacts ◽  
Terrestrial Ecosystems ◽  
Human Populations ◽  
Faunal Remains ◽  
Sociopolitical Complexity ◽  
Intensive Exploitation ◽  
Nearshore Ecosystems ◽  
Human Predation ◽  
Santa Rosa Island

Within the broad framework of historical and behavioral ecology, we analyzed faunal remains from a large habitation site (CA-SRI-147) on Santa Rosa Island to explore a 7,000 year record of coastal subsistence, nearshore ecological dynamics, and human impacts on shellfish populations. This long, stratified sequence provides a rare opportunity to study the effects of prolonged human predation on local intertidal and nearshore habitats. During the past 7,000 years, the Island Chumash and their predecessors had significant impacts on nearshore ecosystems, caused by growing human populations and depletion of marine and terrestrial ecosystems. At CA-SRI-147, local depletion of higher ranked shellfish species stimulated dietary expansion and a heavier reliance on lower-ranked shellfish taxa and more intensive exploitation of nearshore and pelagic fishes. In the Late Holocene, as local ecosystems were increasingly depleted, the Island Chumash relied increasingly on craft specialization and trade to meet their subsistence needs. Native peoples clearly impacted Channel Island ecosystems, but data from CA-SRI-147 suggest that they adjusted their subsistence strategies toward productive fisheries that sustained the high population densities and sociopolitical complexity recorded by early Spanish chroniclers at European contact.

scholarly journals Science vs the Environment

1997 ◽  
Vol 9 (2) ◽  
pp. 119-119
Author(s):  
Clive Howard-Williams
Keyword(s):  
Human Impacts ◽  
Scientific Work ◽  
List Type ◽  
Natural Ecosystems ◽  
Minimal Impact ◽  
Science Community ◽  
Antarctic Treaty ◽  
Will Force ◽  
Future Work ◽  
The Impact

The Environmental Protocol to the Antarctic Treaty is rapidly approaching ratification, and nations which have now signed it see the Protocol as a signal for considerable future debate, if not scrutiny. Everyone has begun to implement, at least in spirit, many of its requirements which are now beginning to have an effect on science on the continent. This is currently evident in at least four different ways: a reallocation of funding from pure science, to �applied� science relating to human impacts,an increase in funding to allow for studies of human impact and the meeting of Protocol obligations,a reassessment by the science community on what can be done with minimal impact, and an imposition on the science community of rules and codes which will restrict many types of scientific work that have been carried out in the past, and will force modifications of future work. Because all science on the continent (as opposed too remote sensing from space) will have an impact there will have to be tradeoffs between the benefit to science and the impact of doing the work. We can only evaluate impacts on those areas of science that we know about at present. The problem is that there will be future, presently unknown areas of science that may be compromised by operations currently considered �safe�. Who knows, for instance, what viruses we are inadvertently spreading and what the importance of these will be in future studies? At present the effects of these organisms are difficult to measure but studies on the role of viruses in natural ecosystems are increasing as technology expands.

scholarly journals Seaduck engineers in the Arctic Archipelago: nesting eiders deliver marine nutrients and transform the chemistry of island soils, plants, and ponds

Oecologia ◽  
2021 ◽  
Vol 195 (4) ◽  
pp. 1041-1052
Author(s):  
N. Clyde ◽  
K. E. Hargan ◽  
M. R. Forbes ◽  
S. A. Iverson ◽  
J. M. Blais ◽  
...  
Keyword(s):  
Human Impacts ◽  
Terrestrial Ecosystems ◽  
The Arctic ◽  
Somateria Mollissima ◽  
Nutrient Inputs ◽  
Arctic Ecosystems ◽  
Coastal Marine ◽  
Common Eiders ◽  
Pond Sediments ◽  
Circumpolar Arctic

AbstractSeabirds are thought to provide ecological services such as the movement of nutrients between marine and terrestrial ecosystems, which may be especially critical to productivity and diversity in nutrient-poor environments. Most Arctic ecosystems are unaffected by local human impacts and are naturally nutrient poor and especially sensitive to warming. Here, we assessed the effects of nesting common eider ducks (Somateria mollissima) on soil, vegetation, and pond sediments on island archipelagoes in Hudson Strait between Nunavut and Québec, Canada. Soil, moss, and pond sediments were significantly higher in nitrogen on islands with large numbers of nesting eiders compared to sites with no nesting birds. The highest concentrations of nitrogen in soils and moss occurred at the margins of ponds on eider islands, which correspond to the areas of highest eider use. δ15N and δ34S values in soils, moss, and sediments indicated substantial marine-derived organic matter inputs at the higher nutrient sites. We propose that by foraging on coastal marine benthic invertebrates and returning to islands to nest, eider ducks bio-transport and concentrate marine-derived nutrients to their colony islands, fertilizing Arctic island ecosystems in the process. As common eiders nest on thousands of low to mid-latitude islands throughout the circumpolar Arctic, these nutrient inputs likely dramatically affect biota and ecosystem functioning throughout the tundra biome.

scholarly journals Towards monitoring ecosystem integrity within the Post-2020 Global Biodiversity Framework

2021 ◽  
Author(s):  
Andrew J. Hansen ◽  
Bengamin P. Noble ◽  
Jaris Veneros ◽  
Alyson East ◽  
Scott J. Goetz ◽  
...  
Keyword(s):  
Biological Diversity ◽  
Human Impacts ◽  
Ecological Integrity ◽  
Convention On Biological Diversity ◽  
Natural Ecosystems ◽  
Ecosystem Integrity ◽  
Essential Biodiversity Variables ◽  
Global Biodiversity ◽  
Restoration Strategies ◽  
Definition Of

Signatory countries to the Convention on Biological Diversity (CBD) are formulating indicators through 2030 under the post-2020 Global Biodiversity Framework (GBF). These goals include increasing the integrity of natural ecosystems. However, the definition of integrity and methods for measuring it remain unspecified. Moreover, nations did not achieve their 2011-2020 CBD targets, partly due to inability to monitor and report progress on these targets. Here, we define ecological integrity (EI) and suggest a framework to measure and evaluate trends in terrestrial EI. Our approach builds on three topics: the concept of ecological integrity, satellite-based Earth observation, and Essential Biodiversity Variables. Within this framework, EI is a measure of the structure, function and composition of an ecosystem relative to the pre-industrial range of variation of these characteristics. We recommend 13 indicators of EI to facilitate the efforts of nations to monitor, evaluate, and report during implementation of the post-2020 GBF. These indicators can help assess the condition of ecosystems relative to benchmark states, and track the degradation or improvement of ecosystem condition due to human impacts or restoration strategies. If operationalized, this framework can help Parties to the CBD systematically evaluate and report progress on achieving ecosystem commitments in the post-2020 GBF

scholarly journals Myanmar’s terrestrial ecosystems: status, threats and conservation opportunities

2020 ◽  
Author(s):  
Nicholas J. Murray ◽  
David A. Keith ◽  
Adam Duncan ◽  
Robert Tizard ◽  
Jose R. Ferrer-Paris ◽  
...  
Keyword(s):  
Human Impacts ◽  
Rapid Change ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Future Research ◽  
Area Network ◽  
Natural Ecosystems ◽  
Conservation Assessment ◽  
Conservation Action ◽  
Amphibian Species

AbstractMyanmar is highly biodiverse, with more than 16,000 plant, 314 mammal, 1131 bird, 293 reptile, and 139 amphibian species. Supporting this biodiversity is a variety of natural ecosystems—mostly undescribed—including tropical and subtropical forests, savannas, seasonally inundated wetlands, extensive shoreline and tidal systems, and alpine ecosystems. Although Myanmar contains some of the largest intact natural ecosystems in Southeast Asia, remaining ecosystems are under threat from accelerating land use intensification and over-exploitation. In this period of rapid change, a systematic risk assessment is urgently needed to estimate the extent and magnitude of human impacts and identify ecosystems most at risk to help guide strategic conservation action. Here we provide the first comprehensive conservation assessment of Myanmar’s natural terrestrial ecosystems using the IUCN Red List of Ecosystems categories and criteria. We identified 64 ecosystem types for the assessment, and used models of ecosystem distributions and syntheses of existing data to estimate declines in distribution, range size, and functioning of each ecosystem. We found that more than a third (36.9%) of Myanmar’s area has been converted to anthropogenic ecosystems over the last 2-3 centuries, leaving nearly half of Myanmar’s ecosystems threatened (29 of 64 ecosystems). A quarter of Myanmar’s ecosystems were identified as Data Deficient, reflecting a paucity of studies and an urgency for future research. Our results show that, with nearly two-thirds of Myanmar still covered in natural ecosystems, there is a crucial opportunity to develop a comprehensive protected area network that sufficiently represents Myanmar’s terrestrial ecosystem diversity.

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