排序方式: 共有39条查询结果,搜索用时 31 毫秒
31.
Stephanie B. Harris Ulrike W. Tschirner Adam Gillespie Madeleine J. Seeger 《Journal of Polymers and the Environment》2018,26(8):3262-3271
Compostable terpolymers of l-lactide (LLA), delta-valerolactone (DVL), and switchgrass organosolv lignin (OSL) were synthesized via ring-opening polymerization to improve on polylactide homopolymer properties for commercial applications. OSL has properties that improve some of the deficiencies of polylactide, including polylactide’s limitations for use in food, beverage and medical applications due to its high water permeability and low ultraviolet light (UV) blocking capabilities. DVL was incorporated into these polymers to add flexibility. The addition of DVL to the polymer had a positive effect on the tensile strain properties of the resultant terpolymer, resulting in a more flexible polymer with a reduced Young’s modulus. Water vapor transmission rate calculations confirmed that water vapor was transported more slowly through terpolymer films than through the PLLA homopolymer under varying hygrostatic conditions. While the addition of DVL increased UV permeability, the addition of even a small amount of lignin can effectively counteract this effect. 相似文献
32.
Pawel Wasowicz Alexander N. Sennikov Kristine B. Westergaard Katie Spellman Matthew Carlson Lynn J. Gillespie Jeffery M. Saarela Steven S. Seefeldt Bruce Bennett Christian Bay Stefanie Ickert-Bond Henry Vre 《Ambio》2020,49(3):693-703
We present a comprehensive list of non-native vascular plants known from the Arctic, explore their geographic distribution, analyze the extent of naturalization and invasion among 23 subregions of the Arctic, and examine pathways of introductions. The presence of 341 non-native taxa in the Arctic was confirmed, of which 188 are naturalized in at least one of the 23 regions. A small number of taxa (11) are considered invasive; these plants are known from just three regions. In several Arctic regions there are no naturalized non-native taxa recorded and the majority of Arctic regions have a low number of naturalized taxa. Analyses of the non-native vascular plant flora identified two main biogeographic clusters within the Arctic: American and Asiatic. Among all pathways, seed contamination and transport by vehicles have contributed the most to non-native plant introduction in the Arctic. 相似文献
33.
Taylor Jason J. Lawler James P. Aronsson Mora Barry Tom Bjorkman Anne D. Christensen Tom Coulson Stephen J. Cuyler Christine Ehrich Dorothee Falk Knud Franke Alastair Fuglei Eva Gillespie Mark A. Heiðmarsson Starri Høye Toke Jenkins Liza K. Ravolainen Virve Smith Paul A. Wasowicz Pawel Schmidt Niels Martin 《Ambio》2020,49(3):833-847
Ambio - This review provides a synopsis of the main findings of individual papers in the special issue Terrestrial Biodiversity in a Rapidly Changing Arctic. The special issue was developed to... 相似文献
34.
Gillespie Mark A. K. Alfredsson Matthias Barrio Isabel C. Bowden Joseph J. Convey Peter Culler Lauren E. Coulson Stephen J. Krogh Paul Henning Koltz Amanda M. Koponen Seppo Loboda Sarah Marusik Yuri Sandström Jonas P. Sikes Derek S. Høye Toke T. 《Ambio》2020,49(3):718-731
Ambio - The Circumpolar Biodiversity Monitoring Programme (CBMP) provides an opportunity to improve our knowledge of Arctic arthropod diversity, but initial baseline studies are required to... 相似文献
35.
Mark A. K. Gillespie Matthias Alfredsson Isabel C. Barrio Joe Bowden Peter Convey Stephen J. Coulson Lauren E. Culler Martin T. Dahl Kathryn M. Daly Seppo Koponen Sarah Loboda Yuri Marusik Jonas P. Sandstrm Derek S. Sikes Jozef Slowik Toke T. Hye 《Ambio》2020,49(3):704-717
The terrestrial chapter of the Circumpolar Biodiversity Monitoring Programme (CBMP) has the potential to bring international multi-taxon, long-term monitoring together, but detailed fundamental species information for Arctic arthropods lags far behind that for vertebrates and plants. In this paper, we demonstrate this major challenge to the CBMP by focussing on spiders (Order: Araneae) as an example group. We collate available circumpolar data on the distribution of spiders and highlight the current monitoring opportunities and identify the key knowledge gaps to address before monitoring can become efficient. We found spider data to be more complete than data for other taxa, but still variable in quality and availability between Arctic regions, highlighting the need for greater international co-operation for baseline studies and data sharing. There is also a dearth of long-term datasets for spiders and other arthropod groups from which to assess status and trends of biodiversity. Therefore, baseline studies should be conducted at all monitoring stations and we make recommendations for the development of the CBMP in relation to terrestrial arthropods more generally. 相似文献
36.
Thomas W. Gillespie 《Conservation biology》2001,15(3):699-709
Abstract: An increasing number of empirical studies have been done on the effects of tropical forest fragmentation on avian communities, but few researchers have applied these theories to assess the vulnerability of birds in poorly researched countries such as Nicaragua. I used a logistic regression to determine which natural-history characteristics were most important in predicting a list of threatened birds known to occur in Nicaragua. The best model included five macroecological variables ( body weight, habitat specificity, trophic group, forest preference, and biogeography within Nicaragua). I used this model to generate predicted probabilities of extinction for all forest birds in Nicaragua. The predicted probability of extinction from the best model ranked 63% of the extinction-prone birds from La Selva, Costa Rica, and 59% of the extinction-prone birds from Barro Colorado, Panama, in the first quartile of all forest birds recorded in Nicaragua. This method provides a first-order approximation of which species deserve global and national priorities for conservation. The central and Atlantic regions of Nicaragua deserve high priority for conservation at a global scale, whereas the Atlantic region deserves the highest priority for conservation at a national scale. The Nicaraguan Ministry of Natural Resources and the Environment has done an adequate job of identifying areas for conservation based on the proportion of decreed nature reserves in each biogeographic region and the distribution of forest birds with a high predicted probability of extinction. Forest birds in central Nicaragua, however, may currently be the most vulnerable to local extinction because of low forest cover within decreed reserves. 相似文献
37.
Comparative studies on plant species richness, endemism, floristic composition, and structure between protected and unprotected
forests are few in the Eastern Arc Mountains, one of the most biodiverse ecosystems in Africa. This study from one mountain
range, the East Usambaras, examines floristic and structural tree data from 41–0.5 ha plots in four types of Eastern Arc forest:
active agroforests, recently abandoned agroforests, mature secondary forest, and natural forest. Active agroforests had significantly
lower tree species richness, endemic species richness, and stand density compared to natural and mature secondary forest.
Recently abandoned agroforests contained a higher tree species richness, density, and tree height than active agroforests.
Active and abandoned agroforests were dominated by an invasive tree, Maesopsis eminii. This tree species makes up a large percentage of the stems in active agroforests (26%), recently abandoned agroforests (32%),
and in the canopy of mature secondary forests ∼ 30 years post logging (30%). Through time the increasing dominance of this
non-native tree in active agroforests is a concern when considering the role of agroforests in a landscape scale conservation
strategy. 相似文献
38.
Effects of mussel aquaculture on the nitrogen cycle and benthic communities in Kenepuru Sound,Marlborough Sounds,New Zealand 总被引:9,自引:0,他引:9
Nitrogen pools and transformations and benthic communities at a Perna canaliculus farm and a nearby reference site without direct influence of marine farming in Kenepuru Sound, New Zealand, were compared on four dates between September 1982 and May 1983. The organic nitrogen pool in the top 12 cm sediment was 7.4 to 10.8 mol m-2 at the mussel farm and 6.1 to 8.9 mol m-2 at the reference site. The nitrate and nitrite pools were similar in both sediments, but the ammonium pool in the mussel farm sediment was about twice as high as in the reference sediment. In January, the sediment ammonium concentrations ranged from 418 nmol cm-3 (surface) to 149 nmol cm-3 (12 cm depth) at the mussel farm and from 86 to 112 nmol cm-3 at the reference site. The molar C:N ratio of the sediment organic matter was 6.2 to 7.2 at the mussel farm and 7.9 to 10.0 at the reference site. The molar N:P ratio of the sediment organic matter was 4.3 to 7.2 and 3.3 to 6.1 at mussel farm and reference site, respectively. The total nitrogen mineralisation rate in the top 12 cm sediment ranged from 21.7 to 37.1 mmol m-2 d-1 at the mussel farm and from 8.5 to 25.0 mmol m-2 d-1 at the reference site. Ammonium excretion by mussels was about 4.7% (January) and 7.4% (May) of the combined nitrogen mineralisation by mussels and sediment. The sediment-denitrification rate was 0.7 to 6.1 mmol m-2 d-1 at the mussel farm and 0.1 to 0.9 mmol m-2 d-1 at the reference site. In January, 76 and 93% of the nitrate reduced in the sediments were denitrified at the mussel farm and reference site, respectively. The denitrification rate on the mussel lines (determined on detritus-covered mussels) was twice the mussel farm sediment-denitrification rate and 10 times the reference sediment-denitrification rate. Total denitrification at the mussel farm was 21% higher than at the reference site. The loss of nitrogen through mussel harvest and denitrification was 68% higher at the mussel farm. The surface layers of both sediments contained about 75 mg m-2 chlorophyll a. Sediment phaeophytin levels were 52 mg m-2 at the reference site and 137 mg m-2 at the mussel farm. While the benthic infauna of the mussel-farm sediment consisted only of polychaete worms, the reference sediment contained also bivalve molluscs, brittle stars and crustaceans. 相似文献
39.
Ray C. Whittemore Larry E. LaFleur William J. Gillespie Gary A. Amendola Jennie Helms 《Chemosphere》1990,20(10-12)
This paper summarizes the distribution of concentrations of 2378 substituted dibenzo-p-dioxins and dibenzofurans in bleached kraft and sulfite mill pulps, wastewater sludges, and treated effluents in the U.S. in mid-1988. 相似文献