1,721,226 research outputs found
After all the forests went up in smoke would your chocolate taste the same?
No full textIn the name of development, short pathways may be taken but ones had never been sure if life will continue. Tensions often felt when litigation go beyond the borders and tingle the nerves of the peasants. Today, it is difficult to differentiate between loves and hates, who are friends and enemies, winners and losers. But one thing is clear, for sure, everyone no longer needs jacket and tie as is the room is heated up
Trace gas fluxes and nitrogen cycling along an elevation sequence of tropical montane forests in Central Sulawesi, Indonesia
No full textStudies on soil-atmosphere flux of N2O, NO and CH4 in tropical forests have mainly focused on tropical lowland forests. Here we present the first intensive study of trace gas fluxes along an elevation sequence of tropical montane forests ranging from 1190 m to 2470 m elevation in Central Sulawesi, Indonesia. Using chamber techniques, we measured monthly flux rates and controlling factors on three elevations, each with three replicate plots for 1 year. Annual N2O fluxes ranged from 0.29 kg N ha−1 yr−1 at 1800 m to 1.01 kg N ha−1 yr−1 at 2470 m and 1.11 kg N ha−1 yr−1 at 1190 m, while annual NO fluxes ranged from 0.17 kg N ha−1 yr−1 at 1800 m, to 0.18 kg N ha−1 yr−1 at 2470 m and 0.48 kg N ha−1 yr−1 at 1190 m. Methane uptake ranged from 1.45 kg C ha−1 yr−1 at 2470 m to 2.45 kg C ha−1 yr−1 at 1190 m and 3.32 kg C ha−1 yr−1 at 1800 m. At the highest elevation, methane uptake was affected by the thick organic layer present at the surface of the soil. Several lines of evidence (soil N stocks, extractable inorganic N, litterfall mass, litterfall-N and δ15N signals in litterfall and soil organic matter) show that the annual N2O + NO emissions could be explained by the inherent N status of these forests. In a test of indices of N cycling to explain N2O and NO fluxes, the robustness of litterfall C/N and litterfall N was confirmed and the δ15N signal of litterfall emerged as promising driver for regional and global biogeochemical models that predict N2O + NO emissions from soil
Land use change effects on trace gas fluxes in the forest margins of Central Sulawesi, Indonesia
No full text1] Land use changes and land use intensification are considered important processes contributing to the increasing concentrations of the greenhouse gases nitrous oxide (N2O) and methane (CH4) and of nitric oxide (NO), a precursor of ozone. Studies on the effects of land use changes and land use intensification on soil trace gas emissions were mostly conducted in Latin America and only very few in Asia. Here we present results from Central Sulawesi where profound changes in land use and cultivation practices take place: traditional agricultural practices like shifting cultivation and slash-and-burn agriculture are replaced by permanent cultivation systems and introduction of income-generating cash crops like cacao. Our results showed that N2O emissions were higher from cacao agroforestry (35 ± 10 μg N m−2 h−1) than maize (9 ± 2 μg N m−2 h−1), whereas intermediate rates were observed from secondary forests (25 ± 11 μg N m−2 h−1). NO emissions did not differ among land use systems, ranging from 12 ± 2 μg N m−2 h−1 for cacao agroforestry and secondary forest to 18 ± 2 μg N m−2 h−1 for maize. CH4 uptake was higher for maize (−30 ± 4 μg C m−2 h−1) than cacao agroforestry (−18 ± 2 μg C m−2 h−1) and intermediate rates were measured from secondary forests (−25 ± 4 μg C m−2 h−1). Combining these data with results from other studies in this area, we present chronosequence effects of land use change on trace gas emissions from natural forest, through maize cultivation, to cacao agroforestry (with or without fertilizer). Compared to the original forests, this typical land use change in the study area clearly led to higher N2O emissions and lower CH4 uptake with age of cacao agroforestry systems. We conclude that this common land use sequence in the area combined with the increasing use of fertilizer will strongly increase soil trace gas emissions. We suggest that the future hot spot regions of high N2O (and to a lesser extend NO) emissions in the tropics are those areas where climatic and edaphic conditions allow for intensive agriculture. This scenario is probably preferable over the alternative of agriculture extensification, which would imply a dramatic increase in deforestation rates with accompanying CO2 emissions
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Analisis Perubahan Tutupan Lahan Mangrove Tahun 1997-2015 (Studi Kasus di Kabupaten Deli Serdang dan Taman Nasional Sembilang). Dibimbing
No full textMangrove adalah ekosistem yang unik karena kondisi tempat tumbuhnya yang terletak pada zona pasang-surut air laut, sehingga terjadi percampuran antara air laut dan air tawar. Karena itu mangrove juga mampu memberikan jasa ekosistem seperti perlindungan kawasan dari erosi dgelombang dan arus laut, habitat bagi berbagai jenis biota laut dan sebagainya. Kondisi tutupan lahan mangrove yang mulai menyusut perlu dimonitor untuk menentukan kebijakan tataruang dan pengelolaan kawasan mangrove. Penelitian ini bertujuan untuk (i) menduga laju deforestasi hutan mangrove, (ii) mendeteksi waktu terjadinya deforestasi berdasarkan indeks vegetasi di Kabupaten Deli Serdang dan TN. Sembilang dan (iii) Membandingkan kondisi tutupan lahan mangrove berdasarkan nilai indeks vegetasi pada periode IOD yang berbeda. Rata-rata laju deforestasi mangrove di Kabupaten Deli Serdang adalah 116,05 ha/tahun dan di Taman Nasional Sembilang sebesar 123,24 ha/tahun. Hal ini dikonfirmasi oleh nilai CUSUM indeks vegetasi (EVI2) yang menunjukkan terjadinya perubahan tutupan lahan mangrove menjadi tutupan lahan lain pada periode 1997-2015 di Kabupaten Deli Serdang yang dimulai pada bulan oktober 2000 sedangkan di Taman Nasional Sembilang dimulai pada bulan September 2001. Nilai EVI2 berbanding lurus dengan nilai curah hujan. Nilai R-square antara curah hujan dan EVI2 sebesar 0,1362 dengan waktu jeda 3 bulan. Nilai anomali EVI2 pada kondisi normal yaitu 0,0015 ± 0,051 sedangkan pada IOD+ nilai rata-rata anomali EVI2 berkurang sebesar 0,011 menjadi -0,0099 ± 0,046 dan pada IOD- bertambah sebesar 0,0046 menjadi 0,0061 ± 0,054
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Effects of Permeable Barriers on Total Ecosystem Carbon Stocks of Mangrove Forests and Abandoned Ponds in Demak Regency.
Get PDFKabupaten Demak mengalami perubahan garis pantai yang parah akibat konversi masal hutan mangrove menjadi tambak budidaya. Oleh karena itu, Kabupaten Demak mengatasi masalah erosi pesisir dengan membangun penghalang permeabel yang memodelkan struktur akar mangrove. Studi ini mengamati pengaruh hambatan tersebut di zona pesisir dataran rendah Kabupaten Demak dalam konteks struktur hutan mangrove dan dinamika karbon (C).
Struktur hutan ditunjukkan oleh kerapatan tegakan, luas bidang dasar, indeks ekologi (kekayaan, keanekaragaman, dan kemerataan), dominasi spesies, kesamaan komposisi spesies, dan penyebaran spesies. Dinamika C, yang dinyatakan sebagai stok karbon ekosistem total (TECS), dinilai dengan memperkirakan C pool dari biomassa di atas dan di bawah tanah, bahan organik mati, dan tanah. Studi ini menetapkan pengambilan sampel secara acak bertingkat untuk mengetahui struktur hutan mangrove dan TECS di hutan mangrove, tambak terbengkali, dan tambak produktif.
Avicennia marina mendominasi sebagian besar hutan mangrove di Kabupaten Demak (INP = 155.44). Hasil penelitian menunjukkan bahwa kerapatan pohon bervariasi dari 1378 ± 128 hingga 2244 ± 237 individu ha−1, sedangkan luas bidang dasar berkisar antara 9.29 ± 1.33 dan 13.56 ± 1.72 m2 ha−1. Secara statistik, hutan mangrove dengan atau tanpa perlindungan penghalang permeabel bervariasi pada kerapatan pohon tetapi tidak terlalu berbeda dalam hal luas bidang dasar. Studi ini juga menyoroti bahwa karbon di atas dan dibawah permukaan tanah tidak memberikan kontribusi yang besar terhadap variasi TECS. Pada saat yang sama, nilai C yang rendah dalam bentuk nekromassa menyiratkan bahwa ukuran C yang terkandung besar pada tanah bertanggung jawab atas variasi yang besar pada TECS.
Penelitian ini menemukan bahwa durasi penghalang permeabel di wilayah pesisir mempengaruhi ukuran C tanah yang ditangkap di lokasi mangrove, yaitu 618,84 ± 30,39 Mg C ha−1; 704,13 ± 17,73 Mg C ha−1; dan 759,88 ± 15,26 Mg C ha−1 masing-masing pada penghalang permeabel berusia 0-, 1-, dan 4 tahun. Analisis kritis TECS di lokasi mangrove, tambak terbengkalai (610,82 ± 29,31 Mg C ha−1), dan tambak produktif (735,57 ± 20,61 Mg C ha−1) menunjukkan bahwa memperkenalkan Avicennia sp. di garis pantai yang baru direklamasi akan memperkaya TECS. Selain itu, keberadaan penghalang permeabel pada tambak terbengkalai secara bertahap dapat menyediakan habitat untuk tumbuh bagi bibit mangrove yang ditemukan melimpah di Kecamatan Sayung. Dengan demikian, kondisi tersebut mampu meningkatkan kerapatan dan ketebalan tegakan mangrove yang berkontribusi pada terjaganya stabilitas alam pesisir di Kabupaten Demak
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