scholarly journals The Phanerozoic diversification of silica-cycling testate amoebae and its possible links to changes in terrestrial ecosystems

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1234 ◽  
Author(s):  
Daniel J.G. Lahr ◽  
Tanja Bosak ◽  
Enrique Lara ◽  
Edward A.D. Mitchell

2021 ◽  
Author(s):  
Daniel Puppe

<p>Biogenic silicon (BSi) has been found to play a fundamental role in the link between global Si and carbon cycles, because it represents a key factor in the control of Si fluxes from terrestrial to aquatic ecosystems. Furthermore, various beneficial effects of Si accumulation in plants have been revealed, i.e., increased resistance against abiotic and biotic stresses. Thus Si is of great importance for agricultural plant-soil systems. Due to intensified land use humans directly influence Si cycling on a global scale. For example, Si exports through harvested crops and increased erosion rates generally lead to a Si loss in agricultural systems with implications for Si bioavailability in agricultural soils, which is controlled by BSi to a great extent. However, while corresponding research on phytogenic BSi (i.e., BSi synthesized by plants) has been established for decades now, studies dealing with protozoic BSi (i.e., BSi synthesized by testate amoebae) have been conducted just recently. By reviewing these studies I found them to indicate that testate amoebae might play a key role in Si cycling in terrestrial ecosystems. Actually, annual biosilicification rates of idiosomic testate amoebae are comparable to or even exceed annual Si uptake rates of trees. Furthermore, it is most likely that total protozoic Si pools (considering not only intact shells but also single idiosomes, the building blocks of testate amoeba shells) are much bigger than given in publications yet, because it can be assumed that idiosomes most likely can be as stable as phytoliths (representing the phytogenic Si pool in soils), and thus are well preserved in soils. Consequently, it would be not surprising if total protozoic Si pool quantities (shells plus single idiosomes) would be found to equal phytogenic Si pool quantities in soils. With my contribution I would like to encourage further field and laboratory research to verify this assumption and gain a deeper understanding of Si cycling by testate amoebae in terrestrial ecosystems.</p>



1999 ◽  
Vol 13 (3) ◽  
pp. 751-760 ◽  
Author(s):  
Nina Buchmann




2020 ◽  
Vol 24 (1) ◽  
pp. 100-105
Author(s):  
Herawati Herawati ◽  
Muhammad Arsyad Thaha ◽  
Chairul Paotonan

Abstrak Wilayah pesisir merupakan pertemuan antara wilayah laut dan wilayah darat, dimana daerah ini merupakan daerah interaksi antara ekosistem darat dan ekosistem laut yang sangat dinamis dan saling mempengaruhi. Tujuan penelitian ini adalah untuk menentukan material lokal yang potensial dapat digunakan sebagai bahan bangunan pelindung pantai dan memilih tipe bangunan pelindung pantai yang sesuai kondisi hidro-oseanografi di lokasi studi dengan metode Analythic Hierarchy Process. Lokasi penelitian berada di Provinsi Sulawesi Tenggara, tepatnya di Pulau Kabaena, Kecamatan Kabaena Barat Desa Sikeli kabupaten Bombana. Pulau Kabaena memiliki luas 873 km2. Secara geografis terletak antara 4°22’ 59,4” - 5°28’ 26,7” Lintang Selatan serta antara 121°27’46,7”-122°09’,4” Bujur Timur. Hasil penelitian menunjukkan perairan disepanjang tanjung perak sangat mempengaruhi hidro-oseonografi disekitar pantai desa Sikeli. Kondisi ini berpengaruh terhadap pola pergerakan arus dan tinggi gelombang datang disekitar pantai desa Sikeli. Tinggi gelombang rata-rata yang paling besar merambat dari arah barat sebesar 0.49 m dengan presentase kajadian sebesar 32.42 %, disusul arah barat laut sebesar 0.39 m (20.56 %), arah tenggara sebesar 0.31 m (8.72 %) arah barat daya sebesar 0.31 m (7.99 %), arah utara sebesar 0.20 m (6.94 %), arah timur sebesar 0.15 m (11.81 %), arah selatan sebesar 0.12 m (3.42 %), dan arah timur laut sebesar 0.11 m (8.15 %). Pengambilan keputusan untuk memilih tipe bangunan pelindung pantai dengan metode AHP (Analytical Hierarchy Process) untuk penanganan abrasi pesisir pantai desa Sikeli berbasis bahan lokal diperoleh bahwa alternatif bangunan dengan nilai keterpilihan yang tertinggi adalah detached breakwater (0,4432) disusul groin (0,2479), sea-wall (0,1700) dan revetment (0.1389). Detached breakwater berfungsi untuk menahan laju sedimen kearah laut, mengurangi ketinggian dan meredam energi gelombang dan tidak dibangun sepanjang garis pantai yang akan dilindungi sehingga kapal nelayan dapat ditambat dipesisir pantai dengan aman. Abstract The Selection Type of Coastal Protection Structures in Sikeli Village Based on Local Materials. The coastal area is a meeting point between the sea and land areas, where this area is an area of interaction between terrestrial ecosystems and marine ecosystems which are very dynamic and influence each other. The purpose of this research is to determine local materials that can be used as coastal protection materials and to select the type of coastal protection that is suitable for the hydro-oceanographic conditions in the study location using the Analythic Hierarchy Process method. The research location is in Southeast Sulawesi Province, precisely on Kabaena Island, Kabaena Barat District, Sikeli Village, Bombana Regency. Kabaena Island has an area of 873 km2. Geographically it is located between 4° 22' 59.4"- 5° 28' 26.7" South Latitude and between 121° 27' 46.7 "-122° 09' 4" Longitude East. The results showed that the waters along Tanjung Perak greatly affect the hydro-oseonography around the coast of Sikeli village. This condition affects the current movement pattern and the height of the incoming waves around the coast of Sikeli village. The largest average wave height propagating from the west is 0.49 m with a kajadian percentage of 32.42%, followed by the northwest direction of 0.39 m (20.56%), southeast direction of 0.31 m (8.72%) to the southwest of 0.31 m (7.99%), to the north of 0.20 m (6.94%), to the east of 0.15 m (11.81%), to the south of 0.12 m (3.42%), and to the northeast of 0.11 m (8.15%). The decision to choose the type of coastal protection using the AHP (Analytical Hierarchy Process) method for the coastal abrasion management model in Sikeli village based on local materials was obtained that the alternative building with the highest electability value was the detached breakwater (0.4432) followed by groins (0.2479), sea-wall (0.1700) and revetment (0.1389). The detached breakwater model which functions to restrain the sediment rate towards the sea, reduce the height and reduce wave energy and is not built along the coastline which will be protected so that fishing boats can be moored to the coast safely.



Author(s):  
Roger G. Sayre ◽  
Patrick Comer ◽  
Jill Cress ◽  
Harumi Warner


1993 ◽  
Vol 36 (1-12) ◽  
pp. 37-50
Author(s):  
Galina A. Korganova


Author(s):  
S. A. Lysenko

The spatial and temporal particularities of Normalized Differential Vegetation Index (NDVI) changes over territory of Belarus in the current century and their relationship with climate change were investigated. The rise of NDVI is observed at approximately 84% of the Belarus area. The statistically significant growth of NDVI has exhibited at nearly 35% of the studied area (t-test at 95% confidence interval), which are mainly forests and undeveloped areas. Croplands vegetation index is largely descending. The main factor of croplands bio-productivity interannual variability is precipitation amount in vegetation period. This factor determines more than 60% of the croplands NDVI dispersion. The long-term changes of NDVI could be explained by combination of two factors: photosynthesis intensifying action of carbon dioxide and vegetation growth suppressing action of air warming with almost unchanged precipitation amount. If the observed climatic trend continues the croplands bio-productivity in many Belarus regions could be decreased at more than 20% in comparison with 2000 year. The impact of climate change on the bio-productivity of undeveloped lands is only slightly noticed on the background of its growth in conditions of rising level of carbon dioxide in the atmosphere.



Sign in / Sign up

Export Citation Format

Share Document