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Land suitability classification (LSC) is an approach of land evaluation, which measures the degree of appropriateness of land for a specific land use. LSC is governed by a myriad of factors at the local and regional level including physiographic, pedologic and a host of socioeconomic and infrastructural determinants. This has called for the application of different multi-criteria decision-making (MCDM) techniques in agricultural LSC. The present study has attempted and compared various MCDM-based agricultural LSCs for Malda District in Eastern India. The study is based on multiple parameters governing agriculture, considering not only the physiographic and pedological attributes (e.g., relief, slope, soil fertility, soil organic carbon, etc.) but also the socioeconomic ones (e.g., the percentage of people engaged in agriculture, cultivator–labor ratio, degree of electrification, etc.). Four major MCDM algorithms have been applied, i.e., composite ranks, composite Z-scores, analytical hierarchy process (AHP) and weighted principal component analysis (WPCA). The results were also compared with the crop productivity-based agricultural efficiency. It was observed that about 15.44% of the area of Malda District is highly suitable for agriculture, whereas limited suitability is displayed by about 12.68% of area. The remaining part falls under moderate and marginal suitability classes. Furthermore, WPCA and AHP are superior to the nonparametric techniques of MCDM, namely composite ranks and composite Z-score. Moreover, the results of WPCA are superior to those of AHP. Due to the inherent limitations of the AHP approach, this study proposes the use of WPCA in the domain of agricultural LSC.
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M. Mistri 《Marine Ecology》1995,16(3):181-188
Abstract. The gorgonian Lophogorgia ceratophyta thrives in turbid water at Tinetto Rock, La Spezia Gulf, Ligurian Sea. Its age structure suggests that the population is in a steady state; nevertheless, it is difficult to discern whether the main factors controlling this population are biological or event-related. Secondary production was estimated by means of an increment-summation method and yielded 0.54 g ash-free dry weight (AFDW)*m-1 a-1 . This estimate does not take into account biomass losses due to reproductive output and non-lethal predation. Standing stock biomass was 5.44 g AFDW e m-2 . The annual P/B ratio was 0.10 and turnover time about 10a 相似文献
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Abstract. Growth of the shallow-water gorgonian Lophogorgia ceratophyta was investigated in an infralittoral station located in La Spezia Gulf, Ligurian Sea. Mean annual height growth rate was estimated to be 2.57 cm · a-1. The fractal dimension of the colonies was found to gradually evolve in complexity, exhibiting a simpler branching pattern in younger specimens. The maintenance of a low, invariable ramification complexity as an optimal choice in managing relationships between water and the colony's living tissues is also discussed. 相似文献
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Cristina Munari Elena Manini Antonio Pusceddu Roberto Danovaro & Michele Mistri 《Marine Ecology》2009,30(2):255-268
The European Water Framework Directive (WFD, 2000/60/EC) recommends the development of biotic indices for assessing the ecological quality status of water bodies. The Benthic Index based on Taxonomic Sufficiency (BITS) was specifically developed for lagoonal systems, according to the tolerant/opportunistic approach. Macrobenthic data, variables indicative of eutrophication and variables indicative of sedimentary organic matter quality were collected during 18 surveys carried out between 2004 and 2005 in three Adriatic coastal lagoons (Venice Lagoon, Sacca di Goro, Lesina Lagoon). The relationship between environmental variables and biotic indices (AMBI, BENTIX, BITS, BOPA and FINE) was tested using multivariate analyses. Indices based on species classification level appeared to relate better with the variables describing organic matter quality, whereas BITS, which is based on family classification level, seemed related to eutrophication indicative variables, such as sulphide, ammonium, dissolved oxygen and orthophosphate concentrations. The BITS approach reduces the costs associated with sorting and identification of organisms. Providing a rapid assessment of ecological quality, and producing an ecologically relevant classification, BITS seems a promising tool for monitoring programs of Adriatic lagoonal ecosystems. Its sensitivity in reflecting the field conditions elsewhere, however, remains to be assessed. 相似文献
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The Adriatic coast of Punta Marina (Ravenna) is protected by 3-km long low crested breakwater structures (LCSs). Through a 3-years long multidisciplinar study, we assessed the impact of such defensive structures on environmental and biological condition. LCSs create pools where conditions are very different from the surrounding nearshore system. Mechanical disturbance by currents and waves varied greatly in intensity and frequency between seaward and landward sides of the structures. Sedimentary budget was positive at the landward side, but it was due to a gain on the seafloor and not on the emerged beach. The budget at seaward was negative. LCSs determine differences in benthic assemblages, alter the seasonal pattern of communities, and modify seasonal fluctuations of animal assemblages. Landward sheltered areas can be seen as “lagoonal island” surrounded by a “sea of marine habitat”. Differences in ecological quality status, obtained through M-AMBI, are due to the sum of these factors. 相似文献
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Abstract. Polychaete community structure in Valle Magnavacca, the largest basin of the Valli di Comacchio (Northern Adriatic Sea) lagoonal ecosystem, was analyzed in a three‐year study. Three shallow‐water stations were sampled at about 3‐month intervals. Univariate and multivariate analyses were utilized to investigate community structure changes in relation to natural and man‐induced disturbance. The polychaete community at station 3, in the central area of the lagoon, was the most disturbed, while that of station 2 was the most well structured. We hypothesize that polychaete community structure results from regular seasonal disturbances which lead to almost predictable fluctuations in species abundance. Superimposed on these regular cycles are acute disturbance events that further reduce species abundance or exclude species from the habitat. 相似文献
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The new index FINE, a multimetric, fuzzy-based index for the evaluation of environmental quality for Mediterranean transitional waters, was calculated using biotic data gathered between 2000 and 2006 at 15 stations in 4 Tyrrhenian transitional water ecosystems (Orbetello Lagoon, Padrongiano Delta, Stagno di S. Teodoro, and Stagno di Tortolì), i.e. in a different biogeographic sub-province respect to the one in which the index was developed and validated. The rationale of FINE is that certain attributes, selected on the basis of established principles of benthic ecology, are fundamental for lagoon ecosystem function. A set of other indices (Simpson's 1-lambda', the W-statistics, AMBI, and BOPA) was also calculated and compared to FINE outputs. FINE, 1-lambda', and the W-statistics were significantly correlated with sedimentary organic matter content. Some stations were unequivocally assigned to the same ecological status, independently from the index used; for others, some discrepancies were evident. Mediterranean transitional waters probably share ecosystem complexities which are not yet fully captured by indices developed and validated elsewhere. 相似文献
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The ecological quality of 127 stations from six Adriatic coastal lagoons was assessed using a suite of biotic indices: H', d, 1-lambda', Delta(*), Delta(+), W, AMBI, BOPA and FINE. The analysis indicated the difficulties in deriving and using the existing indices from benthic communities in highly variable environmental conditions in coastal lagoons. Different metrics rendered different results: the use of H' resulted in the classification of all stations as "Moderate/Poor/Bad", whereas BOPA classified the majority of the stations as "Good/High". Using Delta(+), most of the stations resulted as "Not anthropogenically impacted", while the W-statistics gave 82 stations as "Undisturbed" and 45 as "Moderately/Grossly disturbed". AMBI classified 55 stations as "High/Good" and 72 as "Moderate/Poor/Bad", whereas those were 32 and 95 with FINE, respectively. The latter, which was developed just for Italian coastal lagoons, was the most conservative among the indices studied. Yet, it showed the highest correlation with the species/abundance matrix. Using indices developed for coastal waters in lagoons can give the distorted indication that the water body is degraded, when it might be just a natural, low diversity, high abundance community, i.e. a lagoonal community. Moreover, the outcome of the use of a certain index has a financial dimension such that lagoons misclassified as being "poor status" will then require expensive remediation measures. For the lagoons studied, there is probably an adequate quality and quantity of benthic data available for making management decisions, but this study highlights the limits of the existing indices for lagoonal ecosystems. The challenge for the next future is to couple long term conservation of the natural environment with the highly productive activities carried out in lagoonal ecosystems. 相似文献
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