Context Of Land Research Articles

Soil organic matter fractions under different land uses and soil classes in the Brazilian semi-arid region

Context Land use change (LUC) is considered one of the main factors associated with soil carbon (C) loss worldwide. Aim Evaluate changes in labile and non-labile soil organic matter (SOM) fractions in different land use systems – native vegetation (NV), agriculture with conventional cultivation (CC) and pasture (PA) – in five soil classes in the Brazilian semi-arid region. Methods Soil samples were collected to a depth of 100 cm, and soil C and nitrogen (N) content and stocks were determined and also stocks of labile (LC) and non-labile (NlC) C fractions. In addition, the Carbon Management Index (CMI) was used to evaluate soil health changes. Key results SOC stocks significantly decreased after conversion from NV to CC (by 23%; 0–30 cm) and PA (by 22%; 0–100 cm). Losses due to LUC were greater in the LC than the NlC fraction, and this was reflected in the CMI reducing by 37% for PA and 57% for CC in the 0–100 cm layer. Regarding the different soil classes, LUC reduced SOC stocks only in the Luvisol, Planosol and Leptosol classes, while in the LC fraction, changes were observed in Acrisols, Cambisols and Planosols. Conclusions Clearing NV areas for CC systems and PA reduced the SOC stocks and SOM fractions and, consequently, decreased soil quality. Implications These findings underscore the importance of considering the quality of SOM when evaluating LUC impacts on SOC stocks in the different classes of soil in the Brazilian semi-arid region.

Improving Remote Sensing Multiple Classification by Data and Ensemble Selection

In this article, margin theory is exploited to design better ensemble classifiers for remote sensing data. A semi-supervised version of the ensemble margin is at the core of this work. Some major challenges in ensemble learning are investigated using this paradigm in the difficult context of land cover classification: selecting the most informative instances to form an appropriate training set, and selecting the best ensemble members. The main contribution of this work lies in the explicit use of the ensemble margin as a decision method to select training data and base classifiers in an ensemble learning framework. The selection of training data is achieved through an innovative iterative guided bagging algorithm exploiting low-margin instances. The overall classification accuracy is improved by up to 3%, with more dramatic improvement in per-class accuracy (up to 12%). The selection of ensemble base classifiers is achieved by an ordering-based ensemble-selection algorithm relying on an original margin-based criterion that also targets low-margin instances. This method reduces the complexity (ensemble size under 30) but maintains performance.

Pro-poor Land Transfers and the Importance of Land Abundance and Ethnicity in The Gambia

Summary We ask whether there is empirical evidence that supports the existence of norm-based access rules that give poor households access to important production resources. A substantial literature has investigated informal insurance schemes, which trigger supporting exchanges after negative shocks have occurred. This paper is instead concerned with material exchanges that take place before shocks occur, which has received far less attention in the economic literature. We employ a dataset of 51 rural villages in The Gambia, and we focus on access to the most important production resource in our context—land. We find that poor households are more likely to receive seasonal land usage rights. We also show that these exchanges are more likely to occur in villages where land is abundant and where ethnic fractionalization is low. We argue that this is consistent with the existing qualitative evidence, which argues that informal exchange is thought to be disappearing due to population increases and ethnic fractionalization. Our findings highlight the importance of attention to the local (i.e., village-level) context for assessing welfare and conducting effective policy.

The abandonment of the Decapolis region in Northern Jordan—forced by environmental change?

The Decapolis region in Northern Jordan flourished during the Roman, Byzantine and Umayyad period, leading to the construction of great monuments. They are very well preserved, because the region was abandoned in the 10th century AD and no significant resettlement took place. Earthquakes, diseases and political reasons are in general thought to be responsible for this development. However, rain-fed agriculture was the economic basis of the Decapolis cities, and only a surplus in production made their wealth possible. Thus environmental change, caused by mismanagement or climate change, could have been responsible for the abandonment of the area. Historical land use reconstruction and soil analysis are well-suited to prove environmental changes. Mismanagement should have left erosion on the plateau and colluvial substrates in the valleys, while a change of climate should be detectable in a differentiated soil genesis and indirectly by assessment of agricultural productivity of land use change. The analysis of the land use pattern and the study of soils at the Decapolis city of Abila indicate that a climate change had great influence in the abandonment of the site. In this context land use, soil development and local climate are important interrelated site factors.

Mortuary feasting on New Ireland: the activation of matriliny among the Sursurunga

Preface A Note About Language Introduction Sursurunga Historical and Ethnographic Milieux: Contact, Christianity, Cash and Context Land and Matriliny Rethinking the Logic of Matriliny Sursurunga Mortuary Feasting The Antecedents of Mortuary Feasting Consequents of Mortuary Feasting: the Salience and Activation of Matriliny Conclusion Glossary References Index