This study is focused on farmers’ maintenance of slash-and-burn cultivation in northwestern Zambia’s miombo woodlands and elucidates their ecological knowledge and process of clearing slash-and-burn fields. It also examines farmers’ coexistence in a multi-ethnic community in the context of the locations and ecological classification of fields cultivated by firstcomers and immigrants. The study area was S Ward in northwestern Zambia. It is written as S ward not to be specified the location. Northwestern Zambia is home to five ethnic groups: the Kaonde, who are considered the region’s firstcomers, and the Lunda, Luvale, Chokwe, and Luchazi, who are relative newcomers to S Ward. The number of villages in S Ward increased from 11 Kaonde villages in 1960 to 23 villages in 2000, of which nine were built by non-Kaonde immigrants. The population of S Ward increased with the influx of immigrants. Accordingly, the total area of cultivated land in S Ward in 2014 was 12-times higher than in 1968. Farmers in these five ethnic groups categorized the surrounding ecological environment according to landforms, soils, and vegetation, and classified the ecology as marsh or woodland. Woodland was identified as one of two types based on the accumulated soil: the outer edge of the marsh has gray soil, whereas the upland region is characterized by red soil. According to the farmers, the gray soil was soft and rich in nutrients, whereas red soil contained little sand and hardened when dried. Farmers in S Ward recognized that the gray soil in the woodland was more suitable for cultivation. The Kaonde’s cultivated fields were located at the outer edge of the marsh, as the Kaonde have lived in the area for several generations, so newcomers were forced to clear the uplands, which had remained unoccupied by the Kaonde farmers. The Kaonde and immigrants coexist in S Ward by cultivating different ecological areas and practicing different slash-and-burn cultivation systems.

Iron solubilization in mangrove soils associated with polyphenols leached out from leaf-litter can improve iron bioavailability. In this context, the leaf-removing process by mangrove crabs would increase reacting frequency of the polyphenols in mangrove leaves with iron in the soils. In this study, we investigated ecological roles of a leaf-removing crab, Neosarmatium smithi, on the iron solubilization process. After the fallen leaves carried by the crabs to their burrows and eaten by them, polyphenols may be remained in their feces. If so, contact of polyphenols in the feces with mangrove soils could promote elution of dissolved iron from the soils. In order to demonstrate this hypothesis, we firstly surveyed the appearance ratio of the black part in crab burrows and measured total phenolic content in feces of N. smithi as well as in the black part soil. Then, we examined influences of the crab feces on dissolved iron elution from mangrove soils. As the results, the appearance ratio of the black part in the burrow was 67% and the phenolic content in the feces, the black part, and the yellow part in crab burrows were 9.93, 0.49, and 0.12mg g^－1, respectively. Dissolved iron content in the solution (soil＋water extract from feces) was 0.65μg g^－1 and this content was 4.5 times higher than the control (soil＋distilled water). We suggest that the polyphenols remained in the feces affect to solubilize insoluble forms of iron by iron reduction and chelating properties.

The aim of this study is to obtain the basic wood properties of planted Borneo ironwood (Eusideroxylon zwageri) from a plantation established about 80 years ago. Stem diameter at 1.3m above the ground, tree height, and stress-wave velocity (SWV) of stem were measured on 36 planted E. zwageri trees. Later, core samples were collected from four trees whose measurements represented the average stem diameter of all the measured trees. Using the core samples, the moisture content (MC), basic density (BD), and compressive strength parallel to grain (CS) were measured. Dynamic Young’s modulus for longitudinal direction at green condition (E) was also calculated from SWV. There was no significant relationship between growth characteristics and SWV. Mean values of MC, BD, CS, and E were 37.2%, 0.86g/cm³, 64.3MPa, and 18.47GPa, respectively. Significant differences among individual trees were found in MC, BD, and CS. In addition, radial variations were almost constant from bark side to pith side. The results indicate that longitudinal E is independent from growth characteristics, and that the E. zwageri wood tested in this study has uniform BD and CS in the radial direction.