Terrestrial pteridophytes as indicators of a forest-like environment in rubber production systems in the lowlands of Jambi, Sumatra

Species richness of terrestrial ferns and fern allies (Pteridophyta) may indicate forest habitat quality, as analysed here for a tropical lowland area in Sumatra. A total of 51 standard 0.16 ha plots in primary forest, rubber (Hevea brasiliensis) agroforests and rubber plantations was compared for plot level diversity (average number of species per plot) and landscape level diversity (species–area curves). Average plot level species richness (11 species) was not significantly different amongst the three land use types. However at the landscape level the species–area curve for rubber agroforests (also called jungle rubber) had a significantly higher slope parameter than the curve for rubber plantations, indicating higher beta diversity in jungle rubber as compared to rubber plantations. Plot level species richness is thus not fully indicative of the (relative) richness of a land use type at the landscape scale because scaling relations differ between land use types. Terrestrial fern species can serve as indicators of disturbance or forest quality as many species show clear habitat differentiation with regard to light conditions and/or humidity. To assess forest habitat quality in rubber production systems as compared to primary forest, terrestrial pteridophyte species were grouped according to their ecological requirements into ‘forest species’ and ‘non-forest species’. Species–area curves based on ‘forest species’ alone show that the understorey environment of jungle rubber supports intermediate numbers of ‘forest species’ and is much more forest-like than that of rubber plantations, but less than primary forest. Species richness alone, without a priori ecological knowledge of the species involved, did not provide this information. Jungle rubber systems can play a role in conservation of part of the primary rain forest species, especially in areas where the primary forest has already disappeared. In places where primary forest is gone, jungle rubber can conserve part of the primary forest species, but large areas of jungle rubber are needed. In places where primary forest is still present, priority should be given to conservation of remaining primary forest patches.

Lowland rice yield and profit response to fertilizer application in Rwanda

Rice (Oryza sativa) production in Rwanda increased by 70% while yield ha−1 decreased during the past decade. Yield has biotic and abiotic constraints including inadequate nutrient supply. Yield response functions for N, P, and K were determined in eight marshlands grouped into four clusters. Additional treatment allowed for the diagnosis of response to Mg–S–Zn–B (MgSZnB). Rice grain yield with no fertilizer applied was 2.27 Mg ha−1. Mean yield increases were 2.35, 1.53, and 1.71 Mg ha−1 with N, P, and K application, respectively. The mean economically optimal rates (EOR) were 58 to >150, 11–30, and 21–35 kg ha−1 for N, P, and K, respectively, depending on cluster and the cost of fertilizer. Yield responses to nutrient rates were similar across marshland clusters, and a single response function for each of P and K can serve all four clusters, while the response to N differed for Cluster B compared with A, BC, and C. Net returns to applied P and K were greater than for N, but the application of N is likely needed for such responses to P and K. The MgSZnB resulted in a mean grain yield increase of 1.72 Mg ha−1 with increases in all marshlands, but the information was not sufficient to determine which nutrients of MgSZnB were deficient or their optimal application rates. Fertilizer use can be very profitable for rice production in Rwanda. Profit can be enhanced with the application at less than EOR when fertilizer use is financially constrained.

A political-economy model to reduce fire and improve livelihoods in Indonesia’s lowlands

Deforestation and land degradation have been occurring across the globe, particularly in developing countries. Over the past 30 years, Indonesia’s lowlands have experienced rapid degradation, deforestation and fires. Interventions aimed to achieve sustainable lowlands have been made through the introduction and adoption of commodities that provide sufficient livelihoods and reduce fires. However, these interventions have not guaranteed success as the contribution of the governance and political economy towards sustainability is poorly understood. This study aims to determine how governance and political-economic factors affect sustainability of lowland agriculture. We used structural equation modeling (SEM) to understand the effect of political economy factors (structure, institution and actor) on sustainability and community livelihoods in Indonesian lowlands. Data were collected through interviews with selected respondents. We found Structure, Institution, and Actor explain 31% (0.31) of the variation in the Sustainability and Livelihoods model. The remaining effects were explained by non-political economic factors. Using actor-centered power (ACP) and social network analysis (SNA) approaches, we also identified and assessed different actors’ power and their networks. The central government and private companies are the most powerful actors, while farmers are the least powerful actors. The findings demonstrate that considering governance and political-economic factors in designing and implementing commodity interventions for policy makers is a must. Devolving power to farmers is crucial in achieving power balance among various actors, which leads to better political economy condition that affects sustainability of lowlands.

Changes in selected soil properties across a chronosequence of exclosures in the central dry lowlands of ethiopia

In Ethiopia, rehabilitation of the natural resource-base in degraded lands through area exclosures has become a necessary intervention, albeit empirical studies on the impact of these exclosures are limited. This study was conducted to investigate changes in selected soil properties along exclosures’ age and slope positions in Kewet district, central dry lowlands of Ethiopia. Soil samples were collected from three slope positions of three purposively selected exclosures of 5, 15 and 20 years old and one adjacent open grazing land from 0-10 cm soil depth for analysis of pertinent soil properties. The effect of exclosure age on bulk density, contents of sand, clay, organic carbon, total nitrogen, available phosphorus, CEC, and exchangeable Mg+ and K+ was significant (P<0.05). All exclosures had low bulk density (1.14-1.16 g cm-3) as compared to the grazing land. Higher available water content (173 mm m-1) was recorded in the old exclosure. Soil organic carbon ranged from 2.58% (young exclosure) to 3.37% (middle age exclosure). Soil total nitrogen increased from 0.24-0.34%, while available phosphorus increased from 27-34%, from young to the old exclosure respectively. However, the influence of exclosures’ age on other soil properties was not significant. The young exclosure had the highest CEC (57 cmolc kg-1), whereas the grazing land had the highest total nitrogen and exchangeable Ca2+. From this result, it can be concluded that area exclosures, if managed properly, can improve some of the dynamic soil properties of open degraded grazing lands in the dry lowlands of Ethiopia.

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