Les Loranthaceae et Viscaceae parasites des forêts et des agro-écosystèmes du Burundi : diversité et ampleur d’infestation

Objectif: Cette étude visait à inventorier les hémi-parasites Loranthaceae et Viscaceae occasionnant des dégâts sur les arbres et arbustes des forêts et des milieux agricoles du Burundi ainsi que leur ampleur d’infestation.Méthodologie et Résultats: L’étude a été conduite dans toutes les zones agro-écologiques du pays dans les forêts et les milieux agricoles environnants. Après prospection, 98 sites répartis sur 192 ha ont été retenus sur base de l’abondance des individus parasités. Au total, 15 espèces hémi-parasites ont été inventoriées dont 11 Loranthaceae et 4 Viscaceae. La crête Congo-Nil présente la plus grande diversité avec 8 espèces sur les 15 tandis que la plaine de l’Imbo et la dépression du Kumoso ne comptent que 2 espèces chacune. Nonante cinq espèces hôtes réparties dans 64 genres et 37 familles ont été recensées dont 47 % sont infestées par Phragmanthera usuiensis. Concernant l’ampleur d’infestation, le taux le plus élevé se rencontre dans la dépression du Kumoso tandis que l’intensité d’infestation est la plus forte dans la dépression du Nord-Est. Elle est dominée par 3 espèces: Phragmanthera usuiensis, Phragmanthera capitata et Agelanthus flammeus.Conclusion et application des résultats: L’étude montre une forte infestation des milieux agricoles et forestiers burundais par les Loranthaceae. La lutte par suppression des touffes est peu efficace. Une stratégie de lutte plus efficace à l’échelle de tout le pays devrait être étudiée.Mots clés: Infestation, Loranthaceae, Viscaceae, zone agro-écologiqueEnglish Title: The Loranthaceae and Viscaceae parasites of Burundi's forests and agro-ecosystems: diversity and extent of infestationEnglish AbstractObjective: The purpose of this study was to inventory the Loranthaceaes and Viscaceae as parasites causing damages on trees in Burundi forests and agroecosystems as well as the extent of the infestation.Methodology and Results: The survey has been conducted in all agro-ecological zones of the country in forests and the surrounding agricultural areas. After prospecting, 98 sites of about 192 hectares have been  targeted based on the abundance of infested trees. In total, 15 hemi-parasitic species have been inventoried of which 11 Loranthaceae and 4 Viscaceae. The Congo-Nile crest presents the biggest diversity with 8 species while Imbo and Kumoso count only 2 species each. Ninety five (95) host species distributed in 64 genra and 37 families have been counted of which 47% are infested by Phragmanthera usuiensis. Concerning the infestation extent, the most elevated rate is found in the depression of the Kumoso while the biggest infestation intensity is found in the depression of the Northeastern Burundi. The most elevated infestation intensities are driven by three species: Phragmanthera usuiensis, Phragmanthera capitata and Agelanthus flammeus.Conclusion and application of results: The study shows a strong infestation of agricultural and forest ecosystems by the Loranthaceae. Fighting the parasites by Tufts cutting is not effective. A more efficient strategy should be documented in order to handle the plant parasites at national level.Keywords: infestation, Loranthaceae, Viscaceae, Agro-ecological zon

Diagnostic de l'effet lisière dans les paysages anthropisés du secteur Rwegura dans le Parc National de la Kibira, Burundi

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Developing policy-relevant biodiversity indicators : lessons learnt from case studies in Africa

There is an increasing need for monitoring schemes that help understand the evolution of the global biodiversity crisis and propose solutions for the future. Indicators, including temporal baselines, are crucial to measure the change in biodiversity over time, to evaluate progress towards its conservation and sustainable use and to set conservation priorities. They help design and monitor national and regional policies on biodiversity; they also feed into national reporting on international agreements such as the Convention on Biological Diversity and the Sustainable Development Goals. We analyse the methodological approach of five small African projects resulting from a call to promote indicator development, improve monitoring capacity and strengthen the science-policy interface in the field of biodiversity. We compared their approach to existing guidance provided by the international community, specifically the Biodiversity Indicators Partnership. To this end, we assess whether internationally recommended steps are effectively applied to national/local biodiversity monitoring in selected developing countries. We also present lessons learnt from workshop interactions between partners involved in these projects. Through our pilot projects we identified data availability and data accessibility, together with the involvement of stakeholders, as critical steps in indicator development. Moreover, there is a need for a better awareness and a wider application of the indicator concept itself. Hence, training of key actors both in the policy and science spheres is needed to operationalize indicators and ensure their continuity and sustainability. We hope that these case studies and lessons learnt can stimulate and support countries in the Global South to formulate policy-relevant biodiversity indicators.Peer reviewe

Effet de l'intensité d'éclaircie sur le microclimat et la croissance du pin laricio de Corse (Pinus nigra Arnold subsp. laricio Poir.)

Doctorat en sciences agronomiques et ingénierie biologique - UCL, 200

Comparative Analysis of Different Fertilizers Effects on Maize Growth Parameters

Lower soil fertility was identified as a major problem affecting crop yield in Burundi, especially at Bihunge, a hill of Matongo commune Kayanza province. An experiment was therefore carried out with five treatments to assess the effective and economically affordable treatment on maze growth parameters improvement. The experimental has considered five treatments: the control (T1); Compost from maize residues + mineral adjuvant (T2); Compost from maize residues + organic adjuvant based on Calliandra calothyrsus Meisn (T3); ISABU formula for maize fertilization (T4); the maize compost + Calliandra + recommended mineral fertilization for maize (T5)), in randomized complete blocks with three replications for each. The recorded parameters were the leaves number, plant height, stem girth as well as the leaf area. After analysis with SPSS and Advanced Excel, results showed a significant difference between treatments. The treatment T4 was the most effective in improving all growth parameters than others and showed a significant difference from treatments T1, T2, and T3. However, it did not differ to treatment T5 which also significantly differed from other treatments with P<0.05.  Treatment T5 has also effectively enhanced the leaves number, plant height, stem girth, and leaf area as treatment T4, and was in the same variation range as this treatment T4. As the effectiveness of T5 was based on the combination of calliandra which has more potential in improving soil fertility and nutrient followed by better fostering of nutrients to the plant leading to better-improved plant growth, this treatment was considered as the effective and farmer accessible treatment for maize cultivation

Yield Responses of Maize (Zea mays L.) and Successive Potato (Solanum tuberosum L.) Crops to Maize Stover co-composted with Calliandra Calothyrsus Meisn Green Manure

The present investigation aimed at evaluating the effect of Calliandra calothyrsus Meisn green manure on the quality improvement of maize (Zea mays L.) stover compost. To that end, two field experiments were installed with maize (Zea mays L.) and a successive potato (Solanum tuberosum L.) crop, which was specifically set up to investigate the potential residual effects of tested organo-mineral fertilizers. The potato (Solanum tuberosum L.) crop did not receive any fertilizer, either organic or mineral. The experimental design was a randomized complete block with three replicates. The basic experimental plot was 1.6 m wide and 3 m long (4.8 m²). Treatments under evaluation were: T1=Control, T2=Maize stover co-composted with mineral fertilizer, T3=Maize stover co-compost with Calliandra calothyrsus Meisn green manure; T4=Farm manure+45-60-30; and T5=Maize stover co-composted with Calliandra calothyrsus Meisn green manure+45-60-30. Evaluated parameters were grain yields, root biomass, above-ground biomass, Harvest Index, and Root/Shoot ratio for maize (Zea mays L.). Potato yields were categorized into small size (< 35 mm), medium size (35-65 mm) and big size tubers (> 65 mm). Significant effects (p < 0.001) of tested fertilizer treatments were observed for maize grain yields (GY), above-ground biomass (AGB), and root biomass (RB). No effect (p > 0.05) of fertilizer treatments could be noticed on the harvest index (HI=0.31-0.38) or R/S ratio (0.079-0.088). For the successive potato crop, a significant effect (p < 0.001) of tested treatments was only observed for the seed-oriented medium size tubers (MST) potato yield. Overall, the most relevant observation of the maize experiment is that treatments T4 and T5 gave higher and equivalent grain and biomass yields. From there, we derive that maize stover co-composted with Calliandra calothyrsus Meisn green manure could be a sound substitute to farm manure. Additionally, the potato experiment highlighted the residual effects of the T3 treatment, statistically equivalent to that of T2. Consequently, we advise that the effects of compost-based organo-mineral fertilizers on crop yields should be evaluated beyond a single seasonal crop, in order to fully catch their residual fertilizer potentials. &nbsp

Direct and residual fertilizer values of maize (Zea mays L.) stover co-composted with Tithonia diversifolia (Hemsl.) A. Gray green manure

The present investigation highlights and compares the direct and residual fertilizer values of maize (Zea mays L.) stover composted with Calliandra calothyrsus Meisn and Tithonia diversifolia (Hemsl.) A. Gray-green manure on maize (Zea mays L.) and successive potato (Solanum tuberosum L.).  Two field studies were installed with maize and successive potato crops in a completely randomized block design (CRBD) with three replicates. Statistical analyses were performed using R commander, version 4.0.2. Grain yields, root biomass, above ground biomass and calculated parameters (Root/Shoot ratio, Harvest Index and GinningRate) were evaluated for maize. Total potato yields were evaluated and categorized into small size tubers (SST < 35 mm) medium size tubers (MST: 35-65 mm) and big size tubers (BST > 65 mm). Treatments under evaluation were: T1=Control, T2=Farm (cow) manure alone, T3=Maize stover co-composted with Calliandra calothyrsus Meisn green manure; T4= Maize stover co-composted with Tithonia diversifolia (Hemsl.) A. Gray green manure; T5= Farm (cow) manure+45-60-30; T6= Maize stover co-composted with Calliandra calothyrsus Meisn green manure+45-60-30; T7=Maize stover co-composted with Tithonia diversifolia (Hemsl.) A. Gray green manure+45-60-30; and T8=Farm (cow) manure+FOMI Imbura+FOMI Totahaza. Obtained results indicated highest maize yields with FOMI organo-mineral fertilizers (2.7 T/ha) seconded by the recommended fertilizer practice T5 (2 T/ha). In the same line, highest R/S value (=0.38) was registered with the same FOMI treatment (T8), while the highest HI value (0.21) was observed with the maize stover co-composted with Tithonia diversifolia (Hemsl.) A. Gray (T4). Highest potato total yields were observed with the maize stover compost enriched with Tithonia diversifolia (Hemsl.) A. Gray and supplemented with mineral fertilizer (7.61 T/ha), followed by the same compost without mineral fertilizer addition (6.35 T/ha). We conclude our study with the following statements: i) the highest direct fertilizer value was observed with the FOMI treatment; ii) the residual fertilizer effects were more expressed with the maize stover co-composted with Tithonia diversifolia A. Gray green manure with or without mineral additive, followed by farm manure and maize stover enriched with Calliandra calothyrsus Meisn green manure. Consequently, we restate that the effects of compost-based organo-mineral fertilizers on crop yields should be definitely evaluated on a multiseasonal basis so as to fully capture their residual fertilizer potentials

Benoît Nzigidahera (1964-2018) : au service de la biodiversité et de la conservation de la nature

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