The Disconnect Between Short- and Long-Term Population Projections for Plant Reintroductions

The reintroduction of rare species in natural preserves is a commonly used restoration strategy to prevent species extinction. An essential first step in planning successful reintroductions is identifying which life stages (e.g., seeds or large adults) should be used to establish these new populations. Following this initial establishment phase, it is necessary to determine the level of survival, growth, and recruitment needed to maintain population persistence over time and identify management actions that will achieve these goals. In this 5-year study, we projected the short- and long-term population growth rates of a critically endangered long-lived shrub, Delissea waianaeensis. Using this model system, we show that reintroductions established with mature individuals have the lowest probability of quasi-population extinction (10 individuals) and the highest increase in population abundance. However, our results also demonstrate that short-term increases in population abundances are overly optimistic of long-term outcomes. Using long-term stochastic model simulations, we identified the level of natural seedling regeneration needed to maintain a positive population growth rate over time. These findings are relevant for planning future reintroduction efforts for long-lived species and illustrate the need to forecast short- and long-term population responses when evaluating restoration success.

Etude biophysique et socio-économique du fruitier forestier Detarium senegalense J. F. Gmel. en Basse-Casamance (Thiobon, Bignona, Sénégal)

Au Sénégal, la Basse-Casamance est une zone où la recherche a du terrain à explorer en raison de la situation de conflit qui y prévaut depuis de nombreuses années. C'est l'une des principales zones de production des fruits de Detarium senegalense, qui sont très importants pour la consommation humaine et pour le gain derevenus. L’objectif de cette étude est d’établir les caractéristiques biophysiques et socio-économiques deDetarium senegalense dans le peuplement ligneux du terroir villageois de Thiobon en Basse-Casamance. Pour y parvenir, des enquêtes ont d’abord été menées auprès de la population, puis 64 relevés de végétation ont été effectués sur des placettes de 2500 m². Les résultats ont montré que la flore est constituée de 85 espèces relevant de 73 genres appartenant à 26 familles botaniques. Les familles des Fabaceae, Moraceae, Anacardiaceae et Apocynaceae sont les plus diversifiées. Les espèces les plus fréquentes sont Detarium senegalense (93,75%), Parkia biglobosa (75%), Cassia sieberiana (68,75%), Dialium guineense (64,06%), Anacardium occidentale et Piliostigma reticulatum (54,69%), Terminalia macroptera et Uvaria chamae (50%). La densité réelle est de 342 individus.ha-1, la surface terrière est de 18,07 m².ha-1 avec un taux de recouvrement de 81,49% et un taux de régénération de 81,47% pour le peuplement. Les résultats des enquêtes ont révélé que les principaux usages faits de Detarium senegalense sont l’autoconsommation, la vente des fruits et la pharmacopée. 71% de la population affirment que la tendance de la population de Detarium senegalense est progressive et 56% pensent que sa production augmente au cours des années. Les formes de régénération de l’espèce sont le semis naturel et le rejet de souche. Les fruits de Detarium senegalense sont vendus par comptage et par panier à des prix variant de 5 francs CFA (Communauté Financière Africaine) le fruit à 12000 francs CFA le panier. Cette étude permettra d’établir la situation actuelle des ressources forestières de la zone, mais également d’en améliorer la gestion en proposant des pistes d’amélioration des méthodes de gestion existantes. In Senegal, Basse-Casamance is an area where research has to explore because of the conflict situation that has prevailed there for many years. It is one of the main production areas for Detarium senegalense fruits, which are very important for human consumption and for income generation. The objective of this study was to establish the biophysical and socioeconomic characteristics of Detarium senegalense in the woody stand of the village of Thiobon in Lower Casamance. To achieve this, surveys were first conducted among the population and then 64 vegetation surveys were carried out on 2500 m² plots. The results showed that the flora consists of 85 species from 73 genera belonging to 26 botanical families. The families Fabaceae, Moraceae, Anacardiaceae and Apocynaceae are the most diversified. The most frequent species are Detarium senegalense (93.75%), Parkia biglobosa (75%), Cassia sieberiana (68.75%), Dialium guineense (64.06%), Anacardium occidentale and Piliostigma reticulatum (54.69%), Terminalia macroptera and Uvaria chamae (50%). The actual density is 342 individuals.ha-1, the basal area is 18.07 m².ha-1 with a cover rate of 81.49% and a regeneration rate of 81.47% for the stand. The results of the surveys revealed that the main uses of Detarium senegalense are self-consumption, sale of fruits and pharmacopoeia. 71% of the population affirm that the population trend of Detarium senegalense is progressive and 56% think that its production increases during the years. The forms of regeneration of the species are natural seedling and stump rejection. The fruits of Detarium senegalense are sold by counter and by basket at prices ranging from 5 CFA francs (Communauté Financière Africaine) per fruit to 12,000 CFA francs per basket. This study will establish the current situation of forest resources in the area, but also improve management by proposing ways to improve existing management methods.

Natural Seedling Recruitment and Regeneration in Deforested and Sand-Filled Mangrove Forest at Eagle Island, Niger Delta Nigeria

Seed recruitment is a major driver of mangrove restoration globally. It is hypothesized that soil condition and channel hydrology can accelerate seedling recruitment and regeneration after a major disturbance. Species abundance, diversity indices, microbial and chemical concentrations in sand-filled mangrove forest was studied. Eight plots (area = 3902.16 m2) were established with ten transects in each plot in a random block design to investigate the effect of soil conditions on seedling growth. A total of 1, 886 seedlings were physically counted. Seedling abundance was significantly different between red (Rizophora racemosa), white (Laguncularia racemosa) and black (Avicennia germinans) mangroves and nypa palm (nypa fruticans). The most dominant species was black mangroves and the least dominant species was nypa palm. Muddy soils had the most abundant species while sandy soils had the least abundant species. Furthermore, semi-muddy soils had the highest species diversity (H = 0.948) whereas muddy soils had the least species diversity (H = 0.022). The soil metal concentration has no correlation with seed abundance and occur in the order Iron>Nitrate>Copper>Cadmium. Soil with high species diversity had high soil microbial population; however, seedling abundance was correlated with soil nutrients and not heavy metals. Small seeds are easily recruited while good soil condition plus existing hydrological connection facilitated natural seedling regeneration in the disturbed mangrove forest.

ASOSIASI FUNGI MIKORIZA ARBUSKULA (FMA) PADA BERBAGAI TINGGI SEMAI PERMUDAAN ALAM NYAMPLUNG ( Calophyllum inophyllum L) DI KABUPATEN KETAPANG

Nyamplung (Calophyllum inophyllum L) is known to be associated with AMF, but it is still unknown whether the association has begun to occur when cotyledons are still present or starting at a certain level of regeneration. Research has been done in Pecal Beach Kinjil River in Ketapang district. The purposes of the research are: (1) to assess the amount of spores and genus AMF associated with its development in the rhizosphere of nyamplung regeneration nature seedling stage from 10 cm to 150 cm, and (2) to determine root infection percentage in order to know the level of the association at any size of penage regeneration seedlings. The research is a field research by survey method with sampling technique against natural regeneration seedling level of 10 cm, 30 cm, 60 cm, 90 cm 120 cm, and 150 cm. The data was collectedin laboratoryon the form of the number of spores and genus AMF and the percentage of infections in the roots. The research results showed that there were 616 AMF spores fruit / 100 g of sandy soil consisting of the genus Glomus ( 597 pieces / 100 g sandy soil), Gigaspora ( 15 pieces / 100 g sandy soil) and Scutellospora ( 4 pieces / 100 g sandy soil). The development of the number of spores increased from the height of the seedling's natural regeneration measuring was 10 cm to 150 cm. The results of observations on the roots found thatAMF infection is in the form of vesicles and arbuscular. Infection at the root of natural penage regeneration from 84.44-100%, indicating the level of association between AMF and nyamplung seedling's natural regeneration in the high class ( grade 5 ) . Keywords: Arbuscular Mycorrhizal Fungi (AMF) Nyamplung (Calophyllum inophyllumL) Natural Seedling Regeneration, Pecal Beach

Understanding the Transmissibility of Cucumber Green Mottle Mosaic Virus in Watermelon Seeds and Seed Health Assays

Cucumber green mottle mosaic virus (CGMMV), an emerging tobamovirus, has caused serious disease outbreaks to cucurbit crops in several countries, including the United States. Although CGMMV is seed-borne, the mechanism of its transmission from a contaminated seed to germinating seedling is still not fully understood, and the most suitable seed health assay method has not been well established. To evaluate the mechanism of seed transmissibility, using highly contaminated watermelon seeds collected from CGMMV-infected experimental plants, bioassays were conducted in a greenhouse through seedling grow-out and by mechanical inoculation. Through natural seedling grow-out, we did not observe seed transmission of CGMMV to germinating seedlings. However, efficient transmission of CGMMV was observed using bioassays on melon plants through mechanical inoculation of seed extract prepared from CGMMV-contaminated seeds. Understanding the seed-borne property and the ease of mechanical transmission of CGMMV from a contaminated seed to seedling is an important finding. In comparative evaluation of various laboratory techniques for seed health assays, we found that enzyme-linked immunosorbent assay and loop-mediated isothermal amplification were the most sensitive and reliable methods to detect CGMMV on cucurbit seeds. Because CGMMV is a seed-borne and highly contagious virus, a new infection might not result in a natural seedling grow-out; it could occur through mechanical transmission from contaminated seeds. Therefore, a sensitive seed health test is necessary to ensure CGMMV-free seed lots are used for planting.

Seed longevity and dormancy state in a disturbance-dependent forest herb, Ageratina altissima

Does seed dormancy allow disturbance-oriented forest herbs such as Ageratina altissima to persist in heterogeneous natural communities? To document seed longevity and dormancy state, Ageratina seeds were buried in nylon mesh bags in second-growth forest stands in south-eastern Ohio, USA. Bags were recovered at 2-month intervals, and seeds were tested for viability and germinability in the lab. Live seed numbers declined rapidly, with seed banks exhausted in an estimated 33–37 months. Seeds showed a strong dormancy polymorphism, with 71–84% of live seeds germinable between March and July, the season of natural seedling emergence. At other dates, most seeds appeared to be in a state of induced dormancy, allowing little (0–21%) germination. The slope aspect of the burial site, an important factor controlling above-ground vegetation, had no effect on seed longevity or dormancy condition. Dormancy in Ageratina appears to be adapted to allow opportunistic germination in late spring–early summer, but to prevent germination in less benign periods. Seed longevity is shorter than the natural frequency of gaps in mesophytic forest. We conclude that a long-term dispersal/dormancy trade-off is probably an oversimplification of the spatial ecology of this species. The primary function of dormancy appears to be short-term tracking of seasonal variation.

Long-Term Seedfall, Establishment, Survival, and Growth of Natural and Planted Ponderosa Pine in the Colorado Front Range

Seedfall, natural regeneration establishment, and growth of planted seedlings was observed from 1981 to 2001 under shelterwood and seedtree overstories in a replicated study in ponderosa pine in the Manitou Experimental Forest in the Colorado Front Range. Good seed crops were produced only every 4 to 6 years, with almost no viable seed produced in intervening years. With seed predation, only 14% of total seedfall was available for germination. Shelterwood overstories containing between 6 and 14 m2 ha−1 stem basal area over scarified seedbeds provided optimal conditions for natural seedling establishment. Survival and growth of planted seedlings was much better than that of natural seedlings. However, poor survival and slow initial growth may require many years to establish a fully stocked forest of natural seedlings.