Isolde Dorothea Kossmann Ferraz’s research while affiliated with Instituto Nacional de Pesquisas da Amazônia and other places

This study compared the seed germination of 30 tree species from Central Amazonia using a wide temperature range (5‑40°C with 12 hours of light daily). Seeds were submitted to pre-germination treatments, whenever necessary, sown on vermiculite or germitest paper, and normal seedling development was assessed until stabilisation. With the same data set, seeds’ optimal germination temperature (T opt ) was determined by comparing the following approaches: (i) 2-step, the temperature with the highest germination and the shortest time to seed population reach 50% of germination was chosen; (ii) the highest Germination Speed Index (GSI); (iii) using the formula developed by Olff and collaborators (Olff’s approach); (iv) three species were evaluated with Covell’s approach; and (v) new formulas for T opt calculation are proposed, based on germination success and five different variables of germination rate (Cipriani’s approach). Comparing the results, T opt differed between 0.6-10.0°C. GSI and 2-step indicated generally higher values than Olff’s formula. The minimum and maximum T opt differences between Cipriani’s approaches were between 0.1-2.2°C. Our study showed that T opt should be determined for each species as, even the 30 Amazonian tree species of the same habitat, T opt ranged between 22.5 and 32.5°C.

Este estudo fornece informações sobre germinação de sementes e morfologia de plântulas de Philodendron Schott, da Amazônia Central. Testes de germinação foram realizados com 4x50 sementes em papel de germinação a 25°C com 12 horas de luz ou no escuro. As infrutescências de Philodendron eram compostas por bagas com ca. 7–71 sementes/fruto. As sementes foram distinguidas pela cor, máculas e presença ou não de arilo. As sementes germinaram apenas sob luz. A germinação final foi maior em P. goeldii (99%) com Tempo Médio de Germinação de 4,5 dias, seguido por P. fragrantissimum (90%) em 123 dias. Com base no alongamento do hipocótilo, foram descritos três padrões: alongado (3-6 mm) em P. goeldii, médio (1-2 mm) em P. melloi e P. melinonii e reduzido (<1 mm) em P. fragrantissimum, P. tortum e P. elaphoglossoides. Características morfológicas das sementes, plântulas e germinação revelam-se ferramentas valiosas para distinguir as espécies deste estudo.

Liana density is positively associated with forest fragmentation. The process of colonization by lianas is often reported without considering species composition, and consequent changes in liana species composition is relatively unexplored. To understand the compositional change associated with disturbance, we inventoried lianas in permanent plots of the Biological Dynamics of Forest Fragments Project (BDFFP), north of Manaus, Central Amazonia, Brazil. This analysis was focused exclusively on species of the diverse genus Machaerium Pers. (Fabaceae). All lianas with DBH ≥ 2 cm were marked, measured, collected, and identified to the species level in 34 1-ha plots, distributed in continuous and fragmented forests. Density data were analyzed at three hierarchical taxonomic levels: the whole liana community, the genus Machaerium, and each species within Machaerium. At both the generic and species levels, we calculated absolute and relative density. Density (absolute and relative) was evaluated using two indicators of forest disturbance: (1) continuous versus fragmented forest, and (2) plot proximity to forest edge. We employed Generalized Linear Mixed Model with Template Model Builder for analyses. As expected, whole community liana density was positively related to forest disturbance. However, absolute density of the genus Machaerium was not affected by edge or by forest fragmentation, and consequently relative density of the genus Machaerium was reduced. Among the eight species of Machaerium, we found distinct patterns of response to disturbance. Absolute densities of M. hoehneanum and M. aureiflorum were positively affected by forest disturbance, similar to the pattern of the whole liana community, while absolute densities for M. macrophyllum and M. ferox were negatively affected. Absolute densities of the other four species (M. madeirense, M. leiophyllum, M. multifoliolatum, and M. quinata) were not affected by fragmentation indicators. The relative density of six of the eight Machaerium species was negatively affected by forest fragmentation. The variation of responses in closely related species of lianas suggests that liana species are neither uniformly nor always positively affected by forest fragmentation.

Conservation of the Amazon rainforest is a global concern and is supported by the Brazilian government’s ratification of the Bonn Challenge and Paris Agreement and the introduction of national regulations on vegetation protection and restoration. Amazonas is the largest and least deforested of the states occupied by the Brazilian Amazon (< 3%). We carried out a survey on the current state and growth potential of seed and seedling production in Amazonas state, pointing out constraints where future investment can promote the achievement of large-scale restoration commitments. We visited the 35 officially registered seed producers or nurseries working with native seeds and interviewed their owners or managers using open and closed questions. Enterprises were mainly privately-owned family businesses with small production (10,001 - 100,000 seedlings per year) and concentrated in the metropolitan area of the state capital Manaus. We uncovered a further 54 non-officially registered nurseries. Annual production (2018) was almost four tons of seeds and nearly ten million seedlings. According to the owners, production could be increased five to seven times with existing infrastructure. Production is focused foremost on species for food production (48% seeds, 74% seedlings), while ecological restoration only makes up 35% of seed and 8% of seedling use. Major bottlenecks cited by the producers were low demand for native tree species, high transportation costs and excessive bureaucracy. To achieve large-scale restoration, we recommend enforcement of national policies for vegetation protection and restoration, and a restructuring of the seed and seedling sector with a bottom-up approach.

The most severe global warming is predicted to occur in the Amazon region of Brazil, with an estimated temperature increase of 4 to 8 °C between 2071 and 2100. Our study evaluated the effects of increased temperatures on germination success of seeds in the soil seed bank of secondary forests in Central Amazonia. Soil samples (3-cm depth) were collected in six secondary forests with different land-use histories and ages of regrowth. Soils from all sites were sieved and mixed, and germination and seedling development were assessed during 4 months of incubation in germination chambers at (1) a constant temperature of 25 °C and a 12:12 h alternating temperature regime of 20:30 °C, considered as controls; (2) a simulated 5 °C temperature increase to 30 °C and 25:35 °C and (3) a 10 °C temperature increase to 35 °C and 30:40 °C. To determine the effect of light vs. dark on germination, germination was compared for samples in light (12 h daily photoperiod) vs. continuously dark for 1 month, followed by 3 months in light. Six temperature conditions were tested with 30 subsamples each. In the mixed soil seed bank, 3640 seeds germinated, of which 18 families, 28 genera and 41 species (grouped in 20 trees, 11 shrubs, eight herbs and two lianas) could be identified. A light requirement for germination was detected for 94–97% of the species. Alternating temperatures did not stimulate germination in the dark. Seedling density m⁻² was 1.7 to 2.3 times higher at alternating (20:30 °C and 25:35 °C) than at constant temperatures (25 °C and 30 °C); but an increase of 10 °C decreased seedling density to 47% at 35 °C and 26% at 30:40 °C compared to control (100% at 25 °C and 20:30 °C); and furthermore increased seedling mortality. Thus, the secondary forest at the study area may maintain its integrity with a 5 °C but not with a 10 °C temperature increase. Species-specific sensitivities to temperature were detected. Temperature may function to fine-tune germination at a specific microsite, and the variety of germination requirements may enhance coexistence and maintenance of species diversity within the pioneer species subset. In general, seeds of tree species were more sensitive to increased temperatures than those of shrubs and herbs, supporting the hypothesis of replacement of the tropical forest by savanna-like vegetation in the Amazon region. Our results show that natural regeneration may be significantly affected by global warming and with potential to alter floristic composition.

Across the seed-seedling transition, several germination criteria are used in studies of palm-seed germination. In Oenocarpus bataua, these criteria have differential tolerance to thermal stress. In this study, we evaluated the tolerance of germination criteria to seed desiccation of the congeneric Oenocarpus bacaba. We dried seeds to different moisture contents (MC) before scoring first cataphyll, second cataphyll, enclosed eophyll and expanded eophyll. Seeds without drying had 41.7% MC. Germination success reached close to 70% after 75 and 105 days, depending on the germination criterion. Safe MC was close to initial MC and all seeds were dead with MC < 26.7%. As the primordial organs of the cataphylls and the eophyll are already detectable in the palm-seed embryo, all were affected by drying. Critical MC, defined here as 50% loss of germination capacity, increased from 35.4% (first cataphyll) to 37.1% (expanded eophyll) and confirmed that, across the seed-seedling transition, more advanced germination stages had a higher sensitivity to desiccation. During germination and development, the criteria appear in sequence over several weeks. Consequently, the desiccation damage was only detectable when the last criterion was evaluated. To avoid an underestimation of damages, we suggest that seed-stress studies in palms should take into account an adequate period for seedling development, which, for O. bacaba, was 105 days until the expansion of the eophyll.