There is increasing interest in the restoration/regeneration of degraded tropical habitats yet the potential role of natural regenerators remains unclear. We test the hypothesis that the richness and functional diversity of terrestrial mammals differs between forest regrowth stages. We quantified the richness and functional diversity of eight terrestrial mammal seed-disperser species across a forest regrowth gradient in the eastern Brazilian Amazon. We installed camera-traps in 15 sites within small-holder properties with forest regrowth stage classified into three groups, with five sites each of: late second-regrowth forest, early second-regrowth forest and abandoned pasture. Species richness and functional dispersion from the regrowth sites were compared with 15 paired forest control sites. Multi model selection showed that regrowth class was more important for explaining patterns in richness and functional diversity than other variables from three non-mutually exclusive hypotheses: hunting (distance to house, distance to river, distance to town, small holder residence), land cover (% forest cover within 50 meters, 1 kilometer and 5 kilometers) and land use (regrowth class, time since last use). Differences in functional diversity were most strongly explained by a loss of body mass. We found that diversity in regrowth sites could be similar to control sites even in some early-second regrowth areas. This finding suggests that when surrounded by large intact forest areas the richness and functional diversity close to human small-holdings can return to pre-degradation values. Yet we also found a significant reduction in richness and functional diversity in more intensely degraded pasture sites. This reduction in richness and functional diversity may limit the potential for regeneration and increase costs for ecological regeneration and restoration actions around more intense regrowth areas.

Highlights The occurrence, density and biomass of adult arborescent palms were measured in a National Forest in the eastern Brazilian Amazon. Commercially important arborescent palms were rare. Density and biomass were related to hydrographic and topographic variables. Subsidised agroforestry practices are required to facilitate the commercialization of palm NTFPs. Published as:Norris, D., Chuma, V.J.U.R., Arevalo-Sandi, A.R., Paredes, O.S.L. and Peres, C.A., 2016. Too rare for non-timber resource harvest? Meso-scale composition and distribution of arborescent palms in an Amazonian sustainable-use forest. Forest Ecology and Management, 377,. oleracea, an economically important species. The presence, biomass, and density of palms were uncorrelated with geographic distances among plots. The hydrographic model significantly explained variation in palm presence and biomass, whereas density was only explained by the topographic model. Our findings indicate that arborescent palms are currently too rare to be efficiently harvested as NTFPs in the study area. Yet, comparisons with published estimates suggest that there is significant potential for agroforestry to facilitate the commercialization of palm NTFPs for community based extractive activities.

Degraded Amazonian forests can take decades to recover and the ecological results of natural regeneration are still uncertain. Here we use field data collected across 15 lowland Amazon smallholder properties to examine the relationships between forest structure, mammal diversity, regrowth type, regrowth age, topography and hydrology. Forest structure was quantified together with mammal diversity in 30 paired regrowth-control plots. Forest regrowth stage was classified into three groups: late second-regrowth, early second-regrowth and abandoned pasture. Basal area in regrowth plots remained less than half that recorded in control plots even after 20–25 years. Although basal area did increase in sequence from pasture, early to late-regrowth plots, there was a significant decline in basal area of late-regrowth control plots associated with a decline in the proportion of large trees. Variation in different forest structure responses was explained by contrasting variables, with the proportion of small trees (DBH < 20 cm) most strongly explained by topography (altitude and slope) whereas the proportion of large trees (DBH > 60 cm) was explained by plot type (control vs. regrowth) and regrowth class. These findings support calls for increased efforts to actively conserve large trees to avoid retrogressive succession around edges of degraded Amazon forests.

1Degraded Amazonian forests can take decades to recover and the ecological results of natural 2 regeneration are still uncertain. Here we use field data collected across 15 lowland Amazon 3 smallholder properties to examine the relationships between forest structure, mammal diversity, 4 regrowth type, regrowth age, topography and hydrography. Forest structure was quantified together 5 with mammal diversity in 30 paired regrowth-control plots. Forest regrowth stage was classified into 6 three groups: late second-regrowth, early second-regrowth and abandoned pasture. Basal area in 7 regrowth plots remained less than half that recorded in control plots even after 20-25 years. Although 8 basal area did increase in sequence from pasture, early to late-regrowth plots, there was a significant 9 decline in basal area of late-regrowth control plots associated with a decline in the proportion of 10 large trees. There was also contrasting support for different non-mutually exclusive hypotheses, with 11 proportion of small trees (DBH <20cm) most strongly supported by topography (altitude and slope) 12 whereas the proportion of large trees (DBH >60cm) supported by plot type and regrowth class. These 13 findings support calls for increased efforts to actively conserve large trees to avoid retrogressive 14 succession around edges of degraded Amazon forests. 15 16 17 Healthy tropical forests provide goods and services to human populations. Yet tropical forests show 18 worrying rates of forest loss with an elevated loss / gain ratio and a statistically significant trend in 19 annual forest loss of 2101 km 2 /year 1 . One option to revert tropical forest loss is the restoration of 20 degraded forests and deforested landscapes 2,3 . Although the post-disturbance restoration of forest 21 ecosystems often involves passive restoration strategies (i.e. natural regeneration), the ecological 22 results of this type of restoration are still uncertain 2-4 . 23 Continuing widespread forest losses across Amazonia compromises vital ecosystem services 24 such as carbon storage, regulation of hydrological cycles and climate patterns 5-7 . Riverside forests 25 are particularly threatened and suffer losses due to the conversion of forest cover to pastures, 26 compromising the maintenance of water flows 8 . The recovery of degraded areas is necessary to 27 recuperate the standing forest value and the Amazon offers an excellent recovery opportunity due to 28 its natural potential for regeneration 9,10 . Yet, the regrowth rate of degraded Amazon forests can be 29 slow, as abandoned areas are typically on compacted poor quality soils 11,12 and due to the high 30 structural and biological diversity of the original forests 13 . 31Separating the complex interactions driving recruitment and recovery patterns of highly diverse 32 Amazon forests is challenging 2,3,14,15 , yet we know that different faunal groups can modulate and 33 generate key impacts [16][17][18][19] . Indeed, the successional trajectory of natural regeneration in degraded 34 forests ...

Fruit-fall provides the transfer of biomass and nutrients between forest strata and remains a poorly understood component of Amazon forest systems. Here we detail fruit-fall patterns including those of Vouacapoua americana a Critically Endangered timber species across 25 km2 of lowland Amazon forest in 2016. We use multi-model comparisons and an ensemble model to explain and interpolate fruit-fall data collected in 90 plots (totaling 4.42 ha). By comparing patterns in relation to observed and remotely sensed biomass estimates we establish the seasonal contribution of V. americana fruit-fall biomass. Overall fruit-fall biomass was 44.84 kg ha−1 month−1 from an average of 44.55 species per hectare, with V. americana dominating both the number and biomass of fallen fruits (43% and 64%, number and biomass respectively). Spatially explicit interpolations provided an estimate of 114 Mg dry biomass of V. americana fruit-fall across the 25 km2 area. This quantity represents the rapid transfer by a single species of between 0.01 and 0.02% of the overall above ground standing biomass in the area. These findings support calls for a more detailed understanding of the contribution of individual species to carbon and nutrient flows in tropical forest systems needed to evaluate the impacts of population declines predicted from short (< 65 year) logging cycles.

The role of fire in the management of degraded areas remains strongly debated. Here we experimentally compare removal and infestation of popcorn kernels (Zea mays L. – Poaceae) and açaí fruits (Euterpe oleracea Mart. – Arecaceae) in one burned and two unburned savanna habitats in the eastern Brazilian Amazon. In each habitat, a total of ten experimental units (five per seed type) were installed, each with three treatments: (1) open access, (2) vertebrate access, and (3) invertebrate access. Generalized linear models showed significant differences in both seed removal (P < 0.0001) and infestation (P < 0.0001) among seed type, habitats and access treatments. Burned savanna had the highest overall seed infestation rate (24.3%) and invertebrate access increased açaí seed infestation levels to 100% in the burned savanna. Increased levels of invertebrate seed infestation in burned savanna suggest that preparation burning may be of limited use for the management and restoration of such habitats in tropical regions.