Expansion of the cattle and soy industries in the Amazon basin has increased deforestation rates and will soon push all-weather highways into the region's core. In the face of this growing pressure, a comprehensive conservation strategy for the Amazon basin should protect its watersheds, the full range of species and ecosystem diversity, and the stability of regional climates. Here we report that protected areas in the Amazon basin--the central feature of prevailing conservation approaches--are an important but insufficient component of this strategy, based on policy-sensitive simulations of future deforestation. By 2050, current trends in agricultural expansion will eliminate a total of 40% of Amazon forests, including at least two-thirds of the forest cover of six major watersheds and 12 ecoregions, releasing 32 +/- 8 Pg of carbon to the atmosphere. One-quarter of the 382 mammalian species examined will lose more than 40% of the forest within their Amazon ranges. Although an expanded and enforced network of protected areas could avoid as much as one-third of this projected forest loss, conservation on private lands is also essential. Expanding market pressures for sound land management and prevention of forest clearing on lands unsuitable for agriculture are critical ingredients of a strategy for comprehensive conservation.

The ecology of Bornean rainforests is driven by El Niño-induced droughts that trigger synchronous fruiting among trees and bursts of faunal reproduction that sustain vertebrate populations. However, many of these species- and carbon-rich ecosystems have been destroyed by logging and conversion, which increasingly threaten protected areas. Our satellite, Geographic Information System, and field-based analyses show that from 1985 to 2001, Kalimantan's protected lowland forests declined by more than 56% (>29,000 square kilometers). Even uninhabited frontier parks are logged to supply international markets. "Protected" forests have become increasingly isolated and deforested and their buffer zones degraded. Preserving the ecological integrity of Kalimantan's rainforests requires immediate transnational management.

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Dipterocarpaceae, the dominant family of Bornean canopy trees, display the unusual reproductive strategy of strict interspecific mast-fruiting. During 1986-99, more than 50 dipterocarp species dispersed seed only within a 1- to 2-month period every 3 to 4 years during El Nino-Southern Oscillation events. Synchronous seed production occurred across extensive areas and was essential for satiating seed predators. Logging of dipterocarps reduced the extent and intensity of these reproductive episodes and exacerbated local El Nino conditions. Viable seed and seedling establishment have declined as a result of climate, logging, and predators. Since 1991, dipterocarps have experienced recruitment failure within a national park, now surrounded by logged forest.

Industrial agricultural plantations are a rapidly increasing yet largely unmeasured source of tropical land cover change. Here, we evaluate impacts of oil palm plantation development on land cover, carbon flux, and agrarian community lands in West Kalimantan, Indonesian Borneo. With a spatially explicit land change/carbon bookkeeping model, parameterized using high-resolution satellite time series and informed by socioeconomic surveys, we assess previous and project future plantation expansion under five scenarios. Although fire was the primary proximate cause of 1989-2008 deforestation (93%) and net carbon emissions (69%), by 2007-2008, oil palm directly caused 27% of total and 40% of peatland deforestation. Plantation land sources exhibited distinctive temporal dynamics, comprising 81% forests on mineral soils (1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001), shifting to 69% peatlands (2008)(2009)(2010)(2011). Plantation leases reveal vast development potential. In 2008, leases spanned ∼65% of the region, including 62% on peatlands and 59% of community-managed lands, yet <10% of lease area was planted. Projecting business as usual (BAU), by 2020 ∼40% of regional and 35% of community lands are cleared for oil palm, generating 26% of net carbon emissions. Intact forest cover declines to 4%, and the proportion of emissions sourced from peatlands increases 38%. Prohibiting intact and logged forest and peatland conversion to oil palm reduces emissions only 4% below BAU, because of continued uncontrolled fire. Protecting logged forests achieves greater carbon emissions reductions (21%) than protecting intact forests alone (9%) and is critical for mitigating carbon emissions. Extensive allocated leases constrain land management options, requiring trade-offs among oil palm production, carbon emissions mitigation, and maintaining community landholdings.greenhouse gas emissions | agribusiness | Elaeis guineensis | moratorium | REDD+ G lobal demand for food, biofuels, and natural resources drives capitalized agricultural development, especially for tropical plantations (1-4). Forest and peatland conversion to plantation agriculture may be a substantial source of greenhouse gas (GHG) emissions from land cover change (5, 6), which generates 10-20% of net global GHG emissions (7). By acquiring extensive arable lands, plantations also affect land availability for smallholder farmers and communities, potentially altering local livelihood options (8, 9). Whereas environmental degradation from tropical agribusiness may overwhelm benefits of high-yield plantations for world food security (6, 10), impacts on carbon (C) flux and livelihoods are highly uncertain because locations and land sources for plantations remain largely undocumented.Complex processes of land acquisition and plantation development unfold across heterogeneous biophysical and sociopolitical landscapes in both time and space. Land cover histories constrain present land use and potential outcomes from agribusiness expansion (11). Discerning the land cover traje...

To examine the interspecific reproductive synchrony of Dipterocarpaceae with vertebrate responses to seed availablity, we monitored the spatiotemporal distribution and phenology of more than 2367 adult dipterocarp individuals of 54 species from March 1985 to January 1993 in the Gunung Palung National Park, West Kalimantan, Indonesia. Seven vegetational formations were sampled along an altitudinal gradient from peat swamp forest (5 m a.s.l. [above sea level]) across lowlands to upper montane zones (1100 m a.s.l.) that encompassed two upland valley complexes in a 15‐km2 area. Four significant reproductive events were documented: (1) a common lowland species reproduced outside of mast events in 1986 and in 1990; (2) a localized lowland “minor” mast event in 1986 in which 24.3% of the adult trees (21 spp.) participated; (3) a major community‐wide mast event (92.8%, 48 spp.) in 1987, just 6 mo after the minor event; and (4) another major community‐wide mast fruiting event after a 4‐yr intermast interval (88%, 48 spp.) in 1991. West Kalimantan export records of illipe nut (Dipterocarpaceae: Shorea section Pachycarpae) from 1968 to 1997 were compiled as a baseline measure of the frequency and relative intensity of dipterocarp mast‐fruiting events in the region (cv = 152%). A “bumper crop” occurred about every 5 ± 2.6 yr (mean ± 1 sd; range 3–9 yr). Fruit production was significantly associated with El Niño–Southern Oscillation (ENSO) events. The 1987 and 1991 mast events monitored were the third and fourth largest export years in the province since 1968. Because of the disputed role of vertebrate seed predators in causing and maintaining mast‐fruiting behavior, the response of seed‐eating vertebrates to this spatiotemporal variation in dipterocarp seed production was examined. Seed of a common, but asynchronous, lowland species was largely consumed by vertebrates. In the 1986 minor mast, 21 dipterocarp species that produced 60 000 seeds/ha (dry mass 46 kg/ha) lost all monitored viable seed to a diversity of resident and nomadic vertebrate seed predators. Timed with dipterocarp seed production in all mast events, nomadic vertebrates increased their populations through both reproduction and regional movement (numerical response). However, in both the 1987 and 1991 mast events, resident vertebrates destroyed only 1.5% and 2.6% of community seed production, and predation was recorded only in the tails of the fruit‐fall distribution. During these community mast events, resident vertebrates switched from dipterocarp seed to feed on fruit and seed from other available species. Nomadic vertebrates arrived late in the fruit‐fall period during both major mast events and, thus, were able to destroy only seed dispersed in the final 1–3 wk of fruit‐fall. Seed escape, and thus regeneration, only occurred in major mast events when all dipterocarp species across large areas participated. Considerable seedling recruitment was recorded in both the 1987 (∼95 000 seedlings/ha) and 1991 (155 824 ± 36 764 seedlings/ha) mast events. Results fr...

Summary 1The relative importance of niche-and dispersal-mediated processes in structuring diverse tropical plant communities remains poorly understood. Here, we link mesoscale beta diversity to soil variation throughout a lowland Bornean watershed underlain by alluvium, sedimentary and granite parent materials ( c . 340 ha, 8-200 m a.s.l.). We test the hypothesis that species turnover across the habitat gradient reflects interspecific partitioning of soil resources. 2 Floristic inventories ( ≥ 1 cm d.b.h.) of the Dipterocarpaceae, the dominant Bornean canopy tree family, were combined with extensive soil analyses in 30 (0.16 ha) plots. Six samples per plot were analysed for total C, N, P, K, Ca and Mg, exchangeable K, Ca and Mg, extractable P, texture, and pH. 3 Extractable P, exchangeable K, and total C, N and P varied significantly among substrates and were highest on alluvium. Thirty-one dipterocarp species ( n = 2634 individuals, five genera) were recorded. Dipterocarp density was similar across substrates, but richness and diversity were highest on nutrient-poor granite and lowest on nutrientrich alluvium. 4 Eighteen of 22 species were positively or negatively associated with parent material. In 8 of 16 abundant species, tree distribution ( ≥ 10 cm d.b.h.) was more strongly nonrandom than juveniles (1-10 cm d.b.h.), suggesting higher juvenile mortality in unsuitable habitats. The dominant species Dipterocarpus sublamellatus (> 50% of stems) was indifferent to substrate, but nine of 11 'subdominant' species (> 8 individuals ha − 1 ) were substrate specialists. 5 Eighteen of 22 species were significantly associated with soil nutrients, especially P, Mg and Ca. Floristic variation was significantly correlated with edaphic and geographical distance for all stems ≥ 1 cm d.b.h. in Mantel analyses. However, juvenile variation (1-10 cm d.b.h.) was more strongly related to geographical distance than edaphic factors, while the converse held for established trees ( ≥ 10 cm d.b.h.), suggesting increased importance of niche processes with size class. 6 Pervasive dipterocarp associations with soil factors suggest that niche partitioning structures dipterocarp tree communities. Yet, much floristic variation unrelated to soil was correlated with geographical distance between plots, suggesting that dispersal and niche processes jointly determine mesoscale beta diversity in the Bornean Dipterocarpaceae.

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