Long-Term Patterns in Tropical Reforestation: Plant Community Composition and Aboveground Biomass Accumulation

Mar¡n-Spiotta, E.; Ostertag, Rebecca; Silver, Whendee L.

doi:10.1890/06-1268

Cited by 129 publications

(104 citation statements)

References 54 publications

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“…In the central 60 × 60 m area in each plot, all lianas and trees ≥1 cm were measured in 2008 and then a second time in 2011, immediately before liana removal. Aboveground tree carbon stocks in these 16 plots averaged 75.1 Mg C ha −1 , which is representative of other ∼60-y-old forests in the neotropics (26,27). The forests in Gigante contained only 36.4-81.2% of the carbon measured in old-growth forests in Amazonia (13).…”

Section: Methodsmentioning

confidence: 82%

Lianas reduce carbon accumulation and storage in tropical forests

Heijden

Powers

Schnitzer

2015

Proc. Natl. Acad. Sci. U.S.A.

167

136

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Tropical forests store vast quantities of carbon, account for onethird of the carbon fixed by photosynthesis, and are a major sink in the global carbon cycle. Recent evidence suggests that competition between lianas (woody vines) and trees may reduce forest-wide carbon uptake; however, estimates of the impact of lianas on carbon dynamics of tropical forests are crucially lacking. Here we used a large-scale liana removal experiment and found that, at 3 y after liana removal, lianas reduced net above-ground carbon uptake (growth and recruitment minus mortality) by ∼76% per year, mostly by reducing tree growth. The loss of carbon uptake due to lianainduced mortality was four times greater in the control plots in which lianas were present, but high variation among plots prevented a significant difference among the treatments. Lianas altered how aboveground carbon was stored. In forests where lianas were present, the partitioning of forest aboveground net primary production was dominated by leaves (53.2%, compared with 39.2% in liana-free forests) at the expense of woody stems (from 28.9%, compared with 43.9%), resulting in a more rapid return of fixed carbon to the atmosphere. After 3 y of experimental liana removal, our results clearly demonstrate large differences in carbon cycling between forests with and without lianas. Combined with the recently reported increases in liana abundance, these results indicate that lianas are an important and increasing agent of change in the carbon dynamics of tropical forests.L ianas (woody vines) are a key component of lowland tropical forests, commonly contributing more than 25% of the woody stems and species and competing intensely with trees. By relying on the structural investment of trees for support, lianas are able to allocate a higher proportion of biomass than trees into the production of foliage rather than carbon-dense stems (1). Thus, lianas themselves contribute relatively little to forest-level biomass (1, 2). The ecological effects of lianas may be more extensive than their relatively modest contribution to biomass suggests, however. Liana-tree competition can be far more intense than tree-tree competition (3), substantially reducing tree growth (2, 4), fecundity (5, 6), and survival (4, 7). Furthermore, lianas may constrain net above-ground forest primary productivity, i.e., the total amount of carbon fixed into both canopy material (leaves, flowers, fruits, and seeds) and woody stems (8), by failing to compensate for the biomass that they displace in trees (1, 2).Recent evidence indicates that lianas are now increasing in abundance and biomass in tropical forests, possibly being driven by a combination of increased atmospheric CO 2 concentration, changing climatic conditions, and seasonal droughts, as well as increased natural and anthropogenic disturbances (9, 10). The increase in lianas, combined with the observations that lianas can reduce individual tree growth by up to 84% (11) and increase tree mortality risk twofold to threefold (4, 7), has made it pertin...

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Section: Methodsmentioning

confidence: 82%

Lianas reduce carbon accumulation and storage in tropical forests

Heijden

Powers

Schnitzer

2015

Proc. Natl. Acad. Sci. U.S.A.

167

136

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“…Different species can correlate with different stages of recovery from disturbance. Differential species growth rates, therefore, could potentially influence biomassaccumulation rates (35,36). In our forest stands, the most prevalent pioneer species that could influence stand growth rates were sweet gum (Liquidambar styraciflua) and tulip poplar (Liriodendron tulipifera).…”

Section: Resultsmentioning

confidence: 99%

Evidence for a recent increase in forest growth

McMahon

Parker

Miller

2010

Proc. Natl. Acad. Sci. U.S.A.

351

274

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Forests and their soils contain the majority of the earth's terrestrial carbon stocks. Changes in patterns of tree growth can have a huge impact on atmospheric cycles, biogeochemical cycles, climate change, and biodiversity. Recent studies have shown increases in biomass across many forest types. This increase has been attributed to climate change. However, without knowing the disturbance history of a forest, growth could also be caused by normal recovery from unknown disturbances. Using a unique dataset of tree biomass collected over the past 22 years from 55 temperate forest plots with known land-use histories and stand ages ranging from 5 to 250 years, we found that recent biomass accumulation greatly exceeded the expected growth caused by natural recovery. We have also collected over 100 years of local weather measurements and 17 years of on-site atmospheric CO 2 measurements that show consistent increases in line with globally observed climate-change patterns. Combined, these observations show that changes in temperature and CO 2 that have been observed worldwide can fundamentally alter the rate of critical natural processes, which is predicted by biogeochemical models. Identifying this rate change is important to research on the current state of carbon stocks and the fluxes that influence how carbon moves between storage and the atmosphere. These results signal a pressing need to better understand the changes in growth rates in forest systems, which influence current and future states of the atmosphere and biosphere. T he movement of carbon in our atmosphere, oceans, and terrestrial ecosystems is critical to predicting how climate change may influence the natural systems on which humans rely (1-4). Changes in ecosystems can, in turn, feed back into global atmospheric cycles through evapotranspiration, net ecosystem CO 2 exchange, and surface albedo and roughness, which complicates predictions about future climate states (1, 5-7). Key evidence that global changes may affect the functioning of forests is shown in changes in forest biomass over time, which can have important implications for whether or not forests accumulate biomass at a rate that would alter current trends of atmospheric carbon cycling (8).In densely forested regions across the globe, forests can recover rapidly from agricultural fields, logged stands, or areas cleared because of natural disturbances as long as remnant patches or seed banks remain. Across forest types, the period of recovery consists of a rapid rise in above-ground biomass (AGB) followed by a leveling off as the canopy fills in and biomass shifts from the sum of many small stems to fewer, larger canopy trees. The rate and asymptote of this pattern of biomass recovery can differ across stands because of nutrient availability and species composition or can differ between regions because of climate and disturbance regimens; however, the functional form of this response remains similar across forest types and regions (9, 10).There are indications that forest biomass accumulation...

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“…Aboveground tree biomass was estimated using allometric equations for trees and palms developed for these forests (Frangi and Lugo 1985;Weaver and Gillespie 1992), and biomass increment was calculated over the entire interval for each tree and averaged by plot. Aboveground biomass was estimated to be 46% C as measured previously in other Puerto Rican forests (Marin-Spiotta et al 2007).…”

Section: Aboveground Carbonmentioning

confidence: 92%

Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests

et al. 2010

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Anthropogenic nitrogen (N) deposition is increasing rapidly in tropical regions, adding N to ecosystems that often have high background N availability. Tropical forests play an important role in the global carbon (C) cycle, yet the effects of N deposition on C cycling in these ecosystems are poorly understood. We used a field N-fertilization experiment in lower and upper elevation tropical rain forests in Puerto Rico to explore the responses of above-and belowground C pools to N addition. As expected, tree stem growth and litterfall productivity did not respond to N fertilization in either of these Nrich forests, indicating a lack of N limitation to net primary productivity (NPP). In contrast, soil C concentrations increased significantly with N fertilization in both forests, leading to larger C stocks in fertilized plots. However, different soil C pools responded to N fertilization differently. Labile (low density) soil C fractions and live fine roots declined with fertilization, while mineral-associated soil C increased in both forests. Decreased soil CO 2 fluxes in fertilized plots were correlated with smaller labile soil C pools in the lower elevation forest (R 2 = 0.65, p \ 0.05), and with lower live fine root biomass in the upper elevation forest (R 2 = 0.90, p \ 0.05). Our results indicate that soil C storage is sensitive to N deposition in tropical forests, even where plant productivity is not N-limited. The mineral-associated soil C pool has the potential to respond relatively quickly to N additions, and can drive increases in bulk soil C stocks in tropical forests.

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Long-Term Patterns in Tropical Reforestation: Plant Community Composition and Aboveground Biomass Accumulation

Cited by 129 publications

References 54 publications

Lianas reduce carbon accumulation and storage in tropical forests

Lianas reduce carbon accumulation and storage in tropical forests

Evidence for a recent increase in forest growth

Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests

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