scholarly journals Contributions of secondary forest and nitrogen dynamics to terrestrial carbon uptake

2010 ◽  
Vol 7 (2) ◽  
pp. 2739-2765 ◽  
Author(s):  
X. Yang ◽  
T. K. Richardson ◽  
A. K. Jain

Abstract. We use a terrestrial carbon-nitrogen cycle component of the Integrated Science Assessment Model (ISAM) to investigate the impacts of nitrogen dynamics on regrowing secondary forests over the 20th century. We further examine what the impacts of nitrogen deposition and land use change history are on terrestrial carbon uptake since preindustrial time. Our results suggest that global total net land use emissions for the 1990s associated with changes in cropland, pastureland, and wood harvest are 1.22 GtC/yr. Without considering the secondary forest regrowth, the estimated net global total land use emissions are 1.58 GtC/yr or about 0.36 GtC/yr higher than if secondary forest regrowth is considered. Results also show that without considering the nitrogen dynamics and deposition, the estimated global total secondary forest sink for the 1990s is 0.90 GtC/yr or about 0.54 GtC/yr higher than estimates that include the impacts of nitrogen dynamics and deposition. Nitrogen deposition alone is responsible for about 0.13 GtC/yr of the total secondary forest sink. While nitrogen is not a limiting nutrient in the intact primary forests in tropical regions, our study suggests that nitrogen becomes a limiting nutrient for regrowing secondary forests of the tropical regions, in particular Latin America and Tropical Africa. This is because land use change activities, especially wood harvest, removes large amounts of nitrogen from the system when slash is burnt or wood is removed for harvest. However, our model results show that carbon uptake is enhanced in the tropical secondary forests of the Indian region. We argue that this may be due to enhanced nitrogen mineralization and increased nitrogen availability following land use change in the Indian tropical forest ecosystems. Results also demonstrate that there is a significant amount of carbon accumulating in the Northern Hemisphere where most land use changes and forest regrowth has occurred in recent decades. This study indicates the significance of secondary forests to terrestrial carbon sinks, the importance of nitrogen dynamics to the magnitude of secondary forests carbon uptake, and therefore the need to include both primary and secondary forests and nitrogen dynamics in terrestrial ecosystem models.

2010 ◽  
Vol 7 (10) ◽  
pp. 3041-3050 ◽  
Author(s):  
X. Yang ◽  
T. K. Richardson ◽  
A. K. Jain

Abstract. We use a terrestrial carbon-nitrogen cycle component of the Integrated Science Assessment Model (ISAM) to investigate the impacts of nitrogen dynamics on regrowing secondary forests over the 20th century. We further examine what the impacts of nitrogen deposition and land use change history are on terrestrial carbon uptake since preindustrial time. Our results suggest that global total net land use emissions for the 1990s associated with changes in cropland, pastureland, and wood harvest are 1.22 GtC/yr. Without considering the secondary forest regrowth, the estimated net global total land use emissions are 1.58 GtC/yr or about 0.36 GtC/yr higher than if secondary forest regrowth is considered. Results also show that without considering the nitrogen dynamics and deposition, the estimated global total secondary forest sink for the 1990s is 0.90 GtC/yr or about 0.54 GtC/yr higher than estimates that include the impacts of nitrogen dynamics and deposition. Nitrogen deposition alone is responsible for about 0.13 GtC/yr of the total secondary forest sink. While nitrogen is not a limiting nutrient in the intact primary forests in tropical regions, our study suggests that nitrogen becomes a limiting nutrient for regrowing secondary forests of the tropical regions, in particular Latin America and Tropical Africa. This is because land use change activities, especially wood harvest, removes large amounts of nitrogen from the system when slash is burnt or wood is removed for harvest. However, our model results show that carbon uptake is enhanced in the tropical secondary forests of the Indian region. We argue that this may be due to enhanced nitrogen mineralization and increased nitrogen availability following land use change in the Indian tropical forest ecosystems. Results also demonstrate that there is a significant amount of carbon accumulating in the Northern Hemisphere where most land use changes and forest regrowth has occurred in recent decades. This study indicates the significance of secondary forests to terrestrial carbon sinks, the importance of nitrogen dynamics to the magnitude of secondary forests carbon uptake, and therefore the need to include both primary and secondary forests and nitrogen dynamics in terrestrial ecosystem models.


2021 ◽  
Vol 14 (2) ◽  
pp. 10-18
Author(s):  
Herry Andrisa ◽  
Hairul Basri ◽  
Muhammad Rusdi

Abstrak. Penelitian ini bertujuan untuk mengetahui pengaruh rehabilitasi lahan dan hutan (RHL) terhadap nilai koefisien aliran tahunan (KAT) di sub-DAS Krueng Meulesong. Pelaksanaan RHL di Desa Riting Kecamatan Indrapuri Kabupaten Aceh Besar yang termasuk dalam DAS Krueng Meuleusong dikategorikan tidak berhasil berdasarkan citra satelit perubahan tata guna lahan tahun 2009, 2014, 2017 dan 2019. Hasil interpretasi citra satelit menunjukkan penurunan luasan hutan sekunder, namun luas perdu dan sabana meningkat. Berdasarkan hasil uji korelasi menunjukkan bahwa pelaksanaan kegiatan RHL tidak berpengaruh terhadap perubahan penggunaan lahan menjadi hutan sekunder dan kegiatan RHL tidak berpengaruh terhadap nilai koefisien aliran tahunan (KAT) di Sub-DAS Krueng Meuleusong.Evaluation Of The Effect Of Land And Forest Rehabilitation On Annual Flow Coefficient In Krueng Meuleusong Sub-WatershedAbstract. This study aims to determine the effect of land and forest rehabilitation (RHL) on the value of the annual flow coefficient (KAT) in the Krueng Meulesong sub-watershed. The implementation of RHL in Riting Village, Indrapuri District, Aceh Besar District which is included in the water catchment area of the Krueng Meuleusong sub-watershed is categorized as unsuccessful based on satellite imagery of 2009, 2014, 2017 and, 2019 of land-use change. The results of satellite imagery interpretation showed a decrease in the area of secondary forest, but shrubs and savanna area had increased. Based on the results of the correlation test, shows that the implementation of RHL activities has no effect on changes in land use to secondary forests and RHL activities have no effect on the value of annual flow coefficient (KAT) in the Krueng Krueng Meuleusong sub-watershed.


Author(s):  
Kyle M. Meyer ◽  
Andrew H. Morris ◽  
Kevin Webster ◽  
Ann M. Klein ◽  
Marie E. Kroeger ◽  
...  

ABSTRACTAmazonian rainforest is undergoing increasing rates of deforestation, driven primarily by cattle pasture expansion. Forest-to-pasture conversion has been associated with changes to ecosystem processes, including substantial increases in soil methane (CH4) emission. The drivers of this change in CH4 flux are not well understood. To address this knowledge gap, we measured soil CH4 flux, environmental conditions, and belowground microbial community attributes across a land use change gradient (old growth primary forest, cattle pasture, and secondary forest regrowth) in two Amazon Basin regions. Primary forest soils exhibited CH4 uptake at modest rates, while pasture soils exhibited CH4 emission at high but variable rates. Secondary forest soils exhibited low rates of CH4 uptake, suggesting that forest regrowth following pasture abandonment could reverse the CH4 sink-to-source trend. While few environmental variables were significantly associated with CH4 flux, we identified numerous microbial community attributes in the surface soil that explained substantial variation in CH4 flux with land use change. Among the strongest predictors were the relative abundance and diversity of methanogens, which both increased in pasture relative to forests. We further identified individual taxa that were associated with CH4 fluxes and which collectively explained ~50% of flux variance. These taxa included methanogens and methanotrophs, as well as taxa that may indirectly influence CH4 flux through acetate production, iron reduction, and nitrogen transformations. Each land type had a unique subset of taxa associated with CH4 fluxes, suggesting that land use change alters CH4 cycling through shifts in microbial community composition. Taken together, our results suggest that changes in CH4 flux from agricultural conversion could be driven by microbial responses to land use change in the surface soil, with both direct and indirect effects on CH4 cycling. This demonstrates the central role of microorganisms in mediating ecosystem responses to land use change in the Amazon Basin.


2018 ◽  
Vol 15 (4) ◽  
pp. 1185-1201 ◽  
Author(s):  
Chao Yue ◽  
Philippe Ciais ◽  
Wei Li

Abstract. Several modelling studies reported elevated carbon emissions from historical land use change (ELUC) by including bidirectional transitions on the sub-grid scale (termed gross land use change), dominated by shifting cultivation and other land turnover processes. However, most dynamic global vegetation models (DGVMs) that have implemented gross land use change either do not account for sub-grid secondary lands, or often have only one single secondary land tile over a model grid cell and thus cannot account for various rotation lengths in shifting cultivation and associated secondary forest age dynamics. Therefore, it remains uncertain how realistic the past ELUC estimations are and how estimated ELUC will differ between the two modelling approaches with and without multiple sub-grid secondary land cohorts – in particular secondary forest cohorts. Here we investigated historical ELUC over 1501–2005 by including sub-grid forest age dynamics in a DGVM. We run two simulations, one with no secondary forests (Sageless) and the other with sub-grid secondary forests of six age classes whose demography is driven by historical land use change (Sage). Estimated global ELUC for 1501–2005 is 176 Pg C in Sage compared to 197 Pg C in Sageless. The lower ELUC values in Sage arise mainly from shifting cultivation in the tropics under an assumed constant rotation length of 15 years, being 27 Pg C in Sage in contrast to 46 Pg C in Sageless. Estimated cumulative ELUC values from wood harvest in the Sage simulation (31 Pg C) are however slightly higher than Sageless (27 Pg C) when the model is forced by reconstructed harvested areas because secondary forests targeted in Sage for harvest priority are insufficient to meet the prescribed harvest area, leading to wood harvest being dominated by old primary forests. An alternative approach to quantify wood harvest ELUC, i.e. always harvesting the close-to-mature forests in both Sageless and Sage, yields similar values of 33 Pg C by both simulations. The lower ELUC from shifting cultivation in Sage simulations depends on the predefined forest clearing priority rules in the model and the assumed rotation length. A set of sensitivity model runs over Africa reveal that a longer rotation length over the historical period likely results in higher emissions. Our results highlight that although gross land use change as a former missing emission component is included by a growing number of DGVMs, its contribution to overall ELUC remains uncertain and tends to be overestimated when models ignore sub-grid secondary forests.


2002 ◽  
Vol 46 (1) ◽  
Author(s):  
Dietrich Schmidt-Vogt

AbstractManagement of secondary tropical forests: a new perspective for sustainable use of forests in Asia. The decline of primary forests in the tropics is leading to a reassessment of the role secondary forests might play within the context of tropical forest management. Recent research has shown that secondary forests in the tropics can be both rich in species and complex in terms of stand structure. There is, moreover, a growing recognition of the importance of secondary forests for traditional subsistence economies in the tropics and of their economic potential for land use systems in the future. Management of secondary forests in Asia as an alternative to the extraction of timber from primary forests but also as one among other options to intensify traditional land use systems has a potential for the future especially because of the existence of vast tracts of valuable secondary forest cover, and because of the store of traditional knowledge that can still be found in tropical Asia.


2021 ◽  
Author(s):  
Madelon Lohbeck ◽  
Ben DeVries ◽  
Frans Bongers ◽  
Miguel Martinez-Ramos ◽  
Armando Navarrete-Segueda ◽  
...  

Forest regrowth is key to achieve restoration commitments, but we need to better understand under what circumstances it takes place and how long secondary forests persist. We studied a recently colonized agricultural frontier in southern Mexico. We quantified the spatiotemporal dynamics of forest loss and regrowth and tested how temporal variation in climate, and spatial variation in land availability, land quality and accessibility affect forest disturbance, regrowth and secondary forest persistence. Marqués de Comillas consistently exhibits more forest loss than regrowth, resulting in a net decrease of 30% forest cover (1991-2016). Secondary forest cover remained relatively constant while secondary forest persistence increased, suggesting that farmers are moving away from shifting cultivation. Temporal variation in disturbance and regrowth were explained by the annual variation in the Oceanic El Niño index combined with dry season rainfall and key policy and market interventions.Across communities the availability of high-quality soil overrules the effects of land availability and accessibility, but that at the pixel-level all three factors contributed to explaining forest conservation and restoration. Communities with more high-quality soils were able to spare land for forest conservation, and had less secondary forest that persisted for longer. Old forest and secondary forests were better represented on low-quality lands and on communal land. Both old and secondary forest were less common close to the main road, where secondary forests were also less persistent. Forest conservation and restoration can be explained by a complex interplay of biophysical and social drivers across time, space and scale. We warrant that stimulating private land ownership may cause remaining forest patches to be lost and that conservation initiatives should benefit the whole community. Forest regrowth and secondary forest persistence competes with agricultural production and ensuring farmers can access restoration benefits is key to success.


2016 ◽  
Vol 9 (2) ◽  
pp. 147-156
Author(s):  
Devianti Devianti

Abstrak. Sub Sub DAS Cikujang merupakan salah satu bagian dari Sub DAS Cimanuk hulu yang dapat menyumbang sedimen ke waduk Jatigede yang berasal dari erosi sebagai akibat perubahan penggunaan lahan yang tidak sesuai dengan kondisi fisik lahan. Hasil kajian memperlihatkan  pola perubahan penggunaan lahan di Sub Sub DAS Cikujang periode 1994-2009, terjadi perubahan penggunaan lahan dari kawasan lindung menjadi kawasan budidaya seluas 742,20 ha. Kawasan lindung pada tahun 1994 seluas 3.213,03 ha menurun menjadi 2.470,83 ha pada tahun 2009 dan kawasan budidaya pada tahun 1994 seluas 9.532,41 ha meningkat menjadi 10.274,61 ha pada tahun 2009 dengan laju perubahan 185,55 ha/tahun. Laju penurunan luasan hutan primer mencapai 54,45 ha/tahun, dan pada tahun 2009 tidak terdapat lagi lahan dengan fungsi sebagai hutan primer. Laju penurunan luasan hutan sekunder mencapai 135,90 ha/tahun dari 2.995,25 ha pada tahun 1994 menjadi 2.451,65 ha pada tahun 2009. Pola perubahan penggunaan lahan di Sub Sub DAS Cikujang sebagian besar dipengaruhi dengan pola perubahan hutan primer dan hutan sekunder pada kawasan lindung. Sedangkan pola perubahan penggunaan lahan pada kawasan budidaya dipengaruhi pola perubahan lahan kebun campuran, tegalan/ladang, perkebunan, dan sawah Land-Use Change Pattern in Cikujang Catchment Area Abstract. Cikujang catchment area is one part of the subzone Cimanuk that can contribute sediment upstream reservoirs to Jatigede derived from erosion as a result of changes in land use that is not in accordance with the physical condition of the land. Based on analysis result of land-use change pattern in Cikujang catchment area in 1994 – 2009 period, land-use had changed 742,20ha from protected areas to cultivated areas, where protected area had decreased from 3.213,03ha in 1994 to 2.470,83ha in 2009 and cultivated area had increased from 10.274,61 ha in 1994 to10.274,61 ha in 2009 with changing rate ha/year. The rate of decreasing primary forest area was 54.45ha/year, as a result there was no land function as primary forest in 2009.  The rate of decreasing secondary forest area was 135,90ha/year ranging from 2.995,25ha in 1994 to 2.451,65ha in 2009. Land-use change pattern in Cikujang catchment area dominantly was influenced by changing pattern of protected forest and secondary forest in protected area, but in cultivated area land-use change pattern was influenced by changing pattern of farm, grassland, and rice field.


2008 ◽  
Vol 38 (12) ◽  
pp. 3033-3046 ◽  
Author(s):  
Thomas Knoke ◽  
Patrick Hildebrandt ◽  
Daniel Klein ◽  
Rodrigo Mujica ◽  
Martin Moog ◽  
...  

The expected opportunity costs of conserving a specific land use are usually considered adequate as financial compensation. However, a “conservation premium” is sometimes proposed as an added incentive, i.e., compensation greater than the expected opportunity costs. This paper discusses various methodological opportunities for deriving effective compensation under uncertainty. Based on cumulative distribution functions of possible opportunity costs (a Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) plantation was considered the alternative to conserving a Chilean secondary forest), generated through Monte Carlo simulations, we derived an inclusive range of possible compensations from 77 up to 375 US$·ha–1·year–1. If we assumed that the two land-use alternatives were mutually exclusive and independent from other risky investments, a compensation of 375 US$·ha–1·year–1 was necessary to convince every decision maker to maintain the secondary forest. However, only 77 US$·ha–1·year–1 was enough for a risk-averse decision maker (given average opportunity costs of 113 US$·ha–1·year–1). Yet, it turned out that the greatest possible opportunity costs would already be compensated for with 199 US$·ha–1·year–1, given an error probability of 0.05. Compensating for the last 5% of possible opportunity costs would thus require an additional 176 US$·ha–1·year–1. Our approach had two main limitations, namely we did not consider portfolio effects, which would allow diversifying away unsystematic risks, and we did not take into account the different systematic risks of the compared alternatives. These limitations may have led to an overestimation of effective compensation.


Sign in / Sign up

Export Citation Format

Share Document