scholarly journals Effects of land use change from natural forest to plantation on C, N and natural abundance of 13C and 15N along a climate gradient in eastern China

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Mbezele Junior Yannick Ngaba ◽  
Ya-Lin Hu ◽  
Roland Bol ◽  
Xiang-Qing Ma ◽  
Shao-Fei Jin ◽  
...  

Abstract Soil C and N turnover rates and contents are strongly influenced by climates (e.g., mean annual temperature MAT, and mean annual precipitation MAP) as well as human activities. However, the effects of converting natural forests to intensively human-managed plantations on soil carbon (C), nitrogen (N) dynamics across various climatic zones are not well known. In this study, we evaluated C, N pool and natural abundances of δ13C and δ15N in forest floor layer and 1-meter depth mineral soils under natural forests (NF) and plantation forest (PF) at six sites in eastern China. Our results showed that forest floor had higher C contents and lower N contents in PF compared to NF, resulting in high forest floor C/N ratios and a decrease in the quality of organic materials in forest floor under plantations. In general, soil C, N contents and their isotope changed significantly in the forest floor and mineral soil after land use change (LUC). Soil δ13C was significantly enriched in forest floor after LUC while both δ13C and δ15N values were enriched in mineral soils. Linear and non-linear regressions were observed for MAP and MAT in soil C/N ratios and soil δ13C, in their changes with NF conversion to PF while soil δ15N values were positively correlated with MAT. Our findings implied that LUC alters soil C turnover and contents and MAP drive soil δ13C dynamic.

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8377
Author(s):  
Mbezele Junior Yannick Ngaba ◽  
Xiang-Qing Ma ◽  
Ya-Lin Hu

Forest plantation, either through afforestation or reforestation, has been suggested to reverse and mitigate the process of deforestation. However, uncertainties remain in the potential of plantation forest (PF) to sequestrate carbon (C) and nitrogen (N) compared to natural forest (NF). Soil C and N stocks require a critical and updated look at what is happening especially in the context of increasing rate of land use change and climate change. The current study was conducted in China’s Eastern forest to estimate soil C and N stocks in six depth layers (0–10, 10–20, 20–40, 40–60, 60–80 and 80–100 cm) and two forest types (NF and PF) at four sites along climate factors gradient. The results showed that the overall mean soil C and N amounts to a depth of 20 cm ranged from 2.6 ± 1.1 Mg ha−1 to 38.6 ± 23.1 Mg ha−1, and soil nitrogen stock ranged from 0.2 ± 0.1 Mg ha−1 to 3.3 ± 1.5 Mg ha−1. Moreover, a loss of C stock was observed at Qingyuan (QY) by −7%, Dinghushan (DH) by −26%, Jianfengling (JF) by −13% while that of N stock was observed at QY (−8%), DH (−19%) and JF (−12%) at both depth layers. These results indicate that NFs have a better capacity to accumulate soil C and N. The soil C and N decreased from the southeast to the northeast and increased from tropical to temperate mixed forests zone in the eastern part of the study area. The C and N stock mainly occurred in the topsoil and decreased significantly with depth. Moreover, soil C and N stocks increased with age of plantation. This study provides an overview of the current spatial distribution and soil stocks of C and N, as well as the effects of environmental factors on soil C and N stocks. It also indicated that, although mean annual temperature and mean annual precipitation are the key factors affecting the variations in soil C and N, their vertical and horizontal distribution differed in various aspects.


2020 ◽  
Vol 12 (20) ◽  
pp. 8656
Author(s):  
Daniela Figueroa ◽  
Patricia Ortega-Fernández ◽  
Thalita F. Abbruzzini ◽  
Anaitzi Rivero-Villlar ◽  
Francisco Galindo ◽  
...  

The effects of converting native forests to livestock systems on soil C, N and P contents across various climatic zones are not well understood for the tropical region. The goal of this study was to test how soil C, N and P dynamics are affected by the land-use change from natural forests to livestock production systems (extensive pasture and intensive silvopastoral systems) across a rainfall gradient of 1611–711 mm per year in the Mexican tropics. A total of 15 soil-based biogeochemical metrics were measured in samples collected during the dry and rainy seasons in livestock systems and mature forests for land-use and intersite comparisons of the nutrient status. Our results show that land-use change from natural forests to livestock production systems had a negative effect on soil C, N and P contents. In general, soil basal respiration and C-acquiring enzyme activities increased under livestock production systems. Additionally, reduction in mean annual rainfall affected moisture-sensitive biogeochemical processes affecting the C, N and P dynamics. Our findings imply that land-use changes alter soil C, N and P dynamics and contents, with potential negative consequences for the sustainability of livestock production systems in the tropical regions of Mexico investigated.


2020 ◽  
Vol 31 (7) ◽  
pp. 909-923 ◽  
Author(s):  
Rafael da Silva Teixeira ◽  
Ricardo Cardoso Fialho ◽  
Daniela Cristina Costa ◽  
Rodrigo Nogueira Sousa ◽  
Rafael Silva Santos ◽  
...  

2011 ◽  
Vol 8 (2) ◽  
pp. 353-364 ◽  
Author(s):  
M. R. Hoosbeek ◽  
M. Lukac ◽  
E. Velthorst ◽  
A. R. Smith ◽  
D. L. Godbold

Abstract. Through increases in net primary production (NPP), elevated CO2 is hypothesized to increase the amount of plant litter entering the soil. The fate of this extra carbon on the forest floor or in mineral soil is currently not clear. Moreover, increased rates of NPP can be maintained only if forests can escape nitrogen limitation. In a Free atmospheric CO2 Enrichment (FACE) experiment near Bangor, Wales, 4 ambient and 4 elevated [CO2] plots were planted with patches of Betula pendula, Alnus glutinosa and Fagus sylvatica on a former arable field. After 4 years, biomass averaged for the 3 species was 5497 (se 270) g m−2 in ambient and 6450 (se 130) g m−2 in elevated [CO2] plots, a significant increase of 17% (P = 0.018). During that time, only a shallow L forest floor litter layer had formed due to intensive bioturbation. Total soil C and N contents increased irrespective of treatment and species as a result of afforestation. We could not detect an additional C sink in the soil, nor were soil C stabilization processes affected by elevated [CO2]. We observed a decrease of leaf N content in Betula and Alnus under elevated [CO2], while the soil C/N ratio decreased regardless of CO2 treatment. The ratio of N taken up from the soil and by N2-fixation in Alnus was not affected by elevated [CO2]. We infer that increased nitrogen use efficiency is the mechanism by which increased NPP is sustained under elevated [CO2] at this site.


2007 ◽  
Vol 87 (1) ◽  
pp. 93-102 ◽  
Author(s):  
J M Kranabetter ◽  
A M Macadam

The extent of carbon (C) storage in forests and the change in C stocks after harvesting are important considerations in the management of greenhouse gases. We measured changes in C storage over time (from postharvest, postburn, year 5, year 10 and year 20) in logging slash, forest floors, mineral soils and planted lodgepole pine (Pinus contorta var. latifolia) trees from six prescribed-burn plantations in north central British Columbia. After harvest, site C in these pools averaged 139 Mg ha-1, with approximately equal contributions from mineral soils (0–30 cm), forest floors and logging slash. Together these detrital pools declined by 71 Mg C ha-1, or 51% (28% directly from the broadcast burn, and a further 23% postburn), in the subsequent 20 yr. Postburn decay in logging slash was inferred by reductions in wood density (from 0.40 to 0.34 g cm-3), equal to an average k rate of 0.011 yr-1. Losses in forest floor C, amounting to more than 60% of the initial mass, were immediate and continued to year 5, with no reaccumulation evident by year 20. Mineral soil C concentrations initially fluctuated before declining by 25% through years 10 and 20. Overall, the reductions in C storage were offset by biomass accumulation of lodgepole pine, and we estimate these plantations had become a net sink for C before year 20, although total C storage was still less than postharvest levels. Key words: C sequestration, forest floors; coarse woody debris; soil organic matter


2007 ◽  
Vol 37 (7) ◽  
pp. 1161-1172 ◽  
Author(s):  
C.E. Tewksbury ◽  
H. Van Miegroet

A field study was conducted in a high-elevation spruce–fir ( Picea rubens Sarg. – Abies fraseri (Pursh.) Poir) forest in the Great Smoky Mountains National Park to assess the effect of temperature on soil C storage and dynamics. In eight plots along an elevation gradient (1500–1900 m), we measured soil temperature, forest floor and mineral soil C, litter decomposition, soil respiration, and forest floor mean residence time. Mean annual soil temperature and annual degree-days above 5 °C were inversely correlated with elevation. Total soil C (166–241 Mg·ha–1) showed no trend with elevation, while forest floor C accumulation (16.3–35.9 Mg·ha–1) decreased significantly with elevation. Carbon dynamics did not follow a consistent elevation pattern; however, the cooler upper elevations showed the lowest C turnover as indicated by the lowest needle decomposition rate (k = 0.0231·year–1) and the longest mean residence time of forest floor C (22 years). Mean annual CO2efflux from the soil (1020–1830 kg C·ha–1·year–1) was negatively correlated with mean annual soil temperatures and annual degree-days above 5 °C. This gradient study offers useful insights into C release patterns under future warming scenarios, and suggests that the highest elevation may be most susceptible to global warming.


2021 ◽  
Vol 13 (23) ◽  
pp. 13306
Author(s):  
Qiang Feng ◽  
Siyan Dong ◽  
Baoling Duan

Revealing the spatial differentiation of ecosystem service (ES) trade-offs and their responses to land-use change along precipitation gradients are important issues in the Loess Plateau of China. We selected three watersheds called Dianshi (300 mm < MAP (mean annual precipitation) < 400 mm), Ansai (400 mm < MAP < 500 mm), and Linzhen (500 mm < MAP < 600 mm). A new ES trade-off quantification index was proposed, and quantile regression, piecewise linear regression, and redundancy analysis were used. The results were as follows. (1) Carbon sequestration (TC) and soil conservation (SEC) increased, but water yield (WY) decreased in the three watersheds from 2000 to 2018. (2) The effect of forests on trade-offs was positive in three watersheds, the main effect of shrubs was also positive, but the negative effect appeared in the TC-WY trade-off in Ansai. Grassland exacerbated trade-offs in Dianshi, whereas it reduced trade-offs in Ansai and Linzhen. These effects exhibited respective trends with the quantile in the three watersheds. (3) There were threshold values that trade-offs responded to land-use changes, and we could design land-use conversion types to balance ESs. In general, the water consumption of grass cannot be ignored in Dianshi; shrubs and grass are suitable vegetation types, and forests need to be restricted in Ansai; more forests and shrubs can be supported in Linzen due to higher precipitation, but the current proportions of forests and shrubs are too high. Our research contributes to a better understanding of the response mechanisms of ES trade-offs to land-use changes.


2021 ◽  
Vol 14 (10) ◽  
pp. 6467-6494
Author(s):  
Abhijeet Mishra ◽  
Florian Humpenöder ◽  
Jan Philipp Dietrich ◽  
Benjamin Leon Bodirsky ◽  
Brent Sohngen ◽  
...  

Abstract. Out of 1150 Mha (million hectares) of forest designated primarily for production purposes in 2020, plantations accounted for 11 % (131 Mha) of this area and fulfilled more than 33 % of the global industrial roundwood demand. However, adding additional timber plantations to meet increasing timber demand intensifies competition for scarce land resources between different land uses such as food, feed, livestock and timber production. Despite the significance of plantations with respect to roundwood production, their importance in meeting the long-term timber demand and the implications of plantation expansion for overall land-use dynamics have not been studied in detail, in particular regarding the competition for land between agriculture and forestry in existing land-use models. This paper describes the extension of the modular, open-source land system Model of Agricultural Production and its Impact on the Environment (MAgPIE) using a detailed representation of forest land, timber production and timber demand dynamics. These extensions allow for a better understanding of the land-use dynamics (including competition for land) and the associated land-use change emissions of timber production. We show that the spatial cropland patterns differ when timber production is accounted for, indicating that timber plantations compete with cropland for the same scarce land resources. When plantations are established on cropland, it causes cropland expansion and deforestation elsewhere. Using the exogenous extrapolation of historical roundwood production from plantations, future timber demand and plantation rotation lengths, we model the future spatial expansion of forest plantations. As a result of increasing timber demand, we show a 177 % increase in plantation area by the end of the century (+171 Mha in 1995–2100). We also observe (in our model results) that the increasing demand for timber amplifies the scarcity of land, which is indicated by shifting agricultural land-use patterns and increasing yields from cropland compared with a case without forestry. Through the inclusion of new forest plantation and natural forest dynamics, our estimates of land-related CO2 emissions better match with observed data, in particular the gross land-use change emissions and carbon uptake (via regrowth), reflecting higher deforestation with the expansion of managed land and timber production as well as higher regrowth in natural forests and plantations.


2022 ◽  
Vol 13 (01) ◽  
pp. 32-68
Author(s):  
Johnny Kofi Awoonor ◽  
Fowzia Adiyah ◽  
Bright Fafali Dogbey

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