Open Access
Impacts of enhanced nitrogen deposition and soil acidification on biomass production and nitrogen leaching in Chinese fir plantations
(NRC Research Press, 2012) Blanco Vaca, Juan Antonio; Wei, Xiaohua; Jiang, Hong; Jie, Cheng-Yue; Xin, Zan-Hong; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Atmospheric pollution levels in China are increasing quickly. Experience from other polluted regions shows that tree growth could be affected, but long-term effects of N deposition and soil acidification on Chinese forests remain mostly unknown. Soil acidification and N deposition were simulated for Chinese fir plantations in Southeast China. A factorial experiment combined four levels of rain pHs (2.5, 4.0, 5.6 and 7.0), four N deposition rates (1, 7.5, 15 and 30 kg N ha-1 y-1) and two site qualities (poor and rich sites), managed for 3 consecutive 20-year rotations. Results indicate atmospheric pollution effects are not immediate, but after 1 to 2 rotations soil acidification effects could reduce ecosystem C pools significantly (-25% and -11% in poor and rich sites, respectively). N deposition rates above 15 kg N ha-1 y-1 could offset some of the negative effects of soil acidification and led to more ecosystem C (19 and 28 Mg C ha-1 more in poor and rich sites than in low N deposition). However, at high N deposition rates (>15 kg N ha-1 y-1), N leaching losses could greatly increase, reaching 75 kg N ha-1 y-1. Moderate N deposition could increase tree biomass production and soil organic mass, resulting in increased ecosystem C, but these gains could be associated to important N leaching. Atmospheric pollution could also result in the long-term in nutrient imbalances and additional ecological issues (i.e. biodiversity loss, eutrophication, etc.) not studied here.
Open Access
Land use change effects on carbon and nitrogen stocks in the Pyrenees during the last 150 years: a modelling approach
(Elsevier, 2015) Lo, Yueh-Hsin; Blanco Vaca, Juan Antonio; Canals Tresserras, Rosa María; González de Andrés, Ester; San Emeterio Garciandía, Leticia; Imbert Rodríguez, Bosco; Castillo Martínez, Federico; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
In the southern Pyrenees, human population and therefore land uses have changed from forests to pastures, then crops, and back to pastures and secondary forests during the last two centuries. To understand what such rapid land use changes have meant for carbon (C) and nitrogen (N) stocks, we used data from two forest sites in the western Pyrenees, combined with regional data on pastures and crop production (potato, cereal), to calibrate the ecosystem-level model FORECAST. Then, we simulated 150-year of land use for each site, emulating historical changes. Our estimates show that the conversion from forests into pastures and crops created C and N deficits (378-427 Mg C ha-1, 4.0-4.6 Mg N ha-1) from which these sites are still recovering. The main ecological process behind the creation of these deficits was the loss of the ecological legacy of soil organic matter (SOM) created by the forest, particularly during conversion to farming. Pastures were able to reverse, stop or at least slow down the loss of such legacy. In conclusion, our work shows the deep impact of historical land use in ecosystem attributes, both in magnitude of removed C and N stocks and in duration of such impact. Also, the usefulness of ecological modelling in absence of historical data to estimate such changes is showcased, providing a framework for potential C and N stocks to be reached by climate change mitigation measures such as forest restoration.
Open Access
Modelling the management of forest ecosystems: importance of wood decomposition
(Wiley, 2018) Blanco Vaca, Juan Antonio; Page-Dumroese, Deborah S.; Jurgensen, Martin F.; Curran, Michale P.; Tirocke, Joanne M.; Walitalo, Joanna; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Scarce and uncertain data on woody debris decomposition rates are available for calibrating forest ecosystem models, owing to the diﬃculty of their empirical estimations. Using ﬁeld data from three experimental sites which are part of the North American Long-Term Soil Productivity (LTSP) Study in south-eastern British Columbia (Canada), we developed probability distributions of standard wood stake mass loss of Populus tremuloides and Pinus contorta. Using a Monte Carlo approach, 50 synthetic decomposition rate values per debris type were used to calibrate the ecosystem-level forest model FORECAST. Signiﬁcant eﬀects of uncertainty of pine stake mass loss rates on estimated tree growth were found, especially in moderately managed forests, as estimations of available nitrogen were aﬀected. Consequently, our work has shown that projections of tree growth under management conditions depend on accurate estimations of woody debris decomposition rates, and special eﬀort should be done in create reliable databases of decomposition rates for their use in tree growth and yield modelling.
Open Access
Significant increase in ecosystem C can be achieved with sustainable forest management in subtropical plantation forests
(Public Library of Science, 2014) Wei, Xiaohua; Blanco Vaca, Juan Antonio; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Subtropical planted forests are rapidly expanding. They are traditionally managed for intensive, short-term goals that often lead to long-term yield decline and reduced carbon sequestration capacity. Here we show how it is possible to increase and sustain carbon stored in subtropical forest plantations if management is switched towards more sustainable forestry. We first conducted a literature review to explore possible management factors that contribute to the potentials in ecosystem C in tropical and subtropical plantations. We found that broadleaves plantations have significantly higher ecosystem C than conifer plantations. In addition, ecosystem C increases with plantation age, and reaches a peak with intermediate stand densities of 1500–2500 trees ha-1. We then used the FORECAST model to simulate the regional implications of switching from traditional to sustainable management regimes, using Chinese fir (Cunninghamia lanceolata) plantations in subtropical China as a study case. We randomly simulated 200 traditional short-rotation pure stands and 200 sustainably-managed mixed Chinese fir – Phoebe bournei plantations, for 120 years. Our results showed that mixed, sustainably-managed plantations have on average 67.5% more ecosystem C than traditional pure conifer plantations. If all pure plantations were gradually transformed into mixed plantations during the next 10 years, carbon stocks could rise in 2050 by 260.22 TgC in east-central China. Assuming similar differences for temperate and boreal plantations, if sustainable forestry practices were applied to all new forest plantation types in China, stored carbon could increase by 1,482.80 TgC in 2050. Such an increase would be equivalent to a yearly sequestration rate of 40.08 TgC yr-1, offsetting 1.9% of China’s annual emissions in 2010. More importantly, this C increase can be sustained in the long term through the maintenance of higher amounts of soil organic carbon and the production of timber products with longer life spans.
Open Access
Resilience assessment of lowland plantations using an ecosystem modeling approach
(MDPI, 2015) Wu, Chia-Hsin; Lo, Yueh-Hsin; Blanco Vaca, Juan Antonio; Chang, Shih-Chieh; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
As afforestation programs of former farmlands take hold in Taiwan to achieve a variety of ecological and socio-economic values, it is becoming necessary to define best forest management. Hence, we simulated mixed stands of Cinnamomum camphora and Fraxinus griffithii planted through a gradient of soil fertility and varying camphor/ash density ratios, but maintaining a fixed total stand density of 1500 trees ha −1 . Total stand productivity was slightly lower in mixed stands than the combination of both monocultures in rich and poor sites. Maximum negative yield surpluses for 50-year old stands were 7 Mg ha −1 and 6 Mg ha −1 for rich and poor sites with a 1:1 camphor laurel/ash ratios. Maximum stand woody biomass in rich sites was reached in camphor laurel monocultures (120 Mg ha −1 ) and in poor sites for Himalayan ash monocultures (58 Mg ha −1 ). However, for medium-quality sites, a small yield surplus (11 Mg ha −1 ) was estimated coinciding with a maximum stand woody biomass of 95 Mg ha −1 for a 1:1 camphor laurel/ash density ratio. From an ecological resilience point of view, rotation length was more important than stand composition. Long rotations (100 years) could improve soil conditions in poor sites. In rich sites, short rotations (50 years) should be avoided to reduce risks or fertility loss.
Open Access
Sustainable management of metasequoia glyptostroboides plantation forests in Shanghai
(MDPI, 2018) Zheng, Ji; Blanco Vaca, Juan Antonio; Wei, Xiaohua; Liu, Chunjiang; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Urban forestry is increasingly used as a tool for climate change mitigation and for providing environmental services to inhabitants of urban areas. However, tree species used in urban forestry are usually different from the ones used in commercial forestry. As a consequence, available data on growth and yield under alternative management scenarios are usually scarce. As forest models can be used to explore potential forest futures, they are of special interest as decision-support tools in urban forestry. In this research, we used the FORECAST ecosystem-level forest model to deﬁne the management prescriptions for Metasequoia glyptostroboides plantations in Shanghai that reach the highest net primary productivity (NPP). In a ﬁrst step, a battery of different stand densities (from 500 to 4000 stems ha−1) was used to identify those with the highest NPP at stand level. Then, different thinning regimes (with intensities ranging from 15% to 40% of trees removed and applied at stand age 5 to 20 years) were simulated on those initial densities with the highest NPP (3000 and 4000 stems ha−1). Planting 4000 stems ha−1 and not applying thinning achieved the highest annual NPP (14.39 ± 3.92 Mg ha−1 year−1) during the ﬁrst rotation, but it was not signiﬁcantly different from the NPP achieved with the same initial density but thinning 40% of trees at year 10. NPP was estimated to decrease with consecutive rotations, and for the second rotation thinning was needed to signiﬁcantly increase NPP (10.11 ± 2.59 Mg ha−1 year−1 with 4000 stems ha−1 and 25% thinning at year 10) above non-thinning management. For the third rotation, the highest NPP was reached with initial density 3000 stems ha−1 and 25% thinning at year 10. Nitrogen ﬂows were also estimated to decrease with consecutive rotations. These results indicate the potential of managing M. glyptostroboides urban plantations to reach their maximum productivity potential, but also that additional actions would be needed to ensure adequate nutrient levels over consecutive rotations. For a species such as M. glyptostroboides, which was discovered for science less than 70 years ago and for which no plantations over 50 years exist, the ecosystem-level FORECAST model has been shown as a suitable tool to support management decision when growth and yield data are not available.
Open Access
Effects of nitrogen deposition on carbon sequestration in Chinese fir forests ecosystems
(Elsevier, 2012) Wei, Xiaohua; Blanco Vaca, Juan Antonio; Jiang, Hong; Kimmins, J.P. (Hamish); Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Nitrogen deposition and its ecologic effects on forest ecosystems have received global attention. In this paper, the ecosystem model FORECAST was used to assess the effects of nitrogen deposition on carbon sequestration in Chinese fir plantation forests. This topic is important as China is intensifying its reforestation efforts to increase forest carbon sequestration for combating climate change impacts, and the Chinese fir is the most important plantation species in China. A series of scenarios including N deposition levels (1, 5, 10, 20, 30, 40 and 50 kg ha-1 y-1), management regime (rotation lengths of 15, 30 and 50 years) and site quality (poor and rich nutrient sites) were defined for the simulations. Our simulation results show that N deposition increased carbon sequestration in Chinese fir forests, with a higher increasing effect at lower N deposition levels and lower increasing effect at higher N deposition levels. When N deposition levels exceed 20-30 kg ha-1 y-1, the effects of N deposition on forest C pools were marginal; suggesting that N deposition levels of 20-30 kg ha-1 y-1 could lead to soil N saturation in Chinese fir forests. Any additional amounts of N input from deposition would likely be leached out. It is estimated that the contributions of N deposition to C sequestration in the whole Chinese fir forests, South-East China are 7.4 x 10 6 Mg C year-1 under the current N deposition levels (5 to 10 kg ha-1 y-1) and could reach up to 16 x 10 6 Mg C year-1 under hypothetic future N deposition conditions (7.5 to 15 kg ha-1 y-1).