scholarly journals Application of a new productivity coupling hydrothermal factors (PCH) model for evaluating net primary productivity of grassland in Southern China

2016 ◽  
Author(s):  
Zheng-Guo Sun ◽  
Jie Liu ◽  
Hai-Yang Tang
Keyword(s):  
Primary Productivity ◽  
Net Primary Productivity ◽  
Southern China ◽  
Hot Spot ◽  
Terrestrial Ecosystems ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Significant Relationships ◽  
Grassland Ecosystems ◽  
Global Carbon

Abstract. Grassland ecosystems play important roles in the global carbon cycle. The net primary productivity (NPP) of grassland ecosystems has become the hot spot of terrestrial ecosystems. To simulate grassland NPP in Southern China, a new productivity coupling hydrothermal factors (PCH) model was built and validated based on data recorded from 2003 to 2014. The results show a logarithmic correlation between grassland NPP and mean annual temperature and a linear positive correlation between grassland NPP and mean annual precipitation in Southern China, both highly significant relationships. There was a highly significant correlation between simulated and measured NPP (R2 = 0.8027). Both RMSE and RRMSE were relatively low, showing that the simulation results of the model were reliable. The NPP values in the study area had a decreasing trend from east to west and south to north. Mean NPP was 471.62 g C m−2 from 2003 to 2014. Additionally, the mean annual NPP of Southern grassland presented a rising trend increasing 3.49 g C m−2 yr−2 during the past 12 years. These results document performance and use of a new method to estimate the grassland NPP in Southern China.

scholarly journals Application of a new model using productivity coupled with hydrothermal factors (PCH) for evaluating net primary productivity of grassland in southern China

Solid Earth ◽  
2017 ◽  
Vol 8 (2) ◽  
pp. 545-552
Author(s):  
Zheng-Guo Sun ◽  
Jie Liu ◽  
Hai-Yang Tang
Keyword(s):  
Primary Productivity ◽  
Net Primary Productivity ◽  
Southern China ◽  
Hot Spot ◽  
Terrestrial Ecosystems ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
New Model ◽  
Significant Relationships ◽  
Grassland Ecosystems

Abstract. Grassland ecosystems play important roles in the global carbon cycle. The net primary productivity (NPP) of grassland ecosystems has become the hot spot of terrestrial ecosystems. To simulate grassland NPP in southern China, a new model using productivity coupled with hydrothermal factors (PCH) was built and validated based on data recorded from 2003 to 2014. The results show a logarithmic correlation between grassland NPP and mean annual temperature and a linear positive correlation between grassland NPP and mean annual precipitation in southern China, both highly significant relationships. There was a highly significant correlation between simulated and measured NPP (R2 = 0. 8027). Both RMSE and relative root mean square error (RRMSE) were relatively low, showing that the simulation results of the model were reliable. The NPP values in the study area had a decreasing trend from east to west and south to north. Mean NPP was 471.62 g C m−2 from 2003 to 2014. Additionally, the mean annual NPP of southern grassland presented a rising trend, increasing 3.49 g C m−2 yr−1 during the past 12 years. These results document performance and use of a new method to estimate the grassland NPP in southern China.

Evaluation of net primary productivity and its spatial and temporal patterns in southern China’s grasslands

2013 ◽  
Vol 35 (3) ◽  
pp. 331 ◽  
Author(s):  
Z. G. Sun ◽  
X. H. Long ◽  
C. M. Sun ◽  
W. Zhou ◽  
W. M. Ju ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Production Efficiency ◽  
Net Primary Productivity ◽  
Southern China ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Spatial And Temporal Patterns ◽  
Important Indicator ◽  
Grassland Ecosystems ◽  
The Mean

The net primary productivity (NPP) of grassland ecosystems is an important indicator of the capacity for carbon (C) absorption. The Global Production Efficiency Model was adopted to simulate NPP in southern China’s grasslands and to analyse the temporal and spatial dynamics from 1981 to 2000. There was a high correlation between measured and simulated values (R2 = 0.84). Based on the data from 1981 to 2000, the mean annual NPP was 1082 g C m–2 year–1, and the highest value (1798 g C m–2 year–1) was in Hainan province, and the lowest value (500 g C m–2 year–1) was in south-western Tibet. The highest mean NPP values were in the permanent wetlands (1193 g C m–2 year–1) and savannas (1137 g C m–2 year–1); woody savannas had an intermediate value (1087 g C m–2 year–1), and the lowest NPP occurred in typical grasslands and open shrubs, the mean values were 709 and 689 g C m–2 year–1, respectively. Temporally, the total NPP in southern China’s grasslands slightly increased in the 20-year period, especially from 1981 to 1990. The mean annual total of NPP in the 20 years was 0.758 Pg C. Inter-annual variation in total NPP was driven mainly by mean annual temperature rather than mean annual precipitation. The results suggest that grassland ecosystems in southern China have a large C sink.

scholarly journals FITOPLANKTON DAN SIKLUS KARBON GLOBAL

OSEANA ◽  
2019 ◽  
Vol 44 (2) ◽  
pp. 35-48
Author(s):  
Mochamad Ramdhan Firdaus ◽  
Lady Ayu Sri Wijayanti
Keyword(s):  
Carbon Cycle ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Sedimentary Rocks ◽  
Global Carbon Cycle ◽  
Biological Pump ◽  
Large Role ◽  
The World ◽  
Pump Mechanism ◽  
Global Carbon

PHYTOPLANKTON AND GLOBAL CARBON CYCLE. Scientists around the world believe that phytoplankton, although microscopic, have a large role in the global carbon cycle. Various research results show that the net primary productivity of all phytoplankton in the sea is almost as large as the net primary productivity of all plants on land. Phytoplankton through the process of photosynthesis absorbs 40-50 PgC / year from the atmosphere. Also, phytoplankton is known to be responsible for transporting carbon from the atmosphere to the seafloor through the carbon biological pump mechanism. Phytoplankton from the coccolithophores group is known to play a role in the sequestration of carbon on the seabed through the carbonate pump mechanism. The mechanism is capable of sequestering carbon for thousands of years on the seabed in the form of sedimentary rocks (limestone).

Variability of ecosystem carbon source from microbial respiration is controlled by rainfall dynamics

2021 ◽  
Vol 118 (52) ◽  
pp. e2115283118
Author(s):  
Heng Huang ◽  
Salvatore Calabrese ◽  
Ignacio Rodriguez-Iturbe
Keyword(s):  
Primary Productivity ◽  
Microbial Growth ◽  
Net Primary Productivity ◽  
Carbon Sources ◽  
Terrestrial Ecosystems ◽  
Rainfall Regime ◽  
Physical Factors ◽  
Scale Parameters ◽  
Complex Interactions ◽  
Soil Heterotrophic Respiration

Soil heterotrophic respiration (Rh) represents an important component of the terrestrial carbon cycle that affects whether ecosystems function as carbon sources or sinks. Due to the complex interactions between biological and physical factors controlling microbial growth, Rh is uncertain and difficult to predict, limiting our ability to anticipate future climate trajectories. Here we analyze the global FLUXNET 2015 database aided by a probabilistic model of microbial growth to examine the ecosystem-scale dynamics of Rh and identify primary predictors of its variability. We find that the temporal variability in Rh is consistently distributed according to a Gamma distribution, with shape and scale parameters controlled only by rainfall characteristics and vegetation productivity. This distribution originates from the propagation of fast hydrologic fluctuations on the slower biological dynamics of microbial growth and is independent of biome, soil type, and microbial physiology. This finding allows us to readily provide accurate estimates of the mean Rh and its variance, as confirmed by a comparison with an independent global dataset. Our results suggest that future changes in rainfall regime and net primary productivity will significantly alter the dynamics of Rh and the global carbon budget. In regions that are becoming wetter, Rh may increase faster than net primary productivity, thereby reducing the carbon storage capacity of terrestrial ecosystems.

Quantitatively assessing the effects of climate change and human activities on ecosystem degradation and restoration in southwest China

2019 ◽  
Vol 41 (4) ◽  
pp. 335
Author(s):  
Z. G. Sun ◽  
J. S. Wu ◽  
F. Liu ◽  
T. Y. Shao ◽  
X. B. Liu ◽  
...  
Keyword(s):  
Climate Change ◽  
Primary Productivity ◽  
Human Activities ◽  
Southwest China ◽  
Net Primary Productivity ◽  
Terrestrial Ecosystems ◽  
Ecosystem Degradation ◽  
Relative Contribution ◽  
Degraded Ecosystem ◽  
Annual Means

Identifying the effects of climate change and human activities on the degradation and restoration of terrestrial ecosystems is essential for sustainable management of these ecosystems. However, our knowledge of methodology on this topic is limited. To assess the relative contribution of climate change and human activities, actual and potential net primary productivity (NPPa and NPPp respectively), and human appropriation of net primary productivity (HANPP) were calculated and applied to the monitoring of forest, grassland, and cropland ecosystems in Yunnan–Guizhou–Sichuan Provinces, southwest China. We determined annual means of 476 g C m–2 year–1 for NPPa, 1314 g C m–2 year–1 for NPPp, and 849 g C m–2 year–1 for HANPP during the period between 2007 and 2016. Furthermore, the area with an increasing NPPa accounted for 75.12% of the total area of the three ecosystems. Similarly, the areas with increasing NPPp and HANPP accounted for 77.60 and 57.58% of the study area respectively. Furthermore, we found that ~57.58% of areas with ecosystem restored was due to climate change, 23.39% due to human activities, and 19.03% due to the combined effects of human activities and climate change. In contrast, climate change and human activities contributed to 19.47 and 76.36%, respectively, of the areas of degraded ecosystem. Only 4.17% of degraded ecosystem could be attributed to the combined influences of climate change and human activities. We conclude that human activities were mainly responsible for ecosystem degradation, whereas climate change benefitted ecosystem restoration in southwest China in the past decade.

scholarly journals Net Primary Productivity of Pinus massoniana Dependence on Climate, Soil and Forest Characteristics

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 404 ◽  
Author(s):  
Xin Huang ◽  
Chunbo Huang ◽  
Mingjun Teng ◽  
Zhixiang Zhou ◽  
Pengcheng Wang
Keyword(s):  
Geographical Distribution ◽  
Soil Nutrients ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Southern China ◽  
Regional Scale ◽  
Pinus Massoniana ◽  
Forest Productivity ◽  
Tree Component ◽  
Total Tree

Understanding the spatial variation of forest productivity and its driving factors on a large regional scale can help reveal the response mechanism of tree growth to climate change, and is an important prerequisite for efficient forest management and studying regional and global carbon cycles. Pinus massoniana Lamb. is a major planted tree species in southern China, playing an important role in the development of forestry due to its high economic and ecological benefits. Here, we establish a biomass database for P. massoniana, including stems, branches, leaves, roots, aboveground organs and total tree, by collecting the published literature, to increase our understanding of net primary productivity (NPP) geographical trends for each tree component and their influencing factors across the entire geographical distribution of the species in southern China. P. massoniana NPP ranges from 1.04 to 13.13 Mg·ha−1·year−1, with a mean value of 5.65 Mg·ha−1·year−1. The NPP of both tree components (i.e., stem, branch, leaf, root, aboveground organs, and total tree) show no clear relationships with longitude and elevation, but an inverse relationship with latitude (p < 0.01). Linear mixed-effects models (LMMs) are employed to analyze the effect of environmental factors and stand characteristics on P. massoniana NPP. LMM results reveal that the NPP of different tree components have different sensitivities to environmental and stand variables. Appropriate temperature and soil nutrients (particularly soil available phosphorus) are beneficial to biomass accumulation of this species. It is worth noting that the high temperature in July and August (HTWM) is a significant climate stressor across the species geographical distribution and is not restricted to marginal populations in the low latitude area. Temperature was a key environmental factor behind the inverse latitudinal trends of P. massoniana NPP, because it showed a higher sensitivity than other factors. In the context of climate warming and nitrogen (N) deposition, the inhibition effect caused by high temperatures and the lack or imbalance of soil nutrients, particularly soil phosphorus, should be paid more attention in the future. These findings advance our understanding about the factors influencing the productivity of each P. massoniana tree component across the full geographical distribution of the species, and are therefore valuable for forecasting climate-induced variation in forest productivity.

scholarly journals Net Primary Productivity Loss under different drought levels in different grassland ecosystems

2020 ◽  
Vol 274 ◽  
pp. 111144
Author(s):  
Tianjie Lei ◽  
Jie Feng ◽  
Juan Lv ◽  
Jiabao Wang ◽  
Hongquan Song ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Net Primary Productivity ◽  
Productivity Loss ◽  
Grassland Ecosystems
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