Impacts of forest harvest removal and fertiliser additions on end of rotation biomass, carbon and nutrient stocks of Pinus radiata

During the first 20 years of a Pinus radiata tree rotation, tree growth and pasture yield were assessed under a range of tree spacings at Invermay and Akatore, two coastal sites in Eastern Otago. Pasture yield in association with trees thinned to 100 stems per hectare (sph) was comparable to that from open pasture up to a tree age of 12 years. By the 19th year, however, pasture production declined to 63% of open pasture yield at Invermay and to 42% at Akatore. At 200 and 400 sph at Akatore, pasture yield was similar to that from open pasture at tree age 12 years but declined to 27% and 0% of open pasture yield respectively by year 20. At both Invermay and Akatore, the ryegrass and clover content of open pasture was relatively constant throughout the term of the trial. However, both the ryegrass and clover content of pasture beneath trees began to decline by tree age 12 years with a very rapid decline at Akatore in the number of pasture species at 200 sph by the 19th year. No pasture remained at 400 sph, after 19 years. Livestock carrying capacity with sheep on tree treatments at Invermay decreased from 100% of open pasture at year 6 to 60% by year 10. At Akatore, livestock carrying capacity averaged over the 20-year life of the trial was 4.1 stock units per hectare with a maximum of 8.1 stock units at a tree age of 8 years. Tree growth at both sites was similar, averaging between 1 and 1.1 m/year in height over 20 years, with trees at Invermay at 100 sph averaging 9% greater height and diameter growth than at Akatore. Increasing tree stocking from 100 to 200 to 400 sph at Akatore, resulted in increased tree height, but decreased diameter at breast height. A comparison of the East Otago trees with those in a similar trial at Tikitere (Rotorua) 900 km further north indicated that the southern trees were about 6 years later in their growth pattern by tree age 20 years. On both sites, soil pH tended to be lower in the presence of trees and was significantly lower than in open pasture by year 20. The results and comparisons with the Tikitere data suggest that, in an integrated agroforestry regime, there will be livestock grazing under the trees further into the tree rotation in Otago than in North Island sites. However, slower tree growth would result in a longer rotation time to harvest. Current recommendations to farmers are to plant trees on the less productive areas of the farm and adopt a tree stocking rate which fully utilises the site. Keywords: agroforestry, livestock, pasture, Pinus radiata, soil pH, tree stocking

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Relationship of Soil Microbial Biomass Carbon and Nutrient Removal Rates in Constructed Wetlands

Chinese Journal of Appplied Environmental Biology ◽

10.3724/sp.j.1145.2013.00113 ◽

2013 ◽

Vol 19 (1) ◽

pp. 113-118

Author(s):

Meng WANG ◽

Xin XU ◽

Zhanghe CHEN

Keyword(s):

Microbial Biomass ◽

Constructed Wetlands ◽

Nutrient Removal ◽

Soil Microbial Biomass ◽

Microbial Biomass Carbon ◽

Biomass Carbon ◽

Removal Rates ◽

Soil Microbial ◽

Soil Microbial Biomass Carbon ◽

Relationship Of

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Abandoned Pastures in Eastern Amazonia. II. Nutrient Stocks in the Soil and Vegetation

Journal of Ecology ◽

10.2307/2260567 ◽

1988 ◽

Vol 76 (3) ◽

pp. 682 ◽

Cited By ~ 175

Author(s):

R. Buschbacher ◽

C. Uhl ◽

E. A. S. Serrao

Keyword(s):

Nutrient Stocks

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Assessment of Carbon Density in Natural Mountain Forest Ecosystems at Northwest China

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18042098 ◽

2021 ◽

Vol 18 (4) ◽

pp. 2098

Author(s):

Li Dai ◽

Yufang Zhang ◽

Lei Wang ◽

Shuanli Zheng ◽

Wenqiang Xu

Keyword(s):

Carbon Content ◽

Carbon Storage ◽

Forest Ecosystems ◽

Soil Layer ◽

Northwest China ◽

Biomass Carbon ◽

Forest Age ◽

Carbon Density ◽

Old Growth Forest ◽

Content Ratio

The natural mountain forests in northwest China are recognized as a substantial carbon pool and play an important role in local fragile ecosystems. This study used inventory data and detailed field measurements covering different forest age groups (young, middle-aged, near-mature, mature, old-growth forest), structure of forest (tree, herb, litter and soil layer) and trees (leaves, branches, trunks and root) to estimate biomass, carbon content ratio, carbon density and carbon storage in Altai forest ecosystems. The results showed that the average biomass of the Altai Mountains forest ecosystems was 126.67 t·hm−2, and the descending order of the value was tree layer (120.84 t·hm−2) > herb layer (4.22 t·hm−2) > litter layer (1.61 t·hm−2). Among the tree parts, trunks, roots, leaves and branches accounted for 50%, 22%, 16% and 12% of the total tree biomass, respectively. The average carbon content ratio was 0.49 (range: 0.41–0.52). The average carbon density of forest ecosystems was 205.72 t·hm−2, and the carbon storage of the forest ecosystems was 131.35 Tg (standard deviation: 31.01) inside study area. Soil had the highest carbon storage (65.98%), followed by tree (32.81%), herb (0.78%) and litter (0.43%) layers. Forest age has significant effect on biomass, carbon content ratio, carbon density and carbon storage. The carbon density of forest ecosystems in study area was spatially distributed higher in the south and lower in north, which is influenced by climate, topography, soil types and dominant tree species.

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