Biomass carbon, nitrogen and phosphorus stocks in hybrid poplar buffers, herbaceous buffers and natural woodlots in the riparian zone on agricultural land

Abstract

In many temperate agricultural areas, riparian forests have been converted to cultivated land, and only narrow strips of herbaceous vegetation now buffer many farm streams. The afforestation of these riparian zones has the potential to increase carbon (C) storage in agricultural landscapes by creating a new biomass sink for atmospheric CO2. Occurring at the same time, the storage of nitrogen (N) and phosphorus (P) in plant biomass, is an important water quality function that may greatly vary with types of riparian vegetation. The objectives of this study were (1) to compare C, N and P storage in aboveground, belowground and detrital biomass for three types of riparian vegetation cover (9-year-old hybrid poplar buffers, herbaceous buffers and natural woodlots) across four agricultural sites and (2) to determine potential vegetation cover effects on soil nutrient supply rate in the riparian zone. Site level comparisons suggest that 9-year-old poplar buffers have stored 9-31 times more biomass C, 4-10 times more biomass N, and 3-7 times more biomass P than adjacent non managed herbaceous buffers, with the largest differences observed on the more fertile sites. The conversion of these herbaceous buffers to poplar buffers could respectively increase C, N and P storage in biomass by 3.2-11.9 t/ha/yr, 32-124 kg/ha/yr and 3.2-15.6 kg/ha/yr, over 9 years. Soil NO3 and P supply rates during the summer were respectively 57% and 66% lower in poplar buffers than in adjacent herbaceous buffers, potentially reflecting differences in nutrient storage and cycling between the two buffer types. Biomass C ranged 49-160 t/ha in woodlots, 33-110 t/ha in poplar buffers and 3-4 t/ha in herbaceous buffers. Similar biomass C stocks were found in the most productive poplar buffer and three of the four woodlots studied. Given their large and varied biomass C stocks, conservation of older riparian woodlots is equally important for C balance management in farmland. In addition, the establishment of poplar buffers, in replacement of non managed herbaceous buffers, could rapidly increase biomass C, N and P storage along farm streams, which would be beneficial for water quality protection and global change mitigation.

Plastic Allometry in Coarse Root Biomass of Mature Hybrid Poplar Plantations

“…Being the largest biomass C pool after stems and branches, poplar coarse root biomass needs to be more accurately quantified [96]. Until now, only general allometric relationships had been developed for poplar coarse root biomass [24,26,22,23,19,27,25], with no consideration for the potential effect of plantation environment on allometric trajectory.…”

Root Structure and Belowground Biomass of Hybrid Poplar in Forestry and Agroforestry Systems in Mediterranean France

“…Roots collected from each voxel were brought to the laboratory and categorised into three groups based on size. Although roots are categorized and named differently (Lodhiyal et al, 1995;Laclau, 2003;Tufekcioglu et al, 2003;Das and Chaturvedi, 2005;Fortier et al, 2015a), three categories viz., fine roots (< 2 mm), medium size roots (2 mm to 10 mm) and coarse roots (>10mm) were adopted in the present study.…”

Exotic Invasive Shrub Glossy Buckthorn Reduces Restoration Potential for Native Forest Herbs

“…These results would be consistent with the description of glossy buckthorn as a generalist species with low edaphic requirements. Another hypothesis would be that the hybrid poplars, which are known to have high soil water and nutrient uptakes [37,38], and which represent 94% of the biomass of the plantation (all vegetation strata included) collected most of the soil resources made available by the removal of buckthorn.…”