Soil aggregation and soil fraction associated carbon under different vegetation types in a complex landscape

TY - JOUR

T1 - Soil aggregation and soil fraction associated carbon under different vegetation types in a complex landscape

AU - Li, Xiaoqing

AU - Vogeler, Iris

AU - Schwendenmann, Luitgard

PY - 2019

Y1 - 2019

N2 - Land cover change has been shown to affect soil characteristics and soil organic carbon (SOC) storage. However, little is known about the driving factors associated with soil carbon (C) stabilisation in complex landscapes. This study was conducted to investigate the effects of both inherent soil characteristics and recent vegetation cover change on soil aggregation and soil fraction associated C in a complex landscape. The specific objectives were: (1) determine bulk soil properties and SOC saturation deficit-(2) quantify soil aggregation, soil size-density fractions, and soil fraction associated C-and (3) identify the factors that influence soil fractions and soil fraction associated C in two adjacent catchments differing in vegetation cover, Central Otago, New Zealand. Catchment GH1 (n = 17 plots) was dominated by tussock grassland and native shrubs. Catchment GH2 (n = 21 plots) was converted from tussock grassland into a pine forest in 1981. The catchments differed in soil texture (e.g. sand content GH1: 62.9%, GH2: 50.7%, P = 0.007), soil SOC stocks (GH1: 5.0 kg C m -2, GH2: 4.3 kg C m -2, P = 0.04), mean weight diameter (MWD) (GH1: 782.3 m, GH2: 736.5 m, P = 0.002), and proportion of the macroaggregate heavy fraction (macro-HF) (GH1: 72%, GH2: 55%, P = 0.01). No significant differences were found in SOC saturation deficit (GH1: 14.8 mg g -1, GH2: 13.1 mg g -1, P = 0.13). Dominant vegetation cover explained 21% of the variation in MWD in GH1, whereas silt+clay C content explained 31.6% of the MWD variation in GH2. The macro-HF fraction was negatively correlated with the proportion of silt+clay. Our findings illustrate that physical and chemical soil characteristics are important drivers in such a complex landscape and may have masked the effect of recent vegetation change on soil aggregation, and soil fraction associated C.

AB - Land cover change has been shown to affect soil characteristics and soil organic carbon (SOC) storage. However, little is known about the driving factors associated with soil carbon (C) stabilisation in complex landscapes. This study was conducted to investigate the effects of both inherent soil characteristics and recent vegetation cover change on soil aggregation and soil fraction associated C in a complex landscape. The specific objectives were: (1) determine bulk soil properties and SOC saturation deficit-(2) quantify soil aggregation, soil size-density fractions, and soil fraction associated C-and (3) identify the factors that influence soil fractions and soil fraction associated C in two adjacent catchments differing in vegetation cover, Central Otago, New Zealand. Catchment GH1 (n = 17 plots) was dominated by tussock grassland and native shrubs. Catchment GH2 (n = 21 plots) was converted from tussock grassland into a pine forest in 1981. The catchments differed in soil texture (e.g. sand content GH1: 62.9%, GH2: 50.7%, P = 0.007), soil SOC stocks (GH1: 5.0 kg C m -2, GH2: 4.3 kg C m -2, P = 0.04), mean weight diameter (MWD) (GH1: 782.3 m, GH2: 736.5 m, P = 0.002), and proportion of the macroaggregate heavy fraction (macro-HF) (GH1: 72%, GH2: 55%, P = 0.01). No significant differences were found in SOC saturation deficit (GH1: 14.8 mg g -1, GH2: 13.1 mg g -1, P = 0.13). Dominant vegetation cover explained 21% of the variation in MWD in GH1, whereas silt+clay C content explained 31.6% of the MWD variation in GH2. The macro-HF fraction was negatively correlated with the proportion of silt+clay. Our findings illustrate that physical and chemical soil characteristics are important drivers in such a complex landscape and may have masked the effect of recent vegetation change on soil aggregation, and soil fraction associated C.

KW - land cover change

KW - New Zealand

KW - pine forest

KW - shrub encroachment

KW - size-density fractionation

KW - soil aggregation

KW - soil organic carbon saturation

KW - SIZE-DENSITY FRACTIONS

KW - LAND-USE CHANGE

KW - ORGANIC-CARBON

KW - SOUTH ISLAND

KW - NEW-ZEALAND

KW - GRASSLAND AFFORESTATION

KW - SHRUB ENCROACHMENT

KW - SATURATION DEFICIT

KW - TUSSOCK GRASSLAND

KW - PINE PLANTATIONS

UR - http://www.scopus.com/inward/record.url?scp=85062672046&partnerID=8YFLogxK

U2 - 10.1071/SR18193

DO - 10.1071/SR18193

M3 - Journal article

SN - 1838-675X

VL - 57

SP - 215

EP - 227

JO - Soil Research

JF - Soil Research

IS - 3

ER -