Temporal changes of soil physic‐chemical properties at different soil depths during larch afforestation by multivariate analysis of covariance

Abstract

Soil physic-chemical properties differ at different depths; however, differences in afforestation-induced temporal changes at different soil depths are seldom reported. By examining 19 parameters, the temporal changes and their interactions with soil depth in a large chronosequence dataset (159 plots; 636 profiles; 2544 samples) of larch plantations were checked by multivariate analysis of covariance (MANCOVA). No linear temporal changes were found in 9 parameters (N, K, N:P, available forms of N, P, K and ratios of N: available N, P: available P and K: available K), while marked linear changes were found in the rest 10 parameters. Four of them showed divergent temporal changes between surface and deep soils. At surface soils, changing rates were 262.1 g·kg−1·year−1 for SOM, 438.9 mg·g−1·year−1 for C:P, 5.3 mg·g−1·year−1 for C:K, and −3.23 mg·cm−3·year−1 for bulk density, while contrary tendencies were found in deeper soils. These divergences resulted in much moderated or no changes in the overall 80-cm soil profile. The other six parameters showed significant temporal changes for overall 0–80-cm soil profile (P: −4.10 mg·kg−1·year−1; pH: −0.0061 unit·year−1; C:N: 167.1 mg·g−1·year−1; K:P: 371.5 mg·g−1 year−1; N:K: −0.242 mg·g−1·year−1; EC: 0.169 μS·cm−1·year−1), but without significant differences at different soil depths (P > 0.05). Our findings highlight the importance of deep soils in studying physic-chemical changes of soil properties, and the temporal changes occurred in both surface and deep soils should be fully considered for forest management and soil nutrient balance.

Quantitative Assessment of Soil Physical Quality in Northern China Based on S-theory

“…Because soil physical properties differ at different depths, numerous studies have been conducted to obtain soil samples at different soil depths to get a comprehensive understanding of soil physical quality at the sites studied (Puma et al, 2005;Badía et al, 2013;Penna et al, 2013;Wang et al, 2014). Most sampling depths of the data collected in the Haihe River Basin are within 2.00 m, and all these depths should be considered in assessing soil physical quality.…”

Sampling Method and Tree-Age Affect Soil Organic C and N Contents in Larch Plantations

“…Furthermore, forest age itself [21], soil depth, and other site-related variations [22][23][24][25] have been used to describe the spatial and temporal changes in nutrient accumulation. However, differences in sampling methods (fixed-depth [4,11,13] versus pedogenetic horizon [26][27][28] sampling) are a potentially powerful explanation for between-study differences in soil properties [29,30] that has not been fully studied. Indeed, comprehensive research including soil sampling method, sampling site, sampling depth, and tree age would provide a more holistic view of how different sampling methods alter evaluations of SOC and SON.…”

“…Accurate evaluation of soil properties is important for species-to-location matching during afforestation, precision agroforestry [1][2][3], and the investigation of forest ecological functions such as carbon (C) sequestration and nutrient dynamics [4]. Soil heterogeneity occurs horizontally and vertically [5]; thus, the lack of a standardized sampling procedure to assess soil fertility and C inventory could affect conclusions drawn from different studies.…”

“…Soils can range from being a C sink (11 to 238 g·C·m −2 ·year −1 ) [4,[13][14][15]] to a source of atmospheric CO 2 (0.1 to 14.1 g·C·m −2 ·year −1 ) [11,16]. Additionally, studies examining post-afforestation conditions have reported both the depletion of soil nutrients [4,10,[17][18][19] and the accumulation of soil organic N (SON) with increasing soil organic C (SOC) [9,12,20] over time (e.g., tree age effect).…”

“…Soils can range from being a C sink (11 to 238 g·C·m −2 ·year −1 ) [4,[13][14][15]] to a source of atmospheric CO 2 (0.1 to 14.1 g·C·m −2 ·year −1 ) [11,16]. Additionally, studies examining post-afforestation conditions have reported both the depletion of soil nutrients [4,10,[17][18][19] and the accumulation of soil organic N (SON) with increasing soil organic C (SOC) [9,12,20] over time (e.g., tree age effect). Previous land use, the tree species planted, and soil nutrient supply are thought to explain the contradictions in tree age effects on soil properties after afforestation [9][10][11][12][17][18][19][20].…”