Effects of different thinning intensities on soil carbon storage in Pinus laricio forest of Apennine South Italy

Soil phosphorus (P) is one of the essential macronutrients for plant growth. Phosphatase-mediated P mineralization in particular is critical for the biogeochemical cycling of P, and its activity reflects the organic P (Po) mineralization potential in soils. In recent years, global climate change has led to changes in precipitation, which inevitably has affected the P cycle as well. To study these effects of precipitation on soil acid phosphomonoesterase (AcPME) activity, the following combined thinning and precipitation treatments were conducted across Larix principis-rupprechtii Mayr. plantations in China: control (CK), light (LT), moderate (MT), and high thinning (HT). The precipitation treatments included natural precipitation (NP), 30% reduced precipitation (RP30), and 60% reduced precipitation (RP60). Soil moisture, microbial biomass carbon (MBC), and soil P fractions were also determined to link their effects on soil AcPME. The results show that soil AcPME activity was significantly higher in the rainy season, which is associated with higher microbial activity and increased P demand, than in the dry season. Generally, soil AcPME activity was found to increase with thinning intensity. In the dry season, the NP treatment was more conducive to improving soil AcPME activity. In the rainy season, the RP60 treatment inhibited soil AcPME activity under all thinning treatments. The RP30 treatment was only found to offer a significant boost for MT. These results indicate that the potential transformation rate of Po may be more dependent on water in the dry season than in the rainy season. If drought occurs, the Po mineralization rate would decrease for all L. principis-rupprechtii plantations, but excessive rainfall in the rainy season would also impact the turnover of Po into MT adversely.

Section: Soil Acpme Activity In the Dry And Rainy Seasonssupporting

confidence: 79%

Effects of Post-Thinning Precipitation on Soil Acid Phosphomonoesterase Activity in Larix principis-rupprechtii Mayr. Plantations

Tian¹,

Cheng²,

Han³

2019

“…The assigned harvest within This intensity mainly focused on the trees with low health, lower vigor (e.g., small crown), and high competition status, while only a handful of trees were harvested for the purpose of adjusting the neighborhood-based structure (Figure 4). However, the optimal intensity from the perspective of stand structure optimization was far less than that for the purpose of promoting stand growth and yield (45% in [48]; 38%-52% in [49]), species diversity (44% in [50]), carbon sequestration and stocks (45% in [51]), and soil physical and chemical properties (30% in [52]). Therefore, the effects of removing 10% of the trees on various aspects of forest ecosystems, and the differences compared with other intensities, require more research.…”

Section: Discussionmentioning

confidence: 99%

Optimizing Forest Spatial Structure with Neighborhood-Based Indices: Four Case Studies from Northeast China

Dong

Wei

Liu

2020

The fine-scale spatial patterns of trees and their interactions are of paramount importance for controlling the structure and function of forest ecosystems; however, few management techniques can be employed to adjust the structural characteristics of uneven-aged mixed forests. This research provides an accurate, efficient, and impersonal comprehensive thinning index (P-index) for selecting candidate harvesting trees; the index was proposed by weighting the commonly used quantitative indices with respect to stand fine-scale structures, competition status, tree vigor, and tree stability. The applications of the proposed P-index in evaluating and simulating the process of thinning operations were examined using four 1-ha mapped plots with different forest types, namely, natural secondary forest, natural pine-broadleaved mixed forest, natural larch-birch mixed forest, and natural oak forest, which were widely distributed across the Heilongjiang Province in Northeast China. The results indicated that the proposed P-index could effectively affect the structural differentiations between different forest types and alternative thinning intensities. The marginal benefits of alternative thinning intensities on the integrated forest structure indicated that removing 10% of the trees from the plots might be the optimal thinning intensity from the perspective of optimizing stand structure, in which the P-index values could be increased by approximately 5%–11% for the four tested plots. The main conclusion from this paper was that the proposed P-index could be used as a quantitative tool to manage uneven-aged mixed forests.

“…A lower forest density would moderate competition among trees and understory plants. Lower competition might in turn facilitate the growth of understory plants, resulting in a higher nutrient level as the quantity of decomposable leaf and root litter increases [9,46,47].…”

Section: Variation Of Soil Properties and Stoichiometry Following Thimentioning

confidence: 99%

Soil Element Stoichiometry Drives Bacterial Community Composition Following Thinning in A Larix Plantation in the Subalpine Regions of Northern China

Cai

Peng

Cheng

et al. 2020

It is well established that forest thinning alters aboveground plant community composition and soil resource availability. However, how it regulates the composition and diversity of belowground microbial communities remains unclear. To quantify the effects of thinning on soil bacterial groups and the underlying mechanisms of these effects, this research was conducted in a Larix principis-rupprechtii Mayr. plantation with various thinning intensities, including a control (0% tree removal), a low-intensity treatment (15% tree removal), a medium-intensity treatment (35% tree removal), and a high-intensity treatment (50% tree removal). Compared to the control, the medium and high intensity thinning treatments significantly improved soil moisture, nutrient concentrations (including soil total carbon, nitrogen, phosphorus, and ammonium nitrogen), microbial biomass, and elemental stoichiometry ratios. The abundance and diversity of bacterial communities peaked in the medium-intensity treatment. Thinning also had strong effects on dominant bacterial groups at the phylum level. For instance, Bacteroidetes and Nitrospirae were significantly increased in the medium-intensity treatment (MIT), while the Gemmatimonadetes were significantly decreased in the low-intensity treatment (LIT). Combining Spearman correlation analysis and redundancy analysis demonstrated that thinning could facilitate the assembly of unique bacterial communities, and these shifts in microorganisms could probably be attributed to corresponding changes in soil resource stoichiometry. In conclusion, this study provides novel evidence that rational thinning could promote belowground bacterial community diversity and that elemental stoichiometry is an important indicator in shaping forest soil bacterial communities.