Thinning can increase shrub diversity and decrease herb diversity by regulating light and soil environments

Abstract

Tree thinning affects the light environment, which in turn affects the growth and survival of understory vegetation, thus improving species diversity and nutrient cycling, as well as the ecological habitat factors. However, the response of understory vegetation to the thinning intensity and short-time effects in the temperate broadleaf-conifer mixed forest is not completely clear. In this study, four permanent plots with a total area of 4 hm2 were established in a mixed broadleaf-conifer forest in northeast China, with thinning intensities of 20% (light thinning, LT), 35% (medium thinning, MT), 55% (heavy thinning, HT) and the unthinned plot (CK), respectively, in accordance with the basal area. The responses of species diversity to changes in understory vegetation were conducted by a structural equation model (SEM). The results showed that compared with CK, thinning significantly increased the photosynthetically active radiation (PAR) and the light quality (R/FR) (p < 0.05), while decreased the contents of soil total nitrogen (TN), total phosphorous (TP), organic matter (OM), nitrate nitrogen (NN), ammonia nitrogen (AN) and pH. The degree of fragmentation of light factors among the treatment plots gradually decreased as thinning intensity increased. Among all the thinning treatments, PAR and R/FR were found to be the optimal light condition when the forest thinning intensity was 55%. The light condition was found to have a significant negative correlation with soil TN, TP, OM, and AN. While the soil nutrients were positively correlated with herbaceous layer diversity but negatively correlated with shrub layer diversity. The soil nutrients were lost after thinning in a short time and herb diversity decreased, but shrub diversity increased significantly compared with unthinned plots. For the understory vegetation, the species diversity of shrub and herb layer were showed to be more sensitive to soil nutrients than light environment.

Overstory Thinning Impacts Fruit Production and Handling of the Nonnative Shrub, Rhamnus frangula, in a Young Temperate Forest

“…Management may also impact fruit production through pathways beyond the increase in light availability. Additional mechanisms potentially mediating the effects of management could include changes in nutrient availability (Yu et al 2022) or the competitive effects imposed by neighboring vegetation (Minor and Kobe 2019). For instance, thinning of canopy trees may increase nutrient availability for the remaining vegetation, which could impact fruit production.…”

Geographically associated endophytic fungi contribute to the tropane alkaloids accumulation of Anisodus tanguticus

“…The soil available phosphorus (AP) was extracted with 0.5 M sodium bicarbonate, and then determined by the molybdenum antimony anti-colorimetric method ( Bao, 2018 ). Soil ammonium nitrogen (NO 3 – N) and nitrate nitrogen (NH 4 + -N) were extracted with 2 M potassium chloride and then measured with the determined by an AQ1 discrete analyzer ( Yu et al., 2022 ). Soil organic matter was determined by oxidization with 0.4 M of potassium dichromate–concentrated sulfuric acid solution.…”

Biomass difference between mixed plantations and monocultures and its influencing factors: A meta‐analysis

“…It could affect biodiversity in the forest ecosystem and increase soil C storage (Gong et al, 2021b). Previous studies suggested that understory herb diversities and biomass were decreased under thinning disturbance, emphasizing the significance of considering thinning intensities (Wang et al, 2021;Yu et al, 2022;Zhang, Dong, et al, 2023). As for the combination of thinning and fertilization, positive effects on tree growth were found under long-term treatment due to enhanced soil conditions and reduced competition (Danyagri et al, 2023).…”