Lit on Ecological Effects of Thinning (Positive & Negative)

Workin on it. 

There is a lot of literature on this topic;  it’s clear that the effects vary according to many factors, e.g., slope, forest type, soil type,fire regimens precipitation.

Ecological thinning
In Wikipedia “Ecological thinning is a silvicultural technique used in forest management that involves cutting trees to improve functions of a forest other than timber production. Although thinning originated as a man-made forest management tool, aimed at increasing timber yields, the shift from production forests to multifunctional forests brought with it the cutting of trees to manipulate an ecosystem for various reasons, ranging from removing non-native species from a plot to removing poplars growing on a riverside beach aimed at recreational use.”
It apears that this concept is researched, applied mostly in Australia; see Google Search & Google Scholar Search

The importance of natural forest stewardship in adaptation planning in the United States
Faison et al., 2023. in Conservation Science and Biology “…Natural forests (i.e., those protected and largely free from human management) tend to develop greater complexity, carbon storage, and tree diversity over time than forests that are actively managed; and natural forests often become less susceptible to future insect attacks and fire following these disturbances. Natural forest stewardship is therefore a critical and cost effective strategy in forest climate adaptation.”

Thinning for Value
Module 3 in the Nova Scotia Woodlot Management Home Study Program.
Good description in Lesson 1 of Forest Stages, including self thinning; Lesson 4 discusses ways to conduct commercial thinning in ways that help wildlife or have fewer negative impacts on wildlife.

A global synthesis on the effects of thinning on hydrological processes: Implications for forest management
Antonio D. del Campo 2022 in Forest Ecology and Management

Short-term effects of three commercial thinning treatments on diversity of understory vascular plants in white spruce plantations of northern New Brunswick
Sean R. Haughian, Katherine A. Frego, 2016. in Forest Ecology and Management “We used a modified before-after-control-impact design to examine the response of understory vascular plants to four treatments in 25-year-old white spruce plantations of northwestern New Brunswick. Understory plants increased in overall richness and abundance after thinning, particularly in no-debris treatments. This was driven by (1) expansion of pre-established clonal forest herbs and (2) invasion of graminoids and long-distance dispersers. Several disturbance-sensitive species were significantly more abundant in unthinned controls. Few compositional differences were observed between the moderate and enhanced debris treatments, perhaps because the effects of CWD creation require longer to detect than those of thinning and ground-layer disturbance (from debris-removal).

Short-term effects of alternative thinning treatments on the richness, abundance and composition of epixylic bryophytes, lichens, and vascular plants in conifer plantations at microhabitat and stand scales
Sean R. Haughian, 2018 in Forest Ecology and Management “Epixylic (log-dwelling) flora contribute much to forest biodiversity, but have been shown to decline with intensive management, perhaps through the reduced supply of coarse woody debris, their preferred substrate, and the altered mesoclimate of the understory. Such declines might be ameliorated through modifying the plantation management practices. This study examined the response of epixylic flora to commercial thinning treatments in 6 mid-rotation conifer plantations of northwestern New Brunswick, Canada….I tested alternative thinning & debris-removal treatments to mitigate these impacts. Thinning benefitted many species, but was detrimental for tiny mosses & liverworts.Debris removal negatively impacted richness or cover of many flora. Debris from thinning should be left on-site to promote biodiversity.

A global assessment of amphibian and reptile responses to land-use changes
Javier M. Cordier 2021 in Biological Conservation “…Our results show that almost all of the analyzed types of land-use changes have negative effects on these groups, but with different degree of magnitude. We also show that the time elapsed in disturbed conditions does not ameliorate the effects on species richness, indicating a low recovery capacity of herp communities”

What is good for birds is not always good for lichens: Interactions between forest structure and species richness in managed boreal forests
Julian Klein et al., 2020 in Forest Ecology and Management

Bird abundance is highly dynamic across succession in early seral tree plantations
Scott H. Harris et al. 2021 in Forest Ecology and Management
To our knowledge, our study provides the first quantitative estimates for how bird species abundances change throughout the entire early seral stage in tree plantations in western North America – information that can be used to assess tradeoffs between timber production and biodiversity. We found that the duration of early seral habitat in plantations is short and generally cannot be ameliorated by managing for higher levels of broadleaf cover. This finding has important implications for early seral species in the rapidly shifting mosaic of tree plantation landscapes.

Structural differences between precommercially thinned and unthinned conifer stands
Jessica A Homyack et al., 2004 in Forest Ecology and Management. Study in Maine, USA “ffects of precommercial thinning (PCT) in young, high-density forest stands on the growth and yield of crop trees has been well-studied, but information about the response of habitat characteristics and structural attributes that are related to abundance and diversity of wildlife populations is deficient. We examined changes in habitat characteristics and forest structure that occurred with PCT and stand development in commercial spruce-fir stands within the Acadian forest of northern Maine…The application of PCT accelerated some characteristics of stand development, resulting in a reduction of understory structure and complexity, which conflicts with previous studies of non-herbicide-treated forest that reported increases in understory complexity after thinning… The forest structure in regenerating stands treated with PCT may have negative effects on wildlife that are dependent on the structure of early successional forest, but may positively affect species that use more mature forest.”