Young Growth Forest Research Articles

Variation in adult and pup wolf diets at natal den sites is influenced by forest composition and configuration.

Although wolves are wide-ranging generalist carnivores throughout their life cycle, during the pup-rearing season wolf activity is focused on natal den sites where pup survival depends upon pack members provisioning food. Because prey availability is influenced by habitat quality within the home range, we investigated the relative importance of prey species for adults and pups and further examined the relationship between habitat characteristics, wolf diet, and litter size on Prince of Wales Island (POW) in Southeast Alaska. During 2012-2020, we detected 13 active den sites within the home ranges of nine wolf packs. We estimated minimum pup counts using motion-detecting cameras and individual genotypes from noninvasive samples (hair: n=322; scat: n=227) and quantified wolf diet composition using fecal DNA metabarcoding (n=538). We assessed habitat composition, configuration, and connectivity within denning and annual home ranges estimated using wolf GPS-collar data. Contrary to expectations, wolves had a more constricted diet during denning season (April 15-July 31), and within this season pups had a narrower dietary niche (species richness [S]=4) focused more on deer (relative frequency of occurrence [O/I]=0.924) than adults (S=15; deer O/I=0.591). Litter size had a positive relationship with the relative frequency of deer in a wolf pack's diet. Wolf consumption of deer was positively associated with the proportion of young-growth forest (≤25 years old) within denning and annual home ranges. High levels of vegetation patch interspersion, and the density of closed logging roads were also important predictors, suggesting these habitat qualities were influential for increasing the availability of deer to wolves. Our results contrast with previous research indicating wolf pup diets included more alternate prey (i.e., beaver) than adults and emphasize the importance of deer to wolf viability on POW, especially during denning season.

To what extent does the species composition of Macaronesian laurel forests depend on their human disturbance history and environmental drivers?

Deforestation and forest fragmentation have serious negative consequences for biodiversity and species distribution, but many studies approach species distributions and speciation processes without taking in account the local history of human disturbances. Nevertheless, the complex recovery process after forest destruction is widely distributed around the world and takes place under a wide mosaic of biotic and abiotic factors that may be influencing the species distribution. In this study aerial pictures from 1951 and 2019 were used to assess forest recovery during about sixty years. We tested if the initial stage (forest completely destroyed or young growth forest in 1951) determines the successional process, evaluating the role of different spatial drivers (distance from remnant forest fragments and unfelled areas around each site) and mesoclimate conditions, by examining 40 disturbed sites and 18 old-growth forest sites distinguished in 1951 aerial photos. The final stage during this successional process was assessed using 2019 aerial photos, covering the same these sites. At each plot, plant species composition and forest structure were studied, which allowed us to obtain a maturity index. Our results reveal that the initial stage is not the only driver explaining forest structure and species composition at the end of the 60-year period analyzed. The role of each forest recovery driver varies depending on each stage. In the early successional stages, the slope aspect (exposure) was the most important factor, which is correlated with mesoclimatic conditions, followed by the distance from young-growth forest in 1951. However, in intermediate successional stages the cover of old-growth forest around each plot in 1951 was the main factor in the recovery. At the end of the study period (2019), the differences in species richness between young-growth and old-growth forest were not significant, although old-growth forests were characterized by high densities of endemics, threatened species and β-diversity, showing the species composition a strong dependence on forest structure. Our results reveal the important need to consider human disturbance history in forest research and how climate conditions and the lack of nearby remnants can negatively affect the forest recovery process, greatly increasing the time needed to return to old-growth laurel forest conditions, which requires specific management recommendations.

Understanding land use volatility and agglomeration in northern Southeast Asia

Land use change has generally been considered a cause and consequence of environmental change. Here, we interpreted the land cover in northern Southeast Asia (including parts of Myanmar, Thailand, Laos, Vietnam and China) year by year from 2000 to 2018 with the Google Earth Engine (GEE) platform. The results show that the areas of old growth forest, young growth forest and annual crops have changed dramatically in the study area. The average frequency of land use change was determined to be 5.4 times (that is, the land use changed every 3.4 years) by comparing the land use types in each year throughout the entire study period, and the frequency of land use change showed a significant agglomeration effect. In addition, there was a substantial difference between the land use change determined with an annual approach and that determined with the commonly used time-stage approach; time-stage land use change studies may overlook gradual change processes in land use change, which highlights the necessary of determining a suitable time period for studying land use change at the local scale. The results show that understanding land use volatility and agglomeration has become important to deepen the understanding of land use change and to help formulate land use policy.

Deterministic processes drive functional and phylogenetic temporal changes of woody species in temperate forests in Northeast China

Deterministic processes drive functional and phylogenetic temporal changes of woody species in temperate forest, depending on successional stage and tree size classes. The dominant influential factors changed from abiotic (especially topographic factors) to biotic (e.g., basal area), with both increasing successional stage and tree size, suggesting that deterministic processes shifted from habitat filtering to biotic interactions. Disentangling how deterministic and stochastic processes govern the temporal change of community composition is critical for understanding community assembly and predicting long-term ecosystem change. However, rare studies have examined the distinctive imprint of these two processes on functional and phylogenetic temporal changes of woody species in temperate forests. The objectives of this study are to detect (1) the relative importance of deterministic vs. stochastic process in driving the functional and phylogenetic temporal changes at different successional stages and tree size classes in temperate forests and (2) the relative influence of abiotic vs. biotic factors on temporal change. We analyzed 10 years of detailed species composition, phylogenetic information, and 14 functional traits from 66 woody species in young-growth (5-ha) and old-growth (25-ha) forest plots in Northeast China. We devised a null model approach to determine the relative importance of deterministic and stochastic processes in driving functional and phylogenetic temporal changes. Then, we investigated the influence of abiotic (soil and topography) and biotic (basal area, stem density, and species richness) factors on temporal change using boosted regression tree (BRT) models. All analyses were conducted for different tree sizes (all trees, small trees [diameter at breast height (DBH) < 10 cm], and large trees [DBH ≥ 10 cm]). In young-growth forest, functional and phylogenetic temporal changes were basically higher than expected for all trees, small trees, and large trees. Conversely, in the old-growth forest, functional and phylogenetic temporal changes were lower than expected for all trees, but opposite patterns were found for two size classes; i.e., change was higher than expected for large trees and lower than expected for small trees. BRT models showed that the most influential factors underlying the temporal change of all trees shifted from abiotic (e.g., topography) to biotic (e.g., basal area) factors with increasing succession stage. Regardless of successional stage, the relevant factors changed from abiotic factors for small trees to biotic factors for large trees. Deterministic processes govern tree functional and phylogenetic temporal changes, and the underlying deterministic processes change from habitat filtering to biotic interaction over succession and with increasing tree size.

Changes in the temperature regime of podzolic soils in the course of natural forest restoration after clearcutting

The results of temperature monitoring in podzolic soils under the middle-taiga bilberry spruce forest and secondary mixed forest of the Komi Republic performed in 2008–2014 are presented. The changes in characteristics of soil temperature in the litter horizon and in the mineral horizons at the depths of 20 and 50 cm are outlined. It is shown that soil temperature regimes differ under the native spruce forest, young growth, and middle-aged secondary mixed forest. The soils of secondary phytocenoses are warmed up to a greater depth and are characterized by the higher heat supply. The differences are seen in a number of temperature parameters, such as the accumulated temperatures above 5°C and above 10°C at the depths of 20 and 50 cm. The most significant differences between the studied plots manifest themselves in the values of temperature amplitudes during the warm season. Maximum values of daily temperature amplitudes were obtained on the plot under young growth, whereas the soil under the middle-aged mixed forest was characterized by minimum values of daily temperature amplitudes.

Carbon accretion in unthinned and thinned young-growth forest stands of the Alaskan perhumid coastal temperate rainforest

BackgroundAccounting for carbon gains and losses in young-growth forests is a key part of carbon assessments. A common silvicultural practice in young forests is thinning to increase the growth rate of residual trees. However, the effect of thinning on total stand carbon stock in these stands is uncertain. In this study we used data from 284 long-term growth and yield plots to quantify the carbon stock in unthinned and thinned young growth conifer stands in the Alaskan coastal temperate rainforest. We estimated carbon stocks and carbon accretion rates for three thinning treatments (basal area removal of 47, 60, and 73 %) and a no-thin treatment across a range of productivity classes and ages. We also accounted for the carbon content in dead trees to quantify the influence of both thinning and natural mortality in unthinned stands.ResultsThe total tree carbon stock in naturally-regenerating unthinned young-growth forests estimated as the asymptote of the accretion curve was 484 (±26) Mg C ha−1 for live and dead trees and 398 (±20) Mg C ha−1 for live trees only. The total tree carbon stock was reduced by 16, 26, and 39 % at stand age 40 y across the increasing range of basal area removal. Modeled linear carbon accretion rates of stands 40 years after treatment were not markedly different with increasing intensity of basal area removal from reference stand values of 4.45 Mg C ha−1 year−1to treatment stand values of 5.01, 4.83, and 4.68 Mg C ha−1 year−1 respectively. However, the carbon stock reduction in thinned stands compared to the stock of carbon in the unthinned plots was maintained over the entire 100 year period of observation.ConclusionsThinning treatments in regenerating forest stands reduce forest carbon stocks, while carbon accretion rates recovered and were similar to unthinned stands. However, that the reduction of carbon stocks in thinned stands persisted for a century indicate that the unthinned treatment option is the optimal choice for short-term carbon sequestration. Other ecologically beneficial results of thinning may override the loss of carbon due to treatment. Our model estimates can be used to calculate regional carbon losses, alleviating uncertainty in calculating the carbon cost of the treatments.Electronic supplementary materialThe online version of this article (doi:10.1186/s13021-015-0035-4) contains supplementary material, which is available to authorized users.

Community ecology and spatial distribution of trees in a tropical wet evergreen forest in Kaptai national park in Chittagong Hill Tracts, Bangladesh

We investigated the floristic composition, woody species diversity and spatial distribution of trees in a tropical wet evergreen forest in Kaptai national park in Chittagong Hill Tracks, Bangladesh. We recorded 25 families, 37 genera, 40 species and 1771 woody individuals in a 0.09 ha plot. Euphorbiaceae and Moraceae were the most speciesrich families, and Castanopsis, Ficus and Terminalia were the most species-rich genera. Bursera serrata Wall. ex Colebr. was the dominant species in terms of highest importance value (13%). Trema orientalis (L.) Bl was typically a light demanding species as it appeared in the top canopy with only one individual having the seventh highest IV, but had no regeneration. The expected maximum number of species (Smax) was 140, indicating that many species may invade the forest as the Smax is greater than the recorded total number of species. The nature of the disappearance and appearance of species in the present forest reflects instability of floristic composition. The values of Shannon’s index H′ and Pielou’s index J′ (evenness) were 3.36 bit and 0.63, respectively. These values show moderately high species diversity as compared to other subtropical forests in the tropics. In addition, a sample area of 200 m2 in this forest would be sufficient for measuring the diversity indices H′ and J′, whereas the trend of J′ may indicate the rate of equality of individuals among the different species decreased with increasing area. The distribution pattern for the total stand was completely random. However, the dominant species showed aggregate distribution for small areas, but random distribution for large areas. The spatial association between species showed that the strongest positive interspecific association occurred between Streblus asper Lour. and Castanea indica Roxb. (ω = 0.51). As a whole, most species were weakly associated with each other, of which 58% species associations were completely negative. The result of cluster analysis showed that species pairs were spatially independent at all or most small clusters; stands of species from all clusters are mosaics of complete habitat and pioneer habitat. All patches in this forest community have similar habitat and regeneration niches, which could be a phenomenon for a young growth forest. Thus, the existence of habitat and regeneration niches may be an important factor in the maintenance of diversity in this forest.

Photosynthetic recovery of foliage after wind disturbance activates ecosystem CO2uptake in cool temperate forests of northern Japan

[1] The effects of wind disturbance on forest dynamics and ecosystem CO2 exchange were examined in cool temperate forests of northern Japan during 2004–2008 using eddy covariance (EC) measurements. One site was a young, even-aged, monoculture, deciduous forest; the other was an uneven-aged mixed forest of evergreen and deciduous overstory tree species, including some over 200 years old. On 8 September 2004, a strong typhoon struck the forests, after which leaf and branch amounts decreased in young growth forest, but foliage showed little change in old growth forest. By 2006, foliage at the young-growth forest had recovered to the 2004 pretyphoon state. Average daily accumulated gross primary production (GPPd), terrestrial ecosystem respiration (TERd), and net ecosystem exchange (NEEd) were assessed for six growth stages annually. After the typhoon, large increases in GPPd were found during the growing stage of overstory tree species with high photosynthetic rates compared to that before the typhoon. Pronounced increases in GPPd and corresponding large reductions in NEEd were detected at the young-growth forest, indicating that NEEd was largely regulated by GPPd throughout the growing stages. Although EC measurements contain uncertainty, our continuous EC measurements revealed that interannual variability in meteorological variables and structural changes in foliage have only small impacts on GPP and NEE, while photosynthetic recovery of foliage from typhoon damage has high potential to increase GPP and enhance NEE as compared with those under nondamage conditions.

Maintaining wildlife habitat in southeastern Alaska: implications of new knowledge for forest management and research

We review results and implications from recent wildlife studies that followed from the 1997 Tongass Land Management Plan (TLMP) and identify information needs and directions for research, development, and application. Sustained population viability of wildlife species was identified as a major issue in the TLMP planning process. Several species were identified as management indicator species, and research was conducted to determine their potential sensitivity to forest management. Southeastern Alaska was found to be a region with an especially high degree of endemism in its small mammal fauna, principally because of the combination of its archipelago geography combined with highly dynamic glacial history. Two species of endemic small mammals selected for demographic study, however, appeared to be less dependent on old-growth forests than had been suspected at the time TLMP was written: the northern flying squirrel ( Glaucomys sabrinus) because of relatively high suitability of noncommercial, low-volume, mixed-conifer forest; and the southern red-backed vole ( Clethrionomys gapperi) because of relatively high suitability of precommercially thinned young-growth forest. The northern goshawk ( Accipiter gentilis) was found to be problematic for “management indicator” status because of logistical difficulties involved in monitoring this relatively rare, highly mobile species that frequently changes nest sites. Sampling protocols were developed for marbled murrelet ( Brachyramphus marmoratus), although murrelet populations do not appear to be in trouble on the Tongass. The conservation strategy of TLMP for American marten ( Martes americana) appeared to be sound on Chichagof Island where marten have been studied intensively, but implications for the rest of southeastern Alaska were unclear without further work. Studies of the Alexander Archipelago wolf ( Canis lupus ligoni) indicated that population density of black-tailed deer ( Odocoileus hemionus) and road access (to wolf hunters) were the predominant factors affecting wolf productivity and mortality, respectively. Finally, studies of bird community response to timber-harvest alternatives to clearcutting indicated that although creation of forest “edge” may increase nest predation rates, the actual response depends on a broad array of factors and is highly variable. We suggest that research, development, and application focus on plant and animal communities and management of vegetation to achieve specific objectives for wildlife habitat. We suggest that such efforts emphasize silviculture of second-growth forests, understanding old-growth reserves, distribution of endemic small mammals, and alternatives to clearcutting. Models for evaluating black-tailed deer habitat and populations are needed for subsistence-hunting management, and some work needs to be directed at interactions between tourism and selected wildlife species.

Water holding effect of subalpine dark coniferous forest soil in Gongga Mountain, China

Because of the distinction of soil property and humus content, soil water content is not ideal to indicate whether it is suitable to the growth of plant. Mainly based on the PF-a numerical value denoting the water regime of soil and connected with the growth of plant, the study combined the moisture percentage of soil with PF to research in quantity the interrelation between the moisture percentage and PF in different succession phases of subalpine dark coniferous forest in Gongga Mountain. The results showed that: (1) In the same PF value, the moisture percentage in humus horizon increased gradually with the development of the succession of the dark coniferous forest; The moisture percentage of over-mature forest was the highest and>mature forest>half-mature forest>young growth forest; (2) With the increase of soil depth, the soil bulk density increased and the moisture percentage decreased, but the difference in the percentage of moisture was not notable in different succession phases. (3) In different succession series, the vegetation affected the soil water characteristics by increasing the soil organic matter, improving the soil construction, receding the soil bulk density and enhancing the soil porosity; (4) The humus horizon of the dark coniferous forest soil has the highest water holding capability in this region.

Atrazine and 2,4-D mineralization in relation to microbial biomass in soils of young-, second-, and old-growth riparian forests

Current agricultural practices are responsible for the deposition of unwanted quantities of pesticides into streams throughout the United States. Previous studies in riparian areas have shown that microbial communities are capable of degrading herbicides faster in forest soils than in pasture soils. This study tested the influence of age of riparian forests on herbicide degradation in the soil. Active and total fungal and bacterial biomasses and mineralization of atrazine (2 chloro-4[ethylamino]-6[isopropylamino]S-triazine) and 2,4-D (2,4-dichlorophenoxy-acetic acid) in the litter and top 10 cm of mineral soil were measured in forests 20–40, 60–90, and 120–300 years old on three riparian sites in autumn, winter, spring, and summer. Active and total fungal and active and total bacterial biomasses did not differ in the top 10 cm of mineral soil regardless of forest age. In litter, total bacterial biomass also did not differ with forest age throughout the year, but in spring and autumn, active bacterial biomass was greater in old-growth than in second- or young-growth litter samples, as were both active and total fungal biomasses. Atrazine mineralization in litter did not differ with forest age or season, but in mineral soil it was greater in old-growth than in second or young-growth forest samples in all seasons. Mineralization of 2,4-D in litter was greater in old- and second-growth forest samples than in young-growth samples, except in winter; and in mineral-soil, it was greater in old-growth samples than in those from both younger forest types. Results indicate that microbial communities in old-growth riparian areas have a greater capacity to degrade herbicides than do such communities in second-or young-growth forests. Management of riparian forest to long rotations may tend to increase herbicide degradation and protection of lakes and streams.

Influence of forest age on nutrient availability and storage in coniferous soils of the Oregon Coast Range

A substantial fraction of the organic matter and plant essential nutrients in forest ecosystems are contained in the soil. The role of soils in nutrient storage and availability is an essential component of ecosystem function and stability. The top 10 cm of soil contains the highest concentration of nutrients. To determine the influence of forest age on nutrient storage and availability in riparian soils, we compared concentrations, storage, and extractability of plant nutrients in the litter layer and top 10 cm of mineral soil in old-, second-, and young-growth riparian forests. The analysis of variance for nutrient concentration, nutrient storage, or nutrients extracted in both the litter layer and top 10 cm of mineral soil showed no significant differences among sites or seasons for any nutrient; only differences among forest ages will be discussed. Concentrations of N, P, Mg, Mn, and Cu in forest litter did not differ by forest age, but concentrations of K, Ca, and B were significantly higher in old-growth forest litter than in the litter of second-or young-growth forests. In mineral soil, the concentrations of all nutrients were statistically equal for all forest ages. Old-growth forests stored significantly (P ≤ 0.05) greater amounts of all nutrients measured in the litter layer, and greater amounts of N, P, and K in the mineral soil, than were stored in second- or young-growth forests. Greater amounts of P, B, and Zn were extracted from old-growth forest litter than from either second- or young-growth forest litter, and greater amounts of P, K, Mn, B, and Zn were extracted from old-growth mineral soil than from second- or young-growth mineral soil. The amount of each nutrient stored in the litter layer of the different-aged forests correlated curvilinearly with the amount of C in the litter layer of these forests; r2 ranged from 0.60 to 0.83. Also, the amount of N, K, and Ca stored in the mineral soil correlated curvilinearly with the amount of C in the soil; r2 ranged from 0.50 to 0.76.

Decomposition and nutrient dynamics of ponderosa pine needles in a Mediterranean-type climate

A litter-bag technique was used to measure decay rates and assess changes in organic and inorganic constituents of ponderosa pine (Pinusponderosa Laws.) needle litter during decomposition over a 2-year period in old- and young-growth forests in the Sierra Nevada of California. Rates of mass loss were among the lowest reported for temperate and boreal forests, with annual decomposition constants of about 0.08 and 0.18 year−1 for the old- and young-growth forests, respectively. Apparently, the temporal separation of warm temperatures and moist conditions found in Mediterranean-type climates severely limits decomposition in these coniferous forests. In the old-growth forest, comparison of estimates of tree nutrient uptake with net releases of nutrients from fine litter during their 1st year of decomposition suggests that recent litter fall potentially acts as a significant source of P, Mg, and K for tree uptake in this forest; in contrast, recently fallen litter acts as a net sink for N, S, and Ca. Despite initially lower indices of litter quality for litter originating from the old–growth relative to the young–growth forest, no significant difference in decomposition rates of these two litter age-classes was found when placed at either site. This result does not support the hypothesis that decreases in decomposition rates during forest development are driven by decreases in the quality of litter fall.

A Striped Skunk Population in Virginia, 1963-69

Striped skunks (Mephitis mephitis) were live trapped on a 337-acre area near Richmond, 1.5 miles south of Montpelier, Virginia, from September 1963 until October 1969. Thirty-one skunks were recaptured on 92 occassions. Skunk numbers declined during the study from an average of two per 100 acres in 1963–65 to one per 100 acres in 1966–69. Numbers tended to increase in fall and winter and decrease from spring to summer. The trappable population was predominately adult and few (3) immatures were captured. More males than females were captured. Average time between first and last captures was 2.7±0.7 months. One female was recaptured over a 48 month period. Body weights at first capture were not significantly different (P=0.05) between the sexes. Skunk captures were concentrated in old fields and young second growth forest, and diversity (H) and equitability (E) measures supported this finding.

THE EFFECT OF FOREST SUCCESSION UPON THE QUANTITY AND UPON THE NUTRITIVE VALUES OF WOODY PLANTS USED AS FOOD BY MOOSE

The moose, Alces americana, in British Columbia reaches its greatest populations in the young second growth forest areas. Numbers decrease as the forest approaches its climax stage. The decline in population is known to be mainly the result of malnutrition.The present study of three stages in forest succession growing under virtually identical conditions of soil and climate has concerned itself with quantity of available palatable browse; carotene and ascorbic acid content of available palatable and unpalatable trees and shrubs; and with determination of values for moisture, protein, carbohydrate, ether extractives, and total mineral content. Most of the analyses are confined to the winter dormant period.It is determined that the forest changes studied involve a reduction in quantity of palatable browse to about one-third; that there is an increase of carotene values and possibly of total mineral content in the vegetation on more advanced forest areas, but that in ascorbic acid content, ether extractives, total carbohydrates, and proteins the vegetation upon the younger forest areas is superior to that on the older areas.It is concluded, therefore, that the declining carrying capacity noted in a forest approaching its climax stage results from decreases in both the quantity and quality of food produced.It is further concluded that the most desirable winter range for moose is one upon which there is a variety of palatable species, predominantly in an early stage of growth, but with an intermixture of older forest stands bearing palatable coniferous trees.