Biomass Dynamics Research Articles

Active metabolism and biomass dynamics of biocrusts are shaped by variation in their successional state and seasonal energy sources

Seasonal growth and changes in biomass within communities are the core of ecosystem dynamics. Biocrusts play a prominent role as pioneers in dryland soils. However, the seasonal dynamics of biocrusts remain poorly resolved. In this study, we collected biocrusts across a successional gradient (cyanobacteria, cyanolichen, chlorolichen, and moss-dominated) from southeastern Tengger Desert (China) during the summer and autumn seasons, and explored seasonal changes in metabolism and biomass using multi-omics approaches. We found that Cyanobacteria and Ascomycota were the dominant active taxa and both exhibited higher abundances in autumn. We also found that the dominant primary producers in biocrusts strongly affected community-wide characteristics of metabolism. Along with seasonal differences in light energy utilization, utilization of inorganic energy sources exhibited higher expression in the summer while for organic sources, in the autumn. We found that overall metabolism was significantly regulated by the ratio of intracellular to extracellular polymer degradation, and affected by NO3−, PO43− and EC (in the summer)/NO2− (in the autumn). In summary, biocrust growth varied with seasonal variation in light energy utilization and complementary chemical energy sources, with the most suitable season varying with biocrust successional type.

Borana rangeland of southern Ethiopia: Estimating biomass production and carrying capacity using field and remote sensing data

Assessing rangeland productivity is critical to reduce ecological degradation and promote sustainable livestock management. Here, we estimated biomass productivity and carrying capacity dynamics in the Borana rangeland of southern Ethiopia by using field-based data and remote sensing data (i.e., normalized difference vegetation index (NDVI)). Data was collected from both rainy and dry seasons when biomass production was high and low respectively. Results of linear regression showed that both biomass production (R2adj = 0.672) and NDVI value (R2adj = 0.471) were significantly decreased from 1990 to 2019. Field data and NDVI values for mean annual biomass showed a significant linear relationship. The model accuracy in the annual relationship between the observed and predicted biomass values was strong (R2adj = 0.986) but with high standard error, indicating that the observed biomass production in the rangeland area was not in good condition as compared with the predicted one. This study suggests that, using NDVI data and field-based data in combined way has high potential to estimate rangeland biomass and carrying capacity dynamics at extensively grazed arid and semi-arid rangelands. And to use for estimating stoking rates and predicting future management techniques for decision making.

Population characteristics of benthopelagic Gymnoscopelus nicholsi (Pisces: Myctophidae) on the continental shelf of South Georgia (Southern Ocean) during austral summer

Southern Ocean myctophid fish (Family Myctophidae) are an important conduit of energy through foodwebs and between the surface layers and mesopelagic depths. Species that reside in both pelagic and near-bottom environments of continental shelves, such as Gymnoscopelus nicholsi and Gymnoscopelus bolini, may also be important in benthopelagic coupling, although their ecology and role in such processes remain unresolved. Here, we examined inter-annual variation in the depth of occurrence, biomass and population dynamics of benthopelagic G. nicholsi on the South Georgia shelf (100–350 m) using bottom trawl data collected between 1987 and 2019. Gymnoscopelus nicholsi was a regular component of the local benthopelagic community, particularly northwest of South Georgia, but was patchily distributed. It appeared to enter a benthopelagic phase at ~ 3 years, with annual growth and recruitment of year classes between ~ 3 and 5 years. However, transition of cohorts into the benthopelagic zone was not annual. There was clear inter-annual variation in G. nicholsi biomass and depth of occurrence. Shallower depth of occurrence was significantly (P < 0.05) correlated with years of warmer summer sea surface temperatures, suggesting that inter-annual variation in local environmental conditions has an important influence on its migration behaviour and ecology. Our data also suggest that Antarctic krill is an important dietary component of the older G. nicholsi cohorts (~ 5 years) in the benthopelagic zone. We note that Gymnoscopelus bolini is rare in bottom trawl catches between 100 and 350 m, although Antarctic krill appears to dominate its diet from the available data. Our study provides important information on understudied myctophid species in a poorly investigated region of the water column that is relevant for Southern Ocean ecosystem studies, particularly in relation to understanding trophic connectivity between the pelagic and near-bottom realms.

Quantifying root turnover in grasslands from biomass dynamics: Application of the growth-maintenance respiration paradigm and re-analysis of historical data

Root turnover rates define how frequently plants replace their root systems and input organic matter into soil. Turnover rates are often computed using measurements of total living and dead (standing) root biomass (r) by assuming gross and net production are equivalent during the growing season. This assumption may be inappropriate in grasslands where root lifespans are relatively short, and decomposition substantially offsets growth. The objective of this study was to quantify turnover rates from measurements of r over time assuming growth and decomposition happen simultaneously, and that net r changes (ΔrΔt) decrease linearly as the size of r increases (first-order kinetics). These hypotheses were interpreted with the growth-maintenance respiration paradigm (GMRP) based on whether daily growth is constant (GP) or reduced by the costs of tissue maintenance (MP). The two parameters of the linear GMRP models were inferred using Bayesian methods from 111 growing season records of r versus ΔrΔt from 15 grasslands. Two-level (hierarchical) inferences were setup for the 14 grasslands that had multiple records, assuming parameters from each grassland originated from the same population. For the grassland with one record, a single-level inference was conducted. A total of 89 records, at least one per grassland, substantially supported the GMRP models. Median predicted turnover rates based on production/decomposition for the GP and MP models were 1.8/1.1 and 1.4/1.2 per growing season, respectively. These estimates were 3 to 7 times faster than those from traditional algorithms that neglect decomposition, suggesting organic matter inputs from roots may be larger than expected in some grasslands, especially where growth occurs almost year-round.

Leaf and root phenology and biomass ofEriophorum vaginatumin response to warming in the Arctic

AbstractThe response of plant leaf and root phenology and biomass in the Arctic to global change remains unclear due to the lack of synchronous measurements of above- and belowground parts. Our objective was to determine the phenological dynamics of the above- and belowground parts of Eriophorum vaginatum in the Arctic and its response to warming. We established a common garden located at Toolik Lake Field Station; tussocks of E. vaginatum from three locations, Coldfoot, Toolik Lake and Sagwon, were transplanted into the common garden. Control and warming treatments for E. vaginatum were set up at the Toolik Lake during the growing seasons of 2016 and 2017. Digital cameras, a handheld sensor and minirhizotrons were used to simultaneously observe leaf greenness, normalized difference vegetation index and root length dynamics, respectively. Leaf and root growth rates of E. vaginatum were asynchronous such that the timing of maximal leaf growth (mid-July) was about 28 days earlier than that of root growth. Warming of air temperature by 1 °C delayed the timing of leaf senescence and thus prolonged the growing season, but the temperature increase had no significant effect on root phenology. The seasonal dynamics of leaf biomass were affected by air temperature, whereas root biomass was correlated with soil thaw depth. Therefore, we suggest that leaf and root components should be considered comprehensively when using carbon and nutrient cycle models, as above- and belowground productivity and functional traits may have a different response to climate warming.

Phytoplankton biomass dynamics in the Arabian Sea from VIIRS observations

Using chlorophyll-a (Chl-a) as an indicator for phytoplankton biomass, observations from the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) between 2012 and 2019 in combination with wind, various ocean hydrographic data, and nutrient data are used to conduct a comprehensive study to characterize and quantify the phytoplankton biomass dynamics in the Arabian Sea, and assess the mechanisms that drive the summer and winter phytoplankton blooms. Phytoplankton biomass dynamics in the Arabian Sea are driven by the seasonal reversal of the monsoon wind. The summer phytoplankton bloom located mainly in the western and central Arabian Sea is stronger than the winter phytoplankton bloom in the northern Arabian Sea in terms of both Chl - a values and the extent of phytoplankton bloom coverage. Interannual variability of Chl - a is less significant in comparison to the seasonal variability. Chl-a data measured by the Sea-viewing Wide Field-of-View Sensor (SeaWiFS) from 1997 to 2010 are also used. The comparison of Ch-a climatology data between SeaWiFS and VIIRS shows no long-term trend of Chl-a change in the Arabian Sea. This study provides an improved understanding (with new knowledge) of (1) phytoplankton biomass dynamics, (2) physical, biological, and biogeochemical processes, and (3) nutrient dynamics in the Arabian Sea. The hydrographic and nutrient data reveal two different driving mechanisms for phytoplankton blooms in the summer and winter monsoons. During the summer monsoon, the cold high-nutrient waters are brought to the surface from the thermocline depth through strong coastal upwelling and Ekman pumping, leading to increased Chl-a at the surface-layer. The vertical velocity reaches ~1 m/day at 70 m depth. In comparison, the winter phytoplankton bloom is driven by the moderate boost of the nutrient level due to the mixed-layer deepening and strong vertical mixing caused by the surface cooling in the northern Arabian Sea. The nutrient dynamics in the Arabian Sea also suggests that the nitrate concentration is the major nutrient driver for its seasonal phytoplankton biomass dynamics. • The phytoplankton biomass dynamics was characterized and quantified. • There is no long-term trend of Chl-a change in the Arabian Sea in the last two decades. • Two different driving mechanisms for phytoplankton blooms in the summer and winter

Spatiotemporal dynamics of grassland aboveground biomass and its driving factors in North China over the past 20 years

Although remote sensing has enabled rapid monitoring of grassland aboveground biomass (AGB) at a regional scale, it is still a difficult challenge to construct an accurate estimation model of grassland AGB in a vast region to support the AGB dynamics analysis over a long time series. In this study, extensive grassland AGB measurements (collected in North China during the grassland growing season of 2000–2019), MODIS data, and environmental factors (climate, topography and soil) were employed to construct the grassland AGB models using four machine learning algorithms (random forest, support vector machine, artificial neural network and extreme learning machine) combined with four variable selections. The spatial distributions of annual grassland AGB from 2000 to 2019 were simulated based on the optimal AGB model. The temporal change and future trend of AGB series from 2000 to 2019 were comprehensively analyzed by the slope model and Hurst exponent. The influences of natural and anthropogenic factors on grassland AGB dynamics were explored quantitatively using the Geodetector model. The results showed that (1) the random forest model constructed from the variables selected by the successive projections algorithm is the optimal grassland AGB model. (2) The 20-year average grassland AGB in North China showed an overall spatial distribution of being low in the central and western parts and high in the southeastern part. (3) The annual maximum grassland AGB in most regions (82.71%) showed an increasing trend during 2000–2019; and most of the grasslands with a decreasing trend of AGB were located in regions with low AGB values and arid climates. (4) The future trend of grassland AGB after the study period may be optimistic, as reflected by more grassland AGB was predicted to increase rather than decrease (70.38% vs. 29.62%). (5) The main driving factors of spatiotemporal dynamics of grassland AGB were precipitation, soil type, and livestock density; the interactive influence of two drivers on AGB showed mutual enhancement.

Distribution of biomass dynamics in relation to tree size in forests across the world.

Tree size shapes forest carbon dynamics and determines how trees interact with their environment, including a changing climate. Here, we conduct the first global analysis of among-site differences in how aboveground biomass stocks and fluxes are distributed with tree size. We analyzed repeat tree censuses from 25 large-scale (4-52 ha) forest plots spanning a broad climatic range over five continents to characterize how aboveground biomass, woody productivity, and woody mortality vary with tree diameter. We examined how the median, dispersion, and skewness of these size-related distributions vary with mean annual temperature and precipitation. In warmer forests, aboveground biomass, woody productivity, and woody mortality were more broadly distributed with respect to tree size. In warmer and wetter forests, aboveground biomass and woody productivity were more right skewed, with a long tail towards large trees. Small trees (1-10 cm diameter) contributed more to productivity and mortality than to biomass, highlighting the importance of including these trees in analyses of forest dynamics. Our findings provide an improved characterization of climate-driven forest differences in the size structure of aboveground biomass and dynamics of that biomass, as well as refined benchmarks for capturing climate influences in vegetation demographic models.

Biomass and demographic dynamics of the Brazil nut family (Lecythidaceae) in a mature Central Amazon rain forest

In this study, we analyze the demographic rates and biomass dynamics of Lecythidaceae in a 100-ha permanent forest plot in the Central Amazon. We characterize habitats in the plot, analyze the effect of habitat on tree density, species richness, and biomass and demographic dynamics, and quantify significant species habitat associations. The plot experienced a 13.2 % net loss of Lecythidaceae individuals (n = 1023) but aboveground biomass (AGB; Mg ha−1) did not differ between the two censuses. Growth rates averaged 1.2 mm year−1 with high intraspecific variation and differed significantly among species height classes. Stem density and species richness decreased in all six terra firme habitats and were significantly lower in both years in the flood disturbed habitat. Only the flood disturbed areas experienced a significant loss in AGB, along with the highest annual mortality, recruitment, and growth rates across the plot. The lower-lying habitats experienced higher mortality rates than the slopes and plateaus, suggesting too much moisture is a higher risk to Lecythidaceae individuals than drought in this plot. There were no overlapping habitat associations among sister species, or among the seven most abundant species, which suggests that terra firme habitat association provides a niche partitioning mechanism for closely related Lecythidaceae species. As intended with its establishment, this plot continues to provide integral baseline data for one of the most ecologically dominant and culturally significant tree families in the Amazon region.

Oxy-fuel co-combustion dynamics of phytoremediation biomass and textile dyeing sludge: Gas-to-ash pollution abatement

The environmental pressures of major wastes in the circular economies can be abated leveraging the complementarity and optimal conditions of their co-combustion. The oxy-fuel co-combustion of phytoremediation biomass of Sedum alfredii Hance (SAH) and textile dyeing sludge (TDS) may be a promising choice for sustainable CO2 capture and a waste-to-energy conversion. This study characterized and quantified their co-combustion performances, kinetics, and interactions as a function of blend ratio, atmosphere type, and temperature. With a focus on the characteristic elements of SAH (Ca, K, Zn, and Cd) and TDS (Al and S), changes in the mineral phases and ash melting and slagging trends of K2O-Al2O3-SiO2 and CaO-Al2O3-SiO2 systems were quantified. The Zn and Cd residual rates of the co-combustion of 75% SAH and 25% TDS rose by 58.52% and 5.93%, respectively, in the oxy-fuel atmosphere at the 30% oxygen concentration, relative to the mono-combustion of SAH in the air atmosphere. The co-combustion in the oxy-fuel atmosphere at the 20% oxygen concentration delayed the release peaks of SO2, C2S, and H2S, while the Ca-rich SAH captured S in TDS through the formation of CaSO4. Our findings provide new and practical insights into the oxy-fuel co-combustion toward the enhanced co-circularity.

Over 120 years of landing trends in Japan, for the commercially exploited shark species, Squalus suckleyi

Landing trends denote actual removal of a species by fisheries and may be a useful index of stock biomass dynamics, but accurate records for North Pacific spiny dogfish (Squalus suckleyi) landings in Japan are only available for 1952–1967. We used official Japan statistical yearbook data and bootstrap methodology to estimate landings of Pacific spiny dogfish, for 1894–1951 and 1968–2013, by prefecture. The landing estimates indicate that this species has been continuously exploited around Japan for over 120 years, since at least 1894. The landing trends could be divided into four periods: stable, low catch (1894–1919); increasing catch (1920–1949); decreasing catch (1950–1963); and relative stability (1964–2013). The trend in Pacific spiny dogfish landings appears to have been strongly influenced by societal demand, as supported by unit price trends for sharks. This result suggests that determinations of stock status based only on landing trends are inadequate for this species. After 1990, estimates of Pacific spiny dogfish landings ranged from 2800 to 4500 mt annually. A large proportion (52.7–74.7%) of the annual landings of this species were made by Hokkaido and Aomori prefectures, which are located near important habitat for this species in the northwestern Pacific. Thus, these regions are especially important for effective management and sustainable exploitation of the Pacific spiny dogfish stock in Japan.

High Dynamics of Ciliate Community Revealed via Short-Term, High-Frequency Sampling in a Subtropical Estuarine Ecosystem.

Ciliates are pivotal components of the marine microbial food web, exerting profound impacts on oceanic biogeochemical cycling. However, the temporal dynamics of ciliate assemblages on a short time scale in the highly fluctuating estuarine ecosystem remain largely unexplored. We studied changes in the ciliate community during a short time frame in the high salinity waters (>26) of a subtropical estuary. Ciliate abundance, biomass, size and oral diameter structure, and community composition fluctuated considerably and irregularly over a few days or even a few hours. Spearman correlations and the generalized linear model revealed that heterotrophic prokaryotes (HPs) and viral abundances drove the dynamics of ciliate abundance and biomass. The structural equation model further identified a major path from the high-fluorescence content virus (HFV) to HPs and then ciliates. Given the substantial correlation between salinity and HPs/HFV, we proposed that the response of HPs and HFV to salinity drives the dynamics of ciliate biomass. Additionally, the Mantel test showed that phytoplankton pigments such as Lutein and Neoxanthin, phosphate, and pigmented picoeukaryotes were key covariates of the ciliate community composition. This study demonstrated the highly changing patterns of ciliate assemblages and identified potential processes regulating ciliate biomass and community composition on short timescales in a subtropical, hydrographically complex estuary.

Functionally diverse tree stands reduce herbaceous diversity and productivity via canopy packing

Abstract There is extensive experimental evidence for the importance of biodiversity in sustaining ecosystem functioning. However, such experiments typically prevent immigration by continuously removing non‐target species, thereby questioning the generality of these findings to real‐world ecosystems. This is particularly true in forest ecosystems where understorey herbaceous species are key biodiversity components but are usually weeded in tree diversity experiments. Consequently, little is known about how tree diversity influences the natural dynamics of understorey herbaceous layers. We conducted a 3‐year non‐weeded tree diversity experiment composed of eight woody species differing widely in plant economic strategies. We examined how the functional diversity and identity of tree species mixtures drive the temporal dynamics of understorey productivity, functional diversity and composition through canopy packing (CP). Tree mixtures with high functional diversity experienced increased CP over time, thereby decreasing understorey productivity and diversity. Furthermore, herbaceous communities were dominated by species with functional traits typical of low‐light conditions [lower community‐weighted mean (CWM) of maximum plant height, but larger CWM of specific leaf area] in response to increased CP. Our results provide mechanistic insights into the role of tree functional diversity in shaping the dynamics of biomass, functional diversity and composition of the understorey herbaceous layer during the early successional period. It is expected that the effects of tree functional diversity would also be relevant over time due to the increasing usage of canopy space. This study highlights the significance of natural community processes in determining the effects of tree diversity on the temporal dynamics of previously neglected ecosystem structures and functioning. Read the free Plain Language Summary for this article on the Journal blog.

Variations in biomass of fungal guilds are primarily driven by factors related to soil conditions in Mediterranean Pinus pinaster forests

Soil fungi are vital for regulating ecosystem carbon balance and productivity, by driving processes related to soil carbon and nutrient cycling. The rate and capacity of fungi-mediated processes are linked to fungal biomass dynamics and identifying the drivers of fungal biomass is important for predicting ecosystem responses to environmental changes. Here, ergosterol-based fungal biomass estimates and ITS2-based fungal community composition profiles were used to assess biomass of fungal guilds. Effects of forest management (thinning), environmental factors (soil chemical properties, microclimate, weather and forest stand composition) and season were related to the fungal biomass dynamics to identify the guild-specific drivers of biomass. Biomass of most fungal guilds increased with nutrient availability (nitrogen and potassium in particular) and decreased with forest thinning, and variation in total biomass was mainly driven by variation in mycorrhizal biomass. Most fungal guilds reached a minimum in biomass during summer except for mycorrhizal and root-associated ascomycetes, which instead reached a minimum during winter. Mycorrhizal fungi and root-associated ascomycetes displayed similar spatiotemporal variability in biomass. Yeasts and moulds were the only fungi displaying strong linkages with microclimate, whereas pathogenic and moss-associated fungi largely diverged in their responses to the environmental factors. The results of our study highlight that environmental factors related to the availability of soil nutrients may have an overall stronger effect on variation in biomass of fungal guilds in Mediterranean Pinus pinaster forests than direct influences of microclimate, weather and forest management.

Long-Term Series of Chlorophyll-a Concentration in Brazilian Semiarid Lakes from Modis Imagery

By monitoring the chlorophyll a concentration (chla), it is possible to keep track of the eutrophication status of a lake and to describe the temporal dynamics of the phytoplankton biomass. Such monitoring must be both extensive and intensive to account for the short- and long-term biomass variations. This may be achieved by the remote estimation of chla through an orbital sensor with high temporal resolution. In this study, we used MODIS imagery to produce 21-year time series of chla for three strategic lakes of the Brazilian semi-arid region: Eng. Armando Ribeiro Gonçalves, Castanhão, and Orós. We used data collected in 13 lakes of the region to test new and published regression models for chla estimation. The selected model was validated and applied to daily MODIS images for the three largest lakes. The resulting chla time series revealed that the temporal dynamics of the phytoplankton biomass is associated with the hydraulic regime of the lakes, with chla plummeting upon intense water renewal and keeping high during persistent dry periods. The intense rainy season of 2004 reduced the phytoplankton biomass and its effects even extended to the subsequent years. Our results encourage the exploration of the MODIS archived imagery in limnological studies.

Predicting spatial-temporal patterns of diet quality and large herbivore performance using satellite time series.

Adaptive management of large herbivores requires an understanding of how spatial-temporal fluctuations in forage biomass and quality influence animal performance. Advances in remote sensing have yielded information about the spatial-temporal dynamics of forage biomass, which in turn have informed rangeland management decisions such as stocking rate and paddock selection for free-ranging cattle. However, less is known about the spatial-temporal patterns of diet quality and their influence on large herbivore performance. This is due to infrequent concurrent ground observations of forage conditions with performance (e.g., mass gain), and previously limited satellite data at fine spatial and temporal scales. We combined multi-temporal field observations of diet quality (weekly) and mass gain (monthly) with satellite-derived phenological metrics (pseudo-daily, using data fusion and interpolation) to model daily mass gains of free-ranging yearling cattle in shortgrass steppe. We used this model to predict grazing season (mid-May to October) mass gains, a key management indicator, across 40 different paddocks grazed over a 10-year period (n=138). We found strong relationships between diet quality and the satellite-derived phenological metrics, especially metrics related to the timing and rate of green-up and senescence. Satellite-derived diet quality estimates were strong predictors of monthly mass gains (R2 =0.68) across a wide range of aboveground net herbaceous production. Season-long predictions of average daily gain and cattle off-mass had mean absolute errors of 8.9% and 2.9%, respectively. The model performed better temporally (across repeated observations in the same paddock) than spatially (across all paddocks within a given year), highlighting the need for accurate vegetation maps and robust field data collection across both space and time. This study demonstrates that free-ranging cattle performance in rangelands is strongly affected by diet quality, which is related to the timing of vegetation green-up and senescence. Senescing vegetation suppressed mass gains, even if adequate forage was available. The satellite-based pseudo-daily approach presented here offers new opportunities for adaptive management of large herbivores, such as identifying within-season triggers to move livestock among paddocks, predicting wildlife herd health, or timing the grazing season to better match earlier spring green-up caused by climate change and plant species invasion.

Biomass and nutrient dynamics of major green tides in Ireland: Implications for biomonitoring

The control of macroalgal bloom development is central for protecting estuarine ecosystems. The identification of the nutrients limiting the development of macroalgal blooms, and their most likely sources is crucial for management strategies. Three Irish estuaries (Argideen, Clonakilty and Tolka) affected by green tides were monitored from June 2016 to August 2017. During each sampling occasion, biomass abundances, tissue N and P contents, and δ15N were determined for tubular and laminar morphologies of Ulva. All estuaries showed maximum biomass during summer and minimum during winter. Tissue nutrient contents revealed P rather than N limitation. The δ15N during the peak bloom indicated agriculture as the most likely source of nitrogen in the Argideen and Clonakilty, and urban wastewaters in the Tolka. No differences in the δ15N, and the tissue nutrients content were observed between morphologies. The period between May and July is most suitable for bioassessment of green tides.

Does Elemental Sulfur Act as an Effective Measure to Control the Seasonal Growth Dynamics of Potato Tubers (Solanum tuberosum L.)?

The in-season dynamics of potato tuber biomass (TTB) growth requires effective nitrogen (N) control. This hypothesis was tested in 2006 and 2007. The two-factorial experiment with two rates of N (60, 120 kg ha−1) and sulfur (S; 0, 50 kg ha−1) was carried out in the split-plot design. The third factor was the sampling of plants at 10-day intervals. The collected plant material was divided into leaves, stems, stolons + roots, and tubers. The seasonal trend of TTB was linear, while the biomass of leaves, stems, and stolons + roots was consistent with polynomial regression models. TTB was controlled by (i) the date of potato growth after emergence, when the TTB exceeded the leaf biomass (DAEcrit); (ii) the stem growth rate; and iii) the share of stems in the total potato biomass. TTB growth was reduced when DAEcrit preceded the DAEop for leaf biomass, determining its maximum. This phenomenon appeared in 2007 on plots fertilized only with N. The absolute growth rate of the stem biomass, exceeding ¼ of that of the tuber biomass in the descending phase, resulted in an increased and prolonged share of stems in the total potato biomass, which ultimately led to a decrease in tuber yield. The use of sulfur to balance the N, applied effectively, controlled the growth rate of potato organs competing with tubers.

Eucalyptus replanting model representation for sustainable productivity: A review

The stable natural resources will encourage the productivity of sustainable eucalyptus replanting for the benefit of human life. Replanting eucalyptus plants is one of the things that drive sustainable productivity in eucalyptus processing. Eucalyptus replanting planning requires supporting tool decisions to increase productivity, analyze variability, climate change, measure environmental impacts, and maximize profits. The paper aims to evaluate various models in representing the replanting of sustainable eucalyptus used for crop management. In this review, the discussion started from the history of eucalyptus, the approach to the compilation of literature reviews, the method for reviewing the literature, yields and discussions, and finally providing some significant recommendations. Reviews of physiological models based on 3PG (Physiological Principles in Predicting Growth) processes are considered capable of being optimal support tools in the management of sustainability strategies to evaluate the growth of eucalyptus plant. Its usefulness in providing simulations about the impacts of climate change, simulation of forest management practices, the impact of hydrology on forests, the attributes of location to standing growth, biomass dynamics and potential disruption to forest ecosystems make this model a supporting tool in forest management sustainability strategies. Review literature was obtained relevant literature for qualitative analysis from 2010 to 2021.

Intermediate disturbances drive long‐term fluctuation in old‐growth forest biomass: an 84‐yr temperate forest record

AbstractWhat are typical values and dynamic status of live‐tree biomass pools in old‐growth, mesic, cool temperate forests? A handful of biomass density estimates in eastern North American temperate forests show large biomass/carbon reserves on a per‐area basis. However, it is less clear whether these ecosystems are, over multi‐decade scales, typically steady‐state or non‐equilibrial carbon pools. Previous studies have suggested both possibilities, but claims are based on inferences from short‐term studies or proxy data sets. An unusually long‐term and extensive data set from repeatedly sampled permanent plots (84 yr, ca. 10 ha sample area, 6–8 measurements), from old‐growth conifer‐hardwood forest in northern Michigan, USA, allows direct estimation of multi‐decade trends in aboveground live‐tree biomass. Results confirm prior suggestions of high‐biomass density for old‐growth temperate forests (averaging &gt;300 Mg/ha), but, despite significant decade‐scale variation, show no overall, long‐term directional change. Study plots typically show multi‐decade trends of gradually increasing biomass density, interrupted by sharp declines attributed to intermediate‐severity disturbances, with recovery of pre‐disturbance biomass density requiring upwards of a half‐century. At the stand scale, biomass dynamics are strongly historically contingent, and short‐term studies may yield biased or misleading results. Disturbance legacies, through demographic and structural effects, can have multi‐decade effects on vulnerability to further disturbance. While this study shows no general trend in aboveground biomass pools, it suggests that changes in disturbance regime may drive important feedbacks in biomass pool dynamics.