National Forest Research Articles

Thresholds for adding degraded tropical forest to the conservation estate.

Logged and disturbed forests are often viewed as degraded and depauperate environments compared with primary forest. However, they are dynamic ecosystems1 that provide refugia for large amounts of biodiversity2,3, so we cannot afford to underestimate their conservation value4. Here we present empirically defined thresholds for categorizing the conservation value of logged forests, using one of the most comprehensive assessments of taxon responses to habitat degradation in any tropical forest environment. We analysed the impact of logging intensity on the individual occurrence patterns of 1,681 taxa belonging to 86 taxonomic orders and 126 functional groups in Sabah, Malaysia. Our results demonstrate the existence of two conservation-relevant thresholds. First, lightly logged forests (<29% biomass removal) retain high conservation value and a largely intact functional composition, and are therefore likely to recover their pre-logging values if allowed to undergo natural regeneration. Second, the most extreme impacts occur in heavily degraded forests with more than two-thirds (>68%) of their biomass removed, and these are likely to require more expensive measures to recover their biodiversity value. Overall, our data confirm that primary forests are irreplaceable5, but they also reinforce the message that logged forests retain considerable conservation value that should not be overlooked.

China's future forest carbon sequestration potential under different management scenarios

Enhancing forest carbon storage and carbon sequestration capacity is crucial for achieving carbon neutrality. Scientific forest management can maintain a high level of carbon sequestration capacity in forests, and considering the carbon pool of wood products can extend the time of carbon fixation. However, current predictions of large-scale forest carbon storage and carbon sequestration capacity have overlooked changes in forest carbon absorption with forest age and the buffering effect of wood product carbon pools in the carbon release process. In this paper, we used the Forest Simulation and Optimization System model (FSOS) to analyze the wood supply and carbon sequestration capacities of different management scenarios based on data from the Forest Resources Inventory (2014–2018). The results showed that China's forests could export significant amounts of timber in the future; According to the 9th forest survey report, China's forests produce only 88 million m3 yr-1. Among them, the harvested objects were mainly planted forests, and if all forests (planted forests and natural forests) are involved in forest management planning, the maximum sustainable annual wood supply will reach 286 million m3 yr-1. Moreover, due to the current large proportion of younger forests in China, 358 million m3 of annual wood supply will be achievable in the future (as of the year 2039). Forest management can increase the carbon sequestration capacities in forest ecosystems as well as the wood supply compared to the no management options. In summary, the carbon sequestration potential of unmanaged forests is limited. Appropriate forest management can increase the carbon sequestration potential of forests. The substitution of carbon emission reduction of wood products and bioenergy can also greatly reduce the pressure to achieve carbon neutral strategies.

Floristic Diversity of Natural Forest Patches Across Agroclimatic Zones in Northwestern Ethiopian

Floristic Diversity of Natural Forest Patches Across Agroclimatic Zones in Northwestern Ethiopian

Anthropogenic forests simplify seed- but not pollen-dispersal networks.

Natural native forests are rapidly being replaced by anthropogenic forests often with a strong presence of invasive alien plant species. Eucalypt species are widely planted worldwide, with Eucalyptus globulus plantations being particularly expressive in Portugal. Poor forestry practices often lead to the associated expansion of invasive species, such as Acacia dealbata. However, we still know relatively little about the functioning of anthropogenic forests, such as seed and pollen dispersal services. Here, we compared bird abundance and richness and the seed and pollen dispersal networks in both forest types. Anthropogenic forests presented lower bird abundance, and smaller, more simplified, and more random (abundance-based) seed dispersal services than those of natural forests. Interestingly, the pollen dispersal network was more similar than the seed dispersal network for both forest types and dominated by opportunistic and neutral processes, given the absence of specialized nectarivorous. The proportion of birds transporting seeds decreased, while those carrying pollen significantly increased in the anthropogenic forest compared to the native forest. Our work highlights the impact of anthropogenic forests on bird abundance, with consequences for seed dispersal services and forest regeneration.

Investigating the Potential of Polypore Fungi as Eco-Friendly Materials in Food Industry Applications

Polyporoid fungi represent an untapped resource in the ancillary use of forests, traditionally utilized in both historic and contemporary medicine for their diverse bioactive properties, yet their potential for creating materials within the food industry remains largely unexplored. This article delves into the polyporoid fungi as a promising, yet underutilized, biomaterial resource for eco-friendly applications in the food sector. Despite their widespread use in traditional and modern medicine, the exploration of these fungi for industrial applications, particularly in food storage solutions and utensils, is in its nascent stages. The Białowieża Primeval Forest, characterized by its abundant deadwood and minimal human intervention, offers a rich repository of polyporoid fungi. This study aims to illuminate the ecological significance and potential industrial applications of polyporoid fungi. By reviewing existing research and synthesizing insights into the genetic diversity, biochemical capabilities, and ecological roles of polyporoid species such as Fomes fomentarius, Fomitopsis pinicola, and Trametes versicolor, this article proposes a novel approach to leveraging polyporoid fungi in developing sustainable solutions that meet current environmental and health-conscious trends. The investigation not only underscores the potential of polyporoid fungi in advancing green technologies but also highlights the importance of utilizing renewable resources in material science, fostering a shift towards more sustainable industrial practices.

Demographic and net primary productivity dynamics of primary and secondary tropical forests in Southwest China under a changing climate

AbstractTropical forests are major carbon sinks on the Earth's land surface. However, our understanding of how the demographic rate and carbon sink capacities of tropical forests respond to climate change remains limited. In this study, we investigated the impacts of environmental drivers on forest growth, mortality, recruitment, and stem net primary productivity (NPPstem) over 16 years at five tropical forest plots in Xishuangbanna, Southwest China. These plots are along a successional gradient spanning three tropical secondary forests (tropical secondary forest‐1 [TSF‐1], tropical secondary forest‐2 [TSF‐2], and tropical secondary forest‐3 [TSF‐3]) and two primary forests (tropical rainforest [TRF] and tropical karst forest [TKF]). Our results showed that early successional secondary forests (TSF‐2 and TSF‐3) had higher diameter growth rates and relative mortality rates. An extreme drought event during 2009–2010 reduced the growth rate, relative recruitment rate, and NPPstem for most plots while increasing mortality in early successional forest plots. We observed significant negative effects of maximum temperature (Tmax) on NPPstem and diameter growth rate across all plots. Additionally, we found that precipitation had significant positive effects on diameter growth rate across all plots. Furthermore, tree mortality increased with rising Tmax, whereas precipitation significantly enhanced tree recruitment. Our findings highlight the vulnerability of tree growth, mortality, recruitment, and productivity in tropical forests to extreme drought events in Southwest China. Continued climate warming and more frequent droughts will induce higher mortality rates and impede growth, thus reducing the carbon sink capacity of tropical forests, especially in early successional stage tropical secondary forests.

Home range overlaps of the brushtail possum (Trichosurus vulpecula): implications for disease transmission

Understanding how bovine tuberculosis (TB) is maintained in wildlife reservoirs is critical for the management of this disease impacting cattle in many countries. For the primary wildlife reservoir of the disease in New Zealand, the brushtail possum (Trichosurus vulpecula), transmission of this contagious bacterial disease among possums is often assumed to be linked to home range overlap. Identifying drivers of possum home range, and home range overlap between individuals, is thus important for informing wildlife reservoir TB management in New Zealand. We monitored four sub-populations of free-living possums in New Zealand native forests during 10 consecutive months using live trapping, to give the first direct insight into how the frequency and area of overlaps alters with density, sex and age. A total of 832 individuals were captured (average 9.3, range from 1 to 40 captures per animal with a median value of 7) and 35,820 home range overlaps were recorded. Both the number and area of overlaps were significantly associated with age class, with 66.6% of overlaps occurring between adults, 30% between adults and juveniles, and only 3.4% between juveniles. Overall, adult males showed significantly higher numbers of overlaps than expected, while adult and juvenile females showed significantly lower numbers of overlaps than expected and no differences were observed in juvenile males. In addition, males exhibited more and larger overlaps than females. The number and size of overlaps per individual decreased with increasing local population density. Understanding shared areas of activity among individuals can provide insights into the interactions occurring and potential pathways for diseases transmitted by contact such as TB. These results can inform to develop effective strategies for the control of diseases carried and dispersed by possums.

Japanese Oak Wilt Disease decreased survival probability and mean lifetime of tree populations in a secondary natural forest

ABSTRACT The purpose of this study was to assess the effects of Japanese Oak Wilt Disease on mortality in a tree population. The study site was the permanent plot of 0.26 ha established in the secondary forest dominated by Abies firma, Tsuga sieboldii and Quercus serrata at the University of Tokyo Chiba Forest in the southeastern part of the Boso peninsula, Japan. We set the two observation periods of 1999–2008 and 2009–2021, and Japanese Oak Wilt Disease invaded the study site in the middle of the second period. We collected tree age data for both alive and dead trees in the two periods based on semi-nondestructive drilling measurements for trees using a RESISTOGRAPH. Survival analyses were conducted on the second-period data, and the demographic metrics such as mortality ratios and mean lifetimes were compared between the two periods. The results showed that: the mortality ratio of the tree population at old ages, where oaks (Quercus serrata) concentrated in their age distribution, significantly increased; the effect of the oak group was significant on mortality in the tree population; the hazard for the oak group was 24 times the hazard for the other tree species group; the survival curve reflected the mass mortality in oaks at old ages, which led to the decrease of mean lifetime less than half. Consequently, it was implied that the effects of Japanese Oak Wilt Disease impacted the demographic metrics of oak trees.

Study of the Adsorption/Desorption Behavior of Uranium in a Forest Soil

ABSTRACT The behavior of soluble uranium (VI) on the adsorption/desorption processes in the presence of a natural forest soil (FS) or a gamma-irradiated forest soil (FS-I) provides important knowledge on the fate and mobility of this element in contaminated soils and groundwater. Soil from a forest was irradiated with a dose of 1 MGy 60Co gamma radiation and was compared with natural soil to determine the behavior of U(VI) in these materials. Both natural and gamma irradiated soils were characterized by several physicochemical techniques. Kinetics, isotherms, effects of pH, U(VI) concentration, temperature, and stability of the U(VI)/adsorbents were considered. The equilibrium of adsorption processes U O 2 2 + /FS and U O 2 2 + /FS-I were achieved in 2 h, and the data were well fitted to the pseudo first (FS-I), pseudo second (FS), and Elovich models (FS): qe value was 14 mg g−1 for FS, slightly higher than 12 mg g−1 for FS-I. The isotherm data were well-fitted to the Langmuir and Temkin models for FS and FS-I, respectively. The processes of both materials are independent of the temperature between 30 and 50°C; however, they are sensitive to pH and U(VI) concentration. Furthermore, acidic media and complexing agents were good desorbents for U(VI) from the natural and irradiated soils.

Extraction of Arbors from Terrestrial Laser Scanning Data Based on Trunk Axis Fitting

Accurate arbor extraction is an important element of forest surveys. However, the presence of shrubs can interfere with the extraction of arbors. Addressing the issues of low accuracy and weak generalizability in existing Terrestrial Laser Scanning (TLS) arbor point clouds extraction methods, this study proposes a trunk axis fitting (TAF) method for arbor extraction. After separating the point cloud data by upper and lower, slicing, clustering, fitting circles, obtaining the main central axis, filtering by distance, etc. The canopy point clouds are merged with the extracted trunk point clouds to precisely separate arbors and shrubs. The advantage of the TAF method proposed in this study is that it is not affected by point cloud density or the degree of trunk curvature. This study focuses on a natural forest plot in Shangri-La City, Yunnan Province, and a plantation plot in Kunming City, using manually extracted data from a standardized dataset of samples to test the accuracy of the TAF method and validate the feasibility of the proposed method. The results showed that the TAF method proposed in this study has high extraction accuracy. It can effectively avoid the problem of trunk point cloud loss caused by tree growth curvature. The experimental accuracy for both plots reached over 99%. This study can provide certain technical support for arbor parameter extraction and scientific guidance for forest resource investigation and forest management decision-making.

Do irrigated and rainfed agrosystems change aboveground and root carbon and nitrogen stocks in a semiarid environment?

Determining shoot and root biomass and carbon (C) and nitrogen (N) stocks in different ecosystems is crucial to propose adaptative measures to reduce greenhouse gas emission. Data on systems of semiarid areas are scarce, especially irrigated ones. We compared biomasses of four irrigated (bean, maize, grapevine, and mango) and four rainfed livestock systems (buffel grass, prickly pear, gliricidia and leucaena) with those of a preserved and an open tropical dry forest (Caatinga) used as pasture. Caatinga biomass was estimated by allometry and biomasses of the other systems by the destructive method. Root biomasses were determined in layers down to 100 cm. Mango had the highest aboveground and root biomasses: 34.2 and 91.3 Mg ha−1. Preserved Caatinga was the second in aboveground biomass: 25.1 Mg ha−1, compared 9–14.1 Mg ha−1 of the open Caatinga and permanent crops and 3.0–11.8 Mg ha−1 of the grass and annual crops. Preserved Caatinga, gliricidia and buffel grass formed the second group in root biomass (23.7–25.1 Mg ha−1), while all other systems had less than 13.5 Mg ha−1. Preserved and open Caatinga, annual crops and prickly pear had root:shoot ratios below 1, while the other systems had ratios >1, especially mango (2.7). Most systems had roots concentrated in the 0–15 cm layer, but the permanent crops, except prickly pear, concentrated about half of their roots in deeper layers. C (34.2–46.6%) and N (0.6–3.4%) concentrations varied less than biomasses. Root biomass was the plant factor mostly correlated with soil C and N stocks. Therefore, irrigated crops can accumulate more biomass than the native forest, but substitution by mango led to a severe depletion in soil C and N stocks, and all other systems also lost soil C and N. Management strategies such as green manure and crop diversification should be adopted to maintain plant and soil C and N stocks similar to those of the original vegetation.

Litter decomposition in pure and mixed plantations on the Loess Plateau, China: Lack of home-field advantage

Litter decomposition plays a critical role in the nutrient cycling of terrestrial ecosystems. According to the home-field advantage (HFA) hypothesis, litter decomposes more rapidly in its home habitat (where it originates) compared to other habitats (referred to as away). Although this hypothesis has been widely tested in natural forests, it remains controversial and lacks support for plantations, especially in dry ecosystems where microbial activities are limited. To clarify it, the present study investigated litter mass loss, nutrient dynamics, and decomposer communities in a 549-day reciprocal transplant experiment of litter decomposition in Robinia pseudoacacia (RP) and Hippophae rhamnoides (HR) pure plantations and their mixed plantations (5:5 and 8:2 ratios) on the Loess Plateau, China. The rate of mass, carbon (C), nitrogen (N) and phosphorus (P) loss in litter differed depending on litter type of species component and plantation type they were placed in. HR litter lost mass and released C, N, and P fastest, irrespective of plantation type. The overall mass loss of the four litter types were the fastest under 5:5 mixed plantations. However, litter did not decompose more rapidly in its home soil compared to the away soil. The structural equation modeling revealed that initial litter quality played a significant role in regulating the loss of C and N across decomposition stages, while the climate variations and microbial chemistry also contributed to the process. The similarity in soil microbial communities across plantation types, along with the limited interaction between litter and microbes in arid environments, could help elucidate the lack of HFA, with other factors such as the litter type exerting a minor influence. In summary, this study does not substantiate the hypothesis of home-field advantage but supports its context-dependency. Thus, regional heterogeneity should be taken into account when predicting the carbon cycle of forest ecosystems in future studies.

Diversity and relative abundance of immature mosquitoes (Diptera: Culicidae) in Hohenbergia catingae Ule bromeliads and larvitraps in the Nísia Floresta National Forest, northeast Brazil.

The Nísia Floresta National Forest, located in Rio Grande do Norte (RN), is an important remnant of the Atlantic Forest biome in Brazil. Bromeliad tanks in this forest offer suitable breeding sites for mosquito species that may act as viral vectors, thus posing an epidemiological concern. However, studies investigating the presence of immature Culicidae in natural breeding sites in RN have thus far been restricted to Caatinga vegetation. This study investigated mosquitoes and their natural breeding sites in bromeliads growing in the Nísia Floresta National Forest. From March 2013 to February 2014, monthly samples were collected from the tanks of five randomly selected bromeliads and larvitraps placed in each of the three forest management areas. Hohenbergia catingae Ule (Hohenbergia bromeliad)is an important shelter for immature mosquitoes. Culex (Microculex) was the predominant species, representing 86% of the immature mosquitoes collected. A rare occurrence of Aedes (Stegomyia) aegypti (Linnaeus, 1762) (generally associated with urban areas under high anthropogenic influence) was observed, highlighting the importance of investigating the presence of mosquitoes in different natural habitats. An analysis of species diversity revealed that species such as Culex imitator Theobald, 1903 and Culex davisi Kumm, 1933, have a strong association with bromeliads. In tire traps (larvitraps) Aedes (Stegomyia) albopictus Skuse, 1894 was predominant. Environmental changes, such as deforestation, removal of bromeliads, and climate change in the area, can influence the migration of species and adaptation to new habitats in a peridomiciliary environment around the forest, consequently the possibility of transmission of virus and other pathogens.

Global biomass maps can increase the precision of (sub)national aboveground biomass estimates: A comparison across tropical countries

Countries within the tropics face ongoing challenges in completing or updating their national forest inventories (NFIs), critical for estimating aboveground biomass (AGB) and for forest-related greenhouse gas (GHG) accounting. While previous studies have explored the integration of map information with local reference data to fill in data gaps, limited attention has been given to the specific challenges presented by the clustered plot designs frequently employed by NFIs when combined with remote sensing-based biomass map units. This research addresses these complexities by conducting four country case-studies, encompassing a variety of NFI characteristics within a range of AGB densities. Examining four country case-studies (Peru, Guyana, Tanzania, Mozambique), we assess the potential of European Space Agency's Climate Change Initiative (CCI) global biomass maps to increase precision in (sub)national AGB estimates. We compare a baseline approach using NFI field-based data with a model-assisted scenario incorporating a locally calibrated CCI biomass map as auxiliary information.The original CCI biomass maps systematically underestimate AGB in three of the four countries at both the country and stratum level, with particularly weak agreement at finer map resolution. However, after calibration with country-specific NFI data, stratum and country-level AGB estimates from the model-assisted scenario align well with those obtained solely from field-based data and official country reports. Introducing maps as a source of auxiliary information fairly increased the precision of stratum and country-wise AGB estimates, offering greater confidence in estimating AGB for GHG reporting purposes.Considering the challenges tropical countries face with implementing their NFIs, it is sensible to explore the potential benefits of biomass maps for climate change reporting mechanisms across biomes. While country-specific NFI design assumptions guided our model-assisted inference strategies, this study also uncovers transferable insights from the application of global biomass maps with NFI data, providing valuable lessons for climate research and policy communities.

Same streams in a different forest? Investigations of forest harvest legacies and future trajectories across 30 years of stream habitat monitoring on the Tongass National Forest, Alaska.

The effects of timber harvest practices and climate change have altered forest ecosystems in southeast Alaska. However, quantification of patterns and trends in stream habitats associated with these forests is limited owing to a paucity of data available in remote watersheds. Here, we analyzed a 30-year dataset from southeast Alaska's Tongass National Forest to understand how these factors shape stream habitats. First, we examined differences between broad management classes (i.e., harvested and non-harvested) that have been used to guide stream channel restoration goals. Second, we assessed associations between intrinsic landscape characteristics, watershed management, and timber harvest legacies on aquatic habitat metrics. And third, we examined trends in stream habitat metrics over the duration of the dataset to anticipate future management challenges for these systems. Small effect sizes for some harvest-related predictors suggest that some stream habitat metrics, such as pool densities, are less responsive than others, and management practices such as protecting riparian buffers as well as post-harvest restoration may help conserve fish habitats. Large wood densities increased with time since harvest at sites harvested >50 years ago, indicating that multiple decades of post-harvest forest regrowth may contribute large wood to streams (possibly alder), but that it is not enough time for old-growth trees (e.g., spruce, Picea, or hemlock, Tsuga,), classified as key wood, to develop and be delivered to streams. The declining trend in key wood (i.e., the largest size class of wood) regardless of management history may reflect that pre-harvest legacy old-growth trees are declining along streams, with low replacement. The introduction of wood to maintain complex stream habitats may fill this gap until riparian stands again contribute structural key wood to streams. Trend analyses indicate an increasing spatial extent of undercut banks that may also be influenced by shifting hydrologic regimes under climate change.

Clay mineral composition drives soil structure behavior and the associated physical properties in Brazilian Oxisols

Soil aggregation controls several physical, chemical, and biological processes. Soil organic matter (SOM) and its stabilizing agents are regarded as the most important factors driving formation and stabilization of soil aggregates. However, aggregate stability in highly weathered soils may also be related to clay mineral composition and soil chemical properties. This study aims to evaluate the processes controlling soil aggregate stability and to understand the influence of soil chemical and clay mineral composition on the structural stability of highly weathered soils. Four Brazilian Oxisols were investigated: (P1) Xanthic Kandiustox, (P2) Rhodic Haplustox, (P3) Anionic Acrustox, and (P4) Typic Hapludox. Undisturbed and disturbed soil samples were collected from the Bw horizon under a native forest. Soil structural stability was evaluated using a variety of techniques and indices, including mean weight diameter (MWD) by hydraulic stress, mechanically-dispersible clay (MDC) by turbidimetry, tensile strength (TS) by crushing aggregates, and soil structural stability index (SSI) taking into account soil organic carbon (SOC). In general, P1 exhibited the highest MDC content (3.05 ± 0.54, Nephelometric Turbidity Unit, NTU/g L‐−1), while P4 had the highest MWD (10.26 ± 0.24 mm) and the highest TS (80.42 ± 18.54 kPa) within the 8–4 mm aggregate size class. The TS for the 4–2 mm and 2–1 mm aggregate size classes was found to be equal for P2 and P4, with values ranging from 158.17 ± 24.70 kPa to 148.04 ± 38.50 kPa in the 4–2 mm class, and from 459.51 ± 189 kPa to 328.35 ± 78.22 kPa in the 2–1 mm one. The SSI was found to be inadequate for evaluating the structural stability of the Oxisols. In general, SOC was found to be the main stabilizing agent of larger aggregates, while clay mineral composition determined the stability of smaller aggregates. Goethite associated with gibbsite was more effective in increasing the structural stability of P2 and P4. Furthermore, kaolinites with low crystallinity, which are found in clayey Oxisols, resulted in a high specific surface area, particularly in Rhodic Haplustox and Typic Hapludox soils, which promoted more interactions with other clay minerals (e.g., goethite and gibbsite) and SOC, thereby increasing the tensile strength in these Oxisols. In fact, the formation and stabilization of aggregates in highly weathered soils depends on several factors, but the influence of clay mineral composition stands out as the most pronounced.

Influence of Slope Aspect and Position on Xylem Formation Dynamics in Subtropical Chinese Fir Plantations

Recent studies on the intra-annual dynamics of trees were mainly focused on mature trees in natural forests; however, less is known about how topography (e.g., slope’s position and aspect) shape the intra-annual xylem formation dynamics of young trees in plantation forests. We monitored intra-annual xylem formation dynamics of 6-year-old Chinese fir (Cunninghamia lanceolata (Lamb.)) trees across two different aspects (northeast and southwest) and three different positions (upper, middle, and lower) of the slope in a planted forest in subtropical China. We found that the intra-annual xylem formation of trees on the northeast slope aspect (176.98 ± 34.52 cells) was significantly higher than that on the southwest slope aspect (140.19 ± 36.07 cells) due to the higher growth rate (0.67 ± 0.11 cells/day vs. 0.53 ± 0.10 cells/day). In the middle slope position, xylem formation (187.89 ± 19.81 cells) was also significantly higher than that of the upper (147.35 ± 29.08 cells) and lower slope positions (140.51 ± 48.36 cells), resulting from higher growth rate rather than longer growing season length. Our study demonstrated that intra-annual xylem formation dynamics of Chinese fir were altered by different topographic features and therefore encourage the implementation of management strategies that consider different slope aspects and positions to maximize forest productivity.

Cropping systems and production assessment in southern Myanmar: Informing strategic interventions

Abstract Cropland expansion into natural forests in the Kyunsu Township, southern Myanmar, has diminished the sustainability of natural resources in this area. Analyzing local cropping systems can help explore options for improving land productivity on the existing croplands. To achieve this, a study was conducted between June 2020 and June 2021, involving 301 farmers’ households within the township. The study focused on socioeconomic status, crop production characteristics, key soil properties, and production constraints. Hierarchical clustering on principal components was applied to identify the existing cropping systems. Subsequently, a comparative analysis of variables between identified cropping systems was performed. The findings revealed that in the plantation zone, the median gross value added (GVA) reached US$ 1,276 ha−1 year−1 for perennial monocropping and US$ 1,715 ha−1 year−1 for perennial-multiple cropping. These values were higher than the median GVAs of perennial monocropping (US$ 460 ha−1 year−1) and perennial-multiple cropping (US$ 474 ha−1 year−1) in the sea zone. In the lowland and sea zones, annual monocropping of rice had low median GVAs of 206 and US$ 165 ha−1 year−1, respectively. The combination of rice and perennial species in the lowland zone resulted in a higher median GVA (US$ 383 ha−1 year−1) compared to rice sole cropping in both the lowland and sea zones. Coupled with favorable soil properties, cropping systems that integrated perennial species, particularly multiple cropping with strategic input use, demonstrated enhanced land productivity. However, to optimize land productivity in these cropping systems, it is crucial to address major constraints, such as high input prices, poor soil quality, and scarcity of freshwater.

Evaluation of landscape ecological security pattern via the “pattern-function-stability” framework in the Guanzhong Plain Urban Agglomeration of China

Most studies have assessed and constructed landscape ecological security patterns (LESPs) primarily from the perspective of landscape morphology by employing morphological spatial pattern analysis, with little attention paid to fundamental ecosystem attributes (such as ecosystem functions and stability). Thus, this study proposed a comprehensive evaluation and optimization framework for LESPs from the perspective of “mode function stability” by integrating assessment landscape pattern, ecological function, and landscape stability. A comprehensive evaluation and optimization of the LESPs was conducted using the Minimum Cumulative Resistance (MCR) model in the Guanzhong Plain Urban Agglomeration (GPUA) as the research area. The results showed that: (1) Generally, the landscape quality in urban agglomerations was relatively low because of the large area of agricultural vegetation, high human interference, and landscape fragmentation, which caused low levels of landscape pattern, function, and stability. (2) LESPs were mainly determined by landscape stability in urban agglomerations due to low-quality ecosystems, rapid landscape transformation, and severe anthropogenic disturbances. (3) There was a large variation in the landscape function and stability of a certain landscape type due to their different structures and human interference across space in urban agglomerations. According to assessment by “pattern-function-stability” framework, the ecological sources and corridors covered with natural forest were the crucial cornerstone to constructing LESPs, and the rivers in crop planting areas were the inevitably selected corridors, but their ecological function and stability needed further improvement in construction. (4) The framework can assess spatial patterns and ecological functions to further the stability and sustainability of the landscape in maintaining ecological security and facilitating the identification of improvement objectives or measures of individual ecological sources or corridors in regional ecological infrastructure construction practices.

Biomass carbon stock and allocation of planted and natural forests in the Loess Plateau of China

Establishing planted forests (PF) by afforestation and naturally regenerating forests (NF) are important measures of enhance carbon (C) sequestration in terrestrial ecosystems. However, the difference of biomass C stocks and allocation between NF and PF and their determinants in water-limited areas remain unclear. To address this gap, we conducted a synthesis of above-ground biomass C (AGBC), below-ground biomass C (BGBC) stocks and root to shoot ratios (R:S) of PF and NF in the Chinese Loess Plateau. The changes in biomass C stock and R:S along a climate gradient were investigated, and the relationships between R:S and soil properties were also quantified. We found that PF exhibited lower AGBC and BGBC stocks compared to NF, but the average R:S in PF was significantly higher than that of NF (0.48 ± 0.27 vs. 0.30 ± 0.11, p < 0.05). Turning points existed in biomass C allocation along climatic gradient for both PF and NF. More biomass C was allocated to AGBC in PF and NF when mean annual precipitation exceeded 494 mm and 588 mm, respectively. Higher mean annual temperature promoted larger C allocations to BGBC in PF compared to NF. Soil properties had a stronger effect on the biomass C allocation patterns after afforestation, but to a lesser extent on NF. This study indicates that afforestation promotes a larger allocation of biomass C into the below-ground compared to naturally regenerated forests, and using the default R:S estimates may result in a severe underestimation of below-ground C stocks in water-limited areas. The biomass C stocks and allocation are collectively determined by climate conditions and soil properties, and accumulated below-ground biomass C stock induced by dryland afforestation may be an important C sink at a broad geographic scale.