Muyi Kang

Farmer and professional attitudes to the large-scale ban on livestock grazing of grasslands in China

Grasslands are the most extensive terrestrial landscapes and ecosystems in China and face growing degradation. A policy to protect the grasslands established in 2001 (the Grassland Ban Policy [GBP]), involves four management practices including grazing bans, keeping grasslands fallow, grazing rotations and rearing livestock in sheds. A questionnaire was developed and used to establish attitudes towards and beliefs about the GBP in different sectors (farming households, local officials and extension workers), assess problems with GBP implementation and identify possible solutions. Acceptance of the GBP by farmers varied from 64% in the north to 95% in the north-west region. The responses of both local officials and extension workers indicated that GBP implementation was greater in the central region than in the north-west region. Most farmers changed their livestock production system from grazing to stall feeding after implementation of the GBP, while both farmers and extension workers reported that high input costs were the most serious problem in stall feeding. Incentives need to be provided for sustainable implementation of the GBP by different stakeholders. Improved collaboration among farmers, local officials and extension workers is needed for technology transfer and policy implementation. Furthermore, the role of non-governmental organizations needs to be strengthened in implementation of the GBP.

Impact of land use on plant biodiversity and measures for biodiversity conservation in the Loess Plateau in China – a case study in a hilly-gully region of the Northern Loess Plateau

The Loess Plateau is a special natural–cultural unit in northern China. Intensive land use in the past has had, and forestation and grass planting at present will have inevitable impacts on plant biodiversity in the Loess Plateau. Based on the analysis of floristic features within three sampling sites with different land use practices and analysis of species richness among different land use types, we discuss impacts of land use on species richness and floristic features in the Northern Loess Plateau. The results drawn from this case study are as follows: (1) It appears that forestation and grass planting have had a positive influence on the local species diversity, but they have contributed little to the native vegetation in terms of conserving its floristic features. (2) Caragana intermedia shrubland, Pinus tabulaeformis forestland, and natural grassland have made important contributions to supporting indigenous species and maintaining local plant biodiversity. (3) There is a significant positive correlation between land use diversity and species richness. These results imply that practicing biodiversity conservation in situ is feasible and the suitable choice for the Loess Plateau. Concrete measures for biodiversity conservation in the area can include setting up small nature reserves and diversifying land use patterns to maintain as much habitat as possible for native vegetation. The artificial Hippophae rhamnoides shrubland should not be further promoted, considering its negative influence on biodiversity conservation.

Biomass and Its Allocation in Relation to Temperature, Precipitation, and Soil Nutrients in Inner Mongolia Grasslands, China

Aim Understanding and predicting ecosystem functioning such as biomass accumulation requires an accurate assessment of large-scale patterns of biomass distribution and partitioning in relation to climatic and soil environments. Methods We sampled above- and belowground biomass from 26 sites spanning 1500 km in Inner Mongolian grasslands, compared the difference in aboveground, belowground biomass and below-aboveground biomass ratio (AGB, BGB, and B/A, respectively) among meadow steppe, typical steppe, and desert steppe types. The relationships between AGB, BGB, B/A and climatic and soil environments were then examined. Results We found that AGB and BGB differed significantly among three types of grasslands while B/A did not differ. Structural equation model analyses indicated that mean annual precipitation was the strongest positive driver for AGB and BGB. AGB was also positively associated with soil organic carbon, whereas B/A was positively associated with total soil nitrogen. Conclusions These results indicated that precipitation positively influence plant production in Inner Mongolian grasslands. Contrary to the prediction from the optimal partitioning hypothesis, biomass allocation to belowground increased with soil total nitrogen, suggesting that more productive sites may increase belowground allocation as an adaptive strategy to potentially high fire frequencies.

Elevational trends of biodiversity and plant traits do not converge—a test in the Helan Range, NW China

When elevational gradients include combinations of different climatic gradients, such as a decline in temperature combined with an increase in moisture, vegetation and plant trait responses are difficult to explain. Here, we used plant species richness and morphometric traits data across steep elevational gradients in the Helan Range of Northwestern China in an attempt to separate general trends (temperature related) from regional peculiarity (moisture related). Based on the floristic data of the Helan Range as well as plot-based data, both drought (at low elevation) and low temperature (high elevation) are associated with low species richness presumably also explaining the peak in diversity at mid-elevation, where climatic conditions are moderate. However, this mid-elevation peak in diversity is not mirrored in trends of plant traits such as leaf size and inflorescence size, which show either unidirectional trends or no change with elevation (with impacts of drought and low temperature perhaps gradually replacing each other). Our analysis illustrated the taxonomic and plant functional type (PFT)-related biases in functional trait studies and showed that consistent patterns only emerge after careful data stratification, with taxonomy (family level) holding more promises than PFTs. Inflorescence size increased with elevation in major insect-pollinated families, a trend not seen in wind-pollinated (graminoid) families. However, the reproductive effort expressed as inflorescence/leaf length ratio increases with elevation in the majority of plant families, irrespective of their pollination system. The fact that these biometric responses to elevation do not correlate with responses in species richness (which peaks at mid-elevation) may reflect contrasting drivers of trait selection and biodiversity. Based on our plot-based data, this analysis also confirmed the usefulness of floristic archive data for testing ecological theory related to elevational gradients.

Evaluation of an Ecological Security Model in Zhalute Banner, Inner Mongolia

Abstract The aim of this study was to develop a comprehensive index system based on remote sensing (RS) and geographic information system (GIS) techniques to evaluate the status quo of ecological security in the farming–pastoral zone of northern China, for the purpose of facilitating sustainable development in ecotone regions. Taking a typical transitional piedmont region with farming–pastoral production mode as a case study area, the regions present ecological security situation was evaluated by constructing an index system with 3 types of indicators. These indicators were: 1) vegetation growth, measured by the decadal difference in the normalized difference vegetation index (NDVI); 2) change in landscape patterns, measured by the deviation of present from potential landscapes; and 3) severity of soil erosion, measured by organic matter content in topsoil. Data for the indicators, derived from RS images, historical maps, field surveys, and archival materials, were all mapped with the aid of a digital elevation model (DEM), according to their conjugation relationships. The results were obtained by classifying different combinations of elements in an index matrix of 3 indicators by means of mapping. The final results show that nearly the entire study area was in a condition ranging from somewhat insecure (SIN) to insecure (INS), with an average score of 3.46 in a 5-grade range, indicating declining ecological security. The situation was better in the farming–pastoral district. The whole region needs to adjust its production modes to learn from practices in the farming–pastoral district, in order to alleviate deterioration and improve ecological security in the region.

Radial Growth of Two Dominant Montane Conifer Tree Species in Response to Climate Change in North-Central China

North-Central China is a region in which the air temperature has clearly increased for several decades. Picea meyeri and Larix principis-rupprechtii are the most dominant co-occurring tree species within the cold coniferous forest belt ranging vertically from 1800 m to 2800 m a.s.l. in this region. Based on a tree-ring analysis of 292 increment cores sampled from 146 trees at different elevations, this study aimed to examine if the radial growth of the two species in response to climate is similar, whether the responses are consistent along altitudinal gradients and which species might be favored in the future driven by the changing climate. The results indicated the following: (1) The two species grew in different rhythms at low and high elevation respectively; (2) Both species displayed inconsistent relationships between radial growth and climate data along altitudinal gradients. The correlation between radial growth and the monthly mean temperature in the spring or summer changed from negative at low elevation into positive at high elevation, whereas those between the radial growth and the total monthly precipitation displayed a change from positive into negative along the elevation gradient. These indicate the different influences of the horizontal climate and vertical mountainous climate on the radial growth of the two species; (3) The species-dependent different response to climate in radial growth appeared mainly in autumn of the previous year. The radial growth of L. principis-rupprechtii displayed negative responses both to temperature and to precipitation in the previous September, October or November, which was not observed in the radial growth of P. meyeri. (4) The radial growth of both species will tend to be increased at high elevation and limited at low elevation, and L. principis-rupprechtii might be more favored in the future, if the temperature keeps rising.

Determinants of the N content of Quercus wutaishanica leaves in the Loess Plateau: a structural equation modeling approach.

Most terrestrial ecosystems are nitrogen (N)-limited. The elucidation of the multivariate relationships among environmental drivers, leaf morphological traits, and foliar N of dominant species which are critical to the functioning of forests remains a critical challenge for ecologists. We sampled leaves of Quercus wutaishanica across a broad natural gradient in the Loess Plateau, China, and employed structural equation modelling to evaluate the causal pathways and the relative importance of drivers of the foliar N per unit area (Narea) and per unit mass (Nmass). We found that (1) Nmass and Narea were primarily affected by leaf morphological traits instead of environmental variables and that leaf morphological traits accounted for most of their variations; (2) the total soil potassium and phosphorus and mean annual precipitation had different effects on Nmass and Narea via different pathways and path coefficients, whereas the mean annual temperature and total soil N had non-significant effects on Nmass and Narea. Our results demonstrated that variations in Nmass and Narea within Quercus wutaishanica were strongly linked to their leaf morphological traits and that the leaf N was also influenced by mean annual precipitation and soil phosphorus and potassium instead of soil N in the Loess Plateau, China.

Leaf phosphorus content of Quercus wutaishanica increases with total soil potassium in the Loess Plateau

Phosphorus (P) is arguably more limiting than nitrogen for forest ecosystems being free of disturbances for lengthy time periods. The elucidation of multivariate relationships between foliar P and its primary drivers for dominant species is an urgent issue and formidable challenge for ecologists. Our goal was to evaluate the effects of primary drivers on foliar P of Quercus wutaishanica, the dominant species in broadleaved deciduous forest at the Loess Plateau, China. We sampled the leaves of 90 Q. wutaishanica individuals across broad climate and soil nutrient gradients at the Loess Plateau, China, and employed structural equation models (SEM) to evaluate multiple causal pathways and the relative importance of the drivers for foliar P per unit mass (Pmass) and per unit area (Parea). Our SEMs explained 73% and 81% of the variations in Pmass and Parea, respectively. Pmass was negatively correlated to leaf mass per area, positively correlated to leaf area, and increased with mean annual precipitation and total soil potassium. Parea was positively correlated to leaf mass per area, leaf dry weight, and increased significantly with total soil potassium. Our results demonstrated that leaf P content of Q. wutaishanica increased with total soil potassium in the Loess Plateau accordingly.

Elevational patterns and ecological determinants of mean family age of angiosperm assemblages in temperate forests within Mount Taibai, China

Aims Species assembly is shaped by the interactions among ecological and evolutionary processes. By integrating the niche conservatism and evolutionary history, the tropical niche conservatism hypothesis (TCH) has clarified species latitudinal diversity gradient at large scales. One of the TCH’s central predictions, though lacking empirical evidence, implies that positive relationship between clade age and temperature along the altitudinal gradient should also be observed. Thus, we aim to test this prediction using a data set derived from forest communities of Mt. Taibai, central China. Methods We systematically established 49 plots (20 m × 30 m) along the north slope on Mt. Taibai, China. We calculated the mean family age (MFA) and its corresponding standardized values through rarefication and standardization, for woody and herbaceous angiosperm assemblages in each community respectively. Generalized linear models with Akaike weight and correlation analysis was used to evaluate the relationships between MFA with seven environmental predictors. Important Findings For both woody and herbaceous assemblages, the standardized MFA showed significant decreasing tendencies along the elevational gradient and positive associations with minimum temperature (measured as mean temperature of the coldest month). Additionally, minimum temperature is the dominant predictor compared with the others in the regression models. These findings are generally consistent with the age-related predictions of the TCH, but are contrary to the results of related studies conducted in tropical regions.

Erratum to: Diurnal and seasonal variation of the elevation gradient of air temperature in the northern flank of the western Qinling Mountain range, China

The typically sparse or lacking distribution of meteorological stations in mountainous areas inadequately resolves temperature elevation variability. This study presented the diurnal and seasonal variations of the elevation gradient of air temperature in the northern flank of the western Qinling Mountain range, which has not been thoroughly evaluated. The measurements were conducted at 9 different elevations between 1710 and 2500 m from August 2014 to August 2015 with HOBO Data loggers. The results showed that the annual temperature lapse rates (TLRs) for Tmean, Tmin and Tmax were 0.45°C/100m, 0.44°C/100m and 0.40°C/100m, respectively, which are substantially smaller than the often used value of 0.60°C/100m to 0.60°C/100m. The TLRs showed no obvious seasonal variations, except for the maximum temperature lapse rate, which was steeper in winter and shallower in spring. Additionally, the TLRs showed significant diurnal variations, with the steepest TLR in forenoon and the shallowest in early morning or late-afternoon, and the TLRs changed more severely during the daytime than night time. The accumulated temperature above 0°C, 5°C and 10°C (AT0, AT5 and AT10) decreased at a lapse rate of 112.8°C days/100 m, 104.5°C days/100 m and 137.0°C days/100 m, respectively. The monthly and annual mean diurnal range of temperatures (MDRT and ADRT) demonstrated unimodal curves along the elevation gradients, while the annual range of temperature (ART) showed no significant elevation differences. Our results strongly suggest that the extrapolated regional TLR may not be a good representative for an individual mountainside, in particular, where there are only sparse meteorological stations at high elevations.