Temporal stability of ecosystem functioning increases the predictability and reliability of ecosystem services, and understanding the drivers of stability across spatial scales is important for land management and policy decisions. We used species-level abundance data from 62 plant communities across five continents to assess mechanisms of temporal stability across spatial scales. We assessed how asynchrony (i.e. different units responding dissimilarly through time) of species and local communities stabilised metacommunity ecosystem function. Asynchrony of species increased stability of local communities, and asynchrony among local communities enhanced metacommunity stability by a wide range of magnitudes (1-315%); this range was positively correlated with the size of the metacommunity. Additionally, asynchronous responses among local communities were linked with species' populations fluctuating asynchronously across space, perhaps stemming from physical and/or competitive differences among local communities. Accordingly, we suggest spatial heterogeneity should be a major focus for maintaining the stability of ecosystem services at larger spatial scales.

Summary 1.Stability is an important property of ecological systems, many of which are experiencing increasing levels of anthropogenic environmental changes. However, how these environmental changes influence ecosystem stability remains poorly understood. 2. We conducted an 8-year field experiment in a semi-arid natural grassland to explore the effects of two common environmental changes, precipitation and nitrogen enrichment, on the temporal stability of plant above-ground biomass. A split-plot design, with precipitation as the main plot factor and nitrogen as the subplot factor, was used. Temporal stability was related to potential explanatory abiotic and biotic variables using regressions and structural equation modelling. 3. Increase in growing season precipitation enhanced plant species richness and promoted temporal stability of plant above-ground biomass. Nitrogen fertilization, however, reduced both plant species richness and temporal stability of plant above-ground biomass. Contrary to expectations, species richness was not an important driver of stability. Instead, community temporal stability was mainly driven by water and nitrogen availability that modulated the degree of species asynchrony and, to a lesser extent, by the stability of dominant plant species. 4. Synthesis. Our results highlight the importance of limiting resources for regulating community biomass stability and suggest that the projected increase in growing season precipitation may potentially offset negative effects of increased atmospheric nitrogen deposition on species diversity and community stability in semi-arid grasslands.

Global change drivers (GCDs) are expected to alter community structure and consequently, the services that ecosystems provide. Yet, few experimental investigations have examined effects of GCDs on plant community structure across multiple ecosystem types, and those that do exist present conflicting patterns. In an unprecedented global synthesis of over 100 experiments that manipulated factors linked to GCDs, we show that herbaceous plant community responses depend on experimental manipulation length and number of factors manipulated. We found that plant communities are fairly resistant to experimentally manipulated GCDs in the short term (<10 y). In contrast, long-term (≥10 y) experiments show increasing community divergence of treatments from control conditions. Surprisingly, these community responses occurred with similar frequency across the GCD types manipulated in our database. However, community responses were more common when 3 or more GCDs were simultaneously manipulated, suggesting the emergence of additive or synergistic effects of multiple drivers, particularly over long time periods. In half of the cases, GCD manipulations caused a difference in community composition without a corresponding species richness difference, indicating that species reordering or replacement is an important mechanism of community responses to GCDs and should be given greater consideration when examining consequences of GCDs for the biodiversity–ecosystem function relationship. Human activities are currently driving unparalleled global changes worldwide. Our analyses provide the most comprehensive evidence to date that these human activities may have widespread impacts on plant community composition globally, which will increase in frequency over time and be greater in areas where communities face multiple GCDs simultaneously.

limits the diffusion of chemical species and their interactions with active sites in MOFs. [ 10 ] One of successful strategy from zeolites, silica, and carbon is the fabrication of mesopore structure which has expanded a large variety of potential and existing commercial applications. [1][2][3] Hence, it is worthwhile to develop methods to fabricate MOFs with mesopores so as to enhance the molecular diffusion while preserving their molecular sieve properties.To date, two major synthetic strategies have been explored to synthesize mesoporous-MOFs (meso-MOFs). [ 11 ] One is through ligand extension, either to increase the length of organic ligands [ 12 ] or to use bulky organic scaffolds [ 13 ] to form mesopores inside MOFs. In this case, the largest pore size reported is 9.8 nm in MOF-74 by increasing the length of organic linker to 5 nm. [ 14 ] Besides the diffi culties in complex ligands synthesis, interpenetration, disintegration, and instability of frameworks almost inevitably occur in MOFs with extended organic linkers, which prevent this functionalization method from being generally adopted in the formation of meso-MOFs. Another approach, the surfactanttemplate method, [ 4d , 15 ] has been introduced to increase the pore size in MOFs. For example, the Zhou group has successfully used cetyltrimethylammonium bromide (CTAB) as soft template to build meso-MOFs. [ 16 ] In this system, surfactant mole cules fi rst self-assembled into micelles serving as a soft template for MOFs growth and were subsequently removed to generate mesopores. The pore diameter of the resulting MOFs could be tuned from 3.8 to 31.0 nm. Nevertheless, as is well known, small molecular micelles are usually unstable under the synthesis conditions of most MOFs, so that only a few series of MOFs (such as carboxylic acid ligands) can be obtained by the surfactant-template method. Recently, some new methods have been successively developed to prepare the meso-MOFs, such as the gelation process, [ 17 ] and switchable solvent. [ 18 ] Moreover, the above methods are suitable for preparation of intrinsic meso-MOFs, but lack of control over the shape, position, and space distribution of mesopores in MOFs makes it hard to meet the demand for the growing applications of MOFs. It is well known that the potential applications of MOFs can be further developed and extended by encapsulating various nanoparticles (NPs) within the frameworks matrix so that the functionalized MOFs can exhibit the novel chemical and physical properties endowed by NPs. [ 7b , 19 ] Thus, to the best of our knowledge, general and versatile strategies of synthesizing functionalized MOFs with size-, shape-, and space-distribution-controlled mesopores have been rarely reported, in spite of the need and the signifi cance in application of functionalized meso-MOFs.Herein, we report a facile strategy of crafting mesopores inside MOFs through encapsulation of NPs followed by etching. Especially, the mesopore morphology, hierarchical structure, and space Porous materials, such as sili...

Stromal cell-derived factor 1 (SDF-1) is a critical regulator of endothelial progenitor cells (EPCs) mediated physiological and pathologic angiogenesis. It was considered to act via its unique receptor CXCR4 for a long time. CXCR7 is a second, recently identified receptor for SDF-1, and its role in human EPCs is unclear. In present study, CXCR7 was found to be scarcely expressed on the surface of human EPCs derived from cord blood, but considerable intracellular CXCR7 was detected, which differs from that on EPCs derived from rat bone marrow. CXCR7 failed to support SDF-1 induced human EPCs migration, proliferation, or nitric oxide (NO) production, but mediated human EPCs survival exclusively. Besides that, CXCR7 mediated EPCs tube formation along with CXCR4. Blocking CXCR7 with its antagonist CCX733 impaired SDF-1/CXCR4 induced EPCs adhesion to active HUVECs and trans-endothelial migration. Those results suggested that CXCR7 plays an important role in human cord blood derived EPCs in response to SDF-1.

Metal-organic frameworks (MOFs) have drawn increasing attentions as promising candidates for functional devices. Herein, we present MOF films in constructing memory devices with alcohol mediated resistance switching property, where the resistance state is controlled by applying alcohol vapors to achieve multilevel information storage. The ordered packing mode and the hydrogen bonding system of the guest molecules adsorbed in MOF crystals are shown to be the reason for the alcohol mediated electrical switching. This chemically mediated memory device can be a candidate in achieving environment-responsive devices and exhibits potential applications in wearable information storage systems.

No abstract

Given that plant growth is often water‐limited in grasslands, it has been proposed that projected increases in precipitation could increase plant productivity and carbon sequestration. However, the existing evidence for this hypothesis comes primarily from observational studies along natural precipitation gradients or from short‐term manipulative experiments. It remains unclear whether long‐term increased precipitation persistently stimulates grassland productivity. In the world's largest remaining temperate grassland, we found that experimentally increased precipitation enhanced net primary production, soil‐available nitrogen and foliar nitrogen concentrations during the first six years, but it ceased to do so in the following four years, unless nitrogen was simultaneously added with water. The 15N enrichment of plant and soil nitrogen pools in later years indicates increased nitrogen losses, which exacerbated nitrogen limitation and ended the stimulation of productivity by increased precipitation. Changes in species abundance might have contributed little to the changes in water treatment effects. Our study demonstrates that the long‐term response of grassland ecosystems to increased precipitation will be mediated by nitrogen availability. Our results also point to a shift from co‐limitation by water and nitrogen early to perhaps limitation by nitrogen only later in this temperate grassland, highlighting significant variations in the type of resource limitation induced by climate change.