Renfei Chen

Although debates exist, marine reserves play an important role in fisheries management. Based on stable equilibrium state, theoretical frameworks of various systems suggest that fisheries management with the implementation of marine reserves has obvious advantage in achieving multiple goals such as improving the target fisheries yields as well as maintaining species persistence in comparison with strategy of traditional fishing effort control. More recently, ecologists pay attention to the transient dynamics of fisheries yields when marine reserves are established. Simulation results suggest that the relative advantages between different fisheries management strategies (the implementation of marine reserves vs. traditional fishing effort control) depend on not only life histories but also the measurement metrics of fisheries yields (measured by number vs. measured by weight). Further research on transient dynamic pattern of fisheries yields can help fishery managers adjust relevant policies at an appropriate ecological time scale to achieve both conservation and economic goals, which provide a theoretical foundation for adaptive marine reserve management.

Leaves are the primary photosynthetic organ of vascular land plants as they provide photosynthates that maintain plant growth and reproduction. The extent to which plants allocate biomass to their leaf construction strongly influences photosynthetic performance, net primary productivity [ 1] and thus ecosystem functions [ 2]. Consequently, biomass allocation patterns have been a central focus in ecology. As a simple metric of plant biomass allocation patterns, the leaf mass ratio (i.e. the quotient of leaf biomass and total plant biomass) typically (but not invariably) decreases over time during ontogeny [ 3, 4]. However, contrasting patterns have been reported [ 5] based on direct measurements at different ontogenetic stages or using different proxies of ontogeny, such as total plant biomass and plant height. Classic optimal allocation theory cannot provide reasonable explanations for these contrasting empirical observations, whereas transient biomass allocation pattern theory can [ 6, 7]. This new theoretical framework pays attention to biomass allocation patterns over relatively short time scales rather than asymptotic behavior over long time scales [ 6, 7]. The importance of investigating transient plant biomass allocation patterns emerges from the fact that observations over different time scales reveal statistically significant differences among various plant systems, thereby leading to conflicting theories and unnecessary debate. For example, the time scales of forest trees differ by orders of magnitude from those of annual or biennial crops [ 6]. Consequently, it is reasonable to suggest that the effects of the transient dynamics of plant biomass allocation should be investigated in the context of the ontogenetic time frames characteristic of individual species and/or growth forms. In addition, different researchers have emphasized biomass allocation patterns among different plant organs, whereas theoretical treatments of transient changes have typically focused on populations or communities, which result in the difficulties of applying transient dynamic theory to biomass allocation patterns [ 7]. Thus, a theoretical gap still exists in understanding the mechanism(s) underlying how and why, over transient timescales, leaf mass ratios quantitatively vary in response to biotic factors such as plant competition during plant ontogeny. The issue is especially important for domesticated crops, which are species that can finish their life cycles in one year. Here, we develop a theoretical model based on scaling theory in tandem with deterministic population models to predict the effects of plant–plant interactions on the numerical values of leaf mass ratios ( Appendix A.1 in the supplementary data ). Empirical data drawn from diverse crop species are used to test this model. The goal of the study was to determine (i) whether and how the leaf mass ratio (leaf biomass divided by total plant biomass) varies during ontogeny in transient timescales (perturbations in days), and (ii) whether and how intraspecific plant interactions affect the transient dynamics of leaf biomass allocation patterns.

Marine reserves are considered essential for sustainable fisheries, although their effectiveness compared to traditional fisheries management is debated. The effect of marine reserves is mostly studied on short ecological time scales, whereas fisheries-induced evolution is a well-established consequence of harvesting. Using a size-structured population model for an exploited fish population of which individuals spend their early life stages in a nursery habitat, we show that marine reserves will shift the mode of population regulation from low size-selective survival late in life to low, early-life survival due to strong resource competition. This shift promotes the occurrence of rapid ecological cycles driven by density-dependent recruitment as well as much slower evolutionary cycles driven by selection for the optimal body to leave the nursery grounds, especially with larger marine reserves. The evolutionary changes increase harvesting yields in terms of total biomass but cause disproportionately large decreases in yields of larger, adult fish. Our findings highlight the importance of carefully considering the size of marine reserves and the individual life history of fish when managing eco-evolutionary marine systems to ensure both population persistence as well as stable fisheries yields.

Leonurus japonicus Houtt. is a traditional Chinese medicinal plant with high medicinal and edible value. Wild L. japonicus resources have reduced dramatically in recent years. This study predicted the response of distribution range of L. japonicus to climate change in China, which provided scientific basis for the conservation and utilization. In this study, 489 occurrence points of L. japonicus were selected based on GIS technology and spThin package. The default parameters of MaxEnt model were adjusted by using ENMeva1 package of R environment, and the optimized MaxEnt model was used to analyze the distribution of L. japonicus. When the feature combination in the model parameters is hing and the regularization multiplier is 1.5, the MaxEnt model has a higher degree of optimization. With the AUC of 0.830, our model showed a good predictive performance. The results showed that L. japonicus were widely distributed in the current period. The maximum temperature of warmest month, the min temperature of coldest month, the precipitation of wettest month, the precipitation of driest month, and altitude were the main environmental factors affecting the distribution of L. japonicus. Under the three climate change scenarios, the suitable distribution area of L. japonicus will range shift to high latitudes, indicating that the distribution of L. japonicus has a strong response to climate change. The regional change rate is the lowest under the SSP126‐2090s scenario and the highest under the SSP585‐2090s scenario.

According to the original optimal reproductive allocation theory, plants should shift from vegetative growth to reproductive allocation abruptly and completely. Some plants do this, and it is also considered a good strategy for crop plants to maximize yield, but most plants shift gradually. Modified versions of the theory predict such a gradual transition from growth to reproduction. We hypothesize that kin selection can also alter the predictions of optimal allocation theory. We investigated the theoretical implications of both positive and negative kin selection on the timing of plant reproductive development using mathematical models. Under reasonable assumptions of costs and benefits, plants under kin selection are more likely to shift from growth to reproduction in an abrupt way when the initial value of the ratio between reproductive and vegetative biomass is high. Supported by empirical observations, our theoretical predictions have important implications in linking life history and energy allocation as well as for improving yields in agriculture.

In addition to allometric biomass partitioning theory, optimal partitioning theory is one of the most important theoretical frame-works in predicting plant biomass allocation patterns. However, focus-ing on the equilibrium state leads to a mismatch between some empirical observations and estimations from optimal hypotheses. To address this issue, I developed a heuristic approach with a quantitative metric to study the transient patterns of plants allocating photosynthetic products to various combinations among plant organ parts. Moreover, the approach also discovers the mech-anisms under which various factors drive the transient patterns. With this approach, I provide a case study and find that the per-turbations of the transient patterns of plant leaf and stem biomass periodically decrease and increase in response to plant height, crown diameter, and projected crown area. Predictions with the approach are well demonstrated by empirical data consisting of global forest plants. Synthesis . The approach here complements the limitations of optimal partitioning theory by revealing the variations of plant photosynthetic partitioning in short time scales. Given the central role of plant biomass allocation pattern in both empirical applica-tions and theoretical foundations, there is a large scope for using this approach to investigate the directions in estimations of carbon stock, stabilized yields in agriculture as well as forest management.

To predict suitable growing regions for Leonurus japonicus and to provide scientific sopport for the habitat conservation and the exploitation and utilization of germplasm resources under climate change conditions, this study combined niche and priority conservation models to assess the future potential distribution of L. japonicus in China. To this end, distribution points and samples of L. japonicus were gathered through online and field surveys. The Maxent model with optimized parameters was used for predicting the suitable habitats of L. japonicus at different stages, and the Marxan model was used to determine the priority of protected areas. The results showed that the highest temperature in the hottest month, the lowest temperature in the coldest month, the precipitation in the wettest month, the precipitation in the driest month, and altitude were the main environmental factors influencing the distribution of L. japonicus. Under the three climate change scenarios, the centroid of the suitable area of L. japonicus migrated northward, and the migration position tended to expand further northwest. In the future, there would be no significant niche differentiation of L. japonicus; the Marxan results showed that priority protected areas for L. japonicus were in southwestern central China, Lingnan, southern east China, and Guizhou. Overall, the results of this research can provide a strategy for the determination of priority protection areas for Leonurus japonicus in China.

Marine reserves are becoming an increasingly important tool in fisheries management. Particularly for species with relatively sedentary adults, the basic approach taken is to permanently close areas to fishing which allows species to recover inside the reserve and export larvae outside the reserve which eventually can be harvested. Two key issues are insuring the movement of larvae outside the reserve to support fisheries and the sociological and economic impact of permanent closures. An alternative approach that deals with these issues is rotating spatial closures which have been implemented for some fisheries. What has been missing is a general analysis of the relative impact of permanent closures versus rotating closures on fisheries yield that could be used to provide general principles to guide management. Using a simplified model with clear assumptions, we show that the approach that provides a higher yield depends on both dispersal and the fraction of the coastline in marine reserves. With high larval retention and small rotational fraction rotating closures are superior and the optimal rate of rotation cannot be too slow or too fast. These results provide quantitative guidelines in cases where decisions must be made in the face of limited data as well as providing a framework for more detailed analyses in cases where more data is available.