Dialogue to address the roots of resource competition: Lessons for policy and practice

Conflict management is an intrinsic element of natural resource management, and becomes increasingly important amid growing pressure on natural resources from local uses, as well as from external drivers such as climate change and international investment. If policymakers and practitioners aim to truly improve livelihood resilience and reduce vulnerabilities of poor rural households, issues of resource competition and conflict management cannot be ignored. This synthesis report summarizes outcomes and lessons from three ecoregions: Lake Victoria, with a focus on Uganda; Lake Kariba, with a focus on Zambia; and Tonle Sap Lake in Cambodia. Partners used a common approach to stakeholder engagement and action research that we call “Collaborating for Resilience”. In each region, partners assisted local stakeholders in developing a shared understanding of risks and opportunities, weighing alternative actions, developing action plans, and evaluating and learning from the outcomes. These experiences demonstrate that investing in capacities for conflict management is practical and can contribute to broader improvements in resource governance.

Interdecadal variability in the spatial structure of wind and SST in the California Current system

The physical environment of eastern boundary current systems is rarely uniform in time. ENSO and other perturbations produce profound anomalies in the atmosphere and ocean on interannual to decadal and century time scales. ... The objective of this paper is to describe the temporal variability in the spatial texture of the California Current system, a major eastern boundary current system off the west coast of North America, to provide a base from which to evaluate the effect of climate change - in the recent past, at present, and for the future.

中国暖温带辽东栎林主要树种共存机制的研究

物种共存是植物群落生态学的一个重要问题。对物种共存的研究可以促进人们对生态系统结构与功能的认识，并为生物多样性保护及恢复提供理论指导。在本论文中，通过对辽东栎－棘皮桦林主要树种空间格局及空间关系、竞争作用和繁殖策略的研究，初步确定本地区辽东栎林主要树种共存的机制。 空间点格局分析表明辽东栎、棘皮桦和五角枫的幼苗、幼树和大树均呈聚集分布。辽东栎幼苗和幼树的分布与同种大树个体正相关，与棘皮桦的大树个体负相关，而与死树个体无显著的相关关系。这些结果说明种子散播和萌生繁殖过程影响辽东栎树木个体的空间格局。棘皮桦幼苗和幼树的分布在小的空间尺度上与同种活树和死树个体正相关，而与其它树种的活树及死树个体的分布呈负相关，说明萌生是该物种繁殖的一个重要途径。五角枫的幼苗和幼树呈聚集分布，并与同种大树个体的分布有关，说明其种子有限的散播范围影响其分布。辽东栎大树个体的分布与棘皮桦大树个体在小尺度上呈负相关，表明这两个树种之间可能存在竞争关系。 离散模型（the diffusion model）和生长动态模型（the growth dynamics model）分析表明在一些树种之间存在单向的种间竞争，例如，黄花柳对白桦和棘皮桦的竞争作用，棘皮桦对辽东栎，辽东栎对五角枫，和五角枫对山杨的竞争作用。这些单向竞争主要是林冠层的大树个体对林下层小个体的竞争。在这些树种中没有发现种内竞争。但是，各树种的生长率（G (t, x)）与生长率方差（ ）呈直线相关，而且样地中树木的死亡率较低，说明树种间的竞争强度很小。因此我们推测非对称的种间竞争在塑造该森林群落结构和物种共存过程中的作用不大。 五角枫、辽东栎、糠椴和山杨的幼苗和幼树在森林的林下层占优势，密度和出现频率均较高，可以形成稳定的幼苗库。五角枫、辽东栎和糠椴的幼苗大小级结构呈倒J形，山杨幼苗的大小结构呈单峰形。棘皮桦幼苗很少，但幼树相对较多，说明该树种可以形成幼树库。辽东栎幼苗在林窗中密度较大，而幼树的密度与林窗的出现与否无明显的相关关系，说明林窗的形成对新更新苗有显著影响，而林窗内的幼树可能是由林窗形成前已经建立的幼苗发展而来。林冠下的辽东栎幼苗多数为萌生起源，寿命较长，一旦上层大树死亡，可以迅速生长，进入林冠层。因此，林冠层下的幼苗库和林窗更新对辽东栎种群动态至关重要。五角枫幼苗和幼树的耐荫性或避荫性较强，可以形成巨大的长期存在的幼苗库和幼树库，以维持其种群的更新。糠椴和山杨的幼苗，主要起源于根的萌蘖。由于母树提供营养，幼苗生长速度较其它三个树种快。但它们对土壤湿度和营养的要求较高，这限制了它们很难占据其它生境。 虽然，在所研究的处于不同演替阶段的群落中，树种的组成有所不同，但辽东栎、大叶白腊和五角枫的幼苗均非常丰富，可以形成幼苗库。辽东栎的幼苗库大部分为萌生苗，而大叶白腊的幼苗库主要由实生苗构成。大叶白腊的幼苗种群中小个体丰富，它们生长速度很慢，在林下采取一种“坐－等”（sit-and-wait）的策略。在三个树种中，五角枫幼苗主枝的伸长生长率最高，而且生长率与幼苗的基径和生境的光照强度正相关。 通过以上研究，我们初步得出结论：竞争作用在研究的辽东栎－棘皮桦林主要树种共存中起的作用很小;形成稳定长久的幼苗库是这些树种的主要繁殖策略。因此，理解这些树种共存机制的关键在于这些树种幼苗库或幼树库的不同起源，及幼苗和幼树对生境因子的不同生态响应所创造的丰富的更新生态位。

Decadal hydroclimatic variability in the western coastal United States: temporal and spatial variations in precipitation, streamflow, and lake level

EXTRACT (SEE PDF FOR FULL ABSTRACT): We have analyzed streamflow variations recorded at 15 USGS gauging stations in California during the past 90 years or so. The anomalies (departures from the 1960-1990 mean discharge) of streamflow on annual-to-decadal time scales are strongly correlated with precipitation anomalies in each drainage basin. ... Although causes of the decadal climate (precipitation) variability are not known with certainty, the use of streamflow records may help us understand the relative strengths of moisture sources and shift of the jet stream in atmospheric circulation.